Anti-human FcRn VHH antibody and application thereof

Abstract

The invention belongs to the field of biology, and discloses an anti-human FcRn VHH antibody and application thereof. The complementarity determining regions CDR1-CDR3 of the VHH antibody are as shown in SEQ ID NO. 1 to SEQ ID NO. 9. The anti-human FcRn VHH antibody of some embodiments of the invention can be specifically combined with human FcRn; the antibody can replace a traditional antibody to be applied to treatment and diagnosis of autoimmune diseases; the fused Fc fragment is combined with an FcRn receptor in a targeting manner, so that the half-life period of IgG in blood is effectively shortened while the targeting property of the antibody is enhanced. According to some examples of the anti-human FcRn VHH antibody, the affinity of the anti-human FcRn VHH antibody and an FcRn receptor can be increased by fusing an Fc fragment, the half-life period of IgG in autoimmune diseases is effectively shortened, and meanwhile the ADCC and CDC effects are relieved.

Description

Technical Field

[0001] The invention belongs to the biological field, and specifically relates to an anti-human FcRn VHH antibody and an application thereof. Background Art

[0002] The molecular structure of neonatal Fc receptor (FcRn) is similar to that of MHC-I class molecules, and is composed of a heavy chain (containing α1-α2-α3 domains and transmembrane region) and β2-MG non-covalently bound. FcRn is an atypical FcγR that only acts on IgG and not on other immunoglobulins. Among them, α1 is responsible for binding to IgG, and α2-α3 is responsible for binding to albumin. The two binding sites are independent of each other and do not interfere with each other. FcRn is expressed in a variety of cells and organs in the body, including epidermal cells, endothelial cells, APCs, hematopoietic stem cells, small intestine, kidneys, lungs, central nervous system, etc. It is a multifunctional receptor that can perform different functions. Under acidic conditions (pH 6.0-6.5), FcRn has a high affinity with the Fc segment. IgG molecules are engulfed into the cell through endocytosis and fuse with acidic granules to form inner nucleosomes with an acidic internal environment. Unbound IgG and other proteins enter the lysosome after sorting and are degraded. At physiological pH (7.4), the binding ability between the two is weaker, and the IgG that cannot bind is released back to the extracellular space through exocytosis. This cycle protects IgG and maintains its half-life.

[0003] Antibodies, also called immunoglobulins (Ig), are proteins that can specifically bind to antigens. Antibodies are composed of four peptide chains, two heavy chains (H chains, 50kD) with larger molecular weights and two light chains (L chains, 23kD) with smaller molecular weights. The H chains and L chains are connected by disulfide bonds. At the hydroxyl end of the polypeptide chain, the types of amino acids contained in this region are relatively stable, with no obvious difference in number or order changes. This region is called the constant region or stable region, i.e., the C region. This end accounts for 1 / 2 of the L chain and 3 / 4 of the H chain. The order of arrangement of different types of amino acids at the amino end varies. This region is called the variable region, i.e., the V region. The highly variable characteristics of the variable region determine the diversity of antibodies and also determine that antibodies only bind to specific antigens. Humans have five different types of antibodies, including IgA (including subclasses IgA1 and IgA2), IgD, IgE, IgG (including subclasses IgG1, IgG2, IgG3 and IgG4) and IgM. IgG is the most important type of immunoglobulin in humans and is often used in treatment. In autoimmune diseases, the body's immune system mistakenly identifies its own tissues or organs as foreign antigens and initiates an immune response. After being abnormally activated, B lymphocytes proliferate and differentiate into plasma cells, producing excessive immunoglobulins, including IgG. Excess IgG can bind to antigens in one's own tissues or organs to form immune complexes. These immune complexes are deposited in tissues, activating the complement system, causing inflammatory responses and leading to tissue damage. IgG can also directly kill one's own tissue cells and aggravate tissue damage through antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Therefore, it is crucial to effectively reduce the level of IgG in autoimmune diseases.

