Compositions comprising progranulin and uses thereof

Abstract

Provided herein are complexes comprising an antigen binding domain linked to a progranulin polypeptide that binds to human transferrin receptor or human CD98 heavy chain. Also provided herein are isolated progranulin mutant polypeptides. Provided herein are methods of using and making such complexes and isolated polypeptides.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 627,682, filed January 31, 2024; U.S. Provisional Patent Application No. 63 / 660,926, filed June 17, 2024; and U.S. Provisional Patent Application No. 63 / 744,150, filed January 10, 2025; the disclosure of each of which is incorporated herein by reference in its entirety.

[0002] References to sequence lists submitted electronically The contents of the electronic serial number (735022004340SEQLIST.xml; size: 497,495 bytes; and creation date: January 21, 2025) are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a complex comprising an antigen-binding domain linked to a granulocyte protein precursor (PGRN) polypeptide. The antigen-binding domain can specifically bind to human transferrin receptor (TfR) or human CD98 heavy chain (CD98hc) to facilitate the transport of the PGRN polypeptide across the blood-brain barrier (BBB). Background Technology

[0004] The passive transfer of substances from the blood to the brain is restricted by the blood-brain barrier (BBB). The BBB provides precise control over the homeostasis of the central nervous system (CNS), allowing proper neuronal function and also protecting neural tissue from toxins and pathogens. Alterations in the BBB are a crucial component of the pathology and progression of various neurological diseases. However, the BBB presents challenges in delivering therapeutic agents to the CNS. While recombinant protein and antibody therapeutics have shown great success outside the CNS, such biologics cannot effectively cross the BBB. Therefore, some therapeutic deliveries to the CNS rely on direct injection of the therapeutic agent into the CNS. However, such injections are invasive procedures that, while effective, are limited by the rapid output of cerebrospinal fluid (CSF) containing the therapeutic agent from the brain to the bloodstream. Alternatively, therapeutic agents intended for the CNS can be administered systemically at high doses to allow for adequate penetration of the BBB. However, in some cases, this approach can lead to unintended consequences due to high peripheral doses or the increased manufacturing and formulation burden required to achieve such high doses.

[0005] Granulin precursor (PGRN) is a secreted, growth factor-like, nutritional and anti-inflammatory protein that also functions as an adipokin involved in diet-induced obesity and insulin resistance (Nguyen DA et al., (2013)). Trends in Endocrinology and Metabolism , 24, 597-606). Granulin precursor deficiency accounts for approximately 25% of all hereditary forms of frontotemporal dementia (FTD), an early-onset neurodegenerative disease. Patients with heterozygous loss-of-function mutations in PGRN have approximately 50% reduced extracellular levels of this protein and will always develop FTD, making PGRN a causative gene for the disease (Baker, M et al., (2006)). Nature 442, 916-919; Carecchio M et al., (2011) J Alzheimers Dis 27, 781-790; Cruts, M et al., (2008) Trends Genet 24, 186-194; Galimberti, D et al., (2010) J Alzheimers Dis 19, 171-177). Furthermore, PGRN mutant alleles have been identified in Alzheimer's disease patients (Seelaar, H et al., (2011)). Journal of Neurology , neurosurgery, and psychiatry 82, 476-486). Importantly, PGRN plays a protective role in several disease models with increased PGRN levels, thereby promoting behavioral recovery from ischemia (Tao, J et al., (2012)). Brain Res 1436 , 130-136; Egashira, Y. et al., (2013). J Neuroinflammation 10, 105), suppressing motor deficits in a Parkinson's disease model (Van Kampen, JM et al. (2014). PLoS One 9, e97032), weakening amyotrophic lateral sclerosis (Laird, AS et al., (2010). PLoS One 5 (e13368.) and arthritis (Tang, W et al., (2011). Science 332 The pathology in the model of Alzheimer's disease (478-484) and the prevention of memory deficits in the model of Alzheimer's disease (Minami, SS et al., (2014). Nat Med 20, 1157-1164).

[0006] Therefore, there is a need for improved products and methods for delivering particulate protein precursor therapeutic agents across the BBB. Summary of the Invention

[0007] This article provides a complex comprising an antigen-binding domain linked to a granulin precursor (PGRN) polypeptide, and methods for preparing and using said complex. The antigen-binding domain can specifically bind to human transferrin receptor (TfR) or human CD98 heavy chain (CD98hc) to facilitate the transport of the PGRN polypeptide across the blood-brain barrier (BBB).

[0008] In some respects, this document provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to a human transferrin receptor (TfR), and wherein the PGRN polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, wherein X1 is any amino acid, and wherein X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL.

[0009] In some respects, this document provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to the human transferrin receptor (TfR) and is not located within the Fc domain of the complex.

[0010] In some embodiments, the antigen-binding domain includes a heavy chain variable region (VH) comprising VH CDR1, VH CDR2, and VH CDR3, and a light chain variable region (VL) comprising VL CDR1, VLCDR2, and VL CDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: respectively, SEQ ID NO: 8, 11, 24, 40, 55, and 61; respectively, SEQ ID NO: 8, 11, 25, 41, 55, and 61; respectively, SEQ ID NO: 8, 12, 26, 42, 55, and 61; respectively, SEQ ID NO: 8, 12, 27, 42, 55, and 61; respectively, SEQ ID NO: 8, 13, 25, 42, 55, and 61; respectively, SEQ ID NO: 8, 13, 25, 42, 55, and 61; respectively, SEQ ID NO: 8, 12, 27 ...3, 25, 42, 55, SEQ ID NO: 8, 14, 25, 42, 55 and 61 respectively; SEQ ID NO: 8, 15, 25, 43, 55 and 61 respectively; SEQ ID NO: 8, 16, 25, 42, 55 and 61 respectively; SEQ ID NO: 8, 17, 25, 44, 55 and 61 respectively; SEQ ID NO: 9, 18, 28, 45, 56 and 62 respectively; SEQ ID NO: 9, 19, 28, 45, 56 and 62 respectively; SEQ ID NO: 9, 20, 28, 46, 57 and 62 respectively; SEQ ID NO: 9, 20, 28, 46, 58 and 62 respectively; SEQ ID NO: 9, 20, 28, 47, 59 and 62 respectively; SEQ ID NO: 9, 21, 28, 46, 57, and 62; respectively, SEQ ID NO: 9, 21, 28, 47, 59, and 62; respectively, SEQ ID NO: 9, 22, 28, 46, 57, and 62; respectively, SEQ ID NO: 9, 22, 28, 46, 58, and 62; respectively, SEQ ID NO: 9, 22, 28, 47, 59, and 62; respectively, SEQ ID NO: 10, 22, 28, 46, 58, and 62; respectively, SEQ ID NO: 10, 22, 30, 46, 58, and 62; respectively, SEQ ID NO: 10, 22, 31, 46, 58, and 62; respectively, SEQ ID NO: 10, 22, 32, 46, 58, and 62; respectively, SEQ ID NO: 10, 22, 33, 46, 58 and 62; respectively, SEQ ID NO: 10, 22, 34, 46, 58 and 62;Specifically, SEQ ID NO: 10, 22, 35, 46, 58, and 62; Specifically, SEQ ID NO: 10, 22, 36, 46, 58, and 62; Specifically, SEQ ID NO: 10, 22, 37, 46, 58, and 62; Specifically, SEQ ID NO: 10, 22, 38, 46, 58, and 62; Specifically, SEQ ID NO: 10, 22, 39, 46, 58, and 62; Specifically, SEQ ID NO: 10, 22, 28, 49, 58, and 62; Specifically, SEQ ID NO: 10, 22, 28, 50, 58, and 62; Specifically, SEQ ID NO: 10, 22, 28, 51, 58, and 62; Specifically, SEQ ID NO: 10, 22, 28, 52, 58, and 62; Specifically, SEQ ID NO: 10, 22, 28, 53, 58, and 62; or respectively, SEQ ID NO: 10, 22, 28, 54, 58, and 62.

[0011] In some embodiments, the VH comprises the following amino acid sequence: SEQ ID NO: 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, or 127.

[0012] In some embodiments, the VL comprises the following amino acid sequence: SEQ ID NO: 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 173, 174, 175, 176, 177, or 178.

[0013] In some embodiments, the VH and the VL comprise the following amino acid sequences: respectively, SEQ ID NO: 64 and 129; respectively, SEQ ID NO: 65 and 130; respectively, SEQ ID NO: 66 and 131; respectively, SEQ ID NO: 67 and 130; respectively, SEQ ID NO: 68 and 131; respectively, SEQ ID NO: 69 and 130; respectively, SEQ ID NO: 70 and 131; respectively, SEQ ID NO: 71 and 130; respectively, SEQ ID NO: 72 and 131; respectively, SEQ ID NO: 73 and 130; respectively, SEQ ID NO: 74 and 131; respectively, SEQ ID NO: 75 and 132; respectively, SEQ ID NO: 76 and 131; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 13 ...7 and 133; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 133; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 133; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 132; respectively, SEQ ID NO: 77 and 1 Sequence IDs NO: 78 and 134; Sequence IDs NO: 77 and 135; Sequence IDs NO: 77 and 136; Sequence IDs NO: 77 and 137; Sequence IDs NO: 77 and 138; Sequence IDs NO: 79 and 131; Sequence IDs NO: 77 and 139; Sequence IDs NO: 77 and 131; Sequence IDs NO: 80 and 140; Sequence IDs NO: 81 and 141; Sequence IDs NO: 82 and 131; Sequence IDs NO: 83 and 142; Sequence IDs NO: 77 and 143; Sequence IDs NO: 75 and 131; Sequence IDs NO: 75 and 144; Sequence IDs NO: 77 and 145; Sequence IDs NO: 84 and 131; respectively, SEQ ID NO: 75 and 146; respectively, SEQ ID NO: 85 and 131; respectively, SEQ ID NO: 86 and 138; respectively, SEQ ID NO: 79 and 139; respectively, SEQ ID NO: 77 and 147; respectively, SEQ ID NO: 75 and 148; respectively, SEQ ID NO: 87 and 131; respectively, SEQ ID NO: 88 and 131; respectively, SEQ ID NO: 75 and 149; respectively, SEQ ID NO: 89 and 150; respectively, SEQ ID NO: 90 and 151; respectively, SEQ ID NO: 77 and 152;Specifically, SEQ ID NO: 79 and 153; SEQ ID NO: 91 and 131; SEQ ID NO: 92 and 131; SEQ ID NO: 79 and 154; SEQ ID NO: 93 and 155; SEQ ID NO: 80 and 131; SEQ ID NO: 94 and 131; SEQ ID NO: 95 and 131; SEQ ID NO: 66 and 156; SEQ ID NO: 97 and 138; SEQ ID NO: 95 and 156; SEQ ID NO: 98 and 157; SEQ ID NO: 99 and 157; SEQ ID NO: 100 and 157; SEQ ID NO: 101 and 157; SEQ ID NO: 102 and 158; SEQ ID NO: 103 and 157; respectively, SEQ ID NO: 104 and 159; respectively, SEQ ID NO: 105 and 160; respectively, SEQ ID NO: 106 and 161; respectively, SEQ ID NO: 107 and 162; respectively, SEQ ID NO: 106 and 163; respectively, SEQ ID NO: 108 and 164; respectively, SEQ ID NO: 106 and 165; respectively, SEQ ID NO: 108 and 166; respectively, SEQ ID NO: 109 and 165; respectively, SEQ ID NO: 110 and 167; respectively, SEQ ID NO: 111 and 168; respectively, SEQ ID NO: 112 and 160; respectively, SEQ ID NO: 113 and 169; respectively, SEQ ID NO: 113 and 170; respectively, SEQ ID NO: 113 and 171; respectively, SEQ ID NO: 114 and 169; respectively, SEQ ID NO: 114 and 171; respectively, SEQ ID NO: 115 and 169; respectively, SEQ ID NO: 115 and 170; respectively, SEQ ID NO: 115 and 171; respectively, SEQ ID NO: 116 and 169; respectively, SEQ ID NO: 116 and 170; respectively, SEQ ID NO: 116 and 171; respectively, SEQ ID NO: 117 and 170; respectively, SEQ ID NO: 118 and 170; respectively, SEQ ID NO: 119 and 170; respectively, SEQ ID NO: 120 and 170;Specifically, SEQ ID NO: 121 and 170; SEQ ID NO: 122 and 170; SEQ ID NO: 123 and 170; SEQ ID NO: 124 and 170; SEQ ID NO: 125 and 170; SEQ ID NO: 126 and 170; SEQ ID NO: 127 and 170; SEQ ID NO: 117 and 173; SEQ ID NO: 117 and 174; SEQ ID NO: 117 and 175; SEQ ID NO: 117 and 176; SEQ ID NO: 117 and 177; SEQ ID NO: 117 and 178; or SEQ ID NO: 117 and 173.

[0014] In some embodiments, the antigen-binding domain is VHH, which comprises: (a) VH CDR1, VHCDR2, and VH CDR3, each comprising the following amino acid sequences: respectively, SEQ ID NO: 8, 11, and 24; respectively, SEQ ID NO: 8, 11, and 25; respectively, SEQ ID NO: 8, 12, and 26; respectively, SEQ ID NO: 8, 12, and 27; respectively, SEQ ID NO: 8, 13, and 25; respectively, SEQ ID NO: 8, 14, and 25; respectively, SEQ ID NO: 8, 15, and 25; respectively, SEQ ID NO: 8, 16, and 25; respectively, SEQ ID NO: 8, 17, and 25; respectively, SEQ ID NO: 9, 18, and 28; respectively, SEQ ID NO: 9, 19, and 28; respectively, SEQ ID NO: 9, 20, and 28; respectively, SEQ ID NO: 9, 21, and 28; respectively, SEQ ID NO: 9, 22, and 28; respectively, SEQ ID NO: 10, 22, and 28; respectively, SEQ ID NO: 10, 22, and 30; respectively, SEQ ID NO: 10, 22, and 31; respectively, SEQ ID NO: 10, 22, and 32; respectively, SEQ ID NO: 10, 22, and 33; respectively, SEQ ID NO: 10, 22, and 34; respectively, SEQ ID NO: 10, 22, and 35; respectively, SEQ ID NO: 10, 22, and 36; respectively, SEQ ID NO: 10, 22, and 37; respectively, SEQ ID NO: 10, 22, and 38; or respectively, SEQ ID NO: 10, 22, and 39; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126 or 127.

[0015] In some embodiments, the antigen-binding domain comprises VH and VL on a single polypeptide chain. In some embodiments, the antigen-binding domain comprises a single-chain variable fragment (scFv). In some embodiments, the scFv is VH-linker-VL oriented. In some embodiments, the scFv is VL-linker-VH oriented. In some embodiments, the linker (i) is about 5 to about 25 amino acids, about 5 to about 20 amino acids, about 10 to about 25 amino acids, or about 10 to about 20 amino acids, and / or (ii) comprises the following amino acid sequence: GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6) or GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

[0016] In some embodiments, the antigen-binding domain comprises VH on a first polypeptide and VL on a second polypeptide.

[0017] In some embodiments, the antigen-binding domain is a murine, chimeric, humanized, or human antigen-binding domain, optionally wherein the antigen-binding domain is a humanized antigen-binding domain.

[0018] In some embodiments, the complex further comprises an Fc region, wherein the Fc region comprises first and second polypeptide chains. In some embodiments, the Fc region is capable of binding FcRn.

[0019] In some embodiments, the complex further comprises an Fc domain. In some embodiments, the Fc domain is capable of binding FcRn.

[0020] In some embodiments, the complex comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, and (ii) two copies of the PGRN polypeptide. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is attached to the C-terminus of one of the two copies of the PGRN polypeptide. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the N-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the N-terminus of a second polypeptide chain in the Fc region. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is attached to the N-terminus of either the first or second polypeptide chain in the Fc region. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the C-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the C-terminus of a second polypeptide chain in the Fc region. In some embodiments, the complex comprises: (i) an antibody that binds to human TfR, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of the PGRN polypeptide, wherein each copy of the PGRN polypeptide is linked to the C-terminus of one of the two antibody heavy chains. In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that bind to human TfR, (ii) an Fc region; and (iii) two copies of the PGRN polypeptide, wherein one of the two scFv, Fab, or VHH antigen-binding domains that bind to human TfR is linked to the C-terminus of a first polypeptide chain in the Fc region, wherein the other scFv, Fab, or VHH antigen-binding domain that binds to human TfR is linked to the C-terminus of a second polypeptide chain in the Fc region, wherein one of the two copies of the PGRN polypeptide is linked to the N-terminus of the first polypeptide chain in the Fc region, and wherein the other copy of the PGRN polypeptide is linked to the N-terminus of the second polypeptide chain in the Fc region.

[0021] In some embodiments, the complex comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the C-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is linked to the N-terminus of the first or second polypeptide chain of the Fc region. In some embodiments, the complex comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the C-terminus of the Fc domain, and the PGRN polypeptide is linked to the N-terminus of the Fc domain. In some embodiments, the complex comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is attached to the N-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is attached to the C-terminus of the first or second polypeptide chain of the Fc region. In some embodiments, the complex comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is attached to the N-terminus of the Fc domain, and the PGRN polypeptide is attached to the C-terminus of the Fc domain. In some embodiments, the complex comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the N-terminus of one of the two polypeptide chains of the Fc region, and wherein the PGRN polypeptide is linked to the N-terminus of the other polypeptide chain of the Fc region.

[0022] In some embodiments, the Fc region is a heterodimeric Fc region, optionally containing club and mortar mutations. In some embodiments, the Fc region is a modified Fc region having the modifications listed in Table 8 or Table 9. In some embodiments, the Fc region is a human IgG1 Fc region, wherein the human IgG1 Fc region contains mutations that reduce effector function, optionally wherein the mutations that reduce effector function include: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S. In some embodiments, the Fc domain is a single-stranded monovalent Fc domain. In some embodiments, the Fc domain is a modified Fc domain having the modifications listed in Table 8. In some embodiments, the Fc domain is a human IgG1 Fc domain, wherein the human IgG1 Fc domain contains mutations that reduce effector function, optionally wherein the mutations that reduce effector function include: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S.

[0023] In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0024] In some respects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2 and CH3; and (iii) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.In some embodiments, (i) the first polypeptide comprises the amino acid sequence of SEQ ID NO: 319; (ii) the second polypeptide comprises the amino acid sequence of SEQ ID NO: 320; and (iii) the third polypeptide comprises the amino acid sequence of SEQ ID NO: 321.

[0025] In some respects, this document provides a complex comprising: (i) a first polypeptide comprising VH, CH1, a hinge region, CH2, and CH3 from the N-terminus to the C-terminus; (ii) a second polypeptide comprising CH2, CH3, a linker, and a PGRN polypeptide from the N-terminus to the C-terminus; and (iii) a third polypeptide comprising VL and CL from the N-terminus to the C-terminus; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.In some embodiments, (i) the first polypeptide comprises the amino acid sequence of SEQ ID NO: 322; (ii) the second polypeptide comprises the amino acid sequence of SEQ ID NO: 323; and (iii) the third polypeptide comprises the amino acid sequence of SEQ ID NO: 321.

[0026] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (iii) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A. In some embodiments, the PGRN peptides of the first polypeptide and the second polypeptide each comprise an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.In some embodiments, (i) the first polypeptide comprises the amino acid sequence of SEQ ID NO: 319; (ii) the second polypeptide comprises the amino acid sequence of SEQ ID NO: 323; and (iii) the third polypeptide comprises the amino acid sequence of SEQ ID NO: 321.

[0027] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; and (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, and wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P, and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K, and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I, and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265, and SEQ ID NO: 266. In some embodiments, (i) the first polypeptide comprises the amino acid sequence of SEQ ID NO: 332; and (ii) the second polypeptide comprises the amino acid sequence of SEQ ID NO: 321.

[0028] In some embodiments, (i) the VH comprises VH CDR1, VH CDR2, and VH CDR3; wherein VH CDR1 comprises the amino acid sequence of SEQ ID NO: 8; wherein VH CDR2 comprises the amino acid sequence of SEQ ID NO: 15; and wherein VH CDR3 comprises the amino acid sequence of SEQ ID NO: 25; and / or (ii) the VL comprises VLCDR1, VL CDR2, and VL CDR3; wherein VL CDR1 comprises the amino acid sequence of SEQ ID NO: 43; wherein VLCDR2 comprises the amino acid sequence of SEQ ID NO: 55; and wherein VL CDR3 comprises the amino acid sequence of SEQ ID NO: 61. In some embodiments, (i) the VH comprises the amino acid sequence of SEQ ID NO: 102; and / or (ii) the VL comprises the amino acid sequence of SEQ ID NO: 158.

[0029] In some embodiments, the complex binds to human sorting proteins, whose dissociation constant (K) D The concentration ranges from about 5 nM to about 400 nM. In some embodiments, the complex binds to human sorting proteins, whose K... D The concentration ranges from about 50 nM to about 350 nM. In some embodiments, the complex binds to human sorting proteins, whose K... D The concentration is in the range of about 100 nM to about 300 nM. In some embodiments, the complex increases cellular GCase activity more than the PGRN peptide alone. In some embodiments, the complex increases cellular GCase activity by at least about 0.5 times, at least about 1 time, or at least about 2 times compared to the PGRN peptide alone. In some embodiments, the complex is linked to an imaging agent.

[0030] In some aspects, this document provides a polynucleotide encoding a complex as described in any one of the embodiments. In some aspects, this document provides a vector comprising the polynucleotide as described in the preceding embodiment. In some aspects, this document provides a host cell comprising the vector as described in the preceding embodiment. In some aspects, this document provides a method for generating a complex, the method comprising culturing a host cell as described in the preceding embodiment to generate the complex, optionally wherein the method further comprises isolating the complex from the culture. In some aspects, this document provides an isolated complex generated by the method as described in the preceding embodiment. In some aspects, this document provides a pharmaceutical composition comprising the complex as described in any one of the embodiments. In some embodiments, the pharmaceutical composition further comprises a pharmaceutically acceptable vector.

[0031] In some aspects, this document provides a method for treating a subject with a neurological disease or condition, the method comprising administering to the subject a complex or pharmaceutical composition as described in any one of the embodiments. In some embodiments, the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, ocular diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation. In some aspects, the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) with a predominantly limbic system component. In some embodiments, the dementia is frontotemporal dementia (FTD). In some embodiments, the neurological disease or condition is Alzheimer's disease. In some embodiments, the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease. In some embodiments, the neurological disorder or condition is Parkinson's disease. In some embodiments, the neurological disorder or condition is frontotemporal lobe epilepsy.

[0032] In some aspects, this document provides a method for treating a subject with a lysosomal storage disease, the method comprising administering to the subject a complex or a pharmaceutical composition as described in any one of the embodiments. In some embodiments, the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II, and MPS type III.

[0033] In some respects, this document provides a method for transporting a complex across a subject's BBB, the method comprising administering to the subject a complex as described in any one of the embodiments or a pharmaceutical composition as described in any one of the embodiments.

[0034] In some respects, this document provides a method for increasing the concentration of PGRN in the cerebrospinal fluid (CSF) of a subject, the method comprising administering to the subject a complex as described in any one of the embodiments or a pharmaceutical composition as described in any one of the embodiments, wherein the PGRN concentration is increased compared to administering the PGRN peptide alone to the subject.

[0035] In some aspects, this document provides a method for imaging PGRN in a subject, the method comprising administering a complex as described in any one of the embodiments to the subject and localizing the imaging agent within the subject. In some aspects, this document provides a method for detecting PGRN in vitro, the method comprising contacting an in vitro sample with a complex as described in any one of the embodiments and localizing the imaging agent within the sample.

[0036] In some aspects, this document provides for the use of the complex or pharmaceutical composition as described in any one of the embodiments in the method as described in any one of the embodiments. In some aspects, this document provides for the use of the complex or pharmaceutical composition as described in any one of the embodiments in the method as described in any one of the embodiments.

[0037] In some respects, this article provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human CD98 heavy chain (CD98hc). In some embodiments, the antigen-binding domain comprises VH, which comprises VH CDR1, VH CDR2, and VH CDR3, and VL, which comprises VLCDR1, VL CDR2, and VL CDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VLCDR3 sequences comprise the following amino acid sequences: respectively, SEQ ID NO: 181, 185, 191, 194, 198, and 201; respectively, SEQ ID NO: 182, 186, 191, 195, 199, and 202; respectively, SEQ ID NO: 183, 187, 192, 196, 200, and 203; respectively, SEQ ID NO: 9, 188, 192, 196, 200, and 203; respectively, SEQ ID NO: 184, 189, 193, 197, 198 and 204; respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 204; respectively, SEQ ID NO: 184, 324, 193, 197, 198 and 204; respectively, SEQ ID NO: 184, 325, 193, 197, 198 and 204; or respectively, SEQ ID NO: 184, 326, 193, 197, 198 and 204.

[0038] In some embodiments, the VH comprises the following amino acid sequence: SEQ ID NO: 205, 206, 207, 208, 209, 210, 327, 328, or 329. In some embodiments, the VL comprises the following amino acid sequence: SEQ ID NO: 211, 212, 213, 214, 215, or 216. In some embodiments, the VH and the VL comprise the following amino acid sequences: respectively, SEQ ID NO: 205 and 211; respectively, SEQ ID NO: 206 and 212; respectively, SEQ ID NO: 207 and 213; respectively, SEQ ID NO: 208 and 214; respectively, SEQ ID NO: 209 and 215; respectively, SEQ ID NO: 210 and 216; respectively, SEQ ID NO: 327 and 216; respectively, SEQ ID NO: 328 and 216; or respectively, SEQ ID NO: 329 and 216.

[0039] In some embodiments, the antigen-binding domain is VHH, which comprises: (a) VH CDR1, VHCDR2, and VH CDR3, each comprising the following amino acid sequences: respectively, SEQ ID NO: 181, 185, and 191; respectively, SEQ ID NO: 182, 186, and 191; respectively, SEQ ID NO: 183, 187, and 192; respectively, SEQ ID NO: 9, 188, and 192; respectively, SEQ ID NO: 184, 189, and 193; respectively, SEQ ID NO: 184, 190, and 193; respectively, SEQ ID NO: 184, 324, and 193; respectively, SEQ ID NO: 184, 325, and 193; or respectively, SEQ ID NO: 184, 326, and 193; or (b) VH, which comprises the following amino acid sequence: SEQ ID NO: 205, 206, 207, 208, 209, 210, 327, 328 or 329.

[0040] In some embodiments, the antigen-binding domain comprises VH and VL on a single polypeptide chain. In some embodiments, the antigen-binding domain comprises a single-chain variable fragment (scFv). In some embodiments, the scFv is VH-linker-VL oriented. In some embodiments, the scFv is VL-linker-VH oriented. In some embodiments, the linker is about 5 to about 25 amino acids, about 5 to about 20 amino acids, about 10 to about 25 amino acids, or about 10 to about 20 amino acids. In some embodiments, the linker comprises the following amino acid sequence: GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6) or GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

[0041] In some embodiments, the antigen-binding domain comprises VH on a first polypeptide and VL on a second polypeptide.

[0042] In some embodiments, the antigen-binding domain is a murine, chimeric, humanized, or human antigen-binding domain, optionally wherein the antigen-binding domain is a humanized antigen-binding domain.

[0043] In some embodiments, the complex further comprises an Fc region, wherein the Fc region comprises first and second polypeptide chains. In some embodiments, the Fc region is capable of binding FcRn.

[0044] In some embodiments, the complex further comprises an Fc domain. In some embodiments, the Fc domain is capable of binding FcRn.

[0045] In some embodiments, the complex further comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, and (ii) two copies of the PGRN polypeptide. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is attached to the C-terminus of one of the two copies of the PGRN polypeptide. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the N-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the N-terminus of a second polypeptide chain in the Fc region. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is attached to the N-terminus of either the first or second polypeptide chain in the Fc region. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the C-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the C-terminus of a second polypeptide chain in the Fc region.

[0046] In some embodiments, the complex further comprises (i) an antibody that binds to human CD98hc, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of the PGRN polypeptide, wherein each copy of the PGRN polypeptide is linked to the C-terminus of one of the two antibody heavy chains. In some embodiments, the complex further comprises (i) two scFv, Fab, or VHH antigen-binding domains that bind to human CD98hc, (ii) an Fc region; and (iii) two copies of the PGRN polypeptide, wherein one of the two scFv, Fab, or VHH antigen-binding domains that bind to human CD98hc is linked to the C-terminus of a first polypeptide chain in the Fc region, wherein the other scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is linked to the C-terminus of a second polypeptide chain in the Fc region, wherein one of the two copies of the PGRN polypeptide is linked to the N-terminus of the first polypeptide chain in the Fc region, and wherein the other copy of the PGRN polypeptide is linked to the N-terminus of the second polypeptide chain in the Fc region.

[0047] In some embodiments, the complex further comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is linked to the N-terminus of the first or second polypeptide chain of the Fc region. In some embodiments, the complex further comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of the Fc domain, and the PGRN polypeptide is linked to the N-terminus of the Fc domain. In some embodiments, the complex further comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is linked to the C-terminus of the first or second polypeptide chain of the Fc region. In some embodiments, the complex further comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of the Fc domain, and the PGRN polypeptide is linked to the C-terminus of the Fc domain. In some embodiments, the complex further comprises: (i) a single scFv, VHH, or Fab antigen-binding domain that binds to CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of one of the two polypeptide chains of the Fc region, and wherein the PGRN polypeptide is linked to the N-terminus of the other polypeptide chain of the Fc region.

[0048] In some embodiments, the Fc region is a heterodimeric Fc region, optionally containing club and mortar mutations. In some embodiments, the Fc region is a modified Fc region having the modifications listed in Table 8 or Table 9. In some embodiments, the Fc region is a human IgG1 Fc region, wherein the human IgG1 Fc region contains mutations that reduce effector function, optionally wherein the mutations that reduce effector function include: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S.

[0049] In some embodiments, the Fc domain is a single-stranded, monovalent Fc domain. In some embodiments, the Fc domain is a modified Fc domain having the modifications listed in Table 8. In some embodiments, the Fc domain is a human IgG1 Fc domain, wherein the human IgG1 Fc domain contains a mutation that reduces effector function, optionally wherein the mutation that reduces effector function includes: (i) L234A, L235A, and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A, and / or P329G; or (iv) L234A, L235A, and / or P329S.

[0050] In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P, and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K, and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I, and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256. SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0051] In some implementations, the complex is attached to an imaging agent.

[0052] In some aspects, this document provides a polynucleotide encoding a complex as described in any one of the embodiments. In some aspects, this document provides a vector comprising a polynucleotide as described in any one of the embodiments. In some aspects, this document provides a host cell comprising a vector as described in any one of the embodiments. In some aspects, this document provides a method for generating a complex, the method comprising culturing a host cell as described in any one of the embodiments to generate the complex, optionally wherein the method further comprises isolating the complex from the culture. In some aspects, this document provides an isolated complex generated by a method as described in any one of the embodiments. In some aspects, this document provides a pharmaceutical composition comprising a complex as described in any one of the embodiments. In some embodiments, the pharmaceutical composition further comprises a pharmaceutically acceptable vector.

[0053] In some aspects, this document provides a method for treating a subject with a neurological disease or condition, the method comprising administering to the subject a complex or pharmaceutical composition as described in any one of the embodiments. In some embodiments, the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, ocular diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation. In some aspects, the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) with a predominantly limbic system component. In some embodiments, the dementia is frontotemporal dementia (FTD). In some embodiments, the neurological disease or condition is Alzheimer's disease. In some embodiments, the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease. In some embodiments, the neurological disorder or condition is Parkinson's disease. In some embodiments, the neurological disorder or condition is frontotemporal lobe epilepsy.

[0054] In some aspects, this document provides a method for treating a subject with a lysosomal storage disease, the method comprising administering to the subject a complex or a pharmaceutical composition as described in any one of the embodiments. In some embodiments, the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II, and MPS type III.

[0055] In some aspects, this document provides a method for transporting a complex across a subject's BBB, the method comprising administering to the subject a complex as described in any one of the embodiments or a pharmaceutical composition as described in any one of the embodiments. In some aspects, this document provides a method for increasing the concentration of PGRN in a subject's CSF, the method comprising administering to the subject a complex as described in any one of the embodiments or a pharmaceutical composition as described in any one of the embodiments, wherein the PGRN concentration is increased compared to administering the PGRN peptide alone to the subject. In some aspects, this document provides a method for imaging PGRN in a subject, the method comprising administering to the subject a complex as described in any one of the embodiments and localizing the imaging agent within the subject. In some aspects, this document provides a method for detecting PGRN in vitro, the method comprising contacting an in vitro sample with a complex as described in any one of the embodiments and localizing the imaging agent within the sample.

[0056] In some aspects, this document provides for the use of the complex or pharmaceutical composition as described in any one of the embodiments in the method as described in any one of the embodiments. In some aspects, this document provides for the use of the complex or pharmaceutical composition as described in any one of the embodiments in the method as described in any one of the embodiments.

