Particles and methods for modifying b cells

Abstract

Disclosed herein are compositions and methods for modifying B cells. Particles such as hydrophobic microparticles or nanoparticles are described for use in delivering agents to B cells, generating regulatory B cells and inducing IL-10 production by B cells. Particles, or B cells bound to the same, are also provided for use in methods for treating an inflammatory or autoimmune disease or condition, inducing immune tolerance, and sustained delivery of an agent to a subject.

Description

PARTICLES AND METHODS FOR MODIFYING B CELLSSTATEMENT OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 553,404, filed February 14, 2024, the entire contents of which are incorporated by reference herein.STATEMENT OF GOVERNMENT SUPPORT

[0002] This invention was made with government support under Grant Nos. AI137525, DK130225, and NS140218 awarded by the National Institutes of Health. The government has certain rights in the invention.FIELD OF INVENTION

[0003] The invention relates to a particle for use in delivering agents to B cells, generating regulatory B cells and inducing IL-10 production by B cells, as well as methods for treating an inflammatory or autoimmune disease or condition and inducing immune tolerance in a subject by administering the particle, or a B cell bound to the same, to the subject.BACKGROUND

[0004] B cells are lymphocytes that play a large role in the humoral immune response. They are produced in the bone marrow of most mammals, and represent 5-15% of the circulating lymphoid pool. The principal function of B cells is to make antibodies against various antigens, and they are an essential component of the adaptive immune system. Because of their critical role in regulating the immune system, dysregulation of B cells is associated with a variety of disorders. B cell disorders, also referred to herein as B cell-related diseases, are divided into excessive or uncontrolled proliferation (lymphomas, leukemias), and defects of B cell development / immunoglobulin production (immunodeficiencies). The majority (80%) of lymphoma cases are of B cell origin. These include non-Hodgkin's lymphoma (NHL), acute lymphoblastic leukemia (ALL), and autoimmune-related diseases.

[0005] Autoimmunity results from a breakdown of self-tolerance involving humoral and / or cell- mediated immune mechanisms. Among the consequences of failure in central and / or peripheral tolerance, are survival and activation of self-reactive B cells and T cells. Examples of autoimmunediseases include, for example, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE or lupus), and multiple sclerosis. The pathogenesis of most autoimmune diseases is coupled to the production of autoantibodies against self-antigens, leading to a variety of associated pathologies. Autoantibodies are produced by terminally differentiated plasma cells that are derived from naive or memory B cells. Furthermore, B cells can have other effects on autoimmune pathology, as antigen-presenting cells (APCs) that can interact with and stimulate helper T cells, further stimulating the cycle of anti-self-immune response. Depletion of B cells can have direct impact on the production of autoantibodies. For example, treatment of RA and SLE with B cell depletion therapies such as Rituxan has been demonstrated to have clinical benefit for both disease classes.

[0006] Based on studies using B cell-deficient mice, it has been shown that B cells include a regulatory subset of cells (Bregs) that suppress immune-mediated inflammatory responses and / or facilitate the recovery of inflammation, thereby maintaining tolerance and immune homeostasis. Breg cells have been recognized to play a pivotal role in down-regulation of inflammatory responses through IL-10-dependent mechanisms by producing IL-10, and via IL-10-independent mechanisms by releasing IL-35 and TGF-P, as well as through cell contact-dependent mechanisms and production of enzymes like granzyme B, and IgG4 antibody. Breg cells suppress the differentiation of inflammatory Thl, Thl7 and NK cells, e.g., via surface expression of CDld, and induce regulatory T cells (Tregs) thereby suppressing inflammation. Bregs also cross-talk with other regulatory myeloid cells such as dendritic cells (DC), myeloid-derived suppressor cells (MDSC), and macrophages. See, e.g., Abebe et al. (2021) . / . Inflamm. Res. 14:75-84; and Catalan et al. (2021) Front. Immunol. 12:611795. Taken together, Bregs play a beneficial role in health and different diseases such as autoimmune diseases, allergy, chronic metabolic diseases, cancer, transplantation, and infectious diseases.