[0004] Unlike conventional antibody molecules that consist of four polypeptide chains, heavy and light chains, single-domain antibodies (sdAb) are a type of antibody that lacks the light chain of an antibody and only has the variable region of the heavy chain, called VHH (Variable domain of heavy chain of heavy chain antibody). Because of their small molecular weight, they are also called nanobodies. Although single-domain antibodies have a simple structure, they can still achieve an affinity for binding to specific antigens that is comparable to or even higher than that of traditional antibodies. Compared with traditional antibodies, single-domain antibodies have the advantages of small molecular weight, strong stability, and easy recombinant expression.

[0005] "Autoimmune diseases" encompass diseases that occur when the body's immune system attacks its own normal tissues, organs, or other body components due to an immune system abnormality for which no cause can be found. These autoimmune diseases are systemic diseases that can occur in almost all parts of the body, including the nervous system, gastrointestinal system, endocrine system, skin, skeletal system, and vascular tissue. Autoimmune diseases are known to affect approximately 5-8% of the world's population, but the reported prevalence of autoimmune diseases is lower than the actual level due to limitations in the understanding of autoimmune diseases and the methods used to diagnose these diseases.

[0006] The cause of disease of autoimmune disease has been studied for a long time in heredity, environment and immune factors, but still not clearly identified. Many recent studies reveal that multiple autoimmune diseases are caused by IgG type autoantibodies. In fact, according to the research on disease and autoimmune disease treatment, the relationship between disease-specific autoantibodies and treatment of autoimmune diseases has been widely identified. Therefore, the existence of disease-specific autoantibodies and pathological effects thereof in a large number of autoimmune diseases have been identified, and when the purpose autoantibodies are removed from blood, the effect of rapidly treating the disease can be obtained.

[0007] Autoimmune diseases and alloimmune diseases are mediated by pathogenic antibodies, and common examples thereof include immune neutropenia, Guillain-Barre syndrome, epilepsy, autoimmune encephalitis, Isaac syndrome, nevus syndrome, pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, epidermolysis bullosa acquisita, pemphigoid gestationis, mucous membrane pemphigoid, antiphospholipid syndrome, autoimmune anemia, autoimmune Grave's disease, Goodpasture syndrome, myasthenia gravis, multiple sclerosis, rheumatoid arthritis, lupus, idiopathic thrombocytopenic purpura (ITP), lupus nephritis or membranous nephropathy or others.

[0008] The use of antibodies with a novel mechanism of treating autoimmune diseases by clearing pathogenic autoantibodies is expected to have therapeutic effects against pathogenic IgG-mediated autoimmune diseases (such as pemphigus vulgaris, neuromyelitis optica, and myasthenia gravis) and immune complex-mediated glomerular diseases (such as lupus nephritis or membranous nephropathy).

[0009] The method of treating autoimmune diseases by intravenous administration of large amounts of IgG (IVIG) has been widely used (Arnson Auto Immunity 42:553, 2009). The effect of IVIG is explained by a variety of mechanisms, and is also explained by the mechanism of increasing pathogenic antibody clearance by competing with endogenous IgG for FcRn. It has been shown that intravenous administration of large amounts of human immunoglobulin (IVIG) increases platelet counts in children with immune ITP, and IVIG has been shown to be beneficial as a therapy for several other autoimmune disorders. Many studies have studied the mechanism by which IVIG produces effects in the treatment of autoimmune diseases. For ITP, early studies concluded that the IVIG effect is mainly attributed to the blocking effect of Fc receptors on platelets that are responsible for phagocytosis of antibody-opsonized platelets. Subsequent studies have shown that Fc-depleted IVIG preparations cause elevated platelet counts in some ITP patients, and it has recently been reported that the IVIG effect is attributed to the stimulation of FcγRIIb expression on macrophage cells, resulting in inhibition of platelet phagocytosis.

[0010] The use of inhibitors that competitively inhibit IgG binding to FcRn is a promising therapeutic approach for treating autoimmune diseases. However, due to the high affinity of endogenous IgG for FcRn and the high concentration of endogenous IgG in the blood, competitive inhibition of FcRn will likely require extremely high doses and thus have the same limitations as existing IVIG therapy. Summary of the invention

[0011] The object of the present invention is to overcome at least one deficiency of the prior art and to provide an anti-human FcRn VHH antibody and its application.