[0057] In some aspects, this document provides an isolated PGRN polypeptide wherein: (i) the isolated PGRN polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, and wherein: (a) X1 is an amino acid selected from the group consisting of R, D, E, I, P, or Q; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is an amino acid selected from the group consisting of L, A, C, D, F, G, H, I, K, M, N, P, Q, R, S, T, V, or Y; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, R, or V; and (ii) X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL. In some embodiments, the isolated PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330. In some embodiments, the amino acid sequence is selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265, and SEQ ID NO: 266. In some embodiments, the amino acid sequence is SEQ ID NO: 231. In some embodiments, the amino acid sequence is SEQ ID NO: 232. In some embodiments, the amino acid sequence is SEQ ID NO: 233. In some embodiments, the amino acid sequence is SEQ ID NO: 234. In some embodiments, the amino acid sequence is SEQ ID NO: 235. In some embodiments, the amino acid sequence is SEQ ID NO: 236.In some embodiments, the amino acid sequence is SEQ ID NO: 237. In some embodiments, the amino acid sequence is SEQ ID NO: 238. In some embodiments, the amino acid sequence is SEQ ID NO: 239. In some embodiments, the amino acid sequence is SEQ ID NO: 240. In some embodiments, the amino acid sequence is SEQ ID NO: 241. In some embodiments, the amino acid sequence is SEQ ID NO: 242. In some embodiments, the amino acid sequence is SEQ ID NO: 243. In some embodiments, the amino acid sequence is SEQ ID NO: 244. In some embodiments, the amino acid sequence is SEQ ID NO: 245. In some embodiments, the amino acid sequence is SEQ ID NO: 246. In some embodiments, the amino acid sequence is SEQ ID NO: 248. In some embodiments, the amino acid sequence is SEQ ID NO: 249. In some embodiments, the amino acid sequence is SEQ ID NO: 250. In some embodiments, the amino acid sequence is SEQ ID NO: 251. In some embodiments, the amino acid sequence is SEQ ID NO: 252. In some embodiments, the amino acid sequence is SEQ ID NO: 253. In some embodiments, the amino acid sequence is SEQ ID NO: 254. In some embodiments, the amino acid sequence is SEQ ID NO: 255. In some embodiments, the amino acid sequence is SEQ ID NO: 256. In some embodiments, the amino acid sequence is SEQ ID NO: 257. In some embodiments, the amino acid sequence is SEQ ID NO: 259. In some embodiments, the amino acid sequence is SEQ ID NO: 261. In some embodiments, the amino acid sequence is SEQ ID NO: 262. In some embodiments, the amino acid sequence is SEQ ID NO: 263. In some embodiments, the amino acid sequence is SEQ ID NO: 264. In some embodiments, the amino acid sequence is SEQ ID NO: 265. In some embodiments, the amino acid sequence is SEQ ID NO: 266.

[0058] In some aspects, this document provides an isolated nucleic acid encoding an isolated PGRN polypeptide as described in any one of the embodiments. In some aspects, this document provides a vector comprising the nucleic acid as described in any one of the embodiments. In some aspects, this document provides a host cell comprising the vector as described in any one of the embodiments. In some aspects, this document provides a method for producing an isolated PGRN polypeptide, the method comprising culturing a host cell as described in any one of the embodiments to produce the isolated PGRN polypeptide, optionally wherein the method further comprises isolating the isolated PGRN polypeptide from the culture. In some aspects, this document provides an isolated PGRN polypeptide produced by a method as described in any one of the embodiments. In some aspects, this document provides a pharmaceutical composition comprising an isolated PGRN polypeptide as described in any one of the embodiments.

[0059] In some aspects, this document provides a method for treating a subject with a neurological disease or condition, the method comprising administering to the subject an isolated PGRN polypeptide as described in any one of the embodiments or a pharmaceutical composition as described in any one of the embodiments. In some embodiments, the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, ocular diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation.

[0060] In some embodiments, the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) primarily affecting the limbic system. In some embodiments, the dementia is frontotemporal dementia (FTD). In some embodiments, the neurological disease or condition is Alzheimer's disease. In some embodiments, the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease. In some embodiments, the neurological disease or condition is Parkinson's disease. In some embodiments, the neurological disease or condition is frontotemporal epilepsy.

[0061] In some aspects, this document provides a method for treating a subject with a lysosomal storage disease, the method comprising administering to the subject an isolated PGRN polypeptide as described in any one of the embodiments or a pharmaceutical composition as described in any one of the embodiments. In some embodiments, the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II, and MPS type III.

[0062] In some respects, this article provides a complex comprising (a) an antigen-binding domain that specifically binds to the human transferrin receptor (TfR), and (b) a granule protein precursor (PGRN) polypeptide.

[0063] In some respects, this document provides a complex comprising (a) an affinity-modulated antigen-binding domain that specifically binds to human TfR, wherein the antigen-binding domain binds to human TfR with an affinity of 0.01 nM to 50 nM, and (b) a PGRN peptide.

[0064] In some aspects, this document provides a complex comprising (a) an affinity-modulated antigen-binding domain that specifically binds to human TfR, wherein the antigen-binding domain binds to human TfR with an affinity of 51 nM to 750 nM, and (b) a PGRN peptide. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 600 nM to 650 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 160 nM to 200 nM.

[0065] In some respects, this article provides a complex comprising (a) an affinity-modulated antigen-binding domain that specifically binds to human TfR, wherein the antigen-binding domain binds to human TfR with an affinity of 751 nM to 10,000 nM, and (b) a PGRN peptide.

[0066] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a granule protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to a human transferrin receptor (TfR), wherein the antigen-binding domain comprises a heavy chain variable region (VH) comprising VH CDR1, VH CDR2, and VH CDR3, and a light chain variable region (VL) comprising VL CDR1, VL CDR2, and VLCDR3, and wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0067] In some embodiments, the VH comprises the following amino acid sequence: SEQ ID NO: 101, 102, 342, 117, 343, or 118. In some embodiments, the VL comprises the following amino acid sequence: SEQ ID NO: 154, 344, 345, 174, 346, 347, 348, 349, or 350. In some embodiments, both the VH and the VL comprise the following amino acid sequences: (i) SEQ ID NO: 101 and 154, respectively; (ii) Specifically, SEQ ID NO: 102 and 344; (iii) Specifically, SEQ ID NO: 102 and 345; (iv) Specifically, SEQ ID NO: 342 and 174; (v) Specifically, SEQ ID NO: 117 and 346; (vi) Specifically, SEQ ID NO: 117 and 347; (vii) Specifically, SEQ ID NO: 117 and 348; (viii) Specifically, SEQ ID NO: 117 and 349; (ix) Specifically, SEQ ID NO: 343 and 174; (x) respectively, SEQ ID NO: 118 and 174; or (xi) respectively, SEQ ID NO: 101 and 350.

[0068] In some embodiments, a complex comprises an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human TfR, and wherein the antigen-binding domain is a VHH, the VHH comprising: (a) VH CDR1, VH CDR2, and VH CDR3, which contain the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14 and 25; (ii) Specifically, SEQ ID NO: 8, 15 and 25; (iv) Specifically, SEQ ID NO: 10, 22 and 333; (v) Specifically, SEQ ID NO: 10, 22 and 28; (ix) respectively, SEQ ID NO: 10, 22 and 334; or (x) respectively, SEQ ID NO: 10, 22 and 30; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 101, 102, 342, 117, 343 or 118.

[0069] In some embodiments, the antigen-binding domain comprises VH and VL on a single polypeptide chain. In some embodiments, the antigen-binding domain comprises a single-chain variable fragment (scFv). In some embodiments, the scFv is VH-linker-VL oriented. In some embodiments, the scFv is VL-linker-VH oriented. In some embodiments, the linker (i) is about 5 to about 25 amino acids, about 5 to about 20 amino acids, about 10 to about 25 amino acids, or about 10 to about 20 amino acids, and / or (ii) comprises the following amino acid sequence: GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6) or GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

[0070] In some embodiments, the antigen-binding domain comprises a VH on a first polypeptide and a VL on a second polypeptide. In some embodiments, the antigen-binding domain is a murine, chimeric, humanized, or human antigen-binding domain, optionally wherein the antigen-binding domain is a humanized antigen-binding domain.

[0071] In some embodiments, the complex further comprises an Fc region, wherein the Fc region comprises first and second polypeptide chains. In some embodiments, the Fc region is capable of binding FcRn. In some embodiments, the complex further comprises an Fc domain. In some embodiments, the Fc domain is capable of binding FcRn.

[0072] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, and (ii) two copies of the PGRN polypeptide. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is attached to the C-terminus of one of the two copies of the PGRN polypeptide. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the N-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the N-terminus of a second polypeptide chain in the Fc region. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is attached to the N-terminus of either the first or second polypeptide chain in the Fc region. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the C-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the C-terminus of a second polypeptide chain in the Fc region.

[0073] In some embodiments, the complex comprises (i) an antibody that binds to human TfR, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of the PGRN polypeptide, wherein each copy of the PGRN polypeptide is linked to the C-terminus of one of the two antibody heavy chains.

[0074] In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that bind to human TfR, (ii) an Fc region; and (iii) two copies of the PGRN polypeptide, wherein one of the two scFv, Fab, or VHH antigen-binding domains that bind to human TfR is attached to the C-terminus of a first polypeptide chain in the Fc region, wherein the other scFv, Fab, or VHH antigen-binding domain that binds to human TfR is attached to the C-terminus of a second polypeptide chain in the Fc region, wherein one of the two copies of the PGRN polypeptide is attached to the N-terminus of the first polypeptide chain in the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the N-terminus of the second polypeptide chain in the Fc region.

[0075] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the C-terminus of a first or second polypeptide chain in the Fc region, and the PGRN polypeptide is linked to the N-terminus of a first or second polypeptide chain in the Fc region.

[0076] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the C-terminus of the Fc domain, and the PGRN peptide is linked to the N-terminus of the Fc domain.

[0077] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the N-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is linked to the C-terminus of a first or second polypeptide chain of the Fc region.

[0078] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the N-terminus of the Fc domain, and the PGRN peptide is linked to the C-terminus of the Fc domain.

[0079] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the N-terminus of one of the two polypeptide chains of the Fc region, and wherein the PGRN polypeptide is linked to the N-terminus of the other polypeptide chain of the Fc region.

[0080] In some embodiments, the Fc region is a heterodimeric Fc region, optionally containing club and mortar mutations. In some embodiments, the Fc domain is a single-stranded monovalent Fc domain. In some embodiments, the Fc region is a modified Fc region having the modifications listed in Table 8 or Table 9. In some embodiments, the Fc region is a human IgG1 Fc region, wherein the human IgG1 Fc region contains mutations that reduce effector function, optionally wherein the mutations that reduce effector function include: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S.

[0081] In some embodiments, the Fc domain is a modified Fc domain having the modifications listed in Table 8. In some embodiments, the Fc domain is a human IgG1 Fc domain, wherein the human IgG1 Fc domain contains a mutation that reduces effector function, optionally wherein the mutation that reduces effector function includes: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S.

[0082] In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0083] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2 and CH3; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0084] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, and CH3; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain that specifically binds to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0085] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein VH and VL form an antigen-binding domain that specifically binds to human TfR, and wherein VH comprises VHCDR1, VH CDR2, and VH CDR3, and VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0086] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; and (b) a second polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VLCDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0087] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from N-terminus to C-terminus, VH, CH1, a hinge region, CH2, and CH3; (b) a second polypeptide comprising, from N-terminus to C-terminus, a PGRN polypeptide, a linker, CH2, and CH3; and (c) a third polypeptide comprising, from N-terminus to C-terminus, VL and CL; wherein VH and VL form an antigen-binding domain specifically binding to human TfR, and wherein VH comprises VH CDR1, VH CDR2, and VH CDR3, and VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0088] In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0089] In some embodiments, the VH and the VL comprise the following amino acid sequences: (i) SEQ ID NO: 101 and 154, respectively; (ii) Specifically, SEQ ID NO: 102 and 344; (iii) Specifically, SEQ ID NO: 102 and 345; (iv) Specifically, SEQ ID NO: 342 and 174; (v) Specifically, SEQ ID NO: 117 and 346; (vi) Specifically, SEQ ID NO: 117 and 347; (vii) Specifically, SEQ ID NO: 117 and 348; (viii) Specifically, SEQ ID NO: 117 and 349; (ix) Specifically, SEQ ID NO: 343 and 174; (x) respectively, SEQ ID NO: 118 and 174; or (xi) respectively, SEQ ID NO: 101 and 350.

[0090] In some implementations, the complex is attached to an imaging agent.

[0091] In some aspects, this document provides a polynucleotide encoding a complex as described in any of the preceding embodiments. In some aspects, this document provides a vector comprising the polynucleotide as described in the preceding embodiment. In some aspects, this document provides a host cell comprising the vector as described in the preceding embodiment. In some aspects, this document provides a method for generating a complex, the method comprising culturing a host cell as described in the preceding embodiment to generate the complex, optionally wherein the method further comprises isolating the complex from the culture. In some aspects, this document provides an isolated complex generated by the method as described in the preceding embodiment. In some aspects, this document provides a pharmaceutical composition comprising the complex as described in any of the preceding embodiments. In some embodiments, the pharmaceutical composition further comprises a pharmaceutically acceptable vector.

[0092] In some aspects, this document provides a method for treating a subject with a neurological disease or condition, the method comprising administering to the subject a complex or pharmaceutical composition as described in any of the foregoing embodiments. In some embodiments, the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, ocular diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation. In some aspects, the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) primarily affecting the limbic system. In some embodiments, the dementia is frontotemporal dementia (FTD). In some embodiments, the neurological disease or condition is Alzheimer's disease. In some embodiments, the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease. In some embodiments, the neurological disorder or condition is Parkinson's disease. In some embodiments, the neurological disorder or condition is frontotemporal lobe epilepsy.

[0093] In some aspects, this document provides a method for treating a subject with a lysosomal storage disease, the method comprising administering to the subject a complex or a pharmaceutical composition as described in any of the foregoing embodiments. In some embodiments, the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II, and MPS type III.

[0094] In some respects, this document provides a method for transporting a complex across a subject's BBB, the method comprising administering to the subject a complex as described in any of the foregoing embodiments or a pharmaceutical composition as described in any of the foregoing embodiments.

[0095] In some respects, this document provides a method for increasing the concentration of PGRN in the cerebrospinal fluid (CSF) of a subject, the method comprising administering to the subject a complex as described in any of the foregoing embodiments or a pharmaceutical composition as described in any of the foregoing embodiments, wherein the PGRN concentration is increased compared to administering the PGRN peptide alone to the subject.

[0096] In some aspects, this document provides a method for imaging PGRN in a subject, the method comprising administering a complex as described in any of the foregoing embodiments to the subject and positioning the imaging agent in the subject's body.

[0097] In some respects, this document provides a method for detecting PGRN in vitro, the method comprising contacting an in vitro sample with a complex as described in any of the foregoing embodiments and locating the imaging agent within the sample.

[0098] In some respects, this document provides for the use of a complex or pharmaceutical composition as described in any of the foregoing embodiments in a method as described in any of the foregoing embodiments.

[0099] In some respects, this document provides a complex or pharmaceutical composition as described in any of the foregoing embodiments for use in a method as described in any of the foregoing embodiments.

[0100] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human CD98 heavy chain (CD98hc), and wherein the antigen-binding domain comprises VH, wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and VL, wherein the VL comprises VLCDR1, VL CDR2, and VL CDR3, wherein the sequences of VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VLCDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 184, 352, 193, 197, 198 and 204; (ii) respectively, SEQ ID NO: 184, 353, 193, 197, 198 and 204; (iii) Specifically, SEQ ID NO: 184, 354, 193, 197, 198 and 204; (iv) SEQ ID NO: 184, 355, 193, 197, 198 and 204; (v) Specifically, SEQ ID NO: 184, 356, 193, 197, 198 and 204; (vi) Specifically, SEQ ID NO: 184, 357, 193, 197, 198 and 204; (vii) Specifically, SEQ ID NO: 184, 358, 193, 197, 198 and 204; (viii) Specifically, SEQ ID NO: 184, 190, 193, 369, 198 and 204; (ix) Specifically, SEQ ID NO: 184, 190, 193, 370, 198 and 204; (x) respectively, SEQ ID NO: 184, 190, 193, 371, 198 and 204; (xi) respectively, SEQ ID NO: 184, 190, 193, 372, 198 and 204; (xii) respectively, SEQ ID NO: 184, 190, 193, 373, 198 and 204; (xiii) Specifically, SEQ ID NO: 184, 190, 193, 374, 198 and 204; (xiv) respectively, SEQ ID NO: 184, 190, 193, 375, 198 and 204; (xv) respectively, SEQ ID NO: 184, 354, 193, 371, 198 and 204; (xvi) Specifically, SEQ ID NO: 184, 359, 193, 197, 198 and 204; (xvii) Specifically, SEQ ID NO: 184, 190, 360, 197, 198 and 204; (xviii) Specifically, SEQ ID NO: 184, 190, 361, 197, 198 and 204; (xix) respectively, SEQ ID NO: 184, 190, 362, 197, 198 and 204; (xx) respectively, SEQ ID NO: 184, 190, 363, 197, 198 and 204; (xxi) respectively, SEQ ID NO: 184, 190, 364, 197, 198 and 204; (xxii) Specifically, SEQ ID NO: 184, 190, 365, 197, 198 and 204; (xxiii) Specifically, SEQ ID NO: 184, 190, 366, 197, 198 and 204; (xxiv) Specifically, SEQ ID NO: 184, 190, 367, 197, 198 and 204; (xxv) respectively, SEQ ID NO: 184, 190, 368, 197, 198 and 204; (xxvi) respectively, SEQ ID NO: 184, 190, 193, 376, 198 and 204; (xxvii) respectively, SEQ ID NO: 184, 190, 193, 377, 198 and 204; (xxviii) Specifically, SEQ ID NO: 184, 190, 193, 378, 198 and 204; (xxix) respectively, SEQ ID NO: 184, 190, 193, 379, 198 and 204; (xxx) respectively, SEQ ID NO: 184, 190, 193, 380, 198 and 204; (xxxi) respectively, SEQ ID NO: 184, 190, 193, 381, 198 and 204; (xxxii) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 382; (xxxiii) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 383; (xxxiv) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 384; (xxxv) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 385; (xxxvi) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 386; (xxxvii) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 387; (xxxviii) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 388; (xxxix) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 389; (xl) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 390; (xli) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 391; (xlii) respectively, SEQ ID NO: 351, 190, 193, 197, 198 and 204; or (xliii) respectively, SEQ ID NO: 351, 190, 193, 197, 198 and 391.

[0101] In some embodiments, the VH comprises the following amino acid sequence: SEQ ID NO: 210, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408, or 409. In some embodiments, the VL comprises the following amino acid sequence: SEQ ID NO: 215, 216, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, or 432. In some embodiments, the VH and the VL comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 392 and 216; (ii) respectively, SEQ ID NO: 393 and 216; (iii) Specifically, SEQ ID NO: 394 and 216; (iv) Specifically, SEQ ID NO: 395 and 216; (v) Specifically, SEQ ID NO: 396 and 216; (vi) Specifically, SEQ ID NO: 397 and 216; (vii) Specifically, SEQ ID NO: 398 and 216; (viii) Specifically, SEQ ID NO: 210 and 410; (ix) Specifically, SEQ ID NO: 210 and 411; (x) Specifically, SEQ ID NO: 210 and 412; (xi) Specifically, SEQ ID NO: 210 and 413; (xii) Specifically, SEQ ID NO: 210 and 414; (xiii) Specifically, SEQ ID NO: 210 and 415; (xiv) respectively, SEQ ID NO: 210 and 416; (xv) Specifically, SEQ ID NO: 394 and 412; (xvi) Specifically, SEQ ID NO: 399 and 216; (xvii) Specifically, SEQ ID NO: 400 and 216; (xviii) Specifically, SEQ ID NO: 401 and 216; (xix) Specifically, SEQ ID NO: 402 and 216; (xx) Specifically, SEQ ID NO: 403 and 216; (xxi) respectively, SEQ ID NO: 404 and 216; (xxii) Specifically, SEQ ID NO: 405 and 216; (xxiii) Specifically, SEQ ID NO: 406 and 216; (xxiv) Specifically, SEQ ID NO: 407 and 216; (xxv) respectively, SEQ ID NO: 408 and 216; (xxvi) Specifically, SEQ ID NO: 210 and 417; (xxvii) Specifically, SEQ ID NO: 210 and 418; (xxviii) Specifically, SEQ ID NO: 210 and 419; (xxix) respectively, SEQ ID NO: 210 and 420; (xxx) respectively, SEQ ID NO: 210 and 421; (xxxi) respectively, SEQ ID NO: 210 and 422; (xxxii) Specifically, SEQ ID NO: 210 and 423; (xxxiii) Specifically, SEQ ID NO: 210 and 424; (xxxiv) Specifically, SEQ ID NO: 210 and 425; (xxxv) respectively, SEQ ID NO: 210 and 426; (xxxvi) Specifically, SEQ ID NO: 210 and 427; (xxxvii) respectively, SEQ ID NO: 210 and 428; (xxxviii) Specifically, SEQ ID NO: 210 and 429; (xxxix) respectively, SEQ ID NO: 210 and 430; (xl) Specifically, SEQ ID NO: 210 and 431; (xli) respectively, SEQ ID NO: 210 and 432; (xlii) respectively, SEQ ID NO: 409 and 215; or (xliii) respectively, SEQ ID NO: 409 and 432.

[0102] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to a human CD98 heavy chain (CD98hc), and wherein the antigen-binding domain is a VHH comprising: (a) VH CDR1, VH CDR2, and VH CDR3, which contain the following amino acid sequences: (i) respectively, SEQ ID NO: 184, 352 and 193; (ii) Specifically, SEQ ID NO: 184, 353 and 193; (iii) Specifically, SEQ ID NO: 184, 354 and 193; (iv) Specifically, SEQ ID NO: 184, 355 and 193; (v) Specifically, SEQ ID NO: 184, 356 and 193; (vi) Specifically, SEQ ID NO: 184, 357 and 193; (vii) Specifically, SEQ ID NO: 184, 358 and 193; (viii) Specifically, SEQ ID NO: 184, 190 and 193; (ix) Specifically, SEQ ID NO: 184, 359 and 193; (x) Specifically, SEQ ID NO: 184, 190, and 360; (xi) Specifically, SEQ ID NO: 184, 190 and 361; (xii) Specifically, SEQ ID NO: 184, 190 and 362; (xiii) Specifically, SEQ ID NO: 184, 190 and 363; (xiv) respectively, SEQ ID NO: 184, 190 and 364; (xv) Specifically, SEQ ID NO: 184, 190 and 365; (xvi) Specifically, SEQ ID NO: 184, 190 and 366; (xvii) Specifically, SEQ ID NO: 184, 190 and 367; (xviii) respectively, SEQ ID NO: 184, 190 and 368; or (xix) respectively, SEQ ID NO: 351, 190 and 193; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 210, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408 or 409.

[0103] In some embodiments, the antigen-binding domain comprises VH and VL on a single polypeptide chain. In some embodiments, the antigen-binding domain comprises a single-chain variable fragment (scFv). In some embodiments, the scFv is VH-linker-VL oriented. In some embodiments, the scFv is VL-linker-VH oriented. In some embodiments, the linker is about 5 to about 25 amino acids, about 5 to about 20 amino acids, about 10 to about 25 amino acids, or about 10 to about 20 amino acids. In some embodiments, the linker comprises the following amino acid sequence: GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6) or GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

[0104] In some embodiments, the antigen-binding domain comprises a VH on a first polypeptide and a VL on a second polypeptide. In some embodiments, the antigen-binding domain is a murine, chimeric, humanized, or human antigen-binding domain, optionally wherein the antigen-binding domain is a humanized antigen-binding domain.

[0105] In some embodiments, the complex further comprises an Fc region, wherein the Fc region comprises first and second polypeptide chains. In some embodiments, the Fc region is capable of binding FcRn. In some embodiments, the complex further comprises an Fc domain. In some embodiments, the Fc domain is capable of binding FcRn.

[0106] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, and (ii) two copies of the PGRN polypeptide. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is attached to the C-terminus of one of the two copies of the PGRN polypeptide. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the N-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the N-terminus of a second polypeptide chain in the Fc region. In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is attached to the N-terminus of either the first or second polypeptide chain in the Fc region. In some embodiments, one of the two copies of the PGRN polypeptide is attached to the C-terminus of a first polypeptide chain in the Fc region, and the other copy of the PGRN polypeptide is attached to the C-terminus of a second polypeptide chain in the Fc region.

[0107] In some embodiments, the complex comprises (i) an antibody that binds to human CD98hc, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of the PGRN polypeptide, wherein each copy of the PGRN polypeptide is linked to the C-terminus of one of the two antibody heavy chains.

[0108] In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that bind to human CD98hc, (ii) an Fc region; and (iii) two copies of the PGRN polypeptide, wherein one of the two scFv, Fab, or VHH antigen-binding domains that bind to human CD98hc is attached to the C-terminus of a first polypeptide chain in the Fc region, wherein the other scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is attached to the C-terminus of a second polypeptide chain in the Fc region, wherein one of the two copies of the PGRN polypeptide is attached to the N-terminus of the first polypeptide chain in the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the N-terminus of the second polypeptide chain in the Fc region. In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of a first or second polypeptide chain in the Fc region, and the PGRN polypeptide is linked to the N-terminus of a first or second polypeptide chain in the Fc region.

[0109] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of the Fc domain, and the PGRN peptide is linked to the N-terminus of the Fc domain.

[0110] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of a first or second polypeptide chain in the Fc region, and the PGRN polypeptide is linked to the C-terminus of a first or second polypeptide chain in the Fc region.

[0111] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of the Fc domain, and the PGRN peptide is linked to the C-terminus of the Fc domain.

[0112] In some embodiments, the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of one of the two polypeptide chains of the Fc region, and wherein the PGRN polypeptide is linked to the N-terminus of the other polypeptide chain of the Fc region.

[0113] In some embodiments, the Fc region is a heterodimeric Fc region, optionally containing club and mortar mutations. In some embodiments, the Fc domain is a single-stranded monovalent Fc domain. In some embodiments, the Fc region is a modified Fc region having the modifications listed in Table 8 or Table 9. In some embodiments, the Fc region is a human IgG1 Fc region, wherein the human IgG1 Fc region contains mutations that reduce effector function, optionally wherein the mutations that reduce effector function include: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S.

[0114] In some embodiments, the Fc domain is a modified Fc domain having the modifications listed in Table 8. In some embodiments, the Fc domain is a human IgG1 Fc domain, wherein the human IgG1 Fc domain contains a mutation that reduces effector function, optionally wherein the mutation that reduces effector function includes: (i) L234A, L235A and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A and / or P329G; or (iv) L234A, L235A and / or P329S.

[0115] In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0116] In some implementations, the complex is attached to an imaging agent.

[0117] In some aspects, this document provides a polynucleotide encoding a complex as described in any of the preceding embodiments. In some aspects, this document provides a vector comprising the polynucleotide as described in the preceding embodiment. In some aspects, this document provides a host cell comprising the vector as described in the preceding embodiment. In some aspects, this document provides a method for generating a complex, the method comprising culturing a host cell as described in the preceding embodiment to generate the complex, optionally wherein the method further comprises isolating the complex from the culture. In some aspects, this document provides an isolated complex generated by the method as described in the preceding embodiment. In some aspects, this document provides a pharmaceutical composition comprising the complex as described in the preceding embodiment. In some embodiments, the pharmaceutical composition further comprises a pharmaceutically acceptable vector.

[0118] In some aspects, this document provides a method for treating a subject with a neurological disease or condition, the method comprising administering to the subject a complex or pharmaceutical composition as described in any of the foregoing embodiments. In some embodiments, the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, ocular diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation. In some aspects, the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) primarily affecting the limbic system. In some embodiments, the dementia is frontotemporal dementia (FTD). In some embodiments, the neurological disease or condition is Alzheimer's disease. In some embodiments, the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease. In some embodiments, the neurological disorder or condition is Parkinson's disease. In some embodiments, the neurological disorder or condition is frontotemporal lobe epilepsy.

[0119] In some aspects, this document provides a method for treating a subject with a lysosomal storage disease, the method comprising administering to the subject a complex or a pharmaceutical composition as described in any of the foregoing embodiments. In some embodiments, the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II, and MPS type III.

[0120] In some respects, this document provides a method for transporting a complex across a subject's BBB, the method comprising administering to the subject a complex as described in any of the foregoing embodiments or a pharmaceutical composition as described in any of the foregoing embodiments.

[0121] In some respects, this document provides a method for increasing the concentration of PGRN in the CSF of a subject, the method comprising administering to the subject a complex as described in any of the foregoing embodiments or a pharmaceutical composition as described in any of the foregoing embodiments, wherein the PGRN concentration is increased compared to administering the PGRN peptide alone to the subject.

[0122] In some aspects, this document provides a method for imaging PGRN in a subject, the method comprising administering a complex as described in any of the foregoing embodiments to the subject and positioning the imaging agent in the subject's body.

[0123] In some respects, this document provides a method for detecting PGRN in vitro, the method comprising contacting an in vitro sample with a complex as described in any of the foregoing embodiments and locating the imaging agent within the sample.

[0124] In some respects, this document provides for the use of a complex or pharmaceutical composition as described in any of the foregoing embodiments in a method as described in any of the foregoing embodiments.

[0125] In some respects, this document provides a complex or pharmaceutical composition as described in any of the foregoing embodiments for use in a method as described in any of the foregoing embodiments.

[0126] In some respects, this document provides a method for increasing PGRN in a subject, the method comprising administering to the subject an isolated PGRN mutant peptide as described in any of the foregoing embodiments or a pharmaceutical composition as described in any of the foregoing embodiments.

[0127] It should be understood that one, some, or all of the features of the various embodiments described herein can be combined to form other embodiments of the invention. These and other aspects of the invention will become apparent to those skilled in the art. These and other embodiments of the invention are further described in the following detailed description. Attached Figure Description

[0128] This application can be understood by referring to the following description and the accompanying drawings.

[0129] Figure 1A-1J An example form of the complex is shown.

[0130] Figure 2A-2D An example form of the anti-TfR-PGRN complex is shown. PGRN successively contains a half-granule protein domain, "paragranule protein" (P), and seven granule protein domains (GFBACDE).

[0131] Figures 3A-3C Representative sensory map data obtained on Carterra LSA using the PGRN capture method are shown. Example sensory map data of the PGRN mutant in HEK293 and CHO cells are shown: mvFc-PGRN_16 (QYL C-terminal mutation; SEQ ID NO: 462) Figure 3A ) and mvFc-PGRN_31 (“QKL” C-terminal mutation; SEQ ID NO: 447) Figure 3B ). Figure 3CSensing data of wild-type PGRN in HEK293 and CHO cells are shown (“APLRDPALRQLL” C-terminus; SEQ ID NO:451). Figures 3A-3C In the diagram, each curve represents the concentration of sorted protein analyte (4.9 nM, 14.8 nM, 44.4 nM, 133.3 nM, and 400 nM sorted protein). The measured response (RU) is proportional to the concentration of analyte used (e.g., the highest curve = 400 nM sorted protein and the lowest curve = 4.9 nM sorted protein).

[0132] Figure 4 This study demonstrates that granule protein precursors containing mouse transferrin antigen-binding domains induce higher β-glucocerebrosidase (GCase) activity in RAW 264.7 mouse macrophages. Legend: mTfR1 = mouse anti-TfR1 Fab domain; mvFc = monovalent Fc; Iso = isotype; Wt = wild-type; cis = HC1 (Fab-Fc-potassium-PGRN) and HC2 (Fc-potassium) and LC; trans = HC1 (Fab-Fc-potassium) and HC2 (Fc-potassium-PGRN) and LC; and 1+2 = HC1 (mTfR1Fab-Fc-potassium-PGRN) and HC2 (Fc-potassium-PGRN) and LC. N = 2 pooled experiments.

[0133] Figure 5 The uptake of the anti-TfR-PGRN complex by the mouse brain endothelial cell line bEND.3 over 2 hours is shown. Higher uptake was observed compared to the granule protein precursor protein with an isotype control domain. The images shown were obtained using human Fc detection with an anti-HuIgG antibody conjugated to Alexa Fluor-647. Cell nuclei were labeled with DAPI.

[0134] Figures 6A-6B It shows Figure 5 Quantitative analysis of cellular uptake assays confirmed that bEND.3 cells exhibited significantly greater endocytosis of the TfR-PGRN complex after 2 hours compared to those containing isotype control domains. This was demonstrated by detection using human Fc. Figure 6A ) and human PGRN detection ( Figure 6BCellular uptake of PGRN measured. Legend: mTfR1 = mouse anti-TfR1 Fab domain; mvFc = monovalent Fc; Iso = allotype; Wt = wild-type; cis = HC1 (Fab-Fc-Groodium-PGRN) and HC2 (Fc-Groodium) and LC; trans = HC1 (Fab-Fc-Groodium) and HC2 (Fc-Groodium-PGRN) and LC; and 1+2 = HC1 (mTfR1 Fab-Fc-Groodium-PGRN) and HC2 (Fc-Groodium-PGRN) and LC.

[0135] Figures 7A-7B The nonspecific binding of affinity-modulated anti-TfR antibodies to baculovirus particles (BVP) was demonstrated (BVP score). The BVP scores for the following antibodies are shown: TfR.15.WH8.1.24A.42Q (24A_42Q), TfR.15.WH8.1.42Q.H6-4 (H6-4), TfR.15.WH8.1.42Q.L7-2 (L7-2), TfR.15.WH8.1.42Q.L10-1 (L10-1), TfR.15.WH8.1.42Q.L10-8 (L10-8), TfR.15.WH8.1.42Q.L10-16 (L10-16), TfR.15.WH8.1.42Q.H3-7 (H3-7), TfR.9.1B.39.27.L-35 Antibodies were tested for TfR.9.1B.39.38.L-21 (L-21), TfR.9.1B.39.38.L-6 (L-6), and TfR.9.1B.39.27.L-19 (L-19). Control antibodies (isotype, negative, and positive controls) were also tested. Parental antibodies—TfR.15.WH8.1.24A (24A), TfR.9.1B.39.38 (39.38), and TfR.15.WH8.1.42Q (42Q)—were used as additional controls.

[0136] Figures 8A-8B The nonspecific binding (OD 450 nm) of affinity-modulated anti-TfR antibodies to dsDNA is shown. Absorbance values ​​for the following antibodies are shown: 24A_42Q, H6-4, L7-2, L10-1, L10-8, L10-16, H3-7, L-35, L-21, L-6, and L-19 antibodies. Control antibodies (isotype, negative, and positive controls) were tested. Parental antibodies—24A, 39.38, and 42Q—were used as additional controls.