[0007] Accordingly, there is a need in the art for methods of modulating B cells, e.g., Bregs, and using the same in the treatment B cell-related diseases. The present invention addresses this need in the art.SUMMARY OF THE INVENTION

[0008] The present invention is based, in part, on the discovery that particles, e.g., hydrophobic microparticles or nanoparticles, selectively bind to B cells, in particular induce regulatory B cells, and the production of IL- 10. Thus, in some aspects, the present invention provides a method fordelivering an agent to a B cell, comprising contacting the B cell with a particle comprising the agent, thereby delivering the agent to the B cell.

[0009] In another aspect, the invention provides methods for inducing IL- 10 production by B cells, comprising contacting the B cells with an effective amount of a particle, thereby inducing IL- 10 production by the B cells.

[0010] In a further aspect, the invention relates to methods for treating an inflammatory or autoimmune disease or condition in a subject, comprising administering to the subject an effective amount of a particle, or a B cell bound to the same, thereby treating the subject’s inflammatory or autoimmune disease or condition.

[0011] The invention also provides methods for inducing immune tolerance in a subject, comprising administering to the subject an effective amount of a particle, or a B cell bound to the same, wherein the particle comprises an autoantigen, thereby inducing immune tolerance in the subject.

[0012] The invention further provides a method of generating regulatory B cells, comprising contacting a population of immune cells with an effective amount of a particle, thereby generating regulatory B cells.

[0013] In another aspect, the invention relates to a cellular composition comprising B cells bound to particles.

[0014] In a further aspect, the invention provides a method for sustained delivery of an agent to a subject, comprising administering to the subject a dextran microparticle or dextran nanoparticle encapsulating the agent.

[0015] In another aspect, the invention provides a method of transplanting B cells to a subject comprising contacting the B cells with an effective amount of a particle so that the particle binds to the B cells and transplanting the B cells bound to the particle to the subject.

[0016] In another aspect, the invention provides the use of a particle, or a B cell bound to the same, in the preparation of a medicament for treatment of an inflammatory or autoimmune disease or condition in a subject.

[0017] In a further aspect, the invention provides a particle, or a B cell bound to the same, for use in treating an inflammatory or autoimmune disease or condition in a subject.

[0018] These and other aspects of the invention are set forth in more detail in the description of the invention below.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1. Structure of acetal-modified dextran (Ace-DEX).

[0020] FIGS. 2A-2C. Ace-DEX microparticles (MPs) loaded with different cargo (rapamycin, cGAMP, or blank) associate with B cells at the injection site, spleen, and draining lymph node. (FIG. 2A) Blank counts, (FIG. 2B) Rapamycin counts (FIG. 2C), cGAMP counts. Mean of n=5 animals per time point shown.

[0021] FIGS. 3A-3C. Dendritic cells (DCs) and B cells isolated from a mouse were cultured with DiD (lipophilic fluorescent stain) labeled Ace-DEX MPs. DCs internalized the MPs, but the MPs were found to reside on the surface of the B cells. MPs are outlined with dashed lines. (FIGS. 3A-3B) Individual cells showing labeled MPs (arrows). (FIG. 3C) Rendering of cells in FIG. 3B in Imaris.

[0022] FIGS. 4A-4D. Ace-DEX microparticles (MPs) loaded with different cargo (rapamycin, cGAMP, or blank) associate with B cells at the subcutaneous injection site. (FIG. 4A) Percent of B cells associated with MPs, (FIG. 4B) percent of CD45+ immune cells that are MP+ B cells, (FIG. 4C) median fluorescence intensity (MFI) of B cells, (FIG. 4D) counts of MP+ B cells. Error shown as mean±SEM from n=5 animals per time point. CD45 is a marker of B cell maturation.

[0023] FIGS. 5A-5C. Ace-DEX microparticles (MPs) loaded with different cargo (rapamycin, cGAMP, or blank) and injected subcutaneously have greatest MP+ median fluorescent intensity (MFI), indicative of great capacity to associate with MPs. (FIG. 5A) MFI of Blank MPs, (FIG. 5B) MFI of rapamycin MPs, (FIG. 5C) MFI of cGAMP MPs.