[0012] The technical solution adopted by the present invention is: The first aspect of the present invention provides: An anti-human FcRn VHH antibody, comprising a framework region FR and a complementarity determining region CDR, wherein the amino acid sequence of the complementarity determining region CDR1 to CDR3 of the VHH antibody is selected from any one of the following combinations: Combination 1, wherein the amino acid sequences of CDR1 to CDR3 are shown as SEQ ID NO.1 to SEQ ID NO.3, respectively; Combination 2, wherein the amino acid sequences of CDR1 to CDR3 are shown in SEQ ID NO.4 to SEQ ID NO.6, respectively; Combination 3, the amino acid sequences of CDR1 to CDR3 are shown in SEQ ID NO.7 to SEQ ID NO.9, respectively.

[0013] In some examples of VHH antibodies, the FR of the VHH antibody is selected from any one of the following combinations: Combination 1, wherein the amino acid sequences of FR1 to FR4 are shown as SEQ ID NO.10 to SEQ ID NO.13, respectively; Combination 2, wherein the amino acid sequences of FR1 to FR4 are shown in SEQ ID NO.14 to SEQ ID NO.17, respectively; Combination 3, the amino acid sequences of FR1 to FR4 are shown as SEQ ID NO.18 to SEQ ID NO.21, respectively.

[0014] In some examples of VHH antibodies, the VHH antibody is selected from one of the following amino acid sequences: VHH-1: The amino acid sequences of CDR1 to CDR3 are shown in SEQ ID NO.1 to SEQ ID NO.3, respectively, and the amino acid sequences of FR1 to FR4 are shown in SEQ ID NO.10 to SEQ ID NO.13, respectively; VHH-2: The amino acid sequences of its CDR1 to CDR3 are shown in SEQ ID NO.4 to SEQ ID NO.6, respectively, and the amino acid sequences of its FR1 to FR4 are shown in SEQ ID NO.14 to SEQ ID NO.17, respectively; VHH-3: The amino acid sequences of its CDR1 to CDR3 are shown in SEQ ID NO.7 to SEQ ID NO.9, respectively, and the amino acid sequences of its FR1 to FR4 are shown in SEQ ID NO.18 to SEQ ID NO.21, respectively.

[0015] In some examples of VHH antibodies, they are chimeric antibodies, humanized antibodies, Nanobodies fused to an Fc fragment, bivalent or multivalent Nanobodies.

[0016] In some examples of VHH antibodies, the Fc fragment is selected from the Fc fragment of human IgG1, IgG2, IgG3 or IgG4 or variants and modifications thereof.

[0017] In some examples of VHH antibodies, the amino acid sequence of the Fc fragment is: EPKSSDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMITRTPEVTCVVVAVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTPLHQDWLNGKEYKCKVSNKALPAGIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVGSCSVMHEALHAHYTQKSLSLSPGK.

[0018] The second aspect of the present invention provides: A nucleic acid molecule encoding the VHH antibody according to the first aspect of the present invention.

[0019] The third aspect of the present invention provides: An expression vector comprising the nucleic acid molecule described in the second aspect of the invention.

[0020] A fourth aspect of the present invention provides: The use of the VHH antibody according to the first aspect of the present invention comprises: Preparation of diagnostic reagents for autoimmune diseases; preparing an FcRn adsorbent; preparing preparations for treating autoimmune diseases; preparing FcRn detection reagent; preparing a drug delivery vehicle; preparing biosensors; Prepare reagents for protein structure and function studies.

[0021] VHH antibodies are highly specific and can recognize and bind to specific antigens associated with autoimmune diseases. In autoimmune diseases, the body's immune system mistakenly attacks its own tissues and organs, producing antibodies against its own antigens. At the same time, when VHH antibodies bind to the target antigen, they can generate detectable signals in a variety of ways.

[0022] In some examples of application, the autoimmune disease is one selected from the following: immune neutropenia, Guillain-Barre syndrome, epilepsy, autoimmune encephalitis, Isaac syndrome, nevus syndrome, pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, acquired epidermolysis bullosa, pemphigoid gestationis, mucous membrane pemphigoid, antiphospholipid syndrome, autoimmune anemia, autoimmune Grave's disease, Goodpasture syndrome, myasthenia gravis, multiple sclerosis, rheumatoid arthritis, lupus, idiopathic thrombocytopenic purpura, lupus nephritis and membranous nephropathy.