[0137] Figure 9The extent of cellular uptake of affinity-modulated anti-TfR antibodies by the brain microvascular endothelial cell line (hCMEC / D3) over 2 hours is shown. Cellular uptake of the following antibodies is shown: 24A, 42Q, H6-4, L7-2, L10-1, L10-8, L10-16, H3-7, and L-35 antibodies. Isotypes (Iso mvFc-Iso scFv) and parental antibodies—24A and 42Q—were used as controls. The images shown are obtained from human Fc detection using anti-HuIgG fluorescent antibody.

[0138] Figures 10A-10B The study demonstrates antibody uptake in the brains of huTfR KI mice 24 hours after administration of 5 mg / kg of H6-4, L7-2, L10-1, L10-8, L-35, L10-16, H3-7, or 24A_42Q variant antibodies. Isotype (Iso) and parental antibodies - 24A and 42Q - were used as controls. Figure 10A The antibody concentration (ng / mg tissue) in the brain after vascular clearance is shown. Figure 10B The study shows the fold change in the brain of patients with cleared blood vessels relative to matched isotype controls.

[0139] Figure 11 The ratio of vascularly cleared brain to whole-brain antibody concentrations is shown in huTfR KI mice administered 5 mg / kg of H6-4, L7-2, L10-1, L10-8, L-35, L10-16, H3-7, or 24A_42Q variant antibodies. Isotype (Iso) and parental antibodies—24A and 42Q—were used as controls.

[0140] Figure 12 The effect of affinity-modulated anti-TfR antibodies on circulating reticulocyte levels in mice is shown. Mice were administered 5 mg / kg of H6-4, L7-2, L10-1, L10-8, L-35, L10-16, H3-7, or 24A_42Q variant antibodies and evaluated 24 hours later. Isotype (Iso) and parental antibodies—24A and 42Q—served as controls. Circulating reticulocyte levels are shown as absolute reticulocytes (K / ul) (left side of dashed line) and reticulocyte percentage (right side of dashed line).

[0141] Figure 13 The levels of TfR in whole-brain lysates isolated from mice administered antibodies to L-21, L-6, and L-35 variants are shown. Iso-Fab and parental antibodies -24A, 39.38, and 42Q were used as controls. TfR levels are shown normalized relative to the GAPDH levels in each sample and the mean of the iso-control.

[0142] Figures 14A-14B Data are presented showing increased uptake of the disclosed anti-CD98hc.04.048.WH1 antibody variant in the mouse brain, at ng antibody / mg total protein ( Figure 14A ) and fold change compared to the same type control antibody ( Figure 14B )express.

[0143] Figure 15 Data are presented showing that amino acid uptake was not reduced in cells treated with the anti-CD98hc.04.048.WH1 antibody variant of this disclosure.

[0144] Figure 16 It shows the use for the elderly Grn The binding curves of the msTfR-msPgrn assay item in the proof-of-concept efficacy study in KO mice were assessed by ELISA. Both msTfR-msPgrn fusion protein affinity variants showed binding to the mouse sorting protein with similar EC50 values. 50 value.

[0145] Figure 17 It shows the use for the elderly Grn The protein form of the msTfR-msPgrn fusion protein from the -KO proof-of-concept efficacy study is also shown. The dosing timeline, mouse genotypes, test items, dose levels, and sample amounts are also illustrated. The affinity of 8D3v33-msPgrn and 8D3v12-msPgrn for apex mouse TfR is shown in equilibrium dissociation constant (K). D () indicates. Abbreviation: F = female; M = male.

[0146] Figure 18 The serum pharmacokinetic profile of the msTfR-msPgrn fusion protein administered in aged Grn KO mice over an 8-day period is shown, with mice administered once on day 0 and once on day 7 (as indicated by the arrows on the horizontal axis). Fusion proteins containing the msTfR binders 8D3v12 and 8D3v33 exhibited a faster clearance profile, which is related to their affinity for msTfR.

[0147] Figure 19 The results showed that 24 hours after the second dose, in elderly patients... Grn The level of the msTfR-msPgrn fusion protein detected in the brain lysis products of KO-vascular clearance (previous dose administered seven days prior). Animals receiving 8D3v12-msPgrn showed the highest levels of the tested item, approximately seven times higher than the isotype control -msPgrn. Triangle: female mice; circle: male mice.

[0148] Figure 20The study showed that after two doses of 8D3v12-msPgrn and 8D3v33-msPgrn, elderly patients... Grn The degree of reduction in glucosylsphingosine (GlcSph) accumulation in the brains of -KO mice. Pharmacodynamic readings of GlcSph may reflect the extent of lysosomal dysfunction induced by Grn deficiency and age in mouse models.

[0149] Figure 21 The study showed that after administration of saline, 8D3v12-msPgrn, 8D3v33-msPgrn, or allotype control-msPgrn, elderly patients... Grn Assessment of Gpnmb levels in whole brain lysates of KO mice. In elderly mice given saline... Grn Increased Gpnmb was observed in the brains of -KO mice, and it was partially reduced in the brains of mice administered 8D3v12-msPgrn. Triangles: female mice; circles: male mice. One-way ANOVA and Dennehy multiple comparison test. **** p<0.0001; **: p<0.005; ns: not significant.

[0150] Figure 22 The use of ELISA to assess the binding of huTfR-huPGRN variants to human sorting proteins is shown. No differences were detected in the binding of human sorting proteins to all huTfR-huPGRN variants, and the binding affinity of all proteins was expressed as EC50. 50 express.

[0151] Figure 23 Hematological parameters in huTfR-KI mice were assessed 24 h after administration of different doses of the huTfR-huPGRN fusion protein. Blood reticulocyte and erythrocyte (RBC) counts were assessed by flow cytometry, and no differences were observed between the treatment groups.

[0152] Figure 24 The study demonstrates the assessment of surface huTfR levels on blood reticulocytes in huTfR-KI mice 24 h after administration of either the huTfR-huPGRN variant or the isotype control-huPGRN. No differences were observed between the treatment groups.

[0153] Figure 25The brain levels of huTfR-huPGRN or isotype control-huPGRN detected in the brain lysate products of huTfR-KI mice after vascular clearance were shown. These mice were administered a single dose at different levels and collected at 6 h or 24 h post-administration. As expected, a dose-dependent increase in huTfR10-16-huPGRN was observed. Similar fusion protein brain levels were observed 6 h after administration of 10 mg / kg huTfR10-16-huPGRN and 3 mg / kg huTfR10-8-huPGRN.

[0154] Figure 26 The levels of TfR in the whole brain lysate of mice administered the huTfR-huPGRN fusion protein are shown. Tissues were collected at 6 or 24 hours post-administration and analyzed by quantitative Western blotting. No differences were observed between the treatment groups, indicating that total brain TfR levels were not affected at these time points following a single dose of huTfR-huPGRN.

[0155] Figure 27 The binding of the huCD98-huPGRN fusion protein variants to the human sorting protein was assessed by ELISA. No differences were detected in the binding of all huCD98-huPGRN variants to the human sorting protein, and the binding affinity of all fusion proteins is expressed as EC50.

[0156] Figure 28 The brain levels of huCD98-huPGRN or isotype control-huPGRN detected in the brain lysate of vascular clearance in huCD98-KI mice 72 h after a single dose are shown.

[0157] Figure 29 The analytical hydrophobic interaction chromatogram (aHIC) of the indicated PGRN fusion protein is shown.

[0158] Figure 30A and Figure 30B Brain uptake levels of various anti-CD98hc.04.048.WH1 monovalent Fab variants of this disclosure are shown, expressed as ng binding domain / mg total protein and fold change relative to control.

[0159] Figure 31A Serum clearance in mice of the antibody containing the anti-CD98hc.04.048.WH1 binding domain was demonstrated after three weekly administrations.

[0160] Figure 31BThe study showed that, compared with antibody levels observed with isotype control antibodies, the levels of antibodies containing the anti-CD98hc.04.048.WH1 binding domain were increased in the brain regions of mice with vascular clearance.

[0161] Figure 32A and Figure 32B Serum PK measurements of various anti-CD98hc.04.048.WH1 antibody variants are shown in mice administered 20 mg / kg and 3 mg / kg, respectively.

[0162] Figure 32C and Figure 32D The antibody concentrations in vascular-cleared brain samples from mice after administration of various anti-CD98hc.04.048.WH1 antibody variants at 20 mg / kg and 3 mg / kg are shown, respectively. Detailed Implementation

[0163] This disclosure relates to complexes comprising an antigen-binding domain linked to a granulocyte precursor protein (PGRN) polypeptide, wherein the antigen-binding domain is specifically capable of binding to human transferrin receptor (TfR) or human CD98 heavy chain (CD98hc). The complexes of this disclosure provide compositions that enhance the ability of PGRN polypeptides to be transported across the blood-brain barrier, thereby meeting the need in the art for improved compositions and methods for treating patients with diseases involving PGRN deficiency.

[0164] Certain techniques and procedures described or referenced herein are generally well understood by those skilled in the art and are typically employed using conventional methods, such as those widely used, such as those described below: Sambrook et al., Molecular Cloning: A Laboratory Manual, 3rd Edition (2001), Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY; Current Protocols in Molecular Biology (FM Ausubel et al., eds., (2003); Monoclonal Antibodies: A Practical Approach (P. Shepherd and C. Dean, eds., Oxford University Press, 2000).

[0165] definition The term "central nervous system" or "CNS" refers to a complex of neural tissues that control bodily functions and includes the brain and spinal cord.

[0166] The term "blood-brain barrier" or "BBB" refers to the network of endothelial cells in the brain's capillaries that are tightly sealed by tight junctions.

[0167] "Central Nervous System Antigens" or "CNS Antigens" are antigens expressed in the CNS (including the brain).

[0168] "Brain antigens" are CNS antigens expressed in the brain.

[0169] As used herein, “neurological disorder” refers to a disease or condition affecting the CNS and / or a cause in the CNS. Exemplary CNS diseases or conditions include, but are not limited to, neuropathy, amyloidosis, cancer, eye diseases or conditions, viral or microbial infections, inflammation, ischemia, neurodegenerative diseases, epilepsy, behavioral disorders, and lysosomal storage diseases.

[0170] As used herein, "lysosomal storage disease" or "LSD" refers to a hereditary metabolic disorder characterized by the excessive accumulation of substrates (such as undigested or partially digested macromolecules) in various cells of an organ, ultimately leading to cellular dysfunction and clinical abnormalities. LSD has been defined as a lysosomal dysfunction, typically classified by the substrates accumulated, and includes sphingolipid storage diseases, oligosaccharide storage diseases, mucolipide storage diseases, mucopolysaccharide storage diseases, lipoprotein storage diseases, neuronal ceroid lipofuscin deposition diseases, etc. LSD may also include other protein deficiencies / defects that lead to the accumulation of macromolecules, such as proteins essential for the normal post-translational modification of lysosomal enzymes, or proteins important for proper lysosomal transport. LSD is a disease caused by a single gene defect. Enzyme defects cause nearly 70 percent of LSD cases, with the remainder being defects in enzyme activators or related proteins.

[0171] "Protein replacement therapy" or "PRT" refers to a medical treatment or therapy that supplements or replaces a specific protein in an individual who is deficient, nonfunctional, or missing the protein.

[0172] As used herein, “mutant granulin precursor polypeptide” or “granulin precursor mutant polypeptide” refers to a mutant polypeptide of the wild-type granulin precursor polypeptide. The granulin precursor mutant polypeptide may contain one or more substitutions (e.g., conserved substitutions, insertions, or deletions) in the amino acid sequence of the wild-type granulin precursor polypeptide (e.g., relative to SEQ ID NO: 230). The granulin precursor mutant polypeptide may have similar or substantially the same functions as the wild-type granulin precursor polypeptide. For example, the granulin precursor mutant polypeptide may bind to sorting proteins or sphingolipid-activating proteases, regulate the activity and levels of various lysosomal proteins (e.g., cathepsins), promote neurite spur growth and neuronal survival, and / or any other functions described herein.

[0173] As used herein, a “complex” refers to one or more proteins comprising linked portions. These portions may be linked, for example, via peptide bonds (e.g., in fusion proteins), linkers (e.g., peptide linkers), or via non-covalent protein-protein interactions, such as disulfide bonds (e.g., in antibodies). Exemplary portions that may be included in a complex include a PGRN mutant polypeptide, an antigen-binding domain specifically binding to CD98hc or TfR, an Fc region, and / or an Fc domain. Therefore, non-limiting examples of a “complex” comprising an antigen-binding domain and a PGRN mutant polypeptide include (a) a fusion protein comprising an antigen-binding domain, an Fc domain, and a PGRN mutant polypeptide within a single polypeptide chain (e.g., as shown in the original text). Figure 1A (a) and (b) are three proteins linked via non-covalent protein-protein interactions, wherein the first protein contains a PGRN mutant polypeptide and an Fc domain, the second protein contains a heavy chain with an antigen-binding domain, and the third protein contains a light chain with an antigen-binding domain (e.g., as shown). Figure 2B (As shown). Figures 1 and 2 provide other exemplary forms of the complex.

[0174] Unless otherwise indicated, the terms “transferrin receptor,” “TfR,” “TfR polypeptide,” and “TfR protein” are used interchangeably herein to refer to any native TfR from any vertebrate source, including mammals such as primates (e.g., humans and cynomolgus monkeys) and rodents (e.g., mice and rats). TfR is also known as transferrin receptor protein 1, TR, tfR1, Trfr, T9, and p90. In some embodiments, the terminology covers wild-type sequences and naturally occurring variant sequences, such as splice variants or allele variants. In some embodiments, the terminology covers “full-length” unprocessed TfR, as well as any form of TfR produced by cellular processing. Full-length transferrin receptor proteins include a short N-terminal intracellular region, a transmembrane region, and a large extracellular domain. The extracellular domain is characterized by three domains: a protease-like domain, a helical domain, and a apical domain. In some embodiments, the TfR is human TfR.As used herein, the term "human TfR" refers to a polypeptide having the following amino acid sequence: MMDQARSAFSNLFGGEPLSYTRFSLARQVDGDNSHVEMKLAVDEEENADNNTKANVTKPKRCSGSICYGTIAVIVFFLIGFMIGYLGYCKGVEPKTECERLAGTESPVREEPGEDFPAARRLYWDDLKRKLSEKLDSTDFTGTIKLLNENSYVPREAGSQKDENLALYVENQFREFKLSKVWRDQHFVKIQVKDSAQNSVIIVDKNGRLVYLVENPGGYVAYSKAATVTGKLVHANFGTKKDFEDLYTPVNGSIVIVRAGKITFAEKVANAESLNAIGVLIYMDQTKFPIVNAELSFFGHAHLGTGDPYTPGFPSFNHTQFPPSRSSGLPNIPVQTISRAAAEKLFGNMEGDCPSDWKTDSTCRMVTSESKNVKLTVSNVLKEIKILNIFGVIKGFVEPDHYVVVGAQRDAWGPGAAKSGVGTALLLKLAQMFSDMVLKDGFQPSRSIIFASWSAGDFGSVGATEWLEGYLSSLHLKAFTYINLDKAVLGTSNFKVSASPLLYTLIEKTMQNVKHPVTGQFLYQDSNWASKVEKLTLDNAAFPFLAYSGIPAVSFCFCEDTDYPYLGTTMDTYKELIERIPELNKVARAAAEVAGQFVIKLTHDVELNLDYERYNSQLLSFVRDLNQYRADIKEMGLSLQWLYSARGDFFRATSRLTTDFGNAEKTDRFVMKKLNDRVMRVEYHFLSPYVSPKESPFRHVFWGSGSHTLPALLENLKLRKQNNGAFNETLFRNQLALATWTIQGAANALSGDVWDIDNEF (SEQ ID NO: 1).

[0175] Unless otherwise indicated, as used herein, the terms “CD98hc,” “CD98hc polypeptide,” and “CD98hc protein” are used interchangeably to refer to any native CD98hc from any vertebrate source, including mammals such as primates (e.g., humans and cynomolgus monkeys) and rodents (e.g., mice and rats). CD98hc is also known as 4F2 cell surface antigen heavy chain, 4F2hc, 4F2 heavy chain antigen, lymphocyte activation antigen 4F2 large subunit, solute carrier family 3 member 2, and CD98. The CD98hc protein is encoded by the SLC3A2 gene and is part of the large amino acid transporter (LAT) complex. In some embodiments, the terms cover wild-type sequences and naturally occurring variant sequences, such as splice variants or allelic variants. In some embodiments, the terms cover “full-length” unprocessed CD98hc, as well as any form of CD98hc produced by cellular processing. In some implementations, the CD98hc is human CD98hc. As used herein, the term "CD98hc" is used in conjunction with other medical terms. CD98hc" refers to a polypeptide having the following amino acid sequence: MELQPPEASIAVVSIPRQLPGSHSEAGVQGLSAGDDSELGSHCVAQTGLELLASGDPLPSASQNAEMIETGSDCVTQAGLQLLASSDPPALASKNAEVTGTMSQDTEVDMKEVELNELEPEKQPMNAASGAAMSLAGAEKNGLVKIKVAEDEAEAAAAAKFTGLSKEELLKVAGSPGWVRTRWALLLLFWLGWLGMLAGAVVIIVRAPRCRELPAQKWWHTGALYRIGDLQAFQGHGAGNLAGLKGRLDYLSSLKVKGLVLGPIHKNQKDDVAQTDLLQIDPNFGSKEDFDSLLQSAKKKSIRVILDLTPNYRGENSWFSTQVDTVATKVKDALEFWLQAGVDGFQVRDIENLKDASSFLAEWQNITKGFSEDRLLIAGTNSSDLQQILSLLESNKDLLLTSSYLSDSGSTGEHTKSLVTQYLNATGNRWCSWSLSQARLLTSFLPAQLLRLYQLMLFTLPGTPVFSYGDEIGLDAAALPGQPMEAPVMLWDESSFPDIPGAVSANMTVKGQSEDPGSLLSLFRRLSDQRSKERSLLHGDFHAFSAGPGLFSYIRHWDQNERFLVVLNFGDVGLSAGLQASDLPASASLPAKADLLLSTQPGREEGSPLELERLKLEPHEGLLLRFPYAA (SEQ ID NO: 2).

[0176] As used herein, the terms “antibody” and “immunoglobulin” are used interchangeably and refer to an antibody molecule that recognizes and specifically binds to a target (such as a protein, polypeptide, peptide, carbohydrate, polynucleotide, lipid, or a combination of the foregoing (e.g., glycoprotein)) through at least one antigen recognition site within the variable region of an immunoglobulin molecule. The term “antibody” encompasses monoclonal antibodies, chimeric antibodies, humanized antibodies, human antibodies, multispecific (e.g., bispecific) antibodies, and any other immunoglobulin molecule that exhibits the desired biological activity. Antibodies may belong to any of the five major classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, or their subclasses (isotypes) (e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2), designated α, δ, ε, γ, and μ based on the identity of their heavy chain constant region. Different classes of antibodies have different and well-known subunit structures and three-dimensional conformations. For information on the structure and properties of different classes of antibodies, see, for example, Basic and Clinical Immunology, 8th ed., Daniel P. Stites, Abba I. Terr and Tristram G. Parslow (eds.), Appleton & Lange, Norwalk, CT, 1994, p. 71 and Chapter 6.

[0177] The terms "anti-TfR antibody," "antibody that binds to TfR," and "antibody that specifically binds to TfR" refer to antibodies capable of binding to TfR with sufficient affinity, such that the antibody can be used as a diagnostic and / or therapeutic agent targeting TfR. In some embodiments, the anti-TfR antibody is capable of delivering another diagnostic and / or therapeutic agent to the brain. In some embodiments, the anti-TfR antibody binds to an epitope of TfR that is conserved across different species of TfR.

[0178] The terms "anti-CD98hc antibody," "antibody that binds to CD98hc," and "antibody that specifically binds to CD98hc" refer to antibodies capable of binding to CD98hc with sufficient affinity, such that the antibody can be used as a diagnostic and / or therapeutic agent targeting CD98hc. In some embodiments, the anti-CD98hc antibody is capable of delivering another diagnostic and / or therapeutic agent to the brain. In some embodiments, the anti-CD98hc antibody binds to an epitope of CD98hc that is conserved across different species of CD98hc.

[0179] An "antigen-binding domain" or "antigen-binding region" refers to the monovalent portion of an antibody that binds to an antigen. An "antigen-binding domain" may include an antigen-determining region (e.g., a complementarity-determining region (CDR)) of the antibody. Antibodies or antigen-binding fragments thereof (including monospecific and multispecific (e.g., bispecific) antibodies or antigen-binding fragments thereof) may include an antigen-binding domain. In some embodiments, the antigen-binding domain is not present in the context of the antibody.

[0180] The terms "anti-TfR antigen-binding domain," "antigen-binding domain that binds to TfR," "anti-TfR antigen-binding region," "antigen-binding region that binds to TfR," and "TfR-binding domain" refer to antigen-binding domains that bind to TfR with sufficient affinity, such that the antigen-binding domain can be used as a diagnostic and / or therapeutic agent targeting TfR. On the one hand, the binding degree of the anti-TfR antigen-binding domain to unrelated, non-TfR peptides is less than about 10% of the binding degree of the antigen-binding domain to TfR, as measured, for example, by radioimmunoassay (RIA). In some embodiments, the antibody binding to TfR has a molecular weight of about 0.01 nM to about 50 nM, about 51 nM to about 750 nM, about 751 nM to about 10,000 nM, less than about 20 µM, less than about 15 µM, less than about 12 µM, less than about 10 µM, less than about 7.5 µM, less than about 5 µM, less than about 2.5 µM, less than about 1 μM, less than about 100 nM, less than about 10 nM, less than about 1 nM, less than about 0.1 nM, less than about 0.01 nM, or less than about 0.001 nM (e.g., 10). -8 M or lower, such as 10 -8 M to 10 -13 M, for example, 10 -9 M to 10 -13 The dissociation constant (KD) of M). In some embodiments, the anti-TfR antigen-binding domain binds to an epitope of TfR, which is conserved among TfRs of different species.

[0181] The terms "anti-CD98hc antigen-binding domain," "antigen-binding domain binding to CD98hc," "anti-CD98hc antigen-binding region," "antigen-binding region binding to CD98hc," and "CD98hc binding domain" refer to an antigen-binding domain that binds to CD98hc with sufficient affinity, such that the antigen-binding domain can be used to target CD98hc and / or can be used as a diagnostic agent, therapeutic agent, or to transport molecules or compounds across the BBB. On the other hand, the binding degree of the anti-CD98hc antigen-binding domain to unrelated, non-CD98hc peptides is less than about 10% of the binding degree of the antigen-binding domain to CD98hc, as measured, for example, by radioimmunoassay (RIA). In some embodiments, the antibody binding to CD98hc has a molecular weight of about 10 nM to about 1500 nM, about 500 nM to about 10 µM, about 100 nM to about 500 nM, less than about 0.1 μM, less than about 1 μM, less than about 10 μM, less than about 100 nM, less than about 10 nM, less than about 1 nM, less than about 0.1 nM, less than about 0.01 nM, or less than about 0.001 nM (e.g., 10). -8 M or lower, such as 10 -8 M to 10 -13 M, for example, 10 -9 M to 10 -13 The dissociation constant (KD) of M). In some embodiments, the anti-CD98hc antigen-binding domain binds to an epitope of CD98hc, which is conserved among CD98hc from different species.

[0182] The terms "full-length antibody," "intact antibody," or "whole antibody" are used interchangeably and refer to antibodies that are in their substantially intact form as opposed to antibody fragments. Specifically, whole antibodies include those having both a heavy chain and a light chain that includes an Fc region. The constant region can be a native sequence constant region (e.g., a human native sequence constant region) or a variant of its amino acid sequence. In some cases, intact antibodies may have one or more effector functions.

[0183] The term "native IgG antibody" refers to a heterotetrameric glycoprotein of approximately 150,000 Daltons, composed of two identical light ("L") chains and two identical heavy ("H") chains. Each light chain is connected to the heavy chain by a covalent disulfide bond, the number of which varies among heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has a variable domain (V) at one end. H This is followed by many constant structural domains. Each light chain has a variable structural domain (V0) at one end. LFurthermore, it has a constant domain at its other end; the constant domain of the light chain is aligned with a first constant domain of the heavy chain, and the variable domain of the light chain is aligned with the variable domain of the heavy chain. Specific amino acid residues are considered to form the interface between the variable domains of the light and heavy chains.

[0184] The terms “VH” and “VH domain” are used interchangeably and refer to the variable region of the heavy chain of an antibody.

[0185] As used herein, the term "heavy chain," when used to refer to an antibody, can refer to any different type of amino acid sequence based on a constant region, such as α (alpha), δ (delta), ε (epsilon), γ (gamma), and μ (mu), which produce antibodies of the IgA, IgD, IgE, IgG, and IgM classes, including subclasses of IgG, such as IgG1, IgG2, IgG3, and IgG4. Heavy chain amino acid sequences are well known in the art. In some embodiments, the heavy chain is the human heavy chain.

[0186] The terms “VL” and “VL domain” are used interchangeably and refer to the variable region of the light chain of an antibody.

[0187] As used herein, the term "light chain" when used to refer to an antibody can refer to any different type based on the amino acid sequence of the constant region, such as κ (kappa) or λ (lambda). Light chain amino acid sequences are well known in the art. In some embodiments, the light chain is a human light chain.

[0188] The term "variable region" or "variable domain" refers to the amino-terminal domain of the heavy or light chain of an antibody. Variable domains in the heavy and light chains are referred to as "VH" and "VL," respectively. These domains are typically the most variable parts of an antibody (relative to other antibodies of the same class) and contain antigen-binding sites. Generally, the variable region or variable domain is typically about 110 to 120 amino acids or 110 to 125 amino acids at the amino terminus in the mature heavy chain and about 90 to 115 amino acids in the mature light chain.

[0189] The term "Fv" or "variable fragment" refers to the smallest antibody fragment containing a complete antigen-binding site and consisting of a dimer of a heavy chain variable region (VH) and a light chain variable region (VL). The folding of these two domains produces six hypervariable rings (three rings each in the H chain and L chain), which facilitate antigen binding of amino acid residues and confer antigen-binding specificity to the antibody.

[0190] As used herein, the term "constant region" refers to a region of an antibody that is not a variable region of the antibody, such as the carboxyl-terminal portion of the light and / or heavy chains. It does not directly participate in antibody-antigen binding but can exhibit various effector functions, such as interaction with Fc receptors. The constant region of an immunoglobulin molecule typically has a more conserved amino acid sequence than the variable domain of the immunoglobulin. In some embodiments, the antibody or antigen-binding fragment contains a constant region or a portion thereof sufficient to achieve antibody-dependent cell-mediated cytotoxicity (ADCC).

[0191] "Constant domains" refer to the domains within constant regions that are capable of forming immunoglobulin folds. Constant domains include the CH1, CH2, CH3, and CL domains.

[0192] The term "antibody fragment" refers to a portion of an antibody. An "antigen-binding fragment" of an antibody refers to the portion of the antibody that binds to an antigen. An antigen-binding fragment of an antibody may contain an antigen-determining region (e.g., a complementarity-determining region (CDR)). Examples of antigen-binding fragments of antibodies include, but are not limited to, Fab, Fab', F(ab')2, and Fv fragments, linear antibodies, and single-chain antibodies. An antigen-binding fragment of an antibody can be monovalent or polyvalent (e.g., bivalent). An antigen-binding fragment of an antibody can be monospecific or multispecific (e.g., bispecific). An antigen-binding fragment of an antibody can be derived from any animal species, such as rodents (e.g., mice, rats, or hamsters) and humans, or can be artificially generated.

[0193] The term "Fab" or "fragment antigen-binding region" refers to the region in an antibody that binds to an antigen. It consists of a constant domain, a variable domain of the heavy chain, and a variable domain of the light chain. Each Fab fragment is monovalent in terms of antigen binding, meaning it has a single antigen-binding site.

[0194] The term "F(ab')2 fragment" refers to an antibody fragment produced by pepsin digestion of a whole IgG antibody, which removes most of the Fc region while retaining some of the hinge region. The F(ab')2 fragment has two antigen-binding F(ab) moieties linked together by disulfide bonds and is therefore divalent, with a molecular weight of approximately 110 kDa. The Fab' fragment differs from the Fab fragment in that it has a C... H The carboxyl terminus of the 1 domain has a few additional residues, including one or more cysteine ​​residues from the antibody hinge region. Fab'-SH is the name of Fab' in which the cysteine ​​residues of the constant domain carry a free thiol group.

[0195] As used herein, an "Fc fragment," "fragment crystallizable region," or "Fc region" comprises two or more polypeptides, each of which is an antibody heavy chain fragment and each polypeptide contains at least one (e.g., two or three) heavy chain constant domains. In some embodiments, the Fc region comprises two heavy chain fragments, each containing a CH2 domain and a CH3 domain. Although the boundaries of the Fc region of an immunoglobulin heavy chain can vary, the human IgG heavy chain Fc region is generally defined as extending from an amino acid residue at position Cys226 or from Pro230 to its carboxyl terminus. The C-terminal lysine of the Fc region (residue 447 according to the EU numbering system) may be removed, for example, during antibody production or purification, or by recombinant engineering of the nucleic acid encoding the antibody heavy chain. Thus, the Fc region may not contain any K447 residues, may contain at least one polypeptide containing K447 residues and at least one polypeptide not containing K447 residues, or may contain only a polypeptide including K447 residues. Suitable native sequence Fc regions for use in this disclosure include human IgG1, IgG2, IgG3, and IgG4. In native antibodies, the Fc region refers to a region of the antibody that interacts with cell surface receptors (called Fc receptors) and proteins of the complement system. However, as used herein, the Fc region can be modified to increase, decrease, or eliminate interactions with Fc receptors and / or proteins of the complement system. In native IgG, IgA, and IgD antibody isotypes, the Fc region consists of two identical protein fragments derived from the second and third constant domains of the two heavy chains of the antibody. However, as used herein, the two or more polypeptides in the “Fc region” do not need to have identical sequences. In some embodiments, the “Fc region” comprises a first polypeptide containing an Fc domain with a mortise mutation (e.g., the IgG1 Fc domain) and a second polypeptide containing an Fc domain with a mortise mutation (e.g., the IgG1 Fc domain). In native IgM and IgE antibody isotypes, the Fc region contains three heavy chain constant domains (CH domains 2-4) in each polypeptide chain.

[0196] The "native sequence Fc region" contains the same amino acid sequence as the Fc region found in nature. The native sequence human Fc region includes the native sequence human IgG1 Fc region (non-A and A allotypes); the native sequence human IgG2 Fc region; the native sequence human IgG3 Fc region; and the native sequence human IgG4 Fc region.

[0197] The “variant Fc region” comprises an amino acid sequence that differs from the amino acid sequence of the native Fc region due to at least one amino acid modification, or in some embodiments, substitution of two or more amino acids. In some embodiments, the variant Fc region has at least one amino acid substitution in the native Fc region or the Fc region of the parent polypeptide compared to the native Fc region or the Fc region of the parent polypeptide, for example, about one to about ten amino acid substitutions, and in some embodiments, about one to about five amino acid substitutions. In some embodiments, the variant Fc region has at least 80% homology with the native Fc region and / or with the Fc region of the parent polypeptide, at least 90% homology with it, or at least 95% homology with it.

[0198] The term "Fc domain" refers to one or more domains, such as CH2 or CH3 domains, within the Fc region of a single polypeptide. In some aspects, an Fc domain includes at least one amino acid deletion, addition, or substitution compared to the amino acid sequence of the native Fc domain, for example, by including a set of "mortar and pestle" deletions, additions, or substitutions, or by including amino acid deletions, additions, or substitutions for achieving electrostatic reorientation of the Fc domain to facilitate attractive interactions between different polypeptide chains. In some aspects, the Fc domain is in the form of a "mortar and pestle."

[0199] The term "single-chain Fv," also abbreviated as "sFv" or "scFv," refers to an antibody fragment containing VH and VL antibody domains that form a single polypeptide chain. In some embodiments, the scFv polypeptide contains V... H With V L A polypeptide linker between structural domains, which enables scFv to form the structure required for antigen binding.

[0200] The term "bifunctional antibody" refers to an antibody produced by using V... H With V L Small antibody fragments are prepared by constructing sFv fragments using short linkers (approximately 5-10 residues) between structural domains, enabling inter-chain rather than intra-chain pairing of variable structural domains, thereby producing bivalent fragments (i.e., fragments with two antigen-binding sites). Bispecific bifunctional antibodies are heterodimers of two “crossover” scFv fragments, where the V of each antibody... H and V L Domains exist on different polypeptide chains.

[0201] The term “CDR” or “complementarity-determining region” refers to the hypervariable region (“HVR”) in the variable region of an immunoglobulin, which determines antibody diversity and antigen specificity.

[0202] The term "Kabat number" and similar terms are recognized in the art and refer to a numbering system for amino acid residues in the variable regions of the heavy and light chains of an antibody or its antigen-binding fragment. In some embodiments, the CDR may be determined according to the Kabat numbering system (see, for example, Kabat EA and Wu TT (1971) Ann NY Acad Sci 190: 382-391, and Kabat EA et al., (1991) Sequences of Proteins of Immunological Interest, 5th edition, US Department of Health and Human Services, NIH Publication No. 91-3242). Using the Kabat numbering system, the CDR within the antibody heavy chain molecule is typically located at amino acid positions 31 to 35 (which may optionally include one or two additional amino acids following 35 (referred to as 35A and 35B in the Kabat numbering scheme)) (CDRH1), amino acid positions 50 to 65 (CDRH2), and amino acid positions 95 to 102 (CDRH3). Using the Kabat numbering system, CDRs within antibody light chain molecules are typically located at amino acid positions 24 to 34 (CDRL1), 50 to 56 (CDRL2), and 89 to 97 (CDRL3).

[0203] The term “Chothia” refers to the location of the structural ring (see, for example, Chothia C and Lesk AM, (1987), J Mol Biol 196: 901-917; Al-Lazikani B et al., (1997) J Mol Biol 273: 927-948; Chothia C et al., (1992) J Mol Biol 227: 799-817; Tramontano A et al., (1990) J MolBiol 215(1): 175-82; and U.S. Patent No. 7,709,226). In some embodiments, the Chothia residues are numbered as shown in the table below. In some embodiments, the CDR is a Chothia CDR.