[0024] FIGS. 6A-B. (FIG. 6A) B cell surface association with varied concentrations of Ace- DEX MPs, PLGA MPs, and Dextran at 2 hours. (FIG. 6B) Binding of spray dried Ace-Dex or PLGA microparticles to B cells in cultured PBMCs for 2 hours.

[0025] FIG. 7. Association of a low dose 0.01 mg / mL of Ace-DEX MPs and PLGA MPs using different concentrations of fetal bovine serum (FBS) both heat inactivated (HI), non HI, and Bovine serum albumin (BSA) blocking of MPs (followed by standard media, i.e., 10% HI FBS). Statistics: 2 Way ANOVA with multiple comparisons p < 0.001. Data shown as mean ± standard deviation.

[0026] FIG. 8. Ace-DEX MPs induce antigen-specific tolerance. MOG is Myelin oligodendrocyte glycoprotein, an MS antigen. Rapa is rapamycin, a tolerogenic agent (akasirolimus). Data shown as mean+SEM. Both therapeutic groups are significant from the blank MP group starting at day 19.

[0027] FIG. 9. Spray-dried, emulsion, or iron oxide (I.O.) dextran nanoparticles were cultured with B cells for 2 hours and binding of particles to B cells then analyzed by flow cytometry.

[0028] FIG. 10. IL-10 ELISA results from B cells treated with Ace-DEX MPs and PLGA MPs at 48 hours. Data shown as mean+SEM (n=4). Statistics are multiple unpaired T tests, * < 0.05. Dashed line, untreated B cells.

[0029] FIG.ll. Low levels of the pro-inflammatory cytokine IFNy are produced by B cells treated with Ace-DEX MPs or PLGA MPs.

[0030] FIGS. 12A-12B. Ex vivo administered B cells treated with Ace-DEX MPs containing myelin oligodendrocyte glycoprotein peptide (MOG35-55) antigen reduce experimental autoimmune encephalomyelitis (EAE) clinical score after reaching peak disease. (FIG. 12A) Clinical scores of MOG35-55 Ace-DEX MP treated B cells (n=3), (FIG. 12B) clinical scores of blank Ace-DEX MPs. Arrows indicate treatment day. Scores shown as mean ± SEM. Scoring reference: 0, complete sensation and movement of entire tail; 1, limp tail; 2, weakness in hind limbs; 3, full hind limb paralysis; 4, full hind limb and partial front limb paralysis; 5, euthanized.

[0031] FIGS. 13A-13B. Flow cytometry analysis of spleen and spinal cords from mice treated in FIGS. 12A-12B. Significantly greater Tregs were observed in the spleen and spinal cord (FIG. 13A). Further, increased Bregs in the mice were observed in both the spleen and site of inflammation (spinal cord)(FIG. 13B).

[0032] FIGS. 14A-14B. Spray dried Ace-DEX MPs were injected into mice. Three days later, they were measured by flow. (FIG. 14A) % of B cells that are positive for Ace-DEX MPs in the blood. (FIG. 14B) Percent of cells that are positive for binding to MPs that are B cells.

[0033] FIG. 15. Molecular weight effect of Ace-DEX MPs on binding to B cells.

[0034] FIGS. 16A-16C. Spray dried MPs encapsulating p31 were cultured with B and T cells. (FIG. 16A) as concentration in MPs increases LAG3 on B cells increases. (FIG. 16B) as concentration of MPs increases LAG3 expression in T cells increases. (FIG. 16C) as concentration of MPs increases, CTLA4 expression on T cells increases.DETAILED DESCRIPTION

[0035] The present invention will now be described in more detail with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In addition, any references cited herein are incorporated by reference in their entireties.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. All publications, patent applications, patents, patent publications and other references cited herein are incorporated by reference in their entireties for the teachings relevant to the sentence and / or paragraph in which the reference is presented.

[0037] Amino acids are represented herein in the manner recommended by the IUPAC-IUB Biochemical Nomenclature Commission, or (for amino acids) by either the one-letter code, or the three-letter code, both in accordance with 37 C.F.R. §1.822 and established usage.