[0023] The beneficial effects of the present invention are: The anti-human FcRn VHH antibodies of some embodiments of the present invention can specifically bind to human FcRn.

[0024] The anti-human FcRn VHH antibodies of some examples of the present invention can replace traditional antibodies and be used in the treatment and diagnosis of autoimmune diseases.

[0025] In some examples of the present invention, the anti-human FcRn VHH antibodies, the fused Fc fragments target and bind to the FcRn receptor, thereby enhancing the targeting of the antibody and effectively reducing the half-life of IgG in the blood.

[0026] The anti-human FcRn VHH antibodies of some examples of the present invention can increase their affinity to the FcRn receptor by fusing the Fc fragment, effectively reduce the half-life of IgG in autoimmune diseases, and reduce ADCC and CDC effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the electrophoresis diagram of the purified anti-human FcRn VHH-Fc antibody (45kD).

[0028] Figure 2 It is a schematic diagram of the results of the assay of the binding activity of the VHH-Fc antibody against human FcRn. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further illustrated below in combination with examples and experiments.

[0030] Example 1: Construction of VHH-Fc antibodies specifically targeting human FcRn using alpaca natural library Xinjiang Bactrian camels were immunized with FcRn protein expressed by CHO cells. After 4 immunizations, lymphocytes from 100 ml of peripheral blood of camels were extracted and total RNA was extracted, and the extracted RNA was reverse transcribed into cDNA. The nucleic acid fragment encoding the variable region of the heavy chain antibody and the Fc fragment (whose amino acid sequence is shown in SEQ ID NO.22) were amplified by nested PCR to construct a VHH-Fc antibody phage display library targeting human FcRn. The library capacity is 1.33×10 11 , the insertion rate reaches 100%.

[0031] The amino acid sequence of the Fc fragment is as follows: EPKSSDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMITRTPEVTCVVVAVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTPLHQDWLNGKEYKCKVSNK ALPAGIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVGSCSVMHEALHAHYT QKSLSLSPGK (SEQ ID NO.: 22).

[0032] Example 2: Monoclonal screening of VHH-Fc antibodies targeting human FcRn 100nM biotinylated human FcRn was bound to magnetic beads at room temperature for 30 minutes, and the antigens that did not bind to the magnetic beads were discarded. The blocked phage display library was placed in the magnetic beads and bound at room temperature for 1 hour. Unbound phages were washed with sodium acetate solution, and phages bound to antigens were eluted with Tris buffered saline solution at pH 7.4. The obtained phages were infected with Escherichia coli TG1 in logarithmic phase growth to produce and purify phages for the next round of screening. After the same screening process was repeated 2-3 rounds, positive clones were enriched.

[0033] Pick monoclonal colonies from the screened and enriched clones for phage ELISA testing. Coat the ELISA plate with 2μg / mL FcRn protein, place it at 4℃ overnight, and wash it 3 times with PBST. Block it with 2% skim milk at room temperature for 1h, wash it 3 times with PBST, add phage supernatant diluted with blocking solution, react at room temperature for 1h, and wash it 6 times with PBST. Add anti-M13 secondary antibody, react at room temperature for 1h, and wash it 3 times with PBST. Add 100μL TMB colorimetric substrate, and terminate the reaction with 100μL 1M sulfuric acid. Read the absorbance value at 450nm with an enzyme reader. Sequence the clones with OD450 values ​​greater than 0.5 in the ELISA binding test. Finally, the three VHH-Fc antibodies with the best effects were screened and marked as NO.1~3, among which: The VHH amino acid sequence of NO.1 is: QVQLVESGGGLVQPGGSLRLSCAASGFTESGSGFQYHAWFRQAPGKERERVALSWSGSRIRETISRDNSKNTVYLQMNSLRAEDTAVYYCAATADRMLGYPQGHEDDYGTLVTVSS (SEQ ID NO.23).