[0204] The AbM hypervariable region represents a compromise between the Kabat CDR and the Chothia structural loop, and is used in OxfordMolecular's AbM antibody modeling software. In some implementations, the CDR is the AbM CDR.

[0205] In some implementations, the CDR can be a "contact" CDR. A "contact" CDR is based on the analysis of available complex crystal structures. In some implementations, the CDR is a "contact" CDR.

[0206] The residues of each of these CDRs are listed below.

[0207] CDRs may include the following “extended CDRs”: 24-36 or 24-34 (L1), 46-56 or 50-56 (L2), and 89-97 or 89-96 (L3) in VL, and 26-35 (H1), 50-65 or 49-65 (H2), and 93-102, 94-102, or 95-102 (H3) in VH. The variable domain residues are numbered according to Kabat et al., ibid., for each of these extended CDR definitions.

[0208] CDRs can also be identified according to the IMGT numbering system, as described in Lefranc MP, (1999) The Immunologist 7: 132-136 and Lefranc MP et al., (1999) Nucleic Acids Res 27: 209-212. According to the IMGT numbering scheme, VH-CDR1 is located at positions 26 to 35, VH-CDR2 at positions 51 to 57, VH-CDR3 at positions 93 to 102, VL-CDR1 at positions 27 to 32, VL-CDR2 at positions 50 to 52, and VL-CDR3 at positions 89 to 97.

[0209] The term "monoclonal" when referring to an antibody or its antigen-binding fragment refers to a homogeneous group of antibodies or antigen-binding fragments that participate in the highly specific recognition and binding of a single antigenic determinant or epitope. This contrasts with polyclonal antibodies, which typically comprise different antibodies targeting different antigenic determinants. The term "monoclonal" antibody or its antigen-binding fragment encompasses full-length and complete monoclonal antibodies, as well as antibody fragments (such as Fab, Fab', F(ab')2, Fv), single-chain (scFv) mutants, fusion proteins containing antibodies or antibody moieties, and any other modified immunoglobulin molecules containing antigen recognition sites. Furthermore, "monoclonal" antibody or its antigen-binding fragment refers to such antibodies and their antigen-binding fragments prepared in a variety of ways, including but not limited to hybridomas, phage selection, recombinant expression, and transgenic animals.

[0210] The term "chimeric" antibody or antigen-binding fragment thereof refers to an antibody or antigen-binding fragment thereof whose amino acid sequence is derived from two or more species. Typically, the variable regions of the light and heavy chains correspond to the variable regions of antibodies or antigen-binding fragments thereof derived from one mammalian species (e.g., mouse, rat, rabbit, etc.) and possessing the desired specificity, affinity, and ability, while the constant regions are homologous to sequences in antibodies or antigen-binding fragments thereof derived from another mammalian species (typically human) to avoid inducing an immune response in said species.

[0211] The term “humanized” antibody or its antigen-binding fragment refers to the form of a non-human (e.g., murine) antibody or antigen-binding fragment that is a specific immunoglobulin chain, a chimeric immunoglobulin, or a fragment containing a minimal non-human (e.g., murine) sequence. Typically, humanized antibodies or their antigen-binding fragments are human immunoglobulins in which residues of the complementarity-determining region (CDR) are replaced by residues of the CDR of a molecule derived from a non-human species (e.g., mouse, rat, rabbit, hamster) and having the desired specificity, affinity, and ability (“CDR transplantation”) (Jones et al., Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-327 (1988); Verhoeyen et al., Science 239:1534-1536 (1988)). Humanized antibodies or their antigen-binding fragments can be further modified by substituting additional residues in the Fv frame region and / or within the replaced non-human residues to refine and optimize the specificity, affinity, and / or capability of the antibody or its antigen-binding fragment. Generally, humanized antibodies or their antigen-binding fragments will contain VH and VL, which contain at least one and typically substantially all of two or three CDR regions corresponding to non-human immunoglobulins, while all or substantially all of the FR regions are those common sequences of human immunoglobulins. Humanized antibodies or their antigen-binding fragments may also contain at least a portion of the immunoglobulin constant region or Fc region (typically the constant region or Fc region of a human immunoglobulin). Examples of methods for generating humanized antibodies are described in U.S. Patent 5,225,539; Roguska et al., Proc. Natl. Acad. Sci., USA, 91(3):969-973 (1994), and Roguska et al., Protein Eng. 9(10):895-904 (1996). In some embodiments, the “humanized antibody” is a surface remodeling antibody.

[0212] The term "human" antibody or antigen-binding fragment thereof means an antibody or antigen-binding fragment thereof having an amino acid sequence derived from a human immunoglobulin locus, wherein such antibody or antigen-binding fragment is prepared using any technique known in the art. This definition of human antibody or antigen-binding fragment thereof includes both full-length and fragmented antibodies.

[0213] “Frame” or “FR” residues are those variable domain residues other than CDR residues as defined in this paper.

[0214] As used in this article, the "recipient human framework" refers to a framework containing V derived from the human immunoglobulin framework or the human common framework. L or V H The frame of amino acid sequences. Receptor human frames “derived” from human immunoglobulin frames or human common frames may contain their same amino acid sequences, or they may contain pre-existing amino acid sequence variations. In some embodiments, the number of pre-existing amino acid variations is 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. When pre-existing amino acid variations are present in VH, in some embodiments, those variations are present only at three, two, or one of positions 71H, 73H, and 78H; for example, the amino acid residues at those positions may be 71A, 73T, and / or 78A. In some embodiments, the VL receptor human frame sequence is consistent with the V... L The human immunoglobulin framework sequence or the human common framework sequence is the same.

[0215] The "human shared framework" represents the framework for human immunoglobulin V. L or V H The selection of the framework sequence is based on the most frequently occurring amino acid residues. Typically, human immunoglobulin V... L or V H The sequence selection is from a subgroup of variable domain sequences. Typically, this subgroup is one such as those in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Edition, Public Health Service, National Institutes of Health, Bethesda, MD (1991). Examples include those for V L The subgroup can be subgroup κ I, κ II, κ III, or κ IV, as in Kabat et al., ibid. Additionally, for V... H The subgroup can be subgroup I, subgroup II or subgroup III, as Kabat et al., ibid.

[0216] For example, "amino acid modification" at a specified position in the antibody of this disclosure refers to the substitution or deletion of a specified residue, or the insertion of at least one amino acid residue adjacent to a specified residue. Insertion of a "adjacent" specified residue means insertion into one or two residues therein. The insertion can be at the N-terminus or C-terminus of the specified residue. In some embodiments, the amino acid modification is a substitution.

[0217] Antibody "effector functions" refer to those biological activities attributable to the Fc region of the antibody (the native sequence Fc region or the amino acid sequence variant Fc region), and these vary with antibody isotypes.

[0218] The term "Fc receptor" or "FcR" describes a receptor that binds to the Fc region of an antibody. In some embodiments, the FcR is a native human FcR. In some embodiments, the FcR is an FcR (γ receptor) that binds to IgG antibodies and includes receptors of the FcγRI, FcγRII, and FcγRIII subclasses, including allelic variants and alternative splice forms of these receptors. FcγRII receptors include FcγRIIA ("activating receptor") and FcγRIIB ("inhibitory receptor"), which have similar amino acid sequences, differing primarily in their cytoplasmic domains. The activating receptor FcγRIIA contains an activating motif ("ITAM") based on the immunoreceptor tyrosine residue in its cytoplasmic domain. The inhibitory receptor FcγRIIB contains an inhibitory motif ("ITIM") based on the immunoreceptor tyrosine residue in its cytoplasmic domain. The term "FcR" as used herein encompasses other FcRs, including those to be identified in the future. FcRs can also increase the serum half-life of antibodies.

[0219] "Binding affinity" generally refers to the total strength of all non-covalent interactions between a single binding site of a molecule (e.g., an antibody or its antigen-binding fragment) and its conjugate (e.g., an antigen). Unless otherwise indicated, as used herein, "binding affinity" refers to the intrinsic binding affinity that reflects a 1:1 interaction between members of a binding pair (e.g., an antibody or its antigen-binding fragment and an antigen). The affinity of molecule X for its conjugate Y can generally be expressed using the equilibrium dissociation constant (K0). d Affinity can be measured and / or expressed in a variety of ways known in the art, including but not limited to the equilibrium dissociation constant (K). D ) and equilibrium association constant (K A K D By k 解离 / k 缔合 The quotient is calculated, and K A By k 缔合 / k 解离 The quotient is calculated from k. 缔合 This refers to, for example, the association rate constant between an antibody or its antigen-binding fragment and the antigen, while k...解离 This refers to the rate constant, for example, the dissociation of an antibody or its antigen-binding fragment from an antigen. 缔合 and k 解离 It can be determined by techniques known to those skilled in the art, such as BIAcore. ® Or KinExA. The dissociation constant can be determined by any analytical technique, including any biochemical or biophysical technique, such as ELISA, surface plasmon resonance (SPR), biolayer interferometry (see, for example, ForteBio's Octet system), isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), circular dichroism (CD), stop-flow analysis, and colorimetric or fluorescent protein melting analysis. (See, for example, Estep et al., (2013)) MAbs 5(2):270-8.) Regarding the binding of antibodies to target molecules, the terms "specific binding" or "specifically binds," or "specific to a specific peptide or epitope on a specific peptide target," mean a binding that is measurably distinct from nonspecific interactions. Specific binding can be measured, for example, by determining the binding of a molecule and comparing it to the binding of a control molecule. For example, specific binding can be determined by competition with a control molecule similar to the target (e.g., an excess of unlabeled target). In this case, if the excess of unlabeled target competitively inhibits the binding of the labeled target to the probe, then specific binding is indicated. As used herein, the terms "specific binding" or "specifically binds," or "specific to a specific peptide or epitope on a specific peptide target," can be demonstrated, for example, by molecules having a KD of approximately 10 for the target. -4 M or lower, 10 -5 M or lower, 10 -6 M or lower, 10 -7 M or lower, 10 -8 M or lower, 10 -9 M or lower, 10 -10 M or lower, 10 -11 M or lower, 10 -12 M or lower, or KD in the range of 10 -4 M to 10 -6 M or 10 - 6 M to 10 -10 M or 10 -7 M to 10 -9Within the M range. As a skilled technician will understand, affinity and KD value are negatively correlated. High affinity for an antigen is measured by a low KD value. In some embodiments, the term "specific binding" refers to binding in which a molecule binds to a specific polypeptide or an epitope on a specific polypeptide without substantially binding to any other polypeptide or polypeptide epitope.

[0220] The term "linker" or "connector" refers to a covalent link between two polypeptides or two heterologous molecules. In some embodiments, the linker is a chemical linker. In some embodiments, the linker comprises a peptide bond, and the two polypeptides or two heterologous molecules are linked to each other directly or via one or more additional amino acids. A glycine linker is a linker that contains one or more glycines but no other amino acids, such as GGGG (SEQ ID NO: 3). A glycine-rich linker is a linker that contains one or more glycines and may contain other amino acids, as long as glycine is the dominant substance in the linker, such as GGGNGG (SEQ ID NO: 4), where N is any amino acid. A glycine-serine linker is a linker that contains glycine and serine in any proportion, such as GGGS (SEQ ID NO: 5). Similarly, a proline linker is a linker that contains one or more prolines but no other amino acids. A proline-rich linker is a linker that contains one or more prolines and may contain other amino acids, as long as proline is the dominant substance in the linker.

[0221] As used herein, “amino acid sequence identity percentage (%)” and “homology” for peptide, polypeptide, or antibody sequences refer to the percentage of amino acid residues in a candidate sequence that are identical to amino acid residues in a specific peptide or polypeptide sequence after the sequences have been aligned and gaps have been introduced where necessary to achieve the maximum sequence identity percentage, regardless of any conserved substitutions as identical matches. Alignments used to determine the amino acid sequence identity percentage can be performed in various ways within the skill of the art, such as using publicly available computer software, such as BLAST, BLAST-2, ALIGN, or MEGALIGN™ (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignments, including any algorithms known in the art required to achieve maximum alignment across the full length of the sequences being compared.

[0222] "Isolated" peptides, antibodies, polynucleotides, vectors, cells, or compositions are peptides, antibodies, polynucleotides, vectors, cells, or compositions in a form not found in nature. Isolated peptides, antibodies, polynucleotides, vectors, cells, or compositions include those that have been purified to the point that they no longer appear in their naturally occurring form. In some embodiments, the isolated antibodies, polynucleotides, vectors, cells, or compositions are substantially pure.

[0223] As used in this article, “substantially pure” means material that is at least 50% pure (i.e., free of contaminants), at least 90% pure, at least 95% pure, at least 98% pure, or at least 99% pure.

[0224] The term "expression system" refers to one or more nucleic acid molecules comprising coding and control sequences in an operatively linked manner, together with host cells and / or other in vitro transcription and translation mechanisms, enabling the production of one or more proteins encoded by said nucleic acid molecules.

[0225] As used herein, the term "vector" is intended to refer to a nucleic acid molecule capable of transporting another nucleic acid to which it is linked. One type of vector is a "plasmid," which is a circular double-stranded DNA in which an additional DNA segment can be linked. Another type of vector is a bacteriophage vector. Another type of vector is a viral vector, in which an additional DNA segment can be linked to a viral genome. Some vectors are capable of autonomous replication in a host cell in which they are introduced (e.g., bacterial vectors with bacterial origins of replication and free mammalian vectors). Other vectors (e.g., non-free mammalian vectors) can integrate into the host cell's genome after introduction into the host cell and thereby replicate along with the host genome. Furthermore, some vectors are capable of directing the expression of genes operatively linked to them. Such vectors are referred to herein as "recombinant expression vectors," or simply "expression vectors." Generally, expression vectors useful in recombinant DNA technology are usually in the form of plasmids. In this specification, "plasmid" and "vector" are used interchangeably because plasmids are the most commonly used form of vector.

[0226] As used interchangeably in this document, “polynucleotide” or “nucleic acid” refers to a polymer of nucleotides of any length, including DNA and RNA. Nucleotides can be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases and / or their analogues, or any substrate that can be incorporated into the polymer by DNA or RNA polymerase or by a synthetic reaction.

[0227] "Host cell" includes an individual cell or cell culture that may be, or is already, a recipient of a vector for incorporating a polynucleotide intercalation. Host cells include the offspring of a single host cell, and said offspring may not necessarily be identical to the original parent cell (morphologically or in terms of genomic DNA complement) due to natural, accidental, or intentional mutations. Host cells include cells transfected in vivo with the polynucleotides of this disclosure. In some aspects, said host cell is an isolated host cell.

[0228] As used herein, “carrier” includes pharmaceutically acceptable carriers, excipients, or stabilizers that are non-toxic to cells or mammals exposed to them at the doses and concentrations used.

[0229] As used herein, the term "treatment" refers to a clinical intervention designed to alter the natural processes of an individual being treated during the course of clinicopathology. Desired therapeutic effects may include a reduction in the rate of progression, improvement or alleviation of the pathological state, and recovery or improved prognosis of a specific disease, condition, or disorder. For example, if one or more symptoms associated with a specific disease, condition, or disorder are reduced or eliminated, then the individual is successfully "treated."

[0230] As used herein, the terms “administer”, “administering”, “administration”, etc., refer to methods that can be used to deliver a drug (e.g., an anti-human antibody or its antigen-binding fragment) to a desired biological site of action.

[0231] "Effective amount" means at least the amount that, at the necessary dose and for the necessary duration, effectively achieves the desired therapeutic outcome. An effective amount may be provided in one or more administrations. An effective amount is also the amount in which any toxic or adverse effects of treatment are outweighed by the beneficial effects of treatment. For therapeutic use, beneficial or desired outcomes include clinical results such as relief of one or more symptoms caused by the disease, increased quality of life for the patient, reduced doses of other drug treatments required to treat the disease, enhanced effects of another drug treatment, such as through targeted therapy, delayed disease progression, and / or prolonged survival. An effective amount of a drug, compound, or pharmaceutical composition is an amount sufficient to achieve therapeutic treatment directly or indirectly. As understood in clinical context, an effective amount of a drug, compound, or pharmaceutical composition may or may not be achieved in combination with another drug, compound, or pharmaceutical composition. Therefore, an "effective amount" may be considered in the context of administration of one or more therapeutic agents, and a single agent may be considered to have been administered at an effective amount if, in combination with one or more other agents, the desired outcome is achieved or realized.

[0232] As used herein, the terms "subject" and "patient" are used interchangeably. A subject can be a mammal, such as a non-human animal (e.g., a cow, pig, horse, cat, dog, rat, mouse, monkey, or other primate). In some embodiments, the subject is a cynomolgus monkey. In some embodiments, the subject is a human.

[0233] As used herein, administration in “combination” or “in combination” with another compound or composition includes simultaneous administration and / or administration at different times. Combination administration also encompasses administration as a co-preparation or as a standalone composition, including administration at different frequencies or time intervals and using the same or different routes of administration. In some embodiments, combination administration is administration as part of the same treatment regimen.

[0234] As used herein, the terms “about” and “approximately” when used to modify numerical values ​​or ranges indicate deviations of up to 10% above the value or range and down to 10% below the value or range that are still within the intended meaning of the value or range. It should be understood that wherever the terms “about” or “approximately” are used in this document to describe a numerical value or range, other similar aspects referring to a specific numerical value or range are also provided.

[0235] Unless the context clearly indicates otherwise, as used herein and in the appended claims, the singular forms “a / an” and “the” include a plural number of references. For example, reference to “antibody” refers to one or more antibodies, such as molar amounts, and includes equivalents known to those skilled in the art, etc.

[0236] It should be understood that aspects described herein using the language "comprises" are also provided for other similar aspects described using "consisting of" and / or "consisting essentially of". In this disclosure, "comprises," "containing," and "having" can mean "includes," etc.; "consisting essentially of" is open-ended and allows for more than the stated content, as long as the essential or novel features of the stated content are not altered by the presence of more than the stated content, but does not include prior art aspects.

[0237] I. A complex containing granule protein precursor peptides In some respects, this article provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to the human transferrin receptor (TfR).

[0238] In some respects, this document provides a complex comprising an antigen-binding domain linked to a granule protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to a human transferrin receptor (TfR), wherein the PGRN polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, wherein X1 is any amino acid, and wherein X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL.

[0239] In some respects, this document provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to the human transferrin receptor (TfR) and is not located within the Fc domain of the complex.

[0240] In some respects, this article provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human CD98 heavy chain (CD98hc).

[0241] In some aspects, the “1+1 form” of a complex containing an anti-TfR antigen-binding domain refers to a form comprising (i) an antigen-binding domain that binds to human TfR; (ii) a pregranular protein RN (PGRN) polypeptide; and (iii) optionally, an Fc domain or Fc region. In some aspects, the “1+1 form” of a complex containing an anti-CD98hc antigen-binding domain refers to a form comprising (i) an antigen-binding domain that binds to human CD98hc; (ii) a pregranular protein RN (PGRN) polypeptide; and (iii) optionally, an Fc domain or Fc region. See, for example, [link to relevant documentation]. Figure 1A-1D , Figure 1I and Figure 1H In some implementations, the Fc domain is a single-priced Fc (see [link to implementation]). Figure 1A , Figure 1B ).

[0242] In some respects, the “2+1 form” of a complex containing an anti-TfR antigen-binding domain refers to a form comprising (i) an antigen-binding domain that binds to human TfR, (ii) two granule protein precursor (PGRN) peptides, and (iii) optionally, an Fc domain or Fc region. As used herein, the “2+1 form” of a complex containing an anti-CD98hc antigen-binding domain refers to a form comprising (i) an antigen-binding domain that binds to human CD98hc, (ii) two granule protein precursor (PGRN) peptides, and (iii) optionally, an Fc domain or Fc region. See, for example, [link to relevant documentation]. Figure 1E-1F .

[0243] In some respects, the “1+2 form” of a complex containing an anti-TfR antigen-binding domain refers to a form comprising (i) two antigen-binding domains that bind to human TfR, (ii) a pregranular protein RN (PGRN) polypeptide, and (iii) optionally, an Fc domain or Fc region. As used herein, the “1+2 form” of a complex containing an anti-CD98hc antigen-binding domain refers to a form comprising (i) two antigen-binding domains that bind to human CD98hc, (ii) a pregranular protein RN (PGRN) polypeptide, and (iii) optionally, an Fc domain or Fc region. See, for example, [link to relevant documentation]. Figure 1E-1F .

[0244] In some aspects, the “2+2 form” of a complex containing an anti-TfR antigen-binding domain refers to a form comprising (i) two antigen-binding domains that bind to human TfR, and (ii) two granule protein precursor (PGRN) polypeptides, and (iii) optionally, an Fc domain or Fc region. In some aspects, the “2+2 form” of a complex containing an anti-CD98hc antigen-binding domain refers to a form comprising (i) two antigen-binding domains that bind to human TfR, and (ii) two granule protein precursor (PGRN) polypeptides, and (iii) optionally, an Fc domain or Fc region. See, for example, [link to relevant documentation]. Figure 1G-1H .

[0245] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2 and CH3; and (iii) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. See, for example, [link to relevant documentation]. Figure 2C .

[0246] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from N-terminus to C-terminus, VH, CH1, a hinge region, CH2, and CH3; (ii) a second polypeptide comprising, from N-terminus to C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (iii) a third polypeptide comprising, from N-terminus to C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain that specifically binds to human TfR. See, for example, [link to relevant documentation]. Figure 2B .

[0247] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (iii) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. See, for example, [link to relevant documentation]. Figure 2D .

[0248] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; and (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. See, for example, [link to relevant documentation]. Figure 2A .

[0249] II. Granulin precursor (PGRN) polypeptide This article provides a complex comprising an antigen-binding domain linked to a granulocyte precursor protein (PGRN) polypeptide. The antigen-binding domain specifically binds to human transferrin receptor (TfR) or human CD98 heavy chain (CD98hc) to facilitate the transport of the PGRN polypeptide across the blood-brain barrier (BBB). Isolated PGRN polypeptides are also provided.

[0250] Granulin precursor is also known as PGRN, preepithelium, granulin-epithelium precursor, PC (prostate cancer) cell-derived growth factor (PCDGF), and acrosin. Granulin precursor is a 593-amino acid protein encoding a 68.5 kDa secretory glycoprotein with 7.5 repeats of a smaller granulin (epithelium) motif ranging from 6 to 25 kDa, which can be cleaved from the precursor PGRN protein. Examples of granulin precursor cleavage products include, but are not limited to, granulin A / epithelium 1, granulin B / epithelium 2, granulin C, granulin D, granulin E, granulin F, granulin G, and any other known peptide products derived from granulin precursor.

[0251] Granulin precursors are widely expressed and have been involved in a variety of events in non-neuronal cells, such as cell cycle regulation and cell motility, wound healing, inflammation, induction of growth factors such as vascular endothelial growth factor (VEGF), and tumorigenesis. Granulin precursors are also widely expressed in early neuronal development, but later development is limited to specific neuronal populations, such as cortical neurons, hippocampal pyramidal neurons, and Purkinje cells. However, the role of granulin precursors in neurons was unclear until patients with frontotemporal dementia (FTD) showed mutations in the granulin precursor gene on chromosome 17. Subsequently, granulin precursors have been shown to promote neuronal survival and enhance neurite growth in cortical and motor neurons. Therefore, although granulin precursors are not neurotrophic proteins or members of the neurotrophic protein family, they have been referred to as neurotrophic factors due to their ability to promote neuronal survival.

[0252] Furthermore, haplotype deficiency of granulin precursors (which includes more than 70 different mutations, such as loss-of-function mutations) has been shown to be associated with frontotemporal dementia (FTD) with TDP-43 pathology. In addition, plasma granulin precursor levels are reduced in patients with FTD mutations. Granulin precursor mutations account for 25% of familial FTD. Moreover, low levels of granulin precursors are observed in some FTD patients without granulin precursor mutations, and granulin precursor levels are altered in Alzheimer's disease and ALS. Therefore, it is believed that granulin precursors may be universally associated with degenerative diseases.

[0253] It has also been shown that complete loss of granulin precursors leads to the neuronal ceroid lipofuscin deposition (NPL) phenotype. Therefore, it is believed that individuals with various lysosomal storage disorders may respond to increased levels of granulin precursors. Granulin precursors are widely expressed and produced by neurons and microglia in the central nervous system. Granulin precursors are also generally considered to have anti-inflammatory effects in macrophages and microglia, and pro-survival effects in neurons.

[0254] Therefore, the complex and isolated PGRN mutant peptide that increase granulin precursor levels presented in this article will be beneficial for the prevention, risk reduction, or treatment of disorders and / or diseases associated with reduced granulin precursor expression and / or activity, cell death (e.g., neuronal cell death), frontotemporal dementia, Alzheimer's disease, vascular dementia, seizures, retinal dystrophy, traumatic brain injury, spinal cord injury, chronic depression, atherosclerotic vascular disease, unwanted symptoms of normal aging, dementia, mixed dementia, Creutzfeldt-Jakob disease, normal pressure hydrocephalus, amyotrophic lateral sclerosis, Huntington's disease, tau proteinosis, stroke, acute trauma, chronic trauma, lupus. Acute and chronic colitis, Crohn's disease, inflammatory bowel disease, ulcerative colitis, malaria, essential tremor, central nervous system lupus, Behcet's disease, Parkinson's disease, Lewy body dementia, multiple system atrophy, degenerative intervertebral disc disease, Shy-Drager syndrome, progressive supranuclear palsy, corticobasal degeneration, acute disseminated encephalomyelitis, granulomatous diseases, sarcoidosis, age-related diseases, age-related macular degeneration, glaucoma, retinitis pigmentosa, retinal degeneration, respiratory infections, sepsis, eye infections, systemic infections, inflammatory diseases, arthritis, multiple sclerosis, metabolic diseases, obesity, insulin resistance, type 2 diabetes, tissue or vascular damage, injury and / or one or more unwanted symptoms of normal aging.

[0255] In some embodiments, this disclosure provides a complex and an isolated PGRN mutant peptide that increases granule protein precursor levels, increases PGRN stability, maintains similar binding affinity to sorting proteins compared to wild-type PGRN, and exhibits GCase activity. In some embodiments, the complex binds to human sorting proteins with a dissociation constant (K0). D ) lies in the range of approximately 5 nM to approximately 400 nM, where K D The capture kinetics were determined by capture kinetic analysis (see, for example, Example 6). In some embodiments, the capture kinetics analysis was performed on a Carterra LSA. In some embodiments, the complex binds to a human sorting protein, whose K... D The concentration ranges from about 50 nM to about 350 nM. In some embodiments, the complex binds to human sorting proteins, whose K... D It ranges from approximately 100 nM to approximately 300 nM.

[0256] In some embodiments, the complex increases cellular GCase activity more than the PGRN mutant peptide alone, wherein GCase activity is determined by in vitro GCase activity assays (see, for example, Example 7). In some embodiments, GCase activity assays are performed by flow cytometry. In some embodiments, the complex increases cellular GCase activity by at least about 0.5-fold, at least about 1-fold, or at least about 2-fold compared to the PGRN mutant peptide alone.

[0257] A. A complex containing granule protein precursor peptides In some aspects, this document provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to the human transferrin receptor (TfR). In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide, wherein the PGRN polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, wherein X1 is any amino acid, and wherein X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL. In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A.

[0258] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human TfR, and a PGRN polypeptide selected from the following: PGRN (wt), PGRN_1, PGRN_2, PGRN_3, PGRN_4, PGRN_5, PGRN_6, PGRN_7, PGRN_8, PGRN_9, PGRN_10, PGRN_11, PGRN_12, PGRN_13, PGRN_14, PGRN_15, PGRN_16, PGRN_17, PGRN_18, PGRN_19, PGRN_20, PGRN_21, PGRN_22, PGRN_23, PGRN_24, PGRN_25, PGRN_26, PGRN_27, PGRN_28, PGRN_29, PGRN_30, PGRN_31, PGRN_32, PGRN_33, PGRN_34, PGRN_35, or PGRN_36. (For example, as shown in Table 1).

[0259] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human TfR and a PGRN polypeptide, wherein the PGRN polypeptide comprises an amino acid sequence having at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity with the amino acid sequence of SEQ ID NO: 230. In some embodiments, the PGRN polypeptide comprises an amino acid sequence containing substitutions (e.g., conserved substitutions, insertions, or deletions relative to the amino acid sequence of SEQ ID NO: 230) but retaining the ability to bind to sorting proteins. In some embodiments, in the amino acid sequence of the PGRN polypeptide of SEQ ID NO: 230, at most one, at most two, at most three, at most four, or at most five amino acids are substituted, inserted, and / or deleted.

[0260] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human TfR and a PGRN polypeptide, wherein the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 233, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 24 ... ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0261] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a pre-granule protein (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to human CD98 heavy chain (CD98hc). In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN polypeptide comprises the amino acid sequence of SEQ ID NO: 330, and wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P, and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K, and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I, and A.

[0262] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human CD98hc, and a PGRN polypeptide selected from the following: PGRN (wt), PGRN_1, PGRN_2, PGRN_3, PGRN_4, PGRN_5, PGRN_6, PGRN_7, PGRN_8, PGRN_9, PGRN_10, PGRN_11, PGRN_12, PGRN_13, PGRN_14, PGRN_15, PGRN_16, PGRN_17, PGRN_18, PGRN_19, PGRN_20, PGRN_21, PGRN_22, PGRN_23, PGRN_24, PGRN_25, PGRN_26, PGRN_27, PGRN_28, PGRN_29, PGRN_30, PGRN_31, PGRN_32, PGRN_33, PGRN_34, PGRN_35, or PGRN_36. (For example, as shown in Table 1).

[0263] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human CD98hc and a PGRN polypeptide, wherein the PGRN polypeptide comprises an amino acid sequence having at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity with the amino acid sequence of SEQ ID NO: 230. In some embodiments, the PGRN polypeptide comprises an amino acid sequence containing substitutions (e.g., conserved substitutions, insertions, or deletions relative to the amino acid sequence of SEQ ID NO: 230) but retaining the ability to bind to sorting proteins. In some embodiments, in the amino acid sequence of the PGRN polypeptide of SEQ ID NO: 230, at most one, at most two, at most three, at most four, or at most five amino acids are substituted, inserted, and / or deleted.

[0264] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human CD98hc and a PGRN polypeptide, wherein the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252. SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0265] B. Isolated PGRN mutant peptide In some aspects, this document provides an isolated PGRN mutant polypeptide, wherein: (i) the isolated PGRN mutant polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, and wherein: (a) X1 is an amino acid selected from the group consisting of R, D, E, I, P, or Q; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is an amino acid selected from the group consisting of L, A, C, D, F, G, H, I, K, M, N, P, Q, R, S, T, V, or Y; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, R, or V; and (ii) X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 330.

[0266] In some embodiments, the isolated PGRN mutant peptide is selected from the following isolated PGRN mutant peptides: PGRN_1, PGRN_2, PGRN_3, PGRN_4, PGRN_5, PGRN_6, PGRN_7, PGRN_8, PGRN_9, PGRN_10, PGRN_11, PGRN_12, PGRN_13, PGRN_14, PGRN_15, PGRN_16, PGRN_18, PGRN_19, PGRN_20, PGRN_21, PGRN_22, PGRN_23, PGRN_24, PGRN_25, PGRN_26, PGRN_27, PGRN_29, PGRN_31, PGRN_32, PGRN_33, PGRN_34, PGRN_35, or PGRN_36 (e.g., as shown in Table 1).

[0267] In some embodiments, the isolated PGRN mutant polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.

[0268] In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 231. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 232. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 233. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 234. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 235. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 236. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 237. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 238. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 239. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 240. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 241. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 242. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 243. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 244. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 245. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 246. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 248. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 249. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 250. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 251. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 252. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 253.In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 254. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 255. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 256. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 257. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 259. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 261. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 262. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 263. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 264. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 265. In some embodiments, the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 266.

[0269] Table 1 shows exemplary PGRN mutant peptides. In Table 1, C-terminal mutations relative to the wild type (RQLL; SEQ ID NO: 230) are bolded and underlined. The PGRN mutant peptide of the complex may contain the amino acid sequence of SEQ ID NO: 330, where X is absent or any amino acid.

[0270] Table 1. PGRN mutant peptide sequences

[0271] III. Compositions that bind to blood-brain barrier receptors or proteins This document provides complexes and compositions thereof comprising an antigen-binding domain linked to a PGRN peptide. The antigen-binding domain can specifically bind to a human receptor or protein of the blood-brain barrier. Such complexes are capable of crossing the blood-brain barrier (BBB) ​​and transporting the PGRN peptide across the BBB. Exemplary human receptors or proteins of the blood-brain barrier are transferrin receptor (TfR) and CD98 heavy chain (CD98hc).

[0272] In some embodiments, the antigen-binding domain is a TfR antigen-binding domain. In some embodiments, the antigen-binding domain is a CD98hc antigen-binding domain.

[0273] A. Antigen-binding domain that binds to TfR In some embodiments, the antigen-binding domain specifically binds to human TfR. The anti-TfR antigen-binding domain is capable of crossing the blood-brain barrier (BBB) ​​and thus transporting PGRN peptides linked to the antigen-binding domain across the BBB. Therefore, in some embodiments, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human TfR and is capable of being internalized in BBB epithelial cells.

[0274] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises the six CDRs of the antibodies listed in Tables 2 and 3 below (i.e., the three VH CDRs of the antibodies listed in Table 2 and the three VL CDRs of the same antibody listed in Table 3). In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises the six CDRs of the antibodies listed in Tables 2, 3, or 4 below. In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises the six CDRs of the antibodies listed in Tables 2, 3, or 4, as determined by the Kabat number. In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises the six Chothia CDRs of the antibodies listed in Tables 2, 3, or 4.