[0038] Except as otherwise indicated, standard methods known to those skilled in the art may be used for cloning genes, amplifying and detecting nucleic acids, and the like. Such techniques are known to those skilled in the art. See, e.g., Sambrook et al., Molecular Cloning: A Laboratory Manual 4th Ed. (Cold Spring Harbor, NY, 2012); Ausubel et al. Current Protocols in Molecular Biology (Green Publishing Associates, Inc. and John Wiley & Sons, Inc., New York).

[0039] Unless the context indicates otherwise, it is specifically intended that the various features of the invention described herein can be used in any combination.

[0040] Moreover, the present invention also contemplates that in some embodiments of the invention, any feature or combination of features set forth herein can be excluded or omitted.

[0041] To illustrate, if the specification states that a complex comprises components A, B and C, it is specifically intended that any of A, B or C, or a combination thereof, can be omitted and disclaimed singularly or in any combination.

[0042] As used in the description of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Thus, for example, reference to “a cell” includes a plurality of such cells.

[0043] Also as used herein, “and / or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).

[0044] The term “about,” as used herein when referring to a measurable value such as size or an amount of polypeptide, dose, time, temperature, enzymatic activity or other biological activity and the like, is meant to encompass variations of ± 10%, ± 5%, ± 1%, ± 0.5%, ± 0.1%, or even 0.01% of the specified size or amount.

[0045] As used herein, the transitional phrase “consisting essentially of’ (and grammatical variants) is to be interpreted as encompassing the recited materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. Thus, the term “consisting essentially of’ as used herein should not be interpreted as equivalent to “comprising.”

[0046] The term “consists essentially of’ (and grammatical variants), as applied to a polypeptide or polynucleotide sequence of this invention, means a polypeptide or polynucleotide that consists of both the recited sequence (e.g, SEQ ID NO) and a total of ten or less (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) additional amino acids on the N-terminal and / or C-terminal ends of the recited sequence or additional nucleotides on the 5’ and / or 3’ ends of the recited sequence such that the function of the polypeptide or polynucleotide is not materially altered. The total of ten or less additional amino acids or nucleotides includes the total number of additional amino acids or nucleotides on both ends added together. The term “materially altered,” as applied to polypeptides of the invention, refers to an increase or decrease in biological activities / properties (<?.g, remodeling activity) of at least about 50% or more as compared to the activity of a polypeptide consisting of the recited sequence.

[0047] As used herein, the term “polypeptide,” “peptide” and “protein” are used interchangeably to refer to a polymer of amino acid residues. The term also applies to amino acid polymers in which one or more amino acids are chemical analogues or modified derivatives of a corresponding naturally-occurring amino acids. The following are non-limiting examples of polypeptides: an antibody, an antigen, an enzyme, a growth factor, a cell surface receptor, a nuclear receptor, ahormone, a lymphokine, a cytokine, a reporter protein, a selectable marker, a secreted factor, an epitope tag or functional fragments thereof or combinations thereof

[0048] The terms “polynucleotide,” “nucleic acid,” “nucleic acid molecule,” and “oligonucleotide” are used interchangeably and refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides or analogs thereof. Polynucleotides can have any three-dimensional structure and may perform any function, known or unknown. The following are non-limiting examples of polynucleotides: a gene or gene fragment (for example, a probe, primer, EST or SAGE tag), exons, introns, messenger RNA (mRNA), transfer RNA, ribosomal RNA, ribozymes, cDNA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, genomic DNA, chimeras of RNA and DNA, isolated DNA of any sequence, isolated RNA of any sequence, synthetic DNA of any sequence (e.g., chemically synthesized), synthetic RNA of any sequence (e.g, chemically synthesized), nucleic acid probes and primers. A polynucleotide can comprise modified nucleotides, such as methylated nucleotides and nucleotide analogs or derivatives (e.g.. inosine or phosphorothioate nucleotides). Such nucleotides can be used, for example, to prepare nucleic acid molecules that have altered base-pairing abilities or increased resistance to nucleases.