[0034] The VHH amino acid sequence of NO.2 is: QVQLVESGGGLVQPGGSLRLSCTGSGRGFTDFGIGWFRQAPGKERKFVAGISWSGHSTWYGDSVKGRFTISRDNAKNVVYLQMNDLQPEDTGVYYCGVIGLHLWGQGTEVTVSS (SEQ ID NO.24).

[0035] The VHH amino acid sequence of NO.3 is: AVQLVDSGGGLVQAGGSLRLSCEASGFTFDDYEIGWFRQAPGKEREGVSWIIPKYGDTYYADPVKGRFTISRGNAKSTVSLQMNSLKPEDTAVYYCAADVRTTEWGAPLRYWGQGTQVTVSS (SEQ ID NO.25).

[0036] The three VHHs were further analyzed to determine their CDR and FR regions. The analysis results are shown in Table 1.

[0037] Table 1. Structural analysis results of different VHHs

[0038] Example 3: In vitro expression and purification of VHH-Fc antibodies targeting human FcRn The gene sequence of NO.1 anti-FcRn VHH-Fc antibody was transferred into the PET28 plasmid through the restriction site and expressed in E. coli BL21. After amplification with LB medium containing 70µg / mL kanamycin, the cells were collected, ultrasonically disrupted (on 5s, off 10s, working time 20min), centrifuged at 10000rpm for 10min, and the supernatant was collected.

[0039] The target antibody was purified using protein A filler and eluted with 0.1 M acetic acid. The target antibody was subjected to SDS-PAGE electrophoresis analysis, and the expression level of the VHH-Fc antibody was determined to be 38.4 mg / L.

[0040] Figure 1 This is the electrophoresis diagram of the purified anti-human FcRn VHH-Fc antibody. The molecular weight of the VHH-Fc antibody is about 45 kD.

[0041] Example 4: Anti-FcRn VHH-Fc Antibody Affinity Determination The Octet@RED96 intermolecular interaction detection system was used to measure the affinity of the antibody prepared in Example 3. Ka (association rate constant) refers to the rate at which the antibody and antigen bind to form an immune complex per unit time. A higher Ka value means that the antibody and antigen can bind quickly. Kd (dissociation rate constant) refers to the rate at which the antibody and antigen dissociate in the immune complex per unit time. A lower Kd value indicates that the antibody and antigen are not easy to dissociate after binding. KD is the ratio of Ka to Kd, that is, KD = Kd / Ka. The KD value reflects the affinity of the antibody and antigen. The smaller the KD value, the higher the affinity of the antibody and antigen. The human FcRn protein was diluted to 10 μg / mL, and the antibody obtained in Example 3 was diluted to 50 μg / mL. The diluent used was PBS+0.1% Tween 20+0.1% BSA. The affinity test results are shown in Table 2.

[0042] Table 2 Affinity determination of anti-FcRn VHH-Fc antibodies

[0043] The results in Table 2 show that the three VHH-Fc antibodies screened all have good affinity for FcRn protein, among which NO.1 has the highest affinity for FcRn.

[0044] Example 5: Detection of binding activity of anti-FcRn VHH-Fc antibody to FcRn protein After the FcRn protein was diluted in multiple ratios (1000ng / mL, 500ng / mL, 250ng / mL, 125ng / mL, 62.5ng / mL, 31.25ng / mL, 15.63ng / mL), it was added to the ELISA plate at 100μL / well and coated overnight at 4℃. The plate was washed 3 times with PBST, 300μL of 5% BSA was added, and the plate was blocked at 37℃ for 2h. The plate was washed 3 times with PBST, 100μL of diluted VHH-Fc antibody was added, and the plate was incubated at 37℃ for 1h. The plate was washed 6 times with PBST, 100μL of HRP-labeled M13 secondary antibody was added, and the plate was incubated at 37℃ for 1h. The plate was washed 6 times with PBST, 100μL of TMB substrate solution was added, and the color was developed for 10min. The absorbance value was read at a wavelength of 450nm. The results are as follows: Figure 2 As shown. Figure 2 It can be seen that both VHH-Fc antibodies and FcRn protein have binding activity, and NO.1 has the highest binding activity.