[0275] In some embodiments, the CDR of the antigen-binding domain that specifically binds to human TfR can be determined according to MacCallum RM et al., (1996) J Mol Biol 262: 732-745. See also, for example, Martin A., “Protein Sequence and Structure Analysis of Antibody Variable Domains,” Antibody Engineering, eds. Kontermann and Dübel, Chapter 31, pp. 422-439, Springer-Verlag, Berlin (2001). In some embodiments, this document provides antigen-binding domains that specifically bind to human TfR and contain the VH and VL CDRs of antibodies listed in Tables 2, 3, or 4, as determined by the method of MacCallum RM et al.

[0276] In some embodiments, the CDR of the antigen-binding domain that specifically binds to human TfR can be determined according to the AbM numbering scheme, which refers to the AbM hypervariable region, representing a compromise between the Kabat CDR and the Chothia structural loop, and is used in Oxford Molecular's AbM antibody modeling software (Oxford Molecular Group, Inc.). In some embodiments, this document provides antigen-binding domains that specifically bind to human TfR and include the VH and VL CDRs of the antibodies listed in Tables 2, 3, or 4, as determined by the AbM numbering scheme.

[0277] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises the six IMGT CDRs of the antibodies listed in Tables 2, 3, or 4 (according to the IMGT numbering system, as described in Lefranc MP, (1999) The Immunologist 7: 132-136 and Lefranc MP et al., (1999) Nucleic Acids Res27: 209-212). According to the IMGT numbering scheme, VH-CDR1 is located at positions 26 to 35, VH-CDR2 at positions 51 to 57, VH-CDR3 at positions 93 to 102, VL-CDR1 at positions 27 to 32, VL-CDR2 at positions 50 to 52, and VL-CDR3 at positions 89 to 97.

[0278] In some implementations, the antigen-binding domains that specifically bind to human TfR as described herein are described by their individual VL domain or their individual VH domain, or by their individual three VL CDRs or their individual three VH CDRs. See, for example, Rader C et al., (1998) PNAS 95: 8910-8915, which is incorporated herein by reference in its entirety, describing the humanization of mouse anti-αvβ3 antibodies by identifying complementary light or heavy chains, respectively, from human light or heavy chain libraries, resulting in humanized antibody variants with affinity as high as or higher than that of the original antibody. See also Clackson T et al., (1991) Nature 352: 624-628, which is incorporated herein by reference in its entirety, describing a method for generating antibodies that bind to specific antigens by using specific VL domains (or VH domains) and screening libraries of complementary variable domains. The screening yielded 14 new conjugates for a specific VH domain and 13 new conjugates for a specific VL domain, which are strong binding agents, as determined by ELISA. See also Kim SJ and Hong HJ, (2007) JMicrobiol 45: 572-577, which is incorporated herein by reference in its entirety, describing a method for generating antibodies that bind to specific antigens by using a specific VH domain and screening libraries of complementary VL domains (e.g., human VL libraries); the selected VL domains can then be used to guide the selection of additional complementary (e.g., human) VH domains.

[0279] In some implementations, the antigen-binding domain that specifically binds to human TfR includes the VH of the antibodies listed in Table 4.

[0280] In some implementations, the antigen-binding domain that specifically binds to human TfR includes the VL of the antibody listed in Table 4.

[0281] In some implementations, the antigen-binding domain that specifically binds to human TfR includes the VH and VL of the antibodies listed in Table 4 (i.e., the VH of the antibodies listed in Table 4 and the VL of the same antibody listed in Table 4).

[0282] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 80% of the same amino acid sequence as the VH amino acid sequence of the antibodies listed in Table 4, and (ii) a VL containing at least 80% of the same amino acid sequence as the VL amino acid sequence of the same antibody in Table 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises the CDR of the antibodies in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR). In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 85% of the same amino acid sequence as the VH amino acid sequence of the antibodies in Table 4, and (ii) a VL containing at least 85% of the same amino acid sequence as the VL amino acid sequence of the same antibody in Table 4.

[0283] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 90% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 4, and (ii) a VL containing at least 90% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises a CDR of the antibodies listed in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside said CDR).

[0284] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 95% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 4, and (ii) a VL containing at least 95% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises the CDRs of the antibodies in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0285] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 96% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 4, and (ii) a VL containing at least 96% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises the CDRs of the antibodies in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0286] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 97% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 4, and (ii) a VL containing at least 97% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises the CDRs of the antibodies in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0287] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 98% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 4, and (ii) a VL containing at least 98% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises the CDRs of the antibodies in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0288] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises (i) a VH containing at least 99% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 4, and (ii) a VL containing at least 99% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Tables 3 and 4. In some embodiments, the antigen-binding domain that specifically binds to human TfR also comprises the CDR of the antibodies in Tables 2 and 3 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0289] In some embodiments, this document provides an antigen-binding domain that competitively inhibits the binding of an antibody to TfR, said antibody comprising the VH amino acid sequence of the antibody in Table 4 and the VL amino acid sequence of the same antibody in Table 4.

[0290] In some implementations, the antigen-binding domain that specifically binds to human TfR comprises VH and VL on a single polypeptide chain (e.g., VH and VL in Table 4).

[0291] In some embodiments, the antigen-binding domain comprises an scFv. In some embodiments, the scFv comprises the VH and VL of the antibody listed in Table 4. The scFv may be contained in a VH at the N-terminus of the VL or in a VL at the N-terminus of the VH. The scFv may contain a linker, for example, between the VH and VL. Thus, the scFv may be oriented as VH-linker-VL or VL-linker-VH. Such linkers may be about 5 to about 25 amino acids long. Such linkers may be about 5 to about 20 amino acids long. Such linkers may be about 10 to about 25 amino acids long. Such linkers may be about 10 to about 20 amino acids long. Such linkers may be, for example, glycine linkers, glycine-rich linkers, or glycine-serine linkers. Such linkers may contain the amino acid sequence GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6). Such linkers may contain the amino acid sequence GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

[0292] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises a VH on a first polypeptide and a VL (e.g., Fab) on a second polypeptide. Fab comprises a constant domain, a VH, and a VL. In some embodiments, the antigen-binding domain comprises Fab, which includes a constant domain, a VH of an antibody listed in Table 4, and a VL of the same antibody in Table 4. In some embodiments, the antigen-binding domain comprising Fab comprises a CDR of an antibody from Tables 2 and 3 (e.g., amino acids that are not identical in the VH and / or VL are external to the CDR).

[0293] In some embodiments, the antigen-binding domain that specifically binds to human TfR comprises an antigen-binding fragment of only heavy chain antibodies (e.g., VHHs or nanobodies). In some embodiments, the antigen-binding domain comprises a VHH containing the VH of the antibodies listed in Table 4. In other embodiments, the antigen-binding domain comprises a VHH containing the heavy chain CDR of the antibodies listed in Table 2.

[0294] In some embodiments, the antigen-binding domain that specifically binds to human TfR is a murine antigen-binding domain. In some embodiments, the antigen-binding domain that specifically binds to human TfR is a chimeric antigen-binding domain. In some embodiments, the antigen-binding domain that specifically binds to human TfR is a humanized antigen-binding domain. In some embodiments, the antigen-binding domain that specifically binds to human TfR is a human antigen-binding domain.

[0295] In some implementations, the antigen-binding domain that specifically binds to human TfR, as described herein, also binds to cynomolgus monkey TfR.

[0296] In some embodiments, the antigen-binding domain provided herein binds to human TfR with a “low” affinity. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 500 nM and 10 μM. In some embodiments, the antigen-binding domain provided herein specifically binds to human TfR with an affinity between about 751 nM and about 10,000 nM, such as about 751 nM to about 2,500 nM, about 751 nM to about 5,000 nM, about 2,500 nM to about 5,000 nM, about 2,500 nM to about 10,000 nM, about 5,000 nM to about 10,000 nM, and values ​​and ranges therebetween. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 2 µM and 5 µM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 1 µM and 5 µM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 2 µM and 8 µM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 750 nM and 2 µM.

[0297] In some embodiments, the antigen-binding domain provided herein binds to human TfR with "moderate" affinity. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 10 nM and 500 nM. In some embodiments, the antigen-binding domain provided herein specifically binds to human TfR with an affinity between about 51 nM and about 750 nM, such as about 51 nM to about 100 nM, about 51 nM to about 250 nM, about 51 nM to about 500 nM, about 100 nM to about 250 nM, about 100 nM to about 500 nM, about 100 nM to about 750 nM, about 250 nM to about 500 nM, about 250 nM to about 750 nM, about 500 nM to about 750 nM, and values ​​and ranges therebetween. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 50 nM and 500 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 100 nM and 250 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 10 nM and 100 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 250 nM and 500 nM.

[0298] In some embodiments, the antigen-binding domain provided herein binds to human TfR with "high" affinity. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of less than 10 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 0.01 nM and 10 nM. In some embodiments, the antigen-binding domain provided herein specifically binds to human TfR with an affinity of about 0.01 nM to about 50 nM, such as about 0.01 nM to about 1 nM, about 0.01 nM to about 5 nM, about 0.01 nM to about 25 nM, about 1 nM to about 5 nM, about 1 nM to about 25 nM, about 1 nM to about 50 nM, about 5 nM to about 25 nM, about 5 nM to about 50 nM, about 10 nM to about 25 nM, about 10 nM to about 50 nM, about 25 nM to about 50 nM, and values ​​and ranges therebetween. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 0.1 nM and 10 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity between 0.01 nM and 1 nM.

[0299] In some embodiments, the antigen-binding domain provided herein binds to human TfR with an affinity of 150 nM to 700 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 250 nM to 700 nM, 350 nM to 700 nM, 450 nM to 700 nM, or 550 nM to 700 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 575 nM to 675 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 600 nM to 650 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 630 nM to 650 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of about 635 nM, about 636 nM, about 637 nM, about 638 nM, about 639 nM, about 640 nM, about 641 nM, about 642 nM, about 643 nM, about 644 nM, or about 645 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of about 639 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 639 nM.

[0300] In some embodiments, the antigen-binding domain provided herein binds to human TfR with an affinity of 150 nM to 700 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 150 nM to 650 nM, 150 nM to 550 nM, 150 nM to 450 nM, 150 nM to 350 nM, or 150 nM to 250 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 160 nM to 200 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 170 nM to 190 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 175 nM to 185 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of about 175 nM, about 176 nM, about 177 nM, about 178 nM, about 179 nM, about 180 nM, about 181 nM, about 182 nM, about 183 nM, or about 184 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of about 182 nM. In some embodiments, the antigen-binding domain binds to human TfR with an affinity of 182 nM.

[0301] In some embodiments, the antigen-binding domain provided herein specifically binds to human TfR, and its affinity is measured using surface plasmon resonance (such as the BIACORE™ SPR system). In some embodiments, the Carterra LSA platform is used to measure the affinity between the antigen-binding domain and TfR. In some embodiments, the antigen-binding domain provided herein that specifically binds to human TfR binds to human TfR, such as by radioimmunoassay (RIA), Western blotting, or ELISA OD. 450 The measurements were taken.

[0302] In some embodiments, surface plasmon resonance is used to measure the binding of the antigen-binding domain provided herein to human TfR. In some embodiments, the Carterra LSA platform is used to measure affinity.

[0303] In some implementations, the antigen-binding domain that specifically binds to human TfR, as described herein, reduces cell surface TfR expression by more than 40%, 60%, or 80% compared to cell surface TfR expression on HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0304] In some implementations, the antigen-binding domain that specifically binds to human TfR, as described herein, did not significantly increase cell surface TfR expression on HCMEC / D3 cells compared to cell surface TfR expression on HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0305] In some implementations, the antigen-binding domain that specifically binds to human TfR, as described herein, did not significantly increase cell surface TfR expression on HCMEC / D3 cells compared to cell surface TfR expression on HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0306] In some embodiments, following peripheral injection, the accumulation of the antigen-binding domains provided herein that specifically bind to human TfR is at least 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, or 50 times greater than that of isotype controls. In some embodiments, the antigen-binding domains provided herein bind at least 5 times more specifically to human TfR than to unrelated proteins, and / or bind at least 5 times more specifically to cynomolgus monkey TfR than to unrelated proteins.

[0307] This article also provides antigen-binding domains that bind to the same epitope as the TfR antigen-binding domain provided herein. This article also provides antigen-binding domains that competitively inhibit the binding of the TfR antigen-binding domain provided herein to TfR.

[0308] As provided herein, the antigen-binding domain provided herein is capable of crossing the blood-brain barrier (BBB). In some embodiments, such as compared to internalization of an isotype control, the antigen-binding domain provided herein exhibits greater than 5-fold or 10-fold internalization in blood-brain barrier epithelial cells. Blood-brain barrier endothelial cells may be, for example, HCMEC / D3 cells.

[0309] In some embodiments, the antigen-binding domain provided herein does not reduce cell surface TfR expression in HCMEC / D3 cells by more than 20%, 40%, or 60% compared to cell surface TfR expression in HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS. In some embodiments, the antigen-binding domain provided herein does not significantly increase cell surface TfR expression in HCMEC / D3 cells compared to cell surface TfR expression in HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0310] In some implementations, the antigen-binding domains provided herein accumulate in the brains of angiogenically cleared mice at least 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, or 50 times more than isotype controls.

[0311] Table 2: Heavy chain CDR sequences of anti-TfR antibodies

[0312] Table 3: Light chain CDR sequences of anti-TfR antibodies

[0313] Table 4: VH and VL sequences of anti-TfR antibodies

[0314] B. Antigen-binding domain that binds to CD98hc In some embodiments, the antigen-binding domain specifically binds to human CD98hc. The anti-CD98hc antigen-binding domain is capable of crossing the blood-brain barrier (BBB) ​​and thus transporting PGRN peptides linked to the antigen-binding domain across the BBB. Therefore, in some embodiments, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human CD98hc and is capable of being internalized in BBB epithelial cells.

[0315] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises the six CDRs of the antibodies listed in Tables 5 and 6 (i.e., the three VH CDRs of the antibodies listed in Table 5 and the three VL CDRs of the same antibody listed in Table 6). In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises the six CDRs of the antibodies listed in Tables 5 and 6, as determined by the Kabat number. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises the six Chothia CDRs of the antibodies listed in Tables 5 and 6.

[0316] In some embodiments, the CDR of the antigen-binding domain that specifically binds to human CD98hc can be determined according to MacCallum RM et al., (1996) J Mol Biol 262: 732-745. See also, for example, Martin A., “Protein Sequence and Structure Analysis of Antibody Variable Domains,” Antibody Engineering, eds. Kontermann and Dübel, Chapter 31, pp. 422-439, Springer-Verlag, Berlin (2001). In some embodiments, this document provides antigen-binding domains that specifically bind to human CD98hc and contain the VH and VL CDRs of antibodies listed in Tables 5 and 6, as determined by the method of MacCallum RM et al.

[0317] In some embodiments, the CDR of the antigen-binding domain that specifically binds to human CD98hc can be determined according to the AbM numbering scheme (as described above). In some embodiments, this document provides antigen-binding domains that specifically bind to human CD98hc and contain the VH and VL CDRs of the antibodies listed in Tables 5 and 6, as determined by the AbM numbering scheme.

[0318] In some implementations, the antigen-binding domain that specifically binds to human CD98hc comprises the six IMGT CDRs of the antibodies listed in Tables 5 and 6 (according to the IMGT numbering scheme as described above).

[0319] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc, as provided herein, is described by its single VL domain or its single VH domain, or by its single three VL CDRs or its single three VHCDRs.

[0320] In some implementations, the antigen-binding domain that specifically binds to human CD98hc includes the VH of the antibodies listed in Table 7.

[0321] In some implementations, the antigen-binding domain that specifically binds to human CD98hc includes the VL of the antibody listed in Table 7.

[0322] In some implementations, the antigen-binding domain that specifically binds to human CD98hc includes the VH and VL of the antibodies listed in Table 7 (i.e., the VH of the antibodies listed in Table 7 and the VL of the same antibody listed in Table 7).

[0323] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 80% of the same amino acid sequence as the VH amino acid sequence of the antibody in Table 7, and (ii) a VL containing at least 80% of the same amino acid sequence as the VL amino acid sequence of the same antibody in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR). In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 85% of the same amino acid sequence as the VH amino acid sequence of the antibody in Table 7, and (ii) a VL containing at least 85% of the same amino acid sequence as the VL amino acid sequence of the same antibody in Table 7.

[0324] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 90% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 7, and (ii) a VL containing at least 90% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0325] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 95% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 7, and (ii) a VL containing at least 95% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0326] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 96% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 7, and (ii) a VL containing at least 96% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0327] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 97% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 7, and (ii) a VL containing at least 97% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0328] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 98% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 7, and (ii) a VL containing at least 98% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0329] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises (i) a VH containing at least 99% identical amino acid sequences to the VH amino acid sequences of the antibodies in Table 7, and (ii) a VL containing at least 99% identical amino acid sequences to the VL amino acid sequences of the same antibodies in Table 7. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc also comprises the CDR of the antibodies in Tables 5 and 6 (e.g., amino acids that are not identical in VH and / or VL are outside the CDR).

[0330] In some embodiments, this document provides an antigen-binding domain that competitively inhibits the binding of an antibody to CD98hc, said antibody comprising the VH amino acid sequence of the antibody in Table 7 and the VL amino acid sequence of the same antibody in Table 7.

[0331] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises VH and VL on a single polypeptide chain (e.g., VH and VL in Table 7). In some embodiments, the antigen-binding domain comprises scFv. The scFv may be contained in VH at the N-terminus of VL or in VL at the N-terminus of VH. The scFv may contain a linker, for example, between VH and VL. Thus, the scFv may be oriented as VH-linker-VL or VL-linker-VH. Such linkers may be about 5 to about 25 amino acids long. Such linkers may be about 5 to about 20 amino acids long. Such linkers may be about 10 to about 25 amino acids long. Such linkers may be about 10 to about 20 amino acids long. Such linkers may be, for example, glycine linkers, glycine-rich linkers, or glycine-serine linkers. Such linkers may contain the amino acid sequence GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6). Such connectors may contain the amino acid sequence GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

[0332] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc comprises VH on the first polypeptide and VL (e.g., Fab) on the second polypeptide.

[0333] In some implementations, the antigen-binding domain that specifically binds to human CD98hc contains an antigen-binding fragment of only heavy chain antibodies (e.g., VHH or nanobodies).

[0334] In some embodiments, the antigen-binding domain that specifically binds to human CD98hc is a murine antigen-binding domain. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc is a chimeric antigen-binding domain. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc is a humanized antigen-binding domain. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc is a human antigen-binding domain.

[0335] In some implementations, the antigen-binding domain that specifically binds to human CD98hc, as described herein, also binds to cynomolgus monkey CD98hc.

[0336] In some embodiments, the antigen-binding domain provided herein binds to human CD98hc with a "low" affinity. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between about 500 nM and about 10 μM, such as about 500 nM to about 2.5 µM, about 500 nM to about 5 µM, about 1 µM to about 2.5 µM, about 1 µM to about 5 µM, about 1 µM to about 10 µM, about 2.5 µM to about 5 µM, about 2.5 µM to about 10 µM, about 5 µM to about 10 µM, and values ​​and ranges therebetween. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 2 µM and 5 µM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 1 µM and 5 µM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 2 µM and 8 µM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 750 nM and 2 µM.

[0337] In some embodiments, the antigen-binding domain provided herein binds to human CD98hc with "moderate" affinity. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between about 100 nM and about 500 nM, such as about 100 nM to about 250 nM, about 250 nM to about 500 nM, and values ​​and ranges therebetween. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between about 200 nM and about 300 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 50 nM and 500 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 100 nM and 250 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 10 nM and 100 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 250 nM and 500 nM.

[0338] In some embodiments, the antigen-binding domain provided herein binds to human CD98hc with a "high" affinity. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity of less than about 100 nM, such as less than about 90 nM, less than about 80 nM, less than about 70 nM, less than about 60 nM, less than about 50 nM, less than about 40 nM, less than about 30 nM, less than about 20 nM, and less than about 10 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between about 0.1 nM and about 100 nM, such as about 0.1 nM to about 10 nM, about 0.1 nM to about 25 nM, about 1 nM to about 25 nM, about 1 nM to about 50 nM, about 25 nM to about 50 nM, about 25 nM to about 100 nM, about 50 nM to about 100 nM, and values ​​and ranges therebetween. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 0.01 nM and 10 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 0.1 nM and 10 nM. In some embodiments, the antigen-binding domain binds to human CD98hc with an affinity between 0.01 nM and 1 nM.

[0339] In some embodiments, surface plasmon resonance is used to measure the binding of the antigen-binding domain, which specifically binds to human CD98hc as described herein, to human CD98hc. In some embodiments, the Carterra LSA platform is used to measure affinity. In some embodiments, the antigen-binding domain, which specifically binds to human CD98hc as described herein, binds to human CD98hc, such as by radioimmunoassay (RIA), Western blotting, or ELISA OD. 450 The measurements were taken.

[0340] In some implementations, the antigen-binding domain that specifically binds to human CD98hc, as described herein, does not reduce cell surface CD98hc expression on HCMEC / D3 cells by more than 20% compared to cell surface CD98hc expression on HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0341] In some implementations, the antigen-binding domain that specifically binds to human CD98hc, as described herein, did not increase cell surface CD98hc expression on HCMEC / D3 cells by more than 50% compared to cell surface CD98hc expression on HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0342] In some implementations, the antigen-binding domain specifically binding to human CD98hc provided herein does not reduce cell surface CD98hc expression on HCMEC / D3 cells by more than 20% compared to cell surface CD98hc expression on HCMEC / D3 cells treated with an isotype control, and does not increase cell surface CD98hc expression on HCMEC / D3 cells by more than 50% compared to cell surface CD98hc expression on HCMEC / D3 cells treated with an isotype control. Cell surface expression can be measured, for example, using Western blotting or FACS.

[0343] In some embodiments, following peripheral injection, the antigen-binding domain that specifically binds to human CD98hc, as described herein, accumulates at least 1.5 times more in the brains of angiogenically depleted human CD98hc knock-in mice than in isotype controls. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc, as described herein, accumulates at least 1 time more in the brains of angiogenically depleted mice than in isotype controls.

[0344] In some implementations, 24 hours after administration to mice, the brain:serum concentration ratio of the antigen-binding domain that specifically binds to human CD98hc, as described herein, was increased by at least 5-fold compared to the isotype control.

[0345] This article also provides antigen-binding domains that bind to the same epitope of CD98hc as the CD98hc antigen-binding domain provided herein. This article also provides antigen-binding domains that competitively inhibit the binding of the CD98hc antigen-binding domain provided herein to CD98hc.

[0346] Table 5: Heavy chain CDR sequence of anti-CD98hc antibody

[0347] Table 6: Light chain CDR sequence of anti-CD98hc antibody

[0348] Table 7: VH and VL sequences of anti-CD98hc antibody

[0349] IV. Antigen-binding domains and compositions containing antigen-binding domains In some respects, this document provides complexes and compositions thereof comprising an antigen-binding domain linked to a granule protein precursor (PGRN) polypeptide. The antigen-binding domain can specifically bind to human transferrin receptor (TfR) or human CD98 heavy chain (CD98hc) to facilitate the transport of the PGRN polypeptide across the blood-brain barrier (BBB).

[0350] In some embodiments, the antigen-binding domain is an antigen-binding fragment. Antigen-binding fragments of antibodies include, but are not limited to, Fab, Fab', Fab'-SH, F(ab')2, Fv, and scFv fragments, as well as other fragments described below. For a review of certain antibody fragments, see Hudson et al. Nat. Med.9:129-134 (2003). For a review of scFv fragments, see, for example, WO 93 / 16185; and U.S. Patent Nos. 5,571,894 and 5,587,458. For a discussion of Fab and F(ab')2 fragments containing rescue receptor-binding epitope residues and having an increased in vivo half-life, see U.S. Patent No. 5,869,046.

[0351] A bifunctional antibody is an antibody fragment having two antigen-binding sites, and said antibody fragment may be bivalent and / or bispecific. See, for example, EP404097; WO 1993 / 01161; Hudson et al. Nat. Med. 9:129-134 (2003). Trifunctional and tetrafunctional antibodies are also described by Hudson et al. Nat. Med In 9:129-134 (2003), a single-domain antibody is an antibody fragment containing all or a portion of the variable domain of the heavy chain or the variable domain of the light chain. In some embodiments, the single-domain antibody is a human single-domain antibody (see, for example, U.S. Patent No. 6,248,516).

[0352] Antibody fragments can be prepared using a variety of techniques, including but not limited to the proteolytic digestion of intact antibodies and production from recombinant host cells (e.g., Escherichia coli or bacteriophages), as described herein.

[0353] In some embodiments, the antigen-binding domain is chimeric. Certain chimeric antibodies are described, for example, in U.S. Patent No. 4,816,567. In one instance, a chimeric antibody comprises a non-human variable region (e.g., a variable region derived from a mouse, rat, hamster, rabbit, or non-human primate such as a monkey) and a human constant region. In another instance, a chimeric antibody is a “class-switching” antibody, wherein the class or subclass has been changed from that of the parent antibody.

[0354] In some embodiments, the antigen-binding domain is humanized. Typically, nonhuman antibodies are humanized to reduce immunogenicity in humans while retaining the specificity and affinity of the parent nonhuman antibody. In some embodiments, the humanized antibody is substantially non-immunogenic in humans. In some embodiments, the affinity of the humanized antibody for the target is substantially the same as the affinity of the antibody derived from another species. See, for example, U.S. Patent Nos. 5,530,101; 5,693,761; 5,693,762; and 5,585,089. In some embodiments, amino acids in the antibody variable domain that can be modified without diminishing the native affinity of the antigen-binding domain, while reducing its immunogenicity, are identified. See, for example, U.S. Patent Nos. 5,766,886 and 5,869,619. Typically, humanized antibodies comprise one or more variable domains, wherein the CDR (or a portion thereof) is derived from a nonhuman antibody, and the frame region (FR) (or a portion thereof) is derived from a human antibody sequence. Humanized antibodies may contain at least a portion of the human constant region. In some embodiments, some FR residues in the humanized antibody are replaced by corresponding residues from a non-human antibody (e.g., an antibody derived from CDR residues) to restore or improve antibody specificity or affinity, for example.

[0355] A review of humanized antibodies and their preparation methods can be found in, for example, by Almagro et al. Front. Biosci. 13:161 9-1633 (2008), and further described, for example, in U.S. Patent Nos. 5,821,337; 7,527,791; 6,982,321; and 7,087,409. Human frame regions that can be used for humanization include, but are not limited to, frame regions selected using a “best-fit” method (see, for example, Sims et al.). J. Immunol. 151:2296 (1993)); Frame regions of human antibody common sequences derived from specific subgroups of the light or heavy chain variable regions (see, for example, Carter et al.) Proc. Natl. Acad. Sci. USA 89:4285 (1992); and Presta et al., J. Immunol 151:2623 (1993)); human maturation (somatic mutation) framework region or human germline framework region (see, for example, Almagro and Fransson) Front. Biosci. 13:1619-1633 (2008)); and the frame regions derived from screening FR libraries (see, for example, Baca et al.) J. Biol. Chem. 272:10678-10684 (1997) and Rosok et al. J. Biol. Chem . 271:22611-22618 (1996)).

[0356] In some embodiments, the antigen-binding domain is human. Human antibodies can be generated using various techniques known in the art. Human antibodies are commonly described in van Dijk et al. Curr. Opin. Pharmacol 5:368-74 (2001) and Lonberg Curr. Opin. Immunol 20:450-459 (2008)

[0357] Human antibodies can be prepared by administering immunogens to transgenic animals modified to produce complete human antibodies or complete antibodies with human variable regions in response to antigen challenges. Mouse strains defective in antibody production can be engineered using large fragments of human Ig loci, with the expectation that such mice will produce human antibodies in the absence of mouse antibodies. Large human Ig fragments preserve extensive variable genetic diversity and appropriate regulation of antibody production and expression. By utilizing mouse mechanisms for antibody diversification and selection, and by exploiting the lack of immune tolerance to human proteins, reproducible human antibody lineages in these mouse strains can produce high-affinity complete human antibodies against any antigen of interest, including human antigens. Using hybridoma technology, antigen-specific human MAbs with desired specificity can be generated and selected. Certain exemplary methods are described in U.S. Patent Nos. 5,545,807, EP546073, and EP546073. See also, for example, U.S. Patent Nos. 6,075,181 and 6,150,584, which describe XENOMOUSE™ technology; U.S. Patent No. 5,770,429, which describes HUMAB® technology; U.S. Patent No. 7,041,870, which describes KM MOUSE® technology; and U.S. Patent Application Publication No. US2007 / 0061900, which describes VELOCIMOUSE® technology. The human variable region of an intact antibody derived from such animals can be further modified, for example, by combining it with different human constant regions.

[0358] Human antibodies can also be prepared using hybridoma-based methods. Human myeloma and mouse-human xenograft myeloma cell lines for generating human monoclonal antibodies have been described. (See, for example, Kozbor) J. Immunol 133:3001 (1984) and Boerner et al. J. Immunol. 147:86 (1991)). Human antibodies generated via human B-cell hybridoma technology were also described by Li et al. Proc. Natl. Acad. Sci. USA , 1 03:3557-3562 (2006). Additional methods include those described, for example, in U.S. Patent No. 7,189,826 (Describing the generation of monoclonal human IgM antibodies from hybridoma cell lines). Human hybridoma technology (tri-source hybridoma technology) is also described in Vollmers et al. Histology and Histopathology20(3):927-937 (2005) and Vollmers et al. Methods and Findings in Experimental and Clinical Pharmacology In 27(3):185-91 (2005), human antibodies can also be generated by isolating variable domain sequences of Fv clones selected from human phage display libraries. Such variable domain sequences can then be combined with desired human constant domains. Techniques for selecting human antibodies from antibody libraries are described below.

[0359] In some embodiments, the antigen-binding domain is an antibody, wherein the antibody is a human antibody isolated by in vitro methods and / or screening of a combinatorial library for antibodies having one or more desired activities. Suitable examples include, but are not limited to, phage display (CAT, Morphosys, Dyax, Biosite / Medarex, Xoma, Symptomogen, Alexion (formerly Proliferon), Affimed), ribosome display (CAT), yeast display (Adimab), etc. In some phage display methods, lineages of the VH and VL genes are independently cloned by polymerase chain reaction (PCR) and randomly recombined in a phage library, which can then be screened for antigen-binding phages, as in Winter et al. Ann. Rev. Immunol As described in .12: 433-455 (1994). For example, various methods are known in the art for generating phage display libraries and screening such libraries for antibodies with desired binding characteristics. See also Sidhu et al. J. Mol. Biol. 338(2): 299-310, 2004; Lee et al. J. Mol. Biol. 340(5): 1073-1093, 2004;Fellouse Proc. Natl. Acad. Sci. USA 101(34):12467-12472 (2004); and Lee et al. J. Immunol. Methods 284(-2):1 19-132 (2004). Phages typically display antibody fragments as single-chain Fv (scFv) fragments or as Fab fragments. Libraries derived from immune sources provide high-affinity antibodies against immunogens without the need to construct hybridomas. Alternatively, native lineages (e.g., from humans) can be cloned to provide antibodies from a single source against a variety of non-self and self antigens without any immunization, as Griffiths et al. EMBO J As described in . 12: 725-734 (1993). Finally, native libraries can also be synthesized by cloning the unrearranged V gene segment from stem cells, encoding the highly variable CDR3 region using PCR primers containing random sequences, and performing rearrangement in vitro, as described by Hoogenboom et al. J. Mol. BiolAs described in ., 227: 381-388, 1992. Patent publications describing human antibody phage libraries include, for example, U.S. Patent No. 5,750,373 and U.S. Patent Publications Nos. 2007 / 0292936 and 2009 / 0002360. Antibodies isolated from human antibody libraries are considered herein to be human antibodies or fragments of human antibodies.

[0360] V. Fc structural domain In some embodiments, the complex provided herein comprises an Fc domain or a fragment thereof. In some embodiments, the Fc domain belongs to the IgG, IgM, or IgA class. In some embodiments, the Fc domain or a fragment thereof is an IgG Fc domain or a fragment thereof. In some embodiments, the Fc domain or a fragment thereof is a human IgG Fc domain or a fragment thereof. In some embodiments, the Fc domain or a fragment thereof is a human IgG1 Fc domain or a fragment thereof. In some embodiments, the Fc domain or a fragment thereof is a human IgG2 Fc domain or a fragment thereof. In some embodiments, the Fc domain or a fragment thereof is a human IgG4 Fc domain or a fragment thereof. In some embodiments, the Fc domain or a fragment thereof is a monovalent Fc. In some embodiments, the Fc domain or a fragment thereof is a modified Fc domain or a fragment thereof, comprising one or more modifications relative to the corresponding wild-type Fc domain. In some embodiments, the one or more modifications reduce effector function.