[0049] An isolated cell is a cell that has been removed from its natural environment. The term "isolated" does not necessarily reflect the degree to which the cell has been purified.

[0050] The term “modulate,” “modulates,” or “modulation” refers to enhancement (e.g., an increase) or inhibition (e.g, a decrease) in the specified level or activity.

[0051] The term “enhance” or “increase” refers to an increase in the specified parameter of at least about 1.25-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, 10-fold, twelve-fold, or even fifteen-fold and / or can be expressed in the enhancement and / or increase of a specified level and / or activity of at least about 1%, 5%, 10%, 15%, 25%, 35%, 40%, 50%, 60%, 75%, 80%, 90%, 95% or more.

[0052] The term “induce,” “inducing,” or “induction” refers to the act of initiating, prompting, stimulating, establishing, or otherwise producing a result. For example, inducing immune tolerance may refer to any act leading to initiating, prompting, stimulating, establishing, or otherwise producing immune tolerance. In other examples, inducing the expression of a nucleic acid may include, but not limited to, initiation of the transcription of a nucleic acid, initiation of mRNA translation, and so forth. In other examples, inducing the expression of a protein may include, butnot be limited to, increase in the transcription of a nucleic acid encoding the protein, increase in the stability of mRNA encoding the protein, increase in translation of the protein, increase in the stability of the protein, and so forth.

[0053] As used herein, the term “suppress,” “inhibit” or “reduce” or grammatical variations thereof may refer to the act of decreasing, reducing, prohibiting, limiting, lessening, or otherwise diminishing the presence, or an activity of, a particular target. Suppression may refer to partial suppression or complete suppression. For example, suppressing an immune response may refer to any act leading to decreasing, reducing, prohibiting, limiting, lessening, or otherwise diminishing an immune response, in other examples, suppression of the expression of a nucleic acid may include, but not limited to, reduction in the transcription of a nucleic acid, reduction of mRNA abundance (e.g., silencing mRNA transcription), degradation of mRNA, inhibition of mRNA translation, and so forth. In other examples, suppression of the expression of a protein may include, but not be limited to, reduction in the transcription of a nucleic acid encoding the protein, reduction in the stability of mRNA encoding the protein, inhibition of translation of the protein, reduction in stability of the protein, and so forth. The “suppress,” “inhibit” or “reduce” may refer to a decrease or diminishment in the specified level or activity of at least about 1%, 5%, 10%, 15%, 25%, 35%, 40%, 50%, 60%, 75%, 80%, 90%, 95% or more.

[0054] “Generating” means causing an action, such as the production of regulatory B to occur, either directly or indirectly.

[0055] The term “B cell” or “B lymphocyte” refers a type of lymphocyte in the humoral immunity of the adaptive immune system. B cells principally function to make antibodies, serve as antigen presenting cells, release cytokines, and develop memory B cells after activation by antigen interaction. B cells are distinguished and / or isolated from other lymphocytes, such as T cells, by the presence of a B cell receptor on the cell surface. B cells may include, e.g., pro-B cells, pre-B cells, immature B cells, transitional B cells, marginal zone B cells, naive B cells, Bl cells, memory B cells, regulatory B cells and plasma B cells. Various markers may be used to identify and / or isolate pro-B cells (CD19+CD20+CD34+CD38+CD45R+), pre-B cells (CD19+CD20+CD38+CD40+CD45R+), immature B cells (CD19+CD20+CD40+CD45R+IgM+), transitional B cells (BCL-2lowCD10+CD19+CD20+CD24lllghCD27’ CD28hlg11), marginal zone B cells (CD I c CD19+CD20+CD27+), naive B cells (CD19+CD20+CD23+CD38lowCD40+CD150+IgD+IgM+), Bl cells (CD19+CD20+CD27+CD38’ CD43+CD70+IgDlowIgM+), memory B cells (CD19+CD20+CD23lowCD27+CD38’ CD40+CD150’ IgA+IgG+), and plasma B cells (CD9highCD19lowCD20- CD24highCD27highCD40+CD95- CD138+CXCR4+).