[0045] The above is a further detailed description of the present invention, which should not be regarded as a limitation on the specific implementation of the present invention. For ordinary technicians in the technical field to which the present invention belongs, simple deduction or replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. An anti-human FcRn VHH antibody comprising a framework region FR and a complementarity determining region CDR, characterized in that: The amino acid sequence of the complementary determining regions CDR1 to CDR3 of the VHH antibody is selected from any one of the following combinations: Combination 1, wherein the amino acid sequences of CDR1 to CDR3 are shown as SEQ ID NO.1 to SEQ ID NO.3, respectively; Combination 2, wherein the amino acid sequences of CDR1 to CDR3 are shown in SEQ ID NO.4 to SEQ ID NO.6, respectively; Combination 3, the amino acid sequences of CDR1 to CDR3 are shown in SEQ ID NO.7 to SEQ ID NO.9, respectively.

2. The VHH antibody according to claim 1, characterized in that The FR of the VHH antibody is selected from any one of the following combinations: Combination 1, wherein the amino acid sequences of FR1 to FR4 are shown as SEQ ID NO.10 to SEQ ID NO.13, respectively; Combination 2, wherein the amino acid sequences of FR1 to FR4 are shown in SEQ ID NO.14 to SEQ ID NO.17, respectively; Combination 3, the amino acid sequences of FR1 to FR4 are shown as SEQ ID NO.18 to SEQ ID NO.21, respectively.

3. The VHH antibody according to claim 1, characterized in that The VHH antibody is selected from the following amino acid sequence: VHH-1: The amino acid sequences of CDR1 to CDR3 are shown in SEQ ID NO.1 to SEQ ID NO.3, respectively, and the amino acid sequences of FR1 to FR4 are shown in SEQ ID NO.10 to SEQ ID NO.13, respectively; VHH-2: The amino acid sequences of its CDR1 to CDR3 are shown in SEQ ID NO.4 to SEQ ID NO.6, respectively, and the amino acid sequences of its FR1 to FR4 are shown in SEQ ID NO.14 to SEQ ID NO.17, respectively; VHH-3: The amino acid sequences of its CDR1 to CDR3 are shown in SEQ ID NO.7 to SEQ ID NO.9, respectively, and the amino acid sequences of its FR1 to FR4 are shown in SEQ ID NO.18 to SEQ ID NO.21, respectively.

4. The VHH antibody according to any one of claims 1 to 3, characterized in that It is a chimeric antibody, a humanized antibody, a nanobody fused to an Fc fragment, a bivalent or multivalent nanobody.

5. The VHH antibody according to claim 4, characterized in that The Fc fragment is selected from the Fc segment of human IgG1, IgG2, IgG3 or IgG4 or its variants and modifications.

6. The VHH antibody according to claim 4, characterized in that The amino acid sequence of the Fc fragment is: EPKSSDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMITRTPEVTCVVVAVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTPLHQDWLNGKEYKCKVS NKALPAGIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVGSCSVMHEALHAHYTQKSLSLSPGK.

7. A nucleic acid molecule, characterized in that Encoding the VHH antibody according to any one of claims 1 to 6.

8. An expression vector, characterized in that Comprising the nucleic acid molecule of claim 7.

9. Use of the VHH antibody according to claims 1 to 6, characterized in that: The applications include: Preparation of diagnostic reagents for autoimmune diseases; preparing an FcRn adsorbent; preparing preparations for treating autoimmune diseases; preparing FcRn detection reagent; preparing a drug delivery vehicle; preparing biosensors; Prepare reagents for protein structure and function studies.

10. The use according to claim 9, characterized in that: The autoimmune disease is one selected from the following: immune neutropenia, Guillain-Barre syndrome, epilepsy, autoimmune encephalitis, Isaac syndrome, nevus syndrome, pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, acquired epidermolysis bullosa, pemphigoid gestationis, mucous membrane pemphigoid, antiphospholipid syndrome, autoimmune anemia, autoimmune Grave's disease, Goodpasture syndrome, myasthenia gravis, multiple sclerosis, rheumatoid arthritis, lupus, idiopathic thrombocytopenic purpura, lupus nephritis and membranous nephropathy.

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