[0361] In some embodiments, the Fc domain is a modified Fc domain or a fragment thereof. In some embodiments, the modified Fc domain or fragment thereof is a modified IgG1 Fc containing one or more modifications. For example, in some embodiments, the IgG1 modified Fc contains one or more amino acid substitutions (e.g., relative to the wild-type Fc domain of the same isotype). In some embodiments, the modified Fc domain or fragment thereof is a modified IgG2 Fc domain. In some embodiments, the modified Fc domain or fragment thereof is a modified IgG2 Fc domain, relative to wild-type IgG2, containing one or more modifications, such as one or more modifications that reduce effector function. In some embodiments, the modified Fc domain or fragment thereof is an IgG4 Fc domain modified relative to wild-type IgG4. In some embodiments, the modified Fc domain or fragment thereof is a modified IgG4 Fc domain, relative to wild-type IgG4, containing one or more modifications, such as one or more modifications that reduce effector function. In some embodiments, the modified Fc domain or fragment thereof is a modified IgG4 Fc domain comprising one or more amino acid substitutions selected from IgG4-S228P or IgG4-S228P / L235E, wherein the amino acid positions are according to EU numbering conventions. In some embodiments, the one or more amino acid substitutions are selected from N297A (Bolt S et al. (1993)). Eur J Immunol 23:403-411), D265A (Shields et al. (2001) RJ Biol. Chem. 276, 6591–6604), L234A, L235A (Hutchins et al. (1995) Proc Natl Acad Sci USA, 92:11980-11984; Alegre et al., (1994) Transplantation 57:1537-1543. 31; Xu et al., (2000) Cell Immunol , 200:16-26), G237A (Alegre et al. (1994) Transplantation 57:1537-1543. 31; Xu et al. (2000) Cell Immunol (200:16-26), C226S, C229S, E233P, L234V, L234F, L235E (McEarchern et al., (2007)). Blood ,109:1185-1192), P331S (Sazinsky et al., (2008) Proc Natl Acad Sci USA 2008, 105:20167-20172), K322A (Hezareh et al. (2001) J Virol. 75(24) 12161-12168), S267E, L328F, A330L, M252Y, S254T, E430G and / or T256E, wherein the amino acid positions are according to EU numbering convention. In some embodiments, the Fc domain contains amino acid substitutions L234A, L235A and P331S (LALAPS) according to EU numbers. In some embodiments, the Fc domain contains N325S and L328F mutations according to EU numbers. In some embodiments, the Fc domain contains L234A, L235A and P329G mutations according to EU numbers. In some embodiments, the Fc domain contains L234A, L235A and P329S mutations according to EU numbers. In some embodiments, the Fc domain contains K322A according to EU numbers. In some embodiments, the Fc domain contains S228P according to EU numbers. In some embodiments, the Fc domain comprises L235E according to EU designation. In some embodiments, the Fc domain comprises S228P and L235E according to EU designation. In some embodiments, the modified Fc domain or a fragment thereof is modified IgG4 and comprises S228P and L235E according to EU designation.

[0362] The multispecific proteins described in this article consider any suitable Fc domain or fragment thereof, and Table 8 below provides exemplary Fc domains.

[0363] Table 8: Exemplary Fc structural domains

[0364] In some embodiments provided herein, the complexes provided herein contain one or more mutations to promote heterodimerization of the Fc domain. In some embodiments, the bispecific dimerizing Fc domains provided herein are formed from Fc domains containing amino acid mutations, substitutions, additions, or deletions to promote heterodimerization, wherein different polypeptides containing different Fc domains can dimerize to produce a heterodimeric conformation. In some embodiments, the bispecificity of this disclosure comprises a first Fc sequence containing a first CH3 region and a second Fc sequence containing a second CH3 region, wherein the sequences of the first and second CH3 regions are different, and such that the heterodimeric interaction between the first and second CH3 regions is stronger than the homodimeric interaction between each of the first and second CH3 regions.

[0365] Methods for promoting heterodimerization of the Fc domain include the deletion, addition, or substitution of amino acids in the amino acid sequence of the Fc domain, for example by including a set of "mortar and pestle" deletions, additions, or substitutions, or by including amino acid deletions, additions, or substitutions to achieve electrostatic orientation of the Fc to facilitate attractive interactions between different polypeptide chains. Methods for promoting heterodimerization of complementary Fc peptides have been previously described in, for example, the following literature: Ridgway et al., 1996, ProteinEng, 9:617-621; Merchant et al., 1998, Nature Biotechnol, 16:677-681; Moore et al., 2011, MAbs, 3:546-557; Von Kreudenstein et al., 2013, 5:646-654; Gunasekaran et al., 2010, J Biol Chem, 285:19637-19464; Leaver-Fay et al., 2016, Structure, 24:641-651; Ha et al., 2016, Frontiers in Immunology, 7:1; Davis et al., 2010, Protein EngDes Sel, 23:195-202; PCT Publication Nos. WO1996 / 027011; WO1998 / 050431; WO2006 / 028936; WO2009 / 089004; WO2011 / 143545; WO2014 / 067011; WO2012 / 058768; WO2018 / 027025; US Publication No. US2014 / 036342 6; US2015 / 0307628; US2018 / 0016354; US2015 / 0239991; US2017 / 0058054; US Patent Nos. 5,731,168; 7,183,076; 9,701,759; 9,605,084; 9,650,446; 8,216,805; 8,765,412; and 8,258,268.

[0366] In some implementations, the complementary Fc peptides of the Fc heterodimer include mutations to alter the charge polarity at the Fc dimer interface, such that co-expression of electrostatically matched Fc domains supports favorable attractive interactions, thereby promoting the formation of desired Fc heterodimers; while unfavorable repulsive charge interactions inhibit the formation of unwanted Fc homodimers (Guneskaran et al., 2010, J Biol Chem, 285:19637-19646). When co-expressed in cells, association between peptide chains is possible, but the chains generally do not self-associate due to charge repulsion.

[0367] The "knob-hole" configuration is a complementary Fc polypeptide of an Fc heterodimer that promotes heterodimerization of two Fc polypeptides. The "knob-hole" technique is described in U.S. Patent Nos. 5,731,168; 7,695,936; 8,216,805; 8,765,412; Ridgway et al., Prot Eng 9, 617-621 (1996); and Carter, J ImmunolMeth 248, 7-15 (2001). Typically, the method involves introducing a protrusion ("knob") at the interface of a first polypeptide and a corresponding cavity ("pot") at the interface of a second polypeptide, such that the protrusion can be positioned within the cavity, thereby promoting heterodimer formation and inhibiting homodimer formation. The protrusion is constructed by replacing a small amino acid side chain at the interface of the first polypeptide with a larger side chain (e.g., tyrosine or tryptophan). Compensating cavities of the same or similar size as the protrusions are generated at the interface of the second polypeptide by replacing large amino acid side chains with smaller amino acid side chains (e.g., alanine or threonine). The protrusions and cavities can be prepared by altering the nucleic acids encoding the polypeptides, for example, through site-specific mutagenesis or peptide synthesis.

[0368] In some embodiments, the complex provided herein comprises an Fc dimer containing a "palm" mutation in one Fc domain and a "mortar" mutation in the other Fc domain. In some embodiments, the "palm" mutation comprises the amino acid substitution T366W according to EU designation. In some embodiments, the "mortar" mutation comprises the amino acid substitutions T366S, L368A, and Y407V according to EU designation. In some embodiments, the "palm" mutation comprises the amino acid substitution T366W in one of the two subunits of the Fc dimer, and the "palm" mutation comprises the amino acid substitutions T366S, L368A, and Y407V in the other subunit of the Fc dimer. In some embodiments, the subunit of the Fc dimer containing the "palm" mutation further comprises the amino acid substitution S354C, and the subunit of the Fc dimer containing the "mortar" mutation further comprises the amino acid substitution Y349C. The introduction of these two cysteine ​​residues leads to the formation of a disulfide bridge between the two subunits of the Fc domain, thus further stabilizing the dimer (Carter, J Immunol Methods 248, 7-15 (2001)). Therefore, in this configuration, the first Fc polypeptide contains amino acid modifications to form a "pestle," and the second Fc polypeptide contains amino acid modifications to form a "mortar," thus forming an Fc heterodimer containing complementary Fc polypeptides.

[0369] Table 9 below lists exemplary paired amino acid modifications (EU numbers) for complementary Fc peptides with Fc heterodimer configurations.

[0370] Table 9: Exemplary paired Fc modifications for heterodimeric Fc domains

[0371] VI. Complexes that bind to blood-brain barrier receptors or proteins This document provides a complex and compositions thereof comprising an antigen-binding domain linked to a PGRN peptide. The antigen-binding domain specifically binds to human transferrin receptor (TfR) or human CD98 heavy chain (CD98hc) to facilitate the transport of the PGRN peptide across the blood-brain barrier (BBB).

[0372] A. A complex containing an anti-TfR antigen-binding domain In some aspects, this document provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to the human transferrin receptor (TfR). In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, wherein X1 is any amino acid, and wherein X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL.

[0373] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a granulin precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to a human transferrin receptor (TfR), wherein the antigen-binding domain comprises a heavy chain variable region (VH) comprising VH CDR1, VH CDR2, and VH CDR3, and a light chain variable region (VL) comprising VL CDR1, VL CDR2, and VLCDR3, and wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55, and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55, and 61; (iii) respectively, SEQ ID NO: 8, 15, 25, 336, 55, and 61; (iv) respectively, SEQ ID NO: 10, 22, 333, 50, 58, and 62; (v) respectively, SEQ ID NO: 10, 22, 28, 337, 58, and 62; (vi) respectively, SEQ ID NO: 10, 22, 28, 338, 58, and 62; (vii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (viii) respectively, SEQ ID NO: 10, 22, 28, 340, 58, and 62; (ix) respectively, SEQ ID NO: 10, 22, 334, 50, 58, and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58, and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0374] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human TfR, and wherein the antigen-binding domain is a VHH comprising: (a) VH CDR1, VH CDR2, and VH CDR3 comprising the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, and 25; (ii) respectively, SEQ ID NO: 8, 15, and 25; (iv) respectively, SEQ ID NO: 10, 22, and 333; (v) respectively, SEQ ID NO: 10, 22, and 28; (ix) respectively, SEQ ID NO: 10, 22, and 334; or (x) respectively, SEQ ID NO: 10, 22, and 30; or (b) VH comprising the following amino acid sequences: SEQ ID NO: 101, 102, 342, 117, 343, or 118.

[0375] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2 and CH3; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain specifically binding to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55, and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55, and 61; (iii) respectively, SEQ ID NO: 8, 15, 25, 336, 55, and 61; (iv) respectively, SEQ ID NO: 10, 22, 333, 50, 58, and 62; (v) respectively, SEQ ID NO: 10, 22, 28, 337, 58, and 62; (vi) respectively, SEQ ID NO: 10, 22, 28, 338, 58, and 62; (vii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (viii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (ix) respectively, SEQ ID NO: 10, 22, 334, 50, 58, and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0376] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, and CH3; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain specifically binding to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55, and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55, and 61; (iii) respectively, SEQ ID NO: 8, 15, 25, 336, 55, and 61; (iv) respectively, SEQ ID NO: 10, 22, 333, 50, 58, and 62; (v) respectively, SEQ ID NO: 10, 22, 28, 337, 58, and 62; (vi) respectively, SEQ ID NO: 10, 22, 28, 338, 58, and 62; (vii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (viii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (ix) respectively, SEQ ID NO: 10, 22, 334, 50, 58, and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0377] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain specifically binding to human TfR, and wherein the VH comprises VHCDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55, and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) respectively, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) respectively, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) respectively, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) respectively, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) respectively, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) respectively, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (ix) respectively, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0378] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; and (b) a second polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain specifically binding to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3 and the VL comprises VL CDR1, VL CDR2, and VLCDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55, and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55, and 61; (iii) respectively, SEQ ID NO: 8, 15, 25, 336, 55, and 61; (iv) respectively, SEQ ID NO: 10, 22, 333, 50, 58, and 62; (v) respectively, SEQ ID NO: 10, 22, 28, 337, 58, and 62; (vi) respectively, SEQ ID NO: 10, 22, 28, 338, 58, and 62; (vii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (viii) respectively, SEQ ID NO: 10, 22, 28, 340, 58, and 62; (ix) respectively, SEQ ID NO: 10, 22, 334, 50, 58, and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58, and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0379] In some aspects, this document provides a complex comprising: (a) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, and CH3; (b) a second polypeptide comprising, from the N-terminus to the C-terminus, a PGRN polypeptide, a linker, CH2, and CH3; and (c) a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain specifically binding to human TfR, and wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VL CDR3, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55, and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55, and 61; (iii) respectively, SEQ ID NO: 8, 15, 25, 336, 55, and 61; (iv) respectively, SEQ ID NO: 10, 22, 333, 50, 58, and 62; (v) respectively, SEQ ID NO: 10, 22, 28, 337, 58, and 62; (vi) respectively, SEQ ID NO: 10, 22, 28, 338, 58, and 62; (vii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (viii) respectively, SEQ ID NO: 10, 22, 28, 339, 58, and 62; (ix) respectively, SEQ ID NO: 10, 22, 334, 50, 58, and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

[0380] In some respects, this document provides a complex comprising an antigen-binding domain linked to a granular protein precursor (PGRN) polypeptide, wherein the antigen-binding domain specifically binds to the human transferrin receptor (TfR) and is not located within the Fc domain of the complex.

[0381] In the complexes provided herein, the PGRN polypeptide can be any PGRN polypeptide disclosed herein.

[0382] The exemplary forms of the complexes disclosed herein are depicted in Figure 1A-1J middle.

[0383] In some embodiments, the PGRN peptide in the complex is located at the N-terminus of an antigen-binding domain that specifically binds to human TfR.

[0384] In some embodiments, the PGRN peptide in the complex is located at the C-terminus of an antigen-binding domain that specifically binds to human TfR.

[0385] In some embodiments, the PGRN peptide and the antigen-binding domain that specifically binds to human TfR are directly linked via peptide bonds. In some embodiments, the PGRN peptide and the antigen-binding domain that specifically binds to human TfR are linked via a linker (e.g., a peptide linker). In some embodiments, the complex does not contain an Fc moiety.

[0386] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human TfR, a PGRN peptide, and an Fc moiety. In some embodiments, the antigen-binding domain that specifically binds to human TfR and the PGRN peptide are linked to the N-terminus of the Fc moiety of the complex.

[0387] In some embodiments, both the antigen-binding domain specifically binding to human TfR and the PGRN peptide are linked to the C-terminus of the Fc portion of the complex. In other embodiments, the antigen-binding domain specifically binding to human TfR is linked to the N-terminus of the Fc portion, and the PGRN peptide is linked to the C-terminus of the Fc portion of the complex. In still other embodiments, the PGRN peptide is linked to the N-terminus of the Fc portion of the complex, and the antigen-binding domain specifically binding to human TfR is linked to the C-terminus of the Fc portion.

[0388] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR, and (ii) a PGRN polypeptide, wherein the complex comprises two copies of the PGRN polypeptide. In some embodiments, the complex comprises an Fc domain. The Fc may be a heterodimeric Fc comprising a first Fc polypeptide with a club-shaped mutation and a second Fc polypeptide with a mortise-and-hole mutation (“knob-hole / knob-into-hole” or “knob-hole Fc”, as described herein). In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is linked to the C-terminus of the Fc domain (i.e., to one of the two heavy chains of the Fc domain), while the two copies of the PGRN polypeptide are linked to the N-terminus of the Fc. Examples of this 2+1 form are described in... Figure 1F As shown in the image.

[0389] In some implementations, the single scFv, Fab, or VHH antigen-binding domain that specifically binds to human TfR is linked to the N-terminus of the Fc domain (i.e., to one of the two heavy chains of the Fc domain), while two copies of the PGRN peptide are linked to the C-terminus of the Fc domain. This 2+1 form is exemplified in… Figure 1E As shown in the image.

[0390] exist Figure 2D The image shows an example of a "2+1" form comprising (1) a first heavy chain containing a Fab, an Fc domain with a mortise mutation, and a PGRN polypeptide linked to the C-terminus of the Fc domain; (2) a second heavy chain containing an Fc domain with a mortise mutation and a second PGRN polypeptide linked to the C-terminus of the Fc domain; and (3) a light chain. "2+1" refers to a Fab domain targeting the BBB and two PGRN polypeptides.

[0391] In some embodiments, this document discloses a complex comprising (i) an antibody that specifically binds to human TfR, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of a PGRN polypeptide linked to the C-terminus of the two antibody heavy chains. Examples of this 2+2 form are described in... Figure 1G As shown in the image.

[0392] In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that specifically bind to human TfR, linked to the C-terminus of the heavy chain, and (ii) two copies of a PGRN polypeptide linked to the N-terminus of the Fc domain. Examples of this 2+2 form are shown in... Figure 1H As shown in the figure. In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that specifically bind to human TfR and are linked to the N-terminus of the heavy chain, and (ii) two copies of a PGRN polypeptide linked to the C-terminus of the Fc domain.

[0393] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single human TfR-binding scFv, VHH, or Fab antigen-binding domain is linked to the C-terminus of the Fc domain, and the PGRN peptide is linked to the N-terminus of the Fc domain. In some embodiments, the Fc domain is a single-chain, engineered monovalent Fc domain. Examples of this single-chain 1+1 form of the complex are described in... Figure 1A , Figure 1I and Figure 1J As shown in the image.

[0394] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single human TfR-binding scFv, VHH, or Fab antigen-binding domain is linked to the N-terminus of the Fc domain, and the PGRN peptide is linked to the C-terminus of the Fc domain. In some embodiments, the Fc is a single-chain, engineered monovalent Fc. Examples of this 1+1 form of the complex are... Figure 1B and Figure 1C As shown in the image.

[0395] exist Figure 2A The example “mcFv” form of the anti-TfR-PGRN complex is shown in the figure. The “mcFv” form comprises (1) a heavy chain containing a Fab domain, a single Fc domain and a PGRN polypeptide linked to the C-terminus of the Fc domain, and (2) a light chain.

[0396] exist Figure 2B The example "trans" form is shown, comprising (1) a first heavy chain containing a Fab domain and an Fc with a mortar-mutated structure, (2) a second heavy chain containing an Fc domain with a mortar-mutated structure linked to a PGRN peptide, and (3) a light chain. In some embodiments, the first heavy chain may have an Fc with a mortar-mutated structure, and the second heavy chain may have an Fc domain with a mortar-mutated structure.

[0397] exist Figure 2C The image shows an example of the "cis" form, which comprises (1) a first heavy chain containing Fab, an Fc with a club-shaped mutation, and a PGRN polypeptide linked to the C-terminus of the Fc-club, (2) a second heavy chain containing an Fc with a club-shaped mutation, and (3) a light chain. "1+1" refers to a Fab domain targeting the BBB and a PGRN polypeptide.

[0398] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR and the PGRN peptide are both linked to the N-terminus of the Fc domain. Examples of this 1+1 form of the complex are described in... Figure 1DAs shown in the figure. In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that specifically binds to human TfR and the PGRN polypeptide are both linked to the C-terminus of the Fc domain.

[0399] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from N-terminus to C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (ii) a second polypeptide comprising, from N-terminus to C-terminus, CH2 and CH3; and (iii) a third polypeptide comprising, from N-terminus to C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.In some embodiments, the first polypeptide comprises the amino acid sequence of SEQ ID NO: 319; the second polypeptide comprises the amino acid sequence of SEQ ID NO: 320; and the third polypeptide comprises the amino acid sequence of SEQ ID NO: 321. In some embodiments, the VH comprises VH CDR1, VH CDR2, and VH CDR3; wherein VH CDR1 comprises the amino acid sequence of SEQ ID NO: 8; wherein VH CDR2 comprises the amino acid sequence of SEQ ID NO: 15; and wherein VH CDR3 comprises the amino acid sequence of SEQ ID NO: 25; and / or the VL comprises VL CDR1, VLCDR2, and VL CDR3; wherein VL CDR1 comprises the amino acid sequence of SEQ ID NO: 43; wherein VL CDR2 comprises the amino acid sequence of SEQ ID NO: 55; and wherein VL CDR3 comprises the amino acid sequence of SEQ ID NO: 61. In some embodiments, the VH comprises the amino acid sequence of SEQ ID NO: 102; and / or the VL comprises the amino acid sequence of SEQ ID NO: 158.

[0400] In some aspects, this document provides a complex comprising: a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, and CH3; a second polypeptide comprising, from the N-terminus to the C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and a third polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P, and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K, and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I, and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.In some embodiments, the first polypeptide comprises the amino acid sequence of SEQ ID NO: 322; the second polypeptide comprises the amino acid sequence of SEQ ID NO: 323; and the third polypeptide comprises the amino acid sequence of SEQ ID NO: 321. In some embodiments, the VH comprises VH CDR1, VH CDR2, and VH CDR3; wherein the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 8; wherein the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 15; and wherein the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 25; and / or the VL comprises VL CDR1, VL CDR2, and VLCDR3; wherein the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 43; wherein the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 55; and wherein the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 61. In some embodiments, the VH comprises the amino acid sequence of SEQ ID NO: 102; and / or the VL comprises the amino acid sequence of SEQ ID NO: 158.

[0401] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from N-terminus to C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; (ii) a second polypeptide comprising, from N-terminus to C-terminus, CH2, CH3, a linker, and a PGRN polypeptide; and (iii) a third polypeptide comprising, from N-terminus to C-terminus, VL and CL; wherein the VH and the VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A.In some embodiments, the PGRN peptides of the first polypeptide and the second polypeptide each comprise an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265, and SEQ ID NO: 266. In some embodiments, the first polypeptide comprises the amino acid sequence of SEQ ID NO: 319; the second polypeptide comprises the amino acid sequence of SEQ ID NO: 323; and the third polypeptide comprises the amino acid sequence of SEQ ID NO: 321. In some embodiments, the VH comprises VH CDR1, VH CDR2, and VH CDR3; wherein the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 8; wherein the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 15; and wherein the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 25; and / or the VL comprises VL CDR1, VL CDR2, and VL CDR3; wherein the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 43; wherein the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 55; and wherein the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 61.In some embodiments, the VH comprises the amino acid sequence of SEQ ID NO: 102; and / or the VL comprises the amino acid sequence of SEQ ID NO: 158.

[0402] In some aspects, this document provides a complex comprising: (i) a first polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; and (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, VL and CL; wherein the VH and VL form an antigen-binding domain that specifically binds to human TfR. In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 330, wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or is an amino acid selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K and N; and / or (d) X4 is absent or is an amino acid selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A. In some embodiments, the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO: 266.In some embodiments, the first polypeptide comprises the amino acid sequence of SEQ ID NO: 332; and the second polypeptide comprises the amino acid sequence of SEQ ID NO: 321. In some embodiments, the VH comprises VH CDR1, VH CDR2, and VH CDR3; wherein the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 8; wherein the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 15; and wherein the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 25; and / or the VL comprises VL CDR1, VL CDR2, and VL CDR3; wherein the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 43; wherein the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 55; and wherein the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 61. In some embodiments, the VH comprises the amino acid sequence of SEQ ID NO: 102; and / or the VL comprises the amino acid sequence of SEQ ID NO: 158.

[0403] In some embodiments, the complex includes an antigen-binding domain linked to a PGRN polypeptide, wherein the antigen-binding domain is any antigen-binding domain that specifically binds to human TfR as described herein, and wherein the PGRN polypeptide is any PGRN polypeptide described herein.

[0404] Tables 10 through 12 show exemplary complex sequences. Amino acid linkers are in bold and underlined.

[0405] Table 10: Sequence of the "1+1 cis" TfR9.1B.39.38-PGRN complex (Form 1: 1+1 cis = HC1 (Fab-Fc-Groodium-PGRN) and HC2 (Fc-Groodium) and LC)

[0406] Table 11: Sequence of the "1+1 trans" TfR9.1B.39.38-PGRN complex (Form 2: 1+1 trans = HC1 (Fab-Fc mortar) and HC2 (Fc mortar-PGRN) and LC)

[0407] Table 12: Sequence of the “1+2” TfR9.1B.39.38-PGRN complex (Form 3: 1+2 = HC1 (Fab-Fc-Groodium-PGRN) and HC2 (Fc-Groodium-PGRN2) and LC) Table 13: Sequence of the “1+1” 39.38mv Fc-PGRN complex

[0408] B. Complexes containing CD98hc binding domains In some respects, this article provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human CD98 heavy chain (CD98hc).

[0409] In some embodiments, the PGRN polypeptide is a PGRN mutant polypeptide. In some embodiments, the PGRN mutant polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, wherein X1 is any amino acid, and wherein X2, X3, and X4 are not PIL, PFL, PPL, PYL, QRL, or QHL.

[0410] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to human CD98 heavy chain (CD98hc), and wherein the antigen-binding domain comprises VH, wherein the VH comprises VH CDR1, VH CDR2, and VH CDR3, and VL, wherein the VL comprises VLCDR1, VL CDR2, and VL CDR3, wherein the sequences of VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VLCDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 184, 352, 193, 197, 198, and 204; (ii) respectively, SEQ ID NO: 184, 353, 193, 197, 198, and 204; (iii) respectively, SEQ ID NO: 184, 354, 193, 197, 198, and 204; (iv) respectively, SEQ ID NO: 184, 355, 193, 197, 198, and 204; (v) respectively, SEQ ID NO: 184, 356, 193, 197, 198, and 204; (vi) respectively, SEQ ID NO: 184, 357, 193, 197, 198, and 204; (vii) respectively, SEQ ID NO: 184, 358, 193, 197, 198, and 204; (viii) respectively, SEQ ID NO: 184, 358, 193, 197, 198, and 204; (viii) respectively, SEQ ID NO: 184, 190, 193, 369, 198, and 204; (ix) respectively, SEQ ID NO: 184, 190, 193, 370, 198, and 204; (x) respectively, SEQ ID NO: 184, 190, 193, 371, 198, and 204; (xi) respectively, SEQ ID NO: 184, 190, 193, 372, 198, and 204; (xii) respectively, SEQ ID NO: 184, 190, 193, 373, 198, and 204; (xiii) respectively, SEQ ID NO: 184, 190, 193, 374, 198, and 204; (xiv) respectively, SEQ ID NO: 184, 190, 193, 375, 198, and 204; (xv) respectively, SEQ ID NO: 184, 354, 193, 371, 198, and 204; (xvi) respectively, SEQ ID NO: 184, 359, 193, 197, 198 and 204; (xvii) respectively, SEQ ID NO: 184, 190, 360, 197, 198 and 204; (xviii) respectively, SEQ ID NO: 184, 190, 361, 197, 198 and 204;(xix) respectively, SEQ ID NO: 184, 190, 362, 197, 198 and 204; (xx) respectively, SEQ ID NO: 184, 190, 363, 197, 198 and 204; (xxi) respectively, SEQ ID NO: 184, 190, 364, 197, 198 and 204; (xxii) respectively, SEQ ID NO: 184, 190, 365, 197, 198 and 204; (xxiii) respectively, SEQ ID NO: 184, 190, 366, 197, 198 and 204; (xxiv) respectively, SEQ ID NO: 184, 190, 367, 197, 198 and 204; (xxv) respectively, SEQ ID NO: 184, 190, 368, 197, 198, and 204; (xxvi) respectively, SEQ ID NO: 184, 190, 193, 376, 198, and 204; (xxvii) respectively, SEQ ID NO: 184, 190, 193, 377, 198, and 204; (xxviii) respectively, SEQ ID NO: 184, 190, 193, 378, 198, and 204; (xxix) respectively, SEQ ID NO: 184, 190, 193, 379, 198, and 204; (xxx) respectively, SEQ ID NO: 184, 190, 193, 380, 198, and 204; (xxxi) respectively, SEQ ID NO: 184, 190, 193, 381, 198, and 204; (xxxii) respectively, SEQ ID NO: 184, 190, 193, 197, 198, and 382; (xxxiii) respectively, SEQ ID NO: 184, 190, 193, 197, 198, and 383; (xxxiv) respectively, SEQ ID NO: 184, 190, 193, 197, 198, and 384; (xxxv) respectively, SEQ ID NO: 184, 190, 193, 197, 198, and 385; (xxxvi) respectively, SEQ ID NO: 184, 190, 193, 197, 198, and 386; (xxxvii) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 387; (xxxviii) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 388; (xxxix) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 389; (xl) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 390;(xli) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 391; (xlii) respectively, SEQ ID NO: 351, 190, 193, 197, 198 and 204; or respectively, SEQ ID NO: 351, 190, 193, 197, 198 and 391.

[0411] In some aspects, this document provides a complex comprising an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain specifically binds to a human CD98 heavy chain (CD98hc), and wherein the antigen-binding domain is a VHH comprising: (a) VH CDR1, VH CDR2, and VH CDR3, each comprising the following amino acid sequences: (i) SEQ ID NO: 184, 352, and 193, respectively; (ii) SEQ ID NO: 184, 353, and 193, respectively; (iii) SEQ ID NO: 184, 354, and 193, respectively; (iv) SEQ ID NO: 184, 355, and 193, respectively; (v) SEQ ID NO: 184, 356, and 193, respectively; (vi) SEQ ID NO: 184, 357, and 193, respectively; (vii) SEQ ID NO: 184, 357, and 193, respectively; 184, 358, and 193; (viii) respectively, SEQ ID NO: 184, 190, and 193; (ix) respectively, SEQ ID NO: 184, 359, and 193; (x) respectively, SEQ ID NO: 184, 190, and 360; (xi) respectively, SEQ ID NO: 184, 190, and 361; (xii) respectively, SEQ ID NO: 184, 190, and 362; (xiii) respectively, SEQ ID NO: 184, 190, and 363; (xiv) respectively, SEQ ID NO: 184, 190, and 364; (xv) respectively, SEQ ID NO: 184, 190, and 365; (xvi) respectively, SEQ ID NO: 184, 190, and 366; (xvii) respectively, SEQ ID NO: 184, 190, and 367; (xviii) respectively, SEQ ID NO: 184, 190, and 368; or (xix) respectively, SEQ ID NO: 351, 190, and 193; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 210, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408, or 409.

[0412] The exemplary forms of the complexes disclosed herein are depicted in Figure 1A-1J middle.

[0413] In some embodiments, the PGRN peptide in the complex is located at the N-terminus of an antigen-binding domain that specifically binds to human CD98hc.

[0414] In some embodiments, the PGRN peptide in the complex is located at the C-terminus of an antigen-binding domain that specifically binds to human CD98hc.

[0415] In some embodiments, the PGRN peptide and the antigen-binding domain that specifically binds to human CD98hc are directly linked via peptide bonds. In some embodiments, the PGRN peptide and the antigen-binding domain that specifically binds to human CD98hc are linked via a linker (e.g., a peptide linker).

[0416] In some embodiments, the complex comprises an antigen-binding domain that specifically binds to human CD98hc, a PGRN peptide, and an Fc moiety. In some embodiments, the antigen-binding domain that specifically binds to human CD98hc and the PGRN peptide are linked to the N-terminus of the Fc moiety of the complex.

[0417] In some embodiments, both the antigen-binding domain specifically binding to human CD98hc and the PGRN peptide are linked to the C-terminus of the Fc portion of the complex. In other embodiments, the antigen-binding domain specifically binding to human CD98hc is linked to the N-terminus of the Fc portion, and the PGRN peptide is linked to the C-terminus of the Fc portion of the complex. In still other embodiments, the PGRN peptide is linked to the N-terminus of the Fc portion of the complex, and the antigen-binding domain specifically binding to human CD98hc is linked to the C-terminus of the Fc portion.

[0418] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human CD98hc, and (ii) a PGRN polypeptide, wherein the complex comprises two copies of the PGRN polypeptide. In some embodiments, the complex comprises an Fc domain. The Fc may be a heterodimeric Fc comprising a first Fc polypeptide with a club-shaped mutation and a second Fc polypeptide with a mortise-and-hole mutation (“knob-hole / knob-into-hole”, “knob-hole Fc”, as described herein). In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is linked to the C-terminus of the Fc domain (i.e., to one of the two heavy chains of the Fc domain), while the two copies of the PGRN polypeptide are linked to the N-terminus of the Fc. Examples of this 2+1 form are described in... Figure 1F As shown in the image.

[0419] In some embodiments, the single scFv, Fab, or VHH antigen-binding domain that specifically binds to human CD98hc is linked to the N-terminus of the Fc domain (i.e., to one of the two heavy chains of the Fc domain), while two copies of the PGRN peptide are linked to the C-terminus of the Fc domain. This 2+1 form is exemplified in… Figure 1E As shown in the image.

[0420] In some embodiments, this document discloses a complex comprising (i) an antibody that specifically binds to human CD98hc, wherein said antibody comprises two heavy chains and two light chains; and (ii) two copies of a PGRN polypeptide linked to the C-terminus of the two antibody heavy chains. Examples of this 2+2 form are described in... Figure 1G As shown in the image.

[0421] In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that specifically bind to human CD98hc, linked to the C-terminus of the heavy chain, and (ii) two copies of a PGRN polypeptide linked to the N-terminus of the Fc domain. Examples of this form are shown in... Figure 1H As shown in the figure. In some embodiments, the complex comprises (i) two scFv, Fab, or VHH antigen-binding domains that specifically bind to human CD98hc and are linked to the N-terminus of the heavy chain, and (ii) two copies of a PGRN polypeptide linked to the C-terminus of the Fc domain.

[0422] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of the Fc domain, and the PGRN peptide is linked to the N-terminus of the Fc domain. In some embodiments, the Fc is a single-chain, engineered monovalent Fc domain. Examples of this single-chain 1+1 form of the complex are described in... Figure 1A , Figure 1I and Figure 1J As shown in the image.

[0423] In some embodiments, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of the Fc domain, and the PGRN peptide is linked to the C-terminus of the Fc domain. In some embodiments, the Fc is a single-chain, engineered monovalent Fc. Examples of this 1+1 form of the complex are shown in... Figure 1B and Figure 1C As shown in the image.

[0424] In some respects, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain specifically binding to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain specifically binding to human CD98hc and the PGRN peptide are both linked to the N-terminus of the Fc domain. Examples of this 1+1 form of the complex are described in... Figure 1D As shown in the image.

[0425] In some respects, this document discloses a complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that specifically binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that specifically binds to human CD98hc and the PGRN polypeptide are both linked to the C-terminus of the Fc domain.

[0426] In some embodiments, the complex includes an antigen-binding domain linked to a PGRN peptide, wherein the antigen-binding domain is any antigen-binding domain that specifically binds to human CD98hc as described herein, and wherein the PGRN peptide is any PGRN peptide described herein.

[0427] VII. Polynucleotides and their preparation methods In some aspects, this document provides a nucleotide sequence encoding a complex comprising an antigen-binding domain linked to a PGRN polypeptide, wherein the antigen-binding domain specifically binds to a human BBB protein or receptor. In some embodiments, the human BBB protein or receptor is TfR. In some embodiments, the human BBB protein is CD98hc.

[0428] This article also provides polynucleotides encoding isolated PGRN mutant peptides.

[0429] This document provides polynucleotides comprising nucleotide sequences encoding the complexes described herein or isolated PGRN mutant polypeptides, said polynucleotides being optimized, for example by codon / RNA optimization, substitution with heterologous signal sequences, and / or elimination of unstable elements in the mRNA. Accordingly, methods for generating optimized nucleic acids for recombinant expression by introducing codon changes (e.g., codon changes encoding the same amino acid due to the degeneracy of the genetic code) and / or eliminating repressive regions in the mRNA can be adapted from optimization methods described, for example, in the following documents: U.S. Patent Nos. 5,965,726; 6,174,666; 6,291,664; 6,414,132; and 6,794,498.

[0430] Polynucleotides containing nucleotide sequences encoding the complex or isolated PGRN mutant polypeptide described herein can be generated from nucleic acids from a suitable source (e.g., hybridoma) using methods well-known in the art (e.g., PCR and other molecular cloning methods). For example, PCR amplification using synthetic primers capable of hybridizing to the 3' and 5' ends of a known sequence can be performed using genomic DNA obtained from hybridoma cells that produce antibodies of interest. Such PCR amplification methods can be used to obtain nucleic acids containing sequences, for example, encoding light and / or heavy chains of an antigen-binding domain, an antibody, or an antigen-binding fragment thereof. The amplified nucleic acid can be cloned into a vector for expression in a host cell and further cloning, for example, to generate the complex or isolated PGRN mutant polypeptide described herein.

[0431] The polynucleotides described herein can be in RNA or DNA form. DNA includes cDNA, genomic DNA, and synthetic DNA, and can be double-stranded or single-stranded. If single-stranded, the DNA can be a coding strand or a non-coding (antisense) strand. In some embodiments, the polynucleotide is cDNA or DNA lacking one or more endogenous introns. In some embodiments, the polynucleotide is a non-naturally occurring polynucleotide. In some embodiments, the polynucleotide is recombinant-derived. In some embodiments, the polynucleotide is isolated. In some embodiments, the polynucleotide is substantially pure.

[0432] In some embodiments, the polynucleotides provided herein are in RNA form. In some embodiments, the polynucleotides provided herein are in RNA form encoding the complex provided herein or an isolated PGRN mutant polypeptide. In some embodiments, the polynucleotides provided herein are synthetic messenger RNA (mRNA). In some embodiments, the synthetic mRNA has at least one nucleoside modification. In some embodiments, the at least one nucleoside modification is selected from the group consisting of: pyridine-4-ketoribonucleoside, 5-aza-uridine, 2-thio-5-aza-uridine, 2-thiouridine, 4-thio-pseudouridine, 2-thio-pseudouridine, 5-hydroxyuridine, 3-methyluridine, 5-carboxymethyluridine, 1-carboxymethyl-pseudouridine, 5-propynyluridine, 1-propynyl-pseudouridine, 5-taurate methyluridine, 1-taurate methyl-2-thiouridine, 1-taurate methyl-4-thiouridine, 5-methyluridine, and 1-methyl-pseudouridine. 4-Thio-1-methyl-pseudouridine, 2-Thio-1-methyl-pseudouridine, 1-methyl-1-deaza-pseudouridine, 2-Thio-1-methyl-1-deaza-pseudouridine, dihydrouridine, dihydropseudouridine, 2-Thio-dihydrouridine, 2-Thio-dihydropseudouridine, 2-methoxyuridine, 2-methoxy-4-thio-uridine, 4-methoxy-pseudouridine, 4-methoxy-2-thio-pseudouridine, 5-aza-cytidine, pseudoisocytidine, 3-methylcytidine, N4-acetylcytidine, 5-formylcytidine, N4-methylcytidine, 5-hydroxymethylcytidine, 1-methyl-pseudoisocytidine, pyrrolo -Cytidine, pyrrolo-pseudo-cytidine, 2-thio-cytidine, 2-thio-5-methyl-cytidine, 4-thio-pseudo-cytidine, 4-thio-1-methyl-pseudo-cytidine, 4-thio-1-methyl-1-deazona-pseudo-cytidine, 1-methyl-1-deazona-pseudo-cytidine, zablaline, 5-aza-zablaline, 5-methyl-zablaline, 5-aza-2-thio-zablaline, 2-thio-zablaline, 2-methoxy-cytidine, 2-methoxy-5-methyl-cytidine, 4-methoxy-pseudo-cytidine, 4-methoxy-1-methyl-pseudo-cytidine, 2-aminopurine, 2,6-diaminopurine Adenine, 7-deazino-adenine, 7-deazino-8-aza-adenine, 7-deazino-2-aminopurine, 7-deazino-8-aza-2-aminopurine, 7-deazino-2,6-diaminopurine, 7-deazino-8-aza-2,6-diaminopurine, 1-methyladenine, N6-methyladenine, N6-isopentenyladenine, N6-(cis-hydroxyisopentenyl)adenine, 2-methylthio-N6-(cis-hydroxyisopentenyl)adenine, N6-glycylcarbamoyladenine, N6-threonylcarbamoyladenine, 2-methylthio-N6-threonylcarbamoyladenine, N6,N6-Dimethyladenosine, 7-methyladenosine, 2-methylthio-adenosine, 2-methoxy-adenosine, inosine, 1-methyl-inosine, γ-glycoside, huaistinoside, 7-deazino-guanosine, 7-deazino-8-aza-guanosine, 6-thio-guanosine, 6-thio-7-deazino-guanosine, 6-thio-7-deazino-8-aza-guanosine, 7-methyl-guanosine, 6-thio-7-methyl-guanosine, 7-methylinosine, 6-methoxy-guanosine, 1-methylguanosine, N2-methylguanosine, N2,N2-dimethylguanosine, 8-oxo-guanosine, 7-methyl-8-oxo-guanosine, 1-methyl-6-thio-guanosine, N2-methyl-6-thio-guanosine, and N2,N2-dimethyl-6-thio-guanosine.

[0433] In some aspects, this document provides vectors (e.g., expression vectors) comprising polynucleotides containing a nucleotide sequence encoding the complex or isolated PGRN mutant polypeptide described herein, for recombinant expression in host cells (e.g., mammalian host cells or *E. coli* cells). Vectors for generating the complex or isolated PGRN mutant polypeptide described herein can be generated, for example, using recombinant DNA techniques well-known in the art. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo gene recombination. Replicable vectors are also provided, containing a nucleotide sequence encoding the complex or isolated PGRN mutant polypeptide described herein, the nucleotide sequence being operatively linked to a promoter. Such vectors may, for example, comprise a nucleotide sequence encoding a constant region of an antigen-binding domain, an antibody, or an antigen-binding fragment thereof (see, for example, International Publications WO 86 / 05807 and WO 89 / 01036; and U.S. Patent No. 5,122,464), and variable domains of the antigen-binding domain, antibody, or antigen-binding fragment thereof may be cloned into such vectors to express the entire heavy chain, the entire light chain, or both the heavy and light chains. In some implementations, the vector is a gene therapy vector (e.g., AAV or lentiviral vector).

[0434] In some aspects, this document provides expression systems comprising polynucleotides, said polynucleotides containing nucleotide sequences encoding the complexes described herein or isolated PGRN mutant polypeptides. The expression system may be contained on a vector. The expression system may also be integrated into the chromosome of a host cell. In some embodiments, the expression system is a cell-free expression system. In some embodiments, the expression system comprises a host cell containing the polynucleotides and / or vectors provided herein.

[0435] Accordingly, this document also provides cells (e.g., host cells) containing polynucleotides and / or vectors for recombinant expression of the complexes described herein or isolated PGRN mutant peptides. In some embodiments, for expressing double-stranded antigen-binding proteins, vectors encoding the heavy and light chains separately may be co-expressed in the host cell to express the whole immunoglobulin. In some embodiments, the host cell contains two different vectors, a first vector containing polynucleotides encoding the heavy chain of the antigen-binding protein and the PGRN peptide described herein, and a second vector containing polynucleotides encoding the light chain of the antigen-binding protein. In some embodiments, a first host cell contains a first vector containing polynucleotides encoding the heavy chain and the PGRN peptide, and a second host cell contains a second vector containing polynucleotides encoding the light chain. In some embodiments, this document provides host cell populations comprising such first and second host cells.

[0436] In some respects, this article provides methods for generati...

Claims

1. A complex comprising (a) an antigen-binding domain that specifically binds to the human transferrin receptor (TfR), and (b) a granule protein precursor (PGRN) polypeptide.

2. A complex comprising (a) an affinity-modulated antigen-binding domain that specifically binds to human TfR, wherein the antigen-binding domain binds to human TfR with an affinity of 0.01 nM to 50 nM, and (b) a PGRN peptide.

3. A complex comprising (a) an affinity-modulated antigen-binding domain that specifically binds to human TfR, wherein the antigen-binding domain binds to human TfR with an affinity of 51 nM to 750 nM, and (b) a PGRN peptide.

4. The complex of claim 3, wherein the antigen-binding domain binds to human TfR with an affinity of 600 nM to 650 nM.

5. The complex of claim 3, wherein the antigen-binding domain binds to human TfR with an affinity of 160 nM to 200 nM.

6. A complex comprising (a) an affinity-modulated antigen-binding domain that specifically binds to human TfR, wherein the antigen-binding domain binds to human TfR with an affinity of 751 nM to 10,000 nM, and (b) a PGRN peptide.

7. The complex according to any one of claims 1-6, wherein the complex further comprises an Fc domain.

8. The complex of claim 7, wherein the antigen-binding domain that specifically binds to the human transferrin receptor (TfR) is not located within the Fc domain of the complex.

9. The complex of any one of claims 1-8, wherein the antigen-binding domain comprises VH and VL on separate polypeptides.

10. The complex of any one of claims 1-9, wherein the complex comprises: (i) a first polypeptide, said polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and said PGRN polypeptide; and (ii) A second polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form the antigen-binding domain that specifically binds to human TfR.

11. The complex of claim 10, further comprising (iii) a third polypeptide comprising CH2 and CH3 from the N-terminus to the C-terminus.

12. The complex of claim 10, further comprising (iii) a third polypeptide comprising CH2, CH3, a linker, and a second PGRN polypeptide from the N-terminus to the C-terminus.

13. The complex of claim 10, further comprising: (iii) A third polypeptide, wherein the polypeptide comprises, from the N-terminus to the C-terminus, a second VH, a second CH1, a second hinge region, a second CH2, a second CH3, a second linker, and a second PGRN polypeptide; (iv) A fourth polypeptide, wherein the polypeptide comprises a second VL and a second CL from the N-terminus to the C-terminus; The second VH and the second VL form a second antigen-binding domain that specifically binds to human TfR.

14. The complex according to any one of claims 1-8, wherein the complex comprises: (i) A first polypeptide, wherein the polypeptide comprises VH, CH1, a hinge region, CH2 and CH3 from the N-terminus to the C-terminus; (ii) a second polypeptide, said polypeptide comprising CH2, CH3, a linker, and said PGRN polypeptide from the N-terminus to the C-terminus; and (iii) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form the antigen-binding domain that specifically binds to human TfR.

15. The complex of any one of claims 1-8, wherein the antigen-binding domain is comprised of VH and VL on a single polypeptide chain.

16. The complex of any one of claims 1-8 and 15, wherein the antigen-binding domain comprises a single-stranded variable fragment (scFv).

17. The composite of claim 16, wherein the scFv is VH-connector-VL oriented.

18. The composite of claim 16, wherein the scFv is VL-connector-VH oriented.

19. The complex of claim 17 or claim 18, wherein the linker (A) is about 5 to about 25 amino acids, about 5 to about 20 amino acids, about 10 to about 25 amino acids, or about 10 to about 20 amino acids, and / or (B) comprises the following amino acid sequence: GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6) or GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

20. The complex according to any one of claims 1-8 and 15-19, the complex comprising (i) a first polypeptide comprising the PGRN polypeptide, a first Fc domain and the antigen-binding domain from the N-terminus to the C-terminus, and (ii) a second polypeptide comprising a second Fc domain.

21. The complex according to any one of claims 1-8, the complex comprising (i) a first polypeptide comprising the PGRN polypeptide and a first Fc domain from the N-terminus to the C-terminus, and (ii) a second polypeptide comprising a second Fc domain and the antigen-binding domain from the N-terminus to the C-terminus.

22. The complex according to any one of claims 1-9, wherein the complex comprises: (i) A first polypeptide, wherein the polypeptide comprises the PGRN polypeptide and a first Fc domain from the N-terminus to the C-terminus. (ii) A second polypeptide, wherein the polypeptide comprises VH, CH1, and a second Fc domain from the N-terminus to the C-terminus, and (iii) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form the antigen-binding domain that specifically binds to human TfR.

23. The complex according to any one of claims 1-8 and 15, the complex comprising (i) a first polypeptide comprising, from the N-terminus to the C-terminus, the PGRN polypeptide, a first Fc domain and the antigen-binding domain, and (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, a second PGRN polypeptide and a second Fc domain.

24. The complex of claim 23, wherein the second polypeptide comprises, from the N-terminus to the C-terminus, the second PGRN polypeptide, the second Fc domain, and a second antigen-binding domain that specifically binds to TfR.

25. The complex of any one of claims 1-24, wherein the antigen-binding domain is a murine, chimeric, humanized, or human antigen-binding domain, optionally wherein the antigen-binding domain is a humanized antigen-binding domain.

26. The complex of any one of claims 7-25, wherein the Fc domain is capable of binding FcRn.

27. The complex of any one of claims 1-6, wherein the complex further comprises an Fc region, wherein the Fc region comprises first and second polypeptide chains.

28. The complex of claim 27, wherein the Fc region is capable of binding FcRn.

29. The complex of claim 27 or claim 28, wherein the complex comprises (i) a single scFv or VHH or Fab antigen-binding domain that binds to human TfR, and (ii) two copies of the PGRN polypeptide.

30. The complex of claim 29, wherein the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is linked to the C-terminus of one of the two copies of the PGRN peptide.

31. The complex of claim 29, wherein one of the two copies of the PGRN polypeptide is attached to the N-terminus of the first polypeptide chain of the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the N-terminus of the second polypeptide chain of the Fc region.

32. The complex of claim 29, wherein the single scFv, Fab, or VHH antigen-binding domain that binds to human TfR is linked to the N-terminus of the first or second polypeptide chain of the Fc region.

33. The complex of claim 29, wherein one of the two copies of the PGRN polypeptide is attached to the C-terminus of the first polypeptide chain of the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the C-terminus of the second polypeptide chain of the Fc region.

34. The complex of claim 27 or claim 28, wherein the complex comprises (i) an antibody that binds to human TfR, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of the PGRN polypeptide, wherein each copy of the PGRN polypeptide is linked to the C-terminus of one of the two antibody heavy chains.

35. The complex of claim 27 or claim 28, the complex comprising (i) two scFv, Fab, or VHH antigen-binding domains that bind to human TfR, (ii) the Fc region; and (iii) two copies of the PGRN polypeptide, wherein one of the two scFv, Fab, or VHH antigen-binding domains that bind to human TfR is attached to the C-terminus of a first polypeptide chain in the Fc region, wherein the other scFv, Fab, or VHH antigen-binding domain that binds to human TfR is attached to the C-terminus of a second polypeptide chain in the Fc region, wherein one of the two copies of the PGRN polypeptide is attached to the N-terminus of the first polypeptide chain in the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the N-terminus of the second polypeptide chain in the Fc region.

36. The complex of claim 27 or claim 28, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is attached to the C-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is attached to the N-terminus of a first or second polypeptide chain of the Fc region.

37. The complex of claim 7, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the C-terminus of the Fc domain, and the PGRN peptide is linked to the N-terminus of the Fc domain.

38. The complex of claim 27 or claim 28, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is attached to the N-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is attached to the C-terminus of a first or second polypeptide chain of the Fc region.

39. The complex of claim 7, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) the Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is linked to the N-terminus of the Fc domain, and the PGRN peptide is linked to the C-terminus of the Fc domain.

40. The complex of claim 27 or claim 28, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human TfR, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human TfR is attached to the N-terminus of one of the two polypeptide chains of the Fc region, and wherein the PGRN polypeptide is attached to the N-terminus of the other polypeptide chain of the Fc region.

41. The complex of any one of claims 27-36, 38 and 40, wherein the Fc region is a heterodimeric Fc region, optionally comprising a pestle and mortar mutation.

42. The complex of any one of claims 7, 37 and 39, wherein the Fc domain is a single-chain monovalent Fc domain.

43. The complex according to any one of claims 27-36, 38 and 40-41, wherein the Fc region is a modified Fc region having the modifications listed in Table 8 or Table 9.

44. The complex of any one of claims 27-36, 38, 40-41, and 43, wherein the Fc region is a human IgG1 Fc region, wherein the human IgG1 Fc region contains a mutation that reduces effector function, optionally wherein the mutation that reduces effector function comprises: (i) L234A, L235A, and / or P331S; (ii) N325S, and / or L328F; (iii) L234A, L235A, and / or P329G; or (iv) L234A, L235A, and / or P329S.

45. The complex of any one of claims 7, 37, 39 and 42, wherein the Fc domain is a modified Fc domain having the modifications listed in Table 8.

46. ​​The complex of any one of claims 7, 37, 39, 42, and 45, wherein the Fc domain is a human IgG1 Fc domain, wherein the human IgG1 Fc domain comprises a mutation that reduces effector function, optionally wherein the mutation that reduces effector function comprises: (i) L234A, L235A, and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A, and / or P329G; or (iv) L234A, L235A, and / or P329S.

47. The complex of any one of claims 1 and 7-46, wherein the antigen-binding domain comprises a heavy chain variable region (VH) comprising VH CDR1, VH CDR2, and VH CDR3, and a light chain variable region (VL) comprising VL CDR1, VL CDR2, and VL CDR3, wherein VH CDR1, VH CDR2, VH CDR3, VLCDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 16, 25, 42, 55 and 61; (ii) Specifically, SEQ ID NO: 8, 11, 24, 40, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 11, 25, 41, 55 and 61; (iv) Specifically, SEQ ID NO: 8, 12, 26, 42, 55 and 61; (v) Specifically, SEQ ID NO: 8, 12, 27, 42, 55 and 61; (vi) Specifically, SEQ ID NO: 8, 13, 25, 42, 55 and 61; (vii) Specifically, SEQ ID NO: 8, 14, 25, 42, 55 and 61; (viii) Specifically, SEQ ID NO: 8, 15, 25, 43, 55 and 61; (ix) Specifically, SEQ ID NO: 8, 17, 25, 44, 55 and 61; (x) respectively, SEQ ID NO: 9, 18, 28, 45, 56 and 62; (xi) respectively, SEQ ID NO: 9, 19, 28, 45, 56 and 62; (xii) respectively, SEQ ID NO: 9, 20, 28, 46, 57 and 62; (xiii) Specifically, SEQ ID NO: 9, 20, 28, 46, 58 and 62; (xiv) respectively, SEQ ID NO: 9, 20, 28, 47, 59 and 62; (xv) Specifically, SEQ ID NO: 9, 21, 28, 46, 57 and 62; (xvi) Specifically, SEQ ID NO: 9, 21, 28, 47, 59 and 62; (xvii) Specifically, SEQ ID NO: 9, 22, 28, 46, 57 and 62; (xviii) Specifically, SEQ ID NO: 9, 22, 28, 46, 58 and 62; (xix) Specifically, SEQ ID NO: 9, 22, 28, 47, 59 and 62; (xx) Specifically, SEQ ID NO: 10, 22, 28, 46, 58 and 62; (xxi) respectively, SEQ ID NO: 10, 22, 30, 46, 58 and 62; (xxii) Specifically, SEQ ID NO: 10, 22, 31, 46, 58 and 62; (xxiii) Specifically, SEQ ID NO: 10, 22, 32, 46, 58 and 62; (xxiv) Specifically, SEQ ID NO: 10, 22, 33, 46, 58 and 62; (xxv) respectively, SEQ ID NO: 10, 22, 34, 46, 58 and 62; (xxvi) respectively, SEQ ID NO: 10, 22, 35, 46, 58 and 62; (xxvii) respectively, SEQ ID NO: 10, 22, 36, 46, 58 and 62; (xxviii) Specifically, SEQ ID NO: 10, 22, 37, 46, 58 and 62; (xxix) respectively, SEQ ID NO: 10, 22, 38, 46, 58 and 62; (xxx) respectively, SEQ ID NO: 10, 22, 39, 46, 58 and 62; (xxxi) respectively, SEQ ID NO: 10, 22, 28, 49, 58 and 62; (xxxii) Specifically, SEQ ID NO: 10, 22, 28, 50, 58 and 62; (xxxiii) Specifically, SEQ ID NO: 10, 22, 28, 51, 58 and 62; (xxxiv) Specifically, SEQ ID NO: 10, 22, 28, 52, 58 and 62; (xxxv) respectively, SEQ ID NO: 10, 22, 28, 53, 58 and 62; or (xxxvi) respectively, SEQ ID NO: 10, 22, 28, 54, 58 and 62.

48. The complex of claim 47, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 103, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101, 102, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, or 127.

49. The complex of claim 47 or claim 48, wherein the VL comprises the following amino acid sequence: SEQ ID NO: 157, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 173, 174, 175, 176, 177 or 178.

50. The complex of claim 48 or claim 49, wherein the VH and the VL comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 103 and 157; (ii) respectively, SEQ ID NO: 64 and 129; (iii) Specifically, SEQ ID NO: 65 and 130; (iv) Specifically, SEQ ID NO: 66 and 131; (v) Specifically, SEQ ID NO: 67 and 130; (vi) Specifically, SEQ ID NO: 68 and 131; (vii) Specifically, SEQ ID NO: 69 and 130; (viii) Specifically, SEQ ID NO: 70 and 131; (ix) Specifically, SEQ ID NO: 71 and 130; (x) Specifically, SEQ ID NO: 72 and 131; (xi) Specifically, SEQ ID NO: 73 and 130; (xii) Specifically, SEQ ID NO: 74 and 131; (xiii) Specifically, SEQ ID NO: 75 and 132; (xiv) respectively, SEQ ID NO: 76 and 131; (xv) Specifically, SEQ ID NO: 77 and 132; (xvi) Specifically, SEQ ID NO: 77 and 133; (xvii) Specifically, SEQ ID NO: 78 and 134; (xviii) Specifically, SEQ ID NO: 77 and 135; (xix) Specifically, SEQ ID NO: 77 and 136; (xx) Specifically, SEQ ID NO: 77 and 137; (xxi) respectively, SEQ ID NO: 77 and 138; (xxii) Specifically, SEQ ID NO: 79 and 131; (xxiii) Specifically, SEQ ID NO: 77 and 139; (xxiv) Specifically, SEQ ID NO: 77 and 131; (xxv) respectively, SEQ ID NO: 80 and 140; (xxvi) Specifically, SEQ ID NO: 81 and 141; (xxvii) respectively, SEQ ID NO: 82 and 131; (xxviii) Specifically, SEQ ID NO: 83 and 142; (xxix) respectively, SEQ ID NO: 77 and 143; (xxx) respectively, SEQ ID NO: 75 and 131; (xxxi) respectively, SEQ ID NO: 75 and 144; (xxxii) Specifically, SEQ ID NO: 77 and 145; (xxxiii) Specifically, SEQ ID NO: 84 and 131; (xxxiv) Specifically, SEQ ID NO: 75 and 146; (xxxv) respectively, SEQ ID NO: 85 and 131; (xxxvi) Specifically, SEQ ID NO: 86 and 138; (xxxvii) respectively, SEQ ID NO: 79 and 139; (xxxviii) Specifically, SEQ ID NO: 77 and 147; (xxxix) respectively, SEQ ID NO: 75 and 148; (xl) respectively, SEQ ID NO: 87 and 131; (xli) respectively, SEQ ID NO: 88 and 131; (xlii) respectively, SEQ ID NO: 75 and 149; (xliii) respectively, SEQ ID NO: 89 and 150; (xliv) respectively, SEQ ID NO: 90 and 151; (xlv) respectively, SEQ ID NO: 77 and 152; (xlvi) Specifically, SEQ ID NO: 79 and 153; (xlvii) respectively, SEQ ID NO: 91 and 131; (xlviii) Specifically, SEQ ID NO: 92 and 131; (xlix) respectively, SEQ ID NO: 79 and 154; (l) SEQ ID NO: 93 and 155 respectively; (li) Specifically, SEQ ID NO: 80 and 131; (lii) respectively, SEQ ID NO: 94 and 131; (liii) respectively, SEQ ID NO: 95 and 131; (liv) respectively, SEQ ID NO: 66 and 156; (lv) Specifically, SEQ ID NO: 97 and 138; (lvi) Specifically, SEQ ID NO: 95 and 156; (lvii) respectively, SEQ ID NO: 98 and 157; (lviii) Specifically, SEQ ID NO: 99 and 157; (lix) Specifically, SEQ ID NO: 100 and 157; (lx) respectively, SEQ ID NO: 101 and 157; (lxi) respectively, SEQ ID NO: 102 and 158; (lxii) respectively, SEQ ID NO: 104 and 159; (lxiii) Specifically, SEQ ID NO: 105 and 160; (lxiv) respectively, SEQ ID NO: 106 and 161; (lxv) respectively, SEQ ID NO: 107 and 162; (lxvi) Specifically, SEQ ID NO: 106 and 163; (lxvii) respectively, SEQ ID NO: 108 and 164; (lxviii) Specifically, SEQ ID NO: 106 and 165; (lxix) respectively, SEQ ID NO: 108 and 166; (lxx) respectively, SEQ ID NO: 109 and 165; (lxxi) respectively, SEQ ID NO: 110 and 167; (lxxii) respectively, SEQ ID NO: 111 and 168; (lxxiii) Specifically, SEQ ID NO: 112 and 160; (lxxiv) respectively, SEQ ID NO: 113 and 169; (lxxv) respectively, SEQ ID NO: 113 and 170; (lxxvi) respectively, SEQ ID NO: 113 and 171; (lxxvii) respectively, SEQ ID NO: 114 and 169; (lxxviii) Specifically, SEQ ID NO: 114 and 171; (lxxix) respectively, SEQ ID NO: 115 and 169; (lxxx) respectively, SEQ ID NO: 115 and 170; (lxxxi) respectively, SEQ ID NO: 115 and 171; (lxxxii) respectively, SEQ ID NO: 116 and 169; (lxxxiii) Specifically, SEQ ID NO: 116 and 170; (lxxxiv) respectively, SEQ ID NO: 116 and 171; (lxxxv) respectively, SEQ ID NO: 117 and 170; (lxxxvi) respectively, SEQ ID NO: 118 and 170; (lxxxvii) respectively, SEQ ID NO: 119 and 170; (lxxxviii) Specifically, SEQ ID NO: 120 and 170; (lxxxix) respectively, SEQ ID NO: 121 and 170; (xc) Specifically, SEQ ID NO: 122 and 170; (xci) respectively, SEQ ID NO: 123 and 170; (xcii) respectively, SEQ ID NO: 124 and 170; (xciii) Specifically, SEQ ID NO: 125 and 170; (xciv) respectively, SEQ ID NO: 126 and 170; (xcv) respectively, SEQ ID NO: 127 and 170; (xcvi) respectively, SEQ ID NO: 117 and 173; (xcvii) respectively, SEQ ID NO: 117 and 174; (xcviii) Specifically, SEQ ID NO: 117 and 175; (xcix) respectively, SEQ ID NO: 117 and 176; (c) respectively, SEQ ID NO: 117 and 177; or (ci) respectively, SEQ ID NO: 117 and 178.

51. The complex of any one of claims 1 and 7-46, wherein the antigen-binding domain is VHH, and the VHH comprises: (a) VH CDR1, VH CDR2, and VH CDR3, which contain the following amino acid sequences: (i) Specifically, SEQ ID NO: 8, 16 and 25; (ii) Specifically, SEQ ID NO: 8, 11 and 24; (iii) Specifically, SEQ ID NO: 8, 11 and 25; (iv) Specifically, SEQ ID NO: 8, 12 and 26; (v) Specifically, SEQ ID NO: 8, 12 and 27; (vi) Specifically, SEQ ID NO: 8, 13 and 25; (vii) Specifically, SEQ ID NO: 8, 14 and 25; (viii) Specifically, SEQ ID NO: 8, 15 and 25; (ix) Specifically, SEQ ID NO: 8, 17 and 25; (x) Specifically, SEQ ID NO: 9, 18, and 28; (xi) Specifically, SEQ ID NO: 9, 19 and 28; (xii) Specifically, SEQ ID NO: 9, 20 and 28; (xiii) Specifically, SEQ ID NO: 9, 21 and 28; (xiv) Specifically, SEQ ID NO: 9, 22 and 28; (xv) Specifically, SEQ ID NO: 10, 22 and 28; (xvi) Specifically, SEQ ID NO: 10, 22 and 30; (xvii) Specifically, SEQ ID NO: 10, 22 and 31; (xviii) Specifically, SEQ ID NO: 10, 22 and 32; (xix) Specifically, SEQ ID NO: 10, 22 and 33; (xx) Specifically, SEQ ID NO: 10, 22 and 34; (xxi) respectively, SEQ ID NO: 10, 22 and 35; (xxii) Specifically, SEQ ID NO: 10, 22 and 36; (xxiii) Specifically, SEQ ID NO: 10, 22 and 37; (xxiv) respectively, SEQ ID NO: 10, 22 and 38; or (xxv) respectively, SEQ ID NO: 10, 22 and 39; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 103, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101, 102, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126 or 127.

52. The complex of any one of claims 1-46, wherein the antigen-binding domain comprises a heavy chain variable region (VH), the heavy chain variable region comprising VH CDR1, VH CDR2, and VH CDR3, and a light chain variable region (VL), the light chain variable region comprising VL CDR1, VL CDR2, and VL CDR3, and wherein the VH CDR1, VH CDR2, VH CDR3, VLCDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

53. The complex of claim 52, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 101, 102, 342, 117, 343 or 118.

54. The complex of claim 52 or claim 53, wherein the VL comprises the following amino acid sequence: SEQ ID NO: 154, 344, 345, 174, 346, 347, 348, 349 or 350.

55. The complex of claim 53 or claim 54, wherein the VH and the VL comprise the following amino acid sequence: (i) SEQ ID NO: 101 and 154, respectively; (ii) Specifically, SEQ ID NO: 102 and 344; (iii) Specifically, SEQ ID NO: 102 and 345; (iv) Specifically, SEQ ID NO: 342 and 174; (v) Specifically, SEQ ID NO: 117 and 346; (vi) Specifically, SEQ ID NO: 117 and 347; (vii) Specifically, SEQ ID NO: 117 and 348; (viii) Specifically, SEQ ID NO: 117 and 349; (ix) Specifically, SEQ ID NO: 343 and 174; (x) respectively, SEQ ID NO: 118 and 174; or (xi) respectively, SEQ ID NO: 101 and 350.

56. The complex of any one of claims 1-46, wherein the antigen-binding domain specifically binds to human TfR, and wherein the antigen-binding domain is a VHH, the VHH comprising: (a) VH CDR1, VH CDR2, and VH CDR3, which contain the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14 and 25; (ii) Specifically, SEQ ID NO: 8, 15 and 25; (iv) Specifically, SEQ ID NO: 10, 22 and 333; (v) Specifically, SEQ ID NO: 10, 22 and 28; (ix) respectively, SEQ ID NO: 10, 22 and 334; or (x) respectively, SEQ ID NO: 10, 22 and 30; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 101, 102, 342, 117, 343 or 118.

57. The complex of any one of the preceding claims, wherein the PGRN polypeptide comprises the amino acid sequence shown in SEQ ID NO:

230.

58. The complex of any one of claims 1-56, wherein the PGRN polypeptide is a mutant PGRN polypeptide comprising a C-terminal amino acid sequence defined by X1X2X3X4, wherein X1 is any amino acid, and wherein X2, X3 and X4 are not PIL, PFL, PPL, PYL, QRL or QHL.

59. The complex of claim 58, wherein the PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO: 330, and wherein: (a) X1 is an amino acid selected from the group consisting of R, I, V, Q, T, P and D; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is absent or consists of amino acids selected from the group consisting of L, P, C, G, T, D, Y, R, S, Q, V, A, I, H, K, and N; and / or (d) X4 is either absent or selected from the group consisting of L, E, G, P, R, D, S, H, N, V, T, I and A amino acids.

60. The complex of any one of claims 1-56 and 58-59, wherein the PGRN mutant polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO:

266.

61. The complex of any one of claims 2-56, wherein the PGRN mutant polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 247, SEQ ID NO: 258 and SEQ ID NO:

260.

62. The complex of claim 11, wherein: (i) The first polypeptide contains the amino acid sequence of SEQ ID NO:319; (ii) The second polypeptide comprises the amino acid sequence of SEQ ID NO:321; and (iii) The third polypeptide comprises the amino acid sequence of SEQ ID NO:

320.

63. The complex of claim 14, wherein: (i) The first polypeptide comprises the amino acid sequence of SEQ ID NO:322; (ii) The second polypeptide comprises the amino acid sequence of SEQ ID NO:323; and (iii) The third polypeptide comprises the amino acid sequence of SEQ ID NO:

321.

64. The complex of claim 12, wherein: (i) The first polypeptide contains the amino acid sequence of SEQ ID NO:319; (ii) The second polypeptide comprises the amino acid sequence of SEQ ID NO:321; and (iii) The third polypeptide comprises the amino acid sequence of SEQ ID NO:

323.

65. The complex of claim 10, wherein: (i) The first polypeptide comprises the amino acid sequence of SEQ ID NO:332, and (ii) The second polypeptide comprises the amino acid sequence of SEQ ID NO:

321.

66. A complex comprising: (a) A first polypeptide, said polypeptide comprising VH, CH1, hinge region, CH2, CH3, linker and PGRN polypeptide from N-terminus to C-terminus; (b) A second polypeptide, wherein the polypeptide comprises CH2 and CH3 from the N-terminus to the C-terminus; and (c) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form an antigen-binding domain that specifically binds to human TfR, and The VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VLCDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

67. A complex comprising: (a) A first polypeptide, wherein the polypeptide comprises VH, CH1, a hinge region, CH2 and CH3 from the N-terminus to the C-terminus; (b) A second polypeptide, said polypeptide comprising CH2, CH3, a linker, and a PGRN polypeptide from the N-terminus to the C-terminus; and (c) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form an antigen-binding domain that specifically binds to human TfR, and The VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VLCDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

68. A complex comprising: (a) A first polypeptide, the polypeptide comprising VH, CH1, a hinge region, CH2, CH3, a linker and a PGRN polypeptide from the N-terminus to the C-terminus; (b) A second polypeptide, said polypeptide comprising CH2, CH3, a linker, and a PGRN polypeptide from the N-terminus to the C-terminus; and (c) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form an antigen-binding domain that specifically binds to human TfR, and The VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VLCDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

69. A complex comprising: (a) A first polypeptide, said polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and a PGRN polypeptide; and (b) A second polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form an antigen-binding domain that specifically binds to human TfR, and The VH comprises VH CDR1, VH CDR2, and VH CDR3, and the VL comprises VL CDR1, VL CDR2, and VLCDR3, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 8, 14, 25, 41, 55 and 61; (ii) respectively, SEQ ID NO: 8, 15, 25, 335, 55 and 61; (iii) Specifically, SEQ ID NO: 8, 15, 25, 336, 55 and 61; (iv) Specifically, SEQ ID NO: 10, 22, 333, 50, 58 and 62; (v) Specifically, SEQ ID NO: 10, 22, 28, 337, 58 and 62; (vi) Specifically, SEQ ID NO: 10, 22, 28, 338, 58 and 62; (vii) Specifically, SEQ ID NO: 10, 22, 28, 339, 58 and 62; (viii) Specifically, SEQ ID NO: 10, 22, 28, 340, 58 and 62; (ix) Specifically, SEQ ID NO: 10, 22, 334, 50, 58 and 62; (x) respectively, SEQ ID NO: 10, 22, 30, 50, 58 and 62; or (xi) respectively, SEQ ID NO: 8, 14, 25, 341, 55 and 61.

70. The complex of any one of claims 66-69, wherein the VH and the VL comprise the following amino acid sequence: (i) SEQ ID NO: 101 and 154, respectively; (ii) Specifically, SEQ ID NO: 102 and 344; (iii) Specifically, SEQ ID NO: 102 and 345; (iv) Specifically, SEQ ID NO: 342 and 174; (v) Specifically, SEQ ID NO: 117 and 346; (vi) Specifically, SEQ ID NO: 117 and 347; (vii) Specifically, SEQ ID NO: 117 and 348; (viii) Specifically, SEQ ID NO: 117 and 349; (ix) Specifically, SEQ ID NO: 343 and 174; (x) respectively, SEQ ID NO: 118 and 174; or (xi) respectively, SEQ ID NO: 101 and 350.

71. The complex according to any one of claims 66-70, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2 and VL CDR3 comprise the following amino acid sequences: respectively, SEQ ID NO: 10, 22, 28, 340, 58 and 62.

72. The complex of claim 71, wherein the VH and the VL comprise the following amino acid sequences: 117 and 349, respectively.

73. The complex according to any one of claims 66-70, wherein the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2 and VL CDR3 comprise the following amino acid sequences: respectively, SEQ ID NO: 10, 22, 28, 339, 58 and 62.

74. The complex of claim 73, wherein the VH and the VL comprise the following amino acid sequences: 117 and 348, respectively.

75. The complex of any one of claims 66-74, wherein the PGRN polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 230, SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO:

254. SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO:

266.

76. The complex of any one of claims 1-75, wherein the complex binds to a human sorting protein having a dissociation constant (KD) in the range of about 5 nM to about 400 nM.

77. The complex of any one of claims 1-76, wherein the complex binds to a human sorting protein having a KD in the range of about 50 nM to about 350 nM.

78. The complex of any one of claims 1-77, wherein the complex binds to a human sorting protein having a KD in the range of about 100 nM to about 300 nM.

79. The complex of any one of claims 1-78, wherein the complex increases cellular GCase activity more than the individual PGRN peptide.

80. The complex of any one of claims 1-79, wherein the complex increases cellular GCase activity by at least about 0.5 times, at least about 1 time, or at least about 2 times compared to the individual PGRN peptide.

81. The complex of any one of claims 1-80, wherein the complex is attached to an imaging agent.

82. A polynucleotide encoding a complex as described in any one of claims 1-81.

83. A vector comprising the polynucleotide as described in claim 82.

84. A host cell comprising the vector as described in claim 83.

85. A method of generating a complex, the method comprising culturing a host cell as described in claim 84 to generate the complex, optionally wherein the method further comprises isolating the complex from the culture.

86. A separated complex produced by the method of claim 85.

87. A pharmaceutical composition comprising the complex as described in any one of claims 1-81.

88. The pharmaceutical composition of claim 87, wherein the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

89. A method of treating a neurological disease or condition in a subject, the method comprising administering to the subject a complex as described in any one of claims 1-81 or a pharmaceutical composition as described in claim 87 or 88.

90. The method of claim 89, wherein the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, eye diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation.

91. The method of claim 90, wherein the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) primarily affecting the limbic system.

92. The method of claim 91, wherein the dementia is frontotemporal dementia (FTD).

93. The method of claim 91, wherein the neurological disease or condition is Alzheimer's disease.

94. The method of claim 93, wherein the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease.

95. The method of claim 91, wherein the neurological disease or condition is Parkinson's disease.

96. The method of claim 91, wherein the neurological disease or condition is frontotemporal lobe epilepsy.

97. A method of treating a subject with lysosomal storage disease, the method comprising administering to the subject a complex as described in any one of claims 1-81 or a pharmaceutical composition as described in claim 87 or 88.

98. The method of claim 97, wherein the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II and MPS type III.

99. A method for transporting a complex across the body's blood-brain barrier (BBB) ​​of a subject, the method comprising administering to the subject the complex as described in any one of claims 1-81 or the pharmaceutical composition as described in claim 87 or 88.

100. A method for increasing the concentration of PGRN in the cerebrospinal fluid (CSF) of a subject, the method comprising administering to the subject a complex as described in any one of claims 1-81 or a pharmaceutical composition as described in claim 87 or 88, wherein the PGRN concentration is increased compared to administering the PGRN polypeptide alone to the subject.

101. A method for imaging PGRN in a subject, the method comprising administering the complex of claim 81 to the subject and positioning the imaging agent in the subject's body.

102. A method for detecting PGRN in vitro, the method comprising contacting an in vitro sample with the complex of claim 81 and positioning the imaging agent within the sample.

103. Use of the complex as described in any one of claims 1-81 or the pharmaceutical composition as described in claims 87 or 88 in the method as described in any one of claims 89-102.

104. The complex of any one of claims 1-81 or the pharmaceutical composition of any one of claims 87 or 88, used in the method of any one of claims 89-102.

105. A complex comprising (a) an antigen-binding domain that specifically binds to human CD98 heavy chain (CD98hc), and (b) a granule protein precursor (PGRN) polypeptide.

106. The complex of claim 105, wherein the complex further comprises an Fc domain.

107. The complex of claim 105 or 106, wherein the antigen-binding domain comprises VH and VL on separate polypeptides.

108. The complex of any one of claims 105-107, wherein the complex comprises: (i) a first polypeptide, said polypeptide comprising, from the N-terminus to the C-terminus, VH, CH1, a hinge region, CH2, CH3, a linker, and said PGRN polypeptide; and (ii) A second polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form the antigen-binding domain that specifically binds to human CD98hc.

109. The complex of claim 108, further comprising (iii) a third polypeptide comprising CH2 and CH3 from the N-terminus to the C-terminus.

110. The complex of claim 108, further comprising (iii) a third polypeptide comprising CH2, CH3, a linker, and a second PGRN polypeptide from the N-terminus to the C-terminus.

111. The complex of claim 108, further comprising: (iii) A third polypeptide, wherein the polypeptide comprises, from the N-terminus to the C-terminus, a second VH, a second CH1, a second hinge region, a second CH2, a second CH3, a second linker, and a second PGRN polypeptide; (iv) A fourth polypeptide, wherein the polypeptide comprises a second VL and a second CL from the N-terminus to the C-terminus; The second VH and the second VL form a second antigen-binding domain that specifically binds to human CD98hc.

112. The complex of claim 105, wherein the complex comprises: (i) A first polypeptide, wherein the polypeptide comprises VH, CH1, a hinge region, CH2 and CH3 from the N-terminus to the C-terminus; (ii) a second polypeptide, said polypeptide comprising CH2, CH3, a linker, and said PGRN polypeptide from the N-terminus to the C-terminus; and (iii) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form the antigen-binding domain that specifically binds to human CD98hc.

113. The complex of claim 105 or 106, wherein the antigen-binding domain is contained in VH and VL on a single polypeptide chain.

114. The complex of any one of claims 105, 106 and 113, wherein the antigen-binding domain comprises a single-stranded variable fragment (scFv).

115. The composite of claim 114, wherein the scFv is VH-connector-VL oriented.

116. The composite of claim 114, wherein the scFv is VL-connector-VH oriented.

117. The complex of claim 115 or claim 116, wherein the linker (A) is about 5 to about 25 amino acids, about 5 to about 20 amino acids, about 10 to about 25 amino acids, or about 10 to about 20 amino acids, and / or (B) comprises the following amino acid sequence: GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 6) or GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 7).

118. The complex of any one of claims 105, 106, and 113-117, wherein the complex comprises (i) a first polypeptide comprising, from the N-terminus to the C-terminus, the PGRN polypeptide, a first Fc domain, and the antigen-binding domain, and (ii) a second polypeptide comprising a second Fc domain.

119. The complex of claim 105 or 106, wherein the complex comprises (i) a first polypeptide comprising the PGRN polypeptide and a first Fc domain from the N-terminus to the C-terminus, and (ii) a second polypeptide comprising a second Fc domain and the antigen-binding domain from the N-terminus to the C-terminus.

120. The complex according to any one of claims 105-107, wherein the complex comprises: (i) A first polypeptide, wherein the polypeptide comprises the PGRN polypeptide and a first Fc domain from the N-terminus to the C-terminus. (ii) A second polypeptide, wherein the polypeptide comprises VH, CH1, and a second Fc domain from the N-terminus to the C-terminus, and (iii) A third polypeptide, wherein the polypeptide comprises VL and CL from the N-terminus to the C-terminus; The VH and VL form the antigen-binding domain that specifically binds to human CD98hc.

121. The complex of any one of claims 105, 106, and 113, wherein the complex comprises (i) a first polypeptide comprising, from the N-terminus to the C-terminus, the PGRN polypeptide, a first Fc domain, and the antigen-binding domain, and (ii) a second polypeptide comprising, from the N-terminus to the C-terminus, a second PGRN polypeptide and a second Fc domain.

122. The complex of claim 121, wherein the second polypeptide comprises, from the N-terminus to the C-terminus, the second PGRN polypeptide, the second Fc domain, and a second antigen-binding domain that specifically binds to CD98hc.

123. The complex of any one of claims 105-122, wherein the antigen-binding domain is a murine, chimeric, humanized, or human antigen-binding domain, optionally wherein the antigen-binding domain is a humanized antigen-binding domain.

124. The complex of any one of claims 105-123, wherein the Fc domain is capable of binding FcRn.

125. The complex of claim 105, further comprising an Fc region, wherein the Fc region comprises first and second polypeptide chains.

126. The complex of claim 125, wherein the Fc region is capable of binding FcRn.

127. The complex of claim 125 or claim 126, wherein the complex comprises (i) a single scFv or VHH or Fab antigen-binding domain that binds to human CD98hc, and (ii) two copies of the PGRN polypeptide.

128. The complex of claim 127, wherein the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is linked to the C-terminus of one of the two copies of the PGRN peptide.

129. The complex of claim 127, wherein one of the two copies of the PGRN polypeptide is attached to the N-terminus of the first polypeptide chain of the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the N-terminus of the second polypeptide chain of the Fc region.

130. The complex of claim 127, wherein the single scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is linked to the N-terminus of the first or second polypeptide chain of the Fc region.

131. The complex of claim 127, wherein one of the two copies of the PGRN polypeptide is attached to the C-terminus of the first polypeptide chain of the Fc region, and wherein the other copy of the PGRN polypeptide is attached to the C-terminus of the second polypeptide chain of the Fc region.

132. The complex of claim 125 or claim 126, the complex comprising (i) an antibody that binds to human CD98hc, wherein the antibody comprises two heavy chains and two light chains; and (ii) two copies of the PGRN polypeptide, wherein each copy of the PGRN polypeptide is linked to the C-terminus of one of the two antibody heavy chains.

133. The complex of claim 125 or claim 126, the complex comprising (i) two scFv, Fab, or VHH antigen-binding domains that bind to human CD98hc, (ii) the Fc region; and (iii) two copies of the PGRN polypeptide, wherein one of the two scFv, Fab, or VHH antigen-binding domains that bind to human CD98hc is connected to the C-terminus of a first polypeptide chain in the Fc region, wherein the other scFv, Fab, or VHH antigen-binding domain that binds to human CD98hc is connected to the C-terminus of a second polypeptide chain in the Fc region, wherein one of the two copies of the PGRN polypeptide is connected to the N-terminus of the first polypeptide chain in the Fc region, and wherein the other copy of the PGRN polypeptide is connected to the N-terminus of the second polypeptide chain in the Fc region.

134. The complex of claim 125 or claim 126, the complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is linked to the N-terminus of a first or second polypeptide chain of the Fc region.

135. The complex of claim 106, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the C-terminus of the Fc domain, and the PGRN peptide is linked to the N-terminus of the Fc domain.

136. The complex of claim 125 or claim 126, the complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is attached to the N-terminus of a first or second polypeptide chain of the Fc region, and the PGRN polypeptide is attached to the C-terminus of a first or second polypeptide chain of the Fc region.

137. The complex of claim 106, wherein the complex comprises (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) the Fc domain, and (iii) a single copy of the PGRN peptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is linked to the N-terminus of the Fc domain, and the PGRN peptide is linked to the C-terminus of the Fc domain.

138. The complex of claim 125 or claim 126, the complex comprising (i) a single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc, (ii) an Fc region, and (iii) a single copy of the PGRN polypeptide, wherein the single scFv, VHH, or Fab antigen-binding domain that binds to human CD98hc is attached to the N-terminus of one of the two polypeptide chains of the Fc region, and wherein the PGRN polypeptide is attached to the N-terminus of the other polypeptide chain of the Fc region.

139. The complex of any one of claims 125-134, 136 and 138, wherein the Fc region is a heterodimeric Fc region, optionally comprising a pestle and mortar mutation.

140. The complex of any one of claims 106, 135 and 137, wherein the Fc domain is a single-chain monovalent Fc domain.

141. The complex according to any one of claims 125-134, 136 and 138-139, wherein the Fc region is a modified Fc region having the modifications listed in Table 8 or Table 9.

142. The complex of any one of claims 125-134, 136, 138-139, and 141, wherein the Fc region is a human IgG1 Fc region, wherein the human IgG1 Fc region contains a mutation that reduces effector function, optionally wherein the mutation that reduces effector function comprises: (i) L234A, L235A, and / or P331S; (ii) N325S, and / or L328F; (iii) L234A, L235A, and / or P329G; or (iv) L234A, L235A, and / or P329S.

143. The complex of any one of claims 106, 135, 137 and 140, wherein the Fc domain is a modified Fc domain having the modifications listed in Table 8.

144. The complex of any one of claims 106, 135, 137, 140, and 143, wherein the Fc domain is a human IgG1 Fc domain, wherein the human IgG1 Fc domain comprises a mutation that reduces effector function, optionally wherein the mutation that reduces effector function comprises: (i) L234A, L235A, and / or P331S; (ii) N325S and / or L328F; (iii) L234A, L235A, and / or P329G; or (iv) L234A, L235A, and / or P329S.

145. The complex of any one of claims 105-144, wherein the antigen-binding domain comprises VH, the VH comprising VH CDR1, VH CDR2, and VH CDR3, and VL comprising VL CDR1, VL CDR2, and VL CDR3, wherein the sequences of VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 181, 185, 191, 194, 198 and 201; (ii) respectively, SEQ ID NO: 182, 186, 191, 195, 199 and 202; (iii) Specifically, SEQ ID NO: 183, 187, 192, 196, 200 and 203; (iv) Specifically, SEQ ID NO: 9, 188, 192, 196, 200 and 203; (v) Specifically, SEQ ID NO: 184, 189, 193, 197, 198 and 204; (vi) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 204; (vii) Specifically, SEQ ID NO: 184, 324, 193, 197, 198 and 204; (viii) respectively, SEQ ID NO: 184, 325, 193, 197, 198 and 204; or (ix) Specifically, SEQ ID NO: 184, 326, 193, 197, 198 and 204.

146. The complex of claim 145, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 205, 206, 207, 208, 209, 210, 327, 328 or 329.

147. The complex of claim 145 or 146, wherein the VL comprises the following amino acid sequence: SEQ ID NO: 211, 212, 213, 214, 215 or 216.

148. The complex of claim 146 or 147, wherein the VH and the VL comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 205 and 211; (ii) Specifically, SEQ ID NO: 206 and 212; (iii) Specifically, SEQ ID NO: 207 and 213; (iv) Specifically, SEQ ID NO: 208 and 214; (i) respectively, SEQ ID NO: 209 and 215; (ii) respectively, SEQ ID NO: 210 and 216; (iii) Specifically, SEQ ID NO: 327 and 216; (iv) respectively, SEQ ID NO: 328 and 216; or (v) Specifically, SEQ ID NO: 329 and 216.

149. The complex of any one of claims 105-144, wherein the antigen-binding domain is VHH, and the VHH comprises: (a) VH CDR1, VH CDR2, and VH CDR3, which contain the following amino acid sequences: (i) respectively, SEQ ID NO: 181, 185 and 191; (ii) Specifically, SEQ ID NO: 182, 186 and 191; (iii) Specifically, SEQ ID NO: 183, 187 and 192; (iv) Specifically, SEQ ID NO: 9, 188 and 192; (v) Specifically, SEQ ID NO: 184, 189 and 193; (vi) Specifically, SEQ ID NO: 184, 190 and 193; (vii) Specifically, SEQ ID NO: 184, 324 and 193; (viii) respectively, SEQ ID NO: 184, 325 and 193; or (ix) respectively, SEQ ID NO: 184, 326 and 193; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 205, 206, 207, 208, 209, 210, 327, 328 or 329.

150. The complex of any one of claims 105-144, wherein the antigen-binding domain comprises VH, the VH comprising VH CDR1, VH CDR2, and VH CDR3, and VL comprising VL CDR1, VL CDR2, and VL CDR3, wherein the sequences of VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 comprise the following amino acid sequences: (i) respectively, SEQ ID NO: 184, 352, 193, 197, 198 and 204; (ii) respectively, SEQ ID NO: 184, 353, 193, 197, 198 and 204; (iii) Specifically, SEQ ID NO: 184, 354, 193, 197, 198 and 204; (iv) Specifically, SEQ ID NO: 184, 355, 193, 197, 198 and 204; (v) Specifically, SEQ ID NO: 184, 356, 193, 197, 198 and 204; (vi) Specifically, SEQ ID NO: 184, 357, 193, 197, 198 and 204; (vii) Specifically, SEQ ID NO: 184, 358, 193, 197, 198 and 204; (viii) Specifically, SEQ ID NO: 184, 190, 193, 369, 198 and 204; (ix) Specifically, SEQ ID NO: 184, 190, 193, 370, 198 and 204; (x) respectively, SEQ ID NO: 184, 190, 193, 371, 198 and 204; (xi) respectively, SEQ ID NO: 184, 190, 193, 372, 198 and 204; (xii) respectively, SEQ ID NO: 184, 190, 193, 373, 198 and 204; (xiii) Specifically, SEQ ID NO: 184, 190, 193, 374, 198 and 204; (xiv) respectively, SEQ ID NO: 184, 190, 193, 375, 198 and 204; (xv) respectively, SEQ ID NO: 184, 354, 193, 371, 198 and 204; (xvi) Specifically, SEQ ID NO: 184, 359, 193, 197, 198 and 204; (xvii) Specifically, SEQ ID NO: 184, 190, 360, 197, 198 and 204; (xviii) Specifically, SEQ ID NO: 184, 190, 361, 197, 198 and 204; (xix) respectively, SEQ ID NO: 184, 190, 362, 197, 198 and 204; (xx) respectively, SEQ ID NO: 184, 190, 363, 197, 198 and 204; (xxi) respectively, SEQ ID NO: 184, 190, 364, 197, 198 and 204; (xxii) Specifically, SEQ ID NO: 184, 190, 365, 197, 198 and 204; (xxiii) Specifically, SEQ ID NO: 184, 190, 366, 197, 198 and 204; (xxiv) Specifically, SEQ ID NO: 184, 190, 367, 197, 198 and 204; (xxv) respectively, SEQ ID NO: 184, 190, 368, 197, 198 and 204; (xxvi) respectively, SEQ ID NO: 184, 190, 193, 376, 198 and 204; (xxvii) respectively, SEQ ID NO: 184, 190, 193, 377, 198 and 204; (xxviii) respectively, SEQ ID NO: 184, 190, 193, 378, 198 and 204; (xxix) respectively, SEQ ID NO: 184, 190, 193, 379, 198 and 204; (xxx) respectively, SEQ ID NO: 184, 190, 193, 380, 198 and 204; (xxxi) respectively, SEQ ID NO: 184, 190, 193, 381, 198 and 204; (xxxii) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 382; (xxxiii) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 383; (xxxiv) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 384; (xxxv) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 385; (xxxvi) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 386; (xxxvii) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 387; (xxxviii) Specifically, SEQ ID NO: 184, 190, 193, 197, 198 and 388; (xxxix) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 389; (xl) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 390; (xli) respectively, SEQ ID NO: 184, 190, 193, 197, 198 and 391; (xlii) respectively, SEQ ID NO: 351, 190, 193, 197, 198 and 204; or (xliii) respectively, SEQ ID NO: 351, 190, 193, 197, 198 and 391.

151. The complex of claim 150, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 210, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408 or 409.

152. The complex of claim 150 or 151, wherein the VL comprises the following amino acid sequence: SEQ ID NO: 215, 216, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431 or 432.

153. The complex of claim 151 or 152, wherein the VH and the VL comprise the following amino acid sequence: (i) respectively, SEQ ID NO: 392 and 216; (ii) respectively, SEQ ID NO: 393 and 216; (iii) Specifically, SEQ ID NO: 394 and 216; (iv) Specifically, SEQ ID NO: 395 and 216; (v) Specifically, SEQ ID NO: 396 and 216; (vi) Specifically, SEQ ID NO: 397 and 216; (vii) Specifically, SEQ ID NO: 398 and 216; (viii) Specifically, SEQ ID NO: 210 and 410; (ix) Specifically, SEQ ID NO: 210 and 411; (x) Specifically, SEQ ID NO: 210 and 412; (xi) Specifically, SEQ ID NO: 210 and 413; (xii) Specifically, SEQ ID NO: 210 and 414; (xiii) Specifically, SEQ ID NO: 210 and 415; (xiv) respectively, SEQ ID NO: 210 and 416; (xv) Specifically, SEQ ID NO: 394 and 412; (xvi) Specifically, SEQ ID NO: 399 and 216; (xvii) Specifically, SEQ ID NO: 400 and 216; (xviii) Specifically, SEQ ID NO: 401 and 216; (xix) Specifically, SEQ ID NO: 402 and 216; (xx) Specifically, SEQ ID NO: 403 and 216; (xxi) respectively, SEQ ID NO: 404 and 216; (xxii) Specifically, SEQ ID NO: 405 and 216; (xxiii) Specifically, SEQ ID NO: 406 and 216; (xxiv) Specifically, SEQ ID NO: 407 and 216; (xxv) respectively, SEQ ID NO: 408 and 216; (xxvi) Specifically, SEQ ID NO: 210 and 417; (xxvii) Specifically, SEQ ID NO: 210 and 418; (xxviii) Specifically, SEQ ID NO: 210 and 419; (xxix) respectively, SEQ ID NO: 210 and 420; (xxx) respectively, SEQ ID NO: 210 and 421; (xxxi) respectively, SEQ ID NO: 210 and 422; (xxxii) Specifically, SEQ ID NO: 210 and 423; (xxxiii) Specifically, SEQ ID NO: 210 and 424; (xxxiv) Specifically, SEQ ID NO: 210 and 425; (xxxv) respectively, SEQ ID NO: 210 and 426; (xxxvi) Specifically, SEQ ID NO: 210 and 427; (xxxvii) respectively, SEQ ID NO: 210 and 428; (xxxviii) Specifically, SEQ ID NO: 210 and 429; (xxxix) respectively, SEQ ID NO: 210 and 430; (xl) Specifically, SEQ ID NO: 210 and 431; (xli) respectively, SEQ ID NO: 210 and 432; (xlii) respectively, SEQ ID NO: 409 and 215; or (xliii) respectively, SEQ ID NO: 409 and 432.

154. The complex of any one of claims 105-144, wherein the antigen-binding domain specifically binds to the human CD98 heavy chain (CD98hc), and wherein the antigen-binding domain is a VHH, the VHH comprising: (a) VH CDR1, VH CDR2, and VH CDR3, which contain the following amino acid sequences: (i) respectively, SEQ ID NO: 184, 352 and 193; (ii) Specifically, SEQ ID NO: 184, 353 and 193; (iii) Specifically, SEQ ID NO: 184, 354 and 193; (iv) Specifically, SEQ ID NO: 184, 355 and 193; (v) Specifically, SEQ ID NO: 184, 356 and 193; (vi) Specifically, SEQ ID NO: 184, 357 and 193; (vii) Specifically, SEQ ID NO: 184, 358 and 193; (viii) Specifically, SEQ ID NO: 184, 190 and 193; (ix) Specifically, SEQ ID NO: 184, 359 and 193; (x) Specifically, SEQ ID NO: 184, 190, and 360; (xi) Specifically, SEQ ID NO: 184, 190 and 361; (xii) Specifically, SEQ ID NO: 184, 190 and 362; (xiii) Specifically, SEQ ID NO: 184, 190 and 363; (xiv) respectively, SEQ ID NO: 184, 190 and 364; (xv) Specifically, SEQ ID NO: 184, 190 and 365; (xvi) Specifically, SEQ ID NO: 184, 190 and 366; (xvii) Specifically, SEQ ID NO: 184, 190 and 367; (xviii) respectively, SEQ ID NO: 184, 190 and 368; or (xix) respectively, SEQ ID NO: 351, 190 and 193; or (b) VH, wherein the VH comprises the following amino acid sequence: SEQ ID NO: 210, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408 or 409.

155. The complex of any one of the preceding claims, wherein the PGRN polypeptide comprises the amino acid sequence shown in SEQ ID NO:

230.

156. The complex of any one of claims 105-154, wherein the PGRN mutant polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO:

254. SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO:

265. ID NO:

266.

157. The complex of any one of claims 105-156, wherein the complex is linked to an imaging agent.

158. A polynucleotide encoding a complex as described in any one of claims 105-157.

159. A vector comprising the polynucleotide as described in claim 158.

160. A host cell comprising the vector as described in claim 159.

161. A method of generating a complex, the method comprising culturing a host cell as described in claim 160 to generate the complex, optionally wherein the method further comprises isolating the complex from the culture.

162. A separated complex produced by the method of claim 161.

163. A pharmaceutical composition comprising the complex as described in any one of claims 105-157.

164. The pharmaceutical composition of claim 163, wherein the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

165. A method of treating a subject with a neurological disease or condition, the method comprising administering to the subject a complex as described in any one of claims 105-157 or a pharmaceutical composition as described in claims 163 or 164.

166. The method of claim 165, wherein the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, eye diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation.

167. The method of claim 166, wherein the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) primarily affecting the limbic system.

168. The method of claim 167, wherein the dementia is frontotemporal dementia (FTD).

169. The method of claim 167, wherein the neurological disease or condition is Alzheimer's disease.

170. The method of claim 169, wherein the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease.

171. The method of claim 167, wherein the neurological disease or condition is Parkinson's disease.

172. The method of claim 165, wherein the neurological disease or condition is frontotemporal epilepsy.

173. A method of treating a subject with lysosomal storage disease, the method comprising administering to the subject a complex as described in any one of claims 105-157 or a pharmaceutical composition as described in claims 163 or 164.

174. The method of claim 173, wherein the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II and MPS type III.

175. A method for transporting a complex across the body's blood-brain barrier (BBB) ​​of a subject, the method comprising administering to the subject the complex as described in any one of claims 105-157 or the pharmaceutical composition as described in claims 163 or 164.

176. A method for increasing the concentration of PGRN in the cerebrospinal fluid (CSF) of a subject, the method comprising administering to the subject a complex as described in any one of claims 105-157 or a pharmaceutical composition as described in claims 163 or 164, wherein the PGRN concentration is increased compared to administering the PGRN polypeptide alone to the subject.

177. A method for imaging PGRN in a subject, the method comprising administering the complex of claim 157 to the subject and positioning the imaging agent in the subject's body.

178. A method for detecting PGRN in vitro, the method comprising contacting an in vitro sample with the complex of claim 157 and positioning the imaging agent within the sample.

179. Use of the complex of any one of claims 105-157 or the pharmaceutical composition of any one of claims 163 or 164 in the method of any one of claims 165-178.

180. The complex of any one of claims 105-157 or the pharmaceutical composition of any one of claims 163 or 164, for use in any one of claims 165-178.

181. An isolated PGRN mutant polypeptide, wherein: (i) The isolated PGRN mutant polypeptide comprises a C-terminal amino acid sequence defined by X1X2X3X4, wherein: (a) X1 is an amino acid selected from the group consisting of R, D, E, I, P or Q; (b) X2 is an amino acid selected from the group consisting of Q and P; (c) X3 is an amino acid selected from the group consisting of L, A, C, D, F, G, H, I, K, M, N, P, Q, R, S, T, V, or Y; and / or (d) X4 either does not exist or is selected from the group of amino acids composed of L, R, or V; and (ii) X2, X3 and X4 are not PIL, PFL, PPL, PYL, QRL or QHL.

182. The isolated PGRN mutant polypeptide of claim 181, wherein the isolated PGRN mutant polypeptide comprises the amino acid sequence of SEQ ID NO:

330.

183. The isolated PGRN mutant polypeptide of claim 182, wherein the amino acid sequence is selected from the group consisting of: 231, SEQ ID NO: 232, SEQ ID NO: 233, SEQ ID NO: 234, SEQ ID NO: 235, SEQ ID NO: 236, SEQ ID NO: 237, SEQ ID NO: 238, SEQ ID NO: 239, SEQ ID NO: 240, SEQ ID NO: 241, SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 248, SEQ ID NO: 249, SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255, SEQ ID NO: 256, SEQ ID NO: 257, SEQ ID NO: 259, SEQ ID NO: 261, SEQ ID NO: 262, SEQ ID NO: 263, SEQ ID NO: 264, SEQ ID NO: 265 and SEQ ID NO:

266.

184. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

231.

185. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

232.

186. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

233.

187. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

234.

188. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

235.

189. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

236.

190. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

237.

191. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

238.

192. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

239.

193. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

240.

194. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

241.

195. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

242.

196. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

243.

197. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

244.

198. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

245.

199. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

246.

200. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

248.

201. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

249.

202. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

250.

203. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

251.

204. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

252.

205. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

253.

206. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

254.

207. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

255.

208. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

256.

209. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

257.

210. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

259.

211. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

261.

212. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

262.

213. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

263.

214. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

264.

215. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

265.

216. The isolated PGRN mutant polypeptide of claim 183, wherein the amino acid sequence is SEQ ID NO:

266.

217. An isolated nucleic acid, said nucleic acid encoding an isolated PGRN mutant polypeptide as described in any one of claims 181-216.

218. A vector comprising the nucleic acid as described in claim 217.

219. A host cell comprising the vector as described in claim 218.

220. A method for producing an isolated PGRN mutant polypeptide, the method comprising culturing a host cell as described in claim 219 to produce the isolated PGRN mutant polypeptide, optionally wherein the method further comprises isolating the isolated PGRN mutant polypeptide from the culture.

221. An isolated PGRN mutant polypeptide produced by the method of claim 220.

222. A pharmaceutical composition comprising the isolated PGRN mutant polypeptide as described in any one of claims 181-216 and 221.

223. A method of treating a subject with a neurological disease or condition, the method comprising administering to the subject an isolated PGRN mutant polypeptide as described in any one of claims 181-216 and 221 or a pharmaceutical composition as described in claim 222.

224. The method of claim 223, wherein the neurological disease or condition is selected from neuropathic conditions, neurodegenerative diseases, eye diseases, epilepsy, lysosomal storage diseases, ischemia, behavioral disorders, and CNS inflammation.

225. The method of claim 224, wherein the neurological disease or condition is selected from Alzheimer's disease (AD), Huntington's disease, dystonia, ataxia, stroke, dementia, Lewy body dementia, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson's disease, Pick's disease, encephalitis, traumatic brain injury, and age-related TDP-43 encephalopathy (LATE) primarily affecting the limbic system.

226. The method of claim 225, wherein the dementia is frontotemporal dementia (FTD).

227. The method of claim 225, wherein the neurological disease or condition is Alzheimer's disease.

228. The method of claim 227, wherein the Alzheimer's disease is early-onset Alzheimer's disease, prodromal Alzheimer's disease, mild Alzheimer's disease, or late-onset Alzheimer's disease.

229. The method of claim 225, wherein the neurological disease or condition is Parkinson's disease.

230. The method of claim 223, wherein the neurological disease or condition is frontotemporal epilepsy.

231. A method of treating a subject with lysosomal storage disease, the method comprising administering to the subject an isolated PGRN mutant polypeptide as described in any one of claims 181-216 and 221 or a pharmaceutical composition as described in claim 222.

232. The method of claim 231, wherein the lysosomal storage disease is selected from Gaucher disease, lipofuscinosis (Barton's disease), mucopolysaccharidosis (MPS) type I, MPS type II and MPS type III.

233. A method for increasing PGRN in a subject, the method comprising administering to the subject an isolated PGRN mutant polypeptide as described in any one of claims 181-216 and 221 or a pharmaceutical composition as described in claim 222.

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