[0056] As used herein, the term “regulatory B cell” or“ Breg” refers to a particular sub-set of B lymphocytes that suppress immune responses and contribute to the maintenance of self-tolerance. In some aspects, regulatory B cells may be defined as IL-10 producing (IL-10+) B cells. Regulatory B cells may also express one or more of TGF-[3 (TGF-P+) CD25, or CD86. In some embodiments, regulatory B cells may be further characterized and / or isolated by at least one of the following phenotypes: CD19+CD24+CD27+; CD19+CD24+CD27’ CD38+; CDld+CD5+CD19+; CD19+CD2U CD23+IgM+; or CD19+Tim-1+. See, e.g., Kleffel et al. (2015)DzaZ>etes 64(1): 158-71; Ding et al. (2015) Human Immunology 76:615-621; and US 9,913,863 B2.

[0057] The term “IL- 10” or “Interleukin- 10” refers to a cytokine encoded by the IL- 10 gene. The IL- 10 sequence is represented by the GenBank Accession No. NM_000572.2 (mRNA) and NP_000563.1 (protein).

[0058] The term “particle” refers to a nanoparticle or microparticle. A “nanoparticle” refers to a nanoscale particle having a mean diameter in the range of 1 nm to about 1000 nm in size. A “microparticle” refers to a microscale particle having a mean diameter in the range of 1 pm to about 1000 pm in size. In embodiments, the nanoparticle or microparticle size refers to the average or median diameter of a plurality of nanoparticles or microparticles when a plurality of nanoparticles or microparticles is intended.

[0059] A “hydrophobic particle,” e.g., a hydrophobic nanoparticle or hydrophobic microparticle, means a particle that comprises hydrophobic moieties appended to polymers from which the particle was prepared. In some embodiments, the hydrophobic moieties can be hydrolyzed under certain conditions such as a change in temperature, pH or other activating event.

[0060] A “dextran particle,” e.g., a dextran nanoparticle or dextran microparticle, refers to a particle composed of dextran. Depending on its origin, the dextran main chain may be composed of a-l,6-glucosidic linkages with different lengths and different ratios of branches via 1,3 linkages.

[0061] The term “oxidized dextran” refers to a compound resulting from oxidation of one or more of the hydroxyl groups of the glucose monomeric units of a dextran. This oxidation may independently convert each of these hydroxyl groups to an aldehyde. Dextran may be oxidized herein by contacting the dextran with one or more oxidizing / oxidation agents (e.g., an N- oxoammonium salt, periodate compound, and / or peroxide compound) under aqueous conditions,for example. See, e.g., U.S. Patent No. 1 1,535,683, incorporated herein by reference. Oxidized dextran may also be prepared via application of other oxidation processes, such as processes disclosed in Canadian Patent Publication Nos. 2,028,284 and 2,038,640, and U.S. Patent Nos. 4,985,553, 2,894,945, 5,747,658 and 7,595,392, all of which are incorporated herein by reference. Any method that increases the number of available aldehydes on the dextran molecule may be used herein to generate an oxidized dextran particle. Accordingly, provided herein is a general method of preparing a particle using a polymer, e.g., a dextran polymer, containing one or more aldehyde groups.

[0062] The “molecular weight” of a dextran (e.g., an acetalated dextran, oxidized dextran, or acetalated and oxidized dextran) or particle herein (e.g., a dextran nanoparticle or dextran microparticle such as an acetalated dextran nanoparticle or microparticle, or acetalated dextran nanoparticle or microparticle) may be represented as number-average molecular weight (Mn) or as weight-average molecular weight (Mw), the units of which are in Daltons (e.g., kDa) or grams / mole. Alternatively, with reference to dextran, molecular weight may be represented as DPw (weight average degree of polymerization) or DPn(number average degree of polymerization). Various means are known in the art for calculating these molecular weight measurements such as with high-pressure liquid chromatography (HPLC), size exclusion chromatography (SEC), or gel permeation chromatography (GPC).

[0063] As used herein, the term “bound” refers to the interaction between two entities that results in a stable association in which the entities are in close proximity to each other, for example, a particle bound to a B cell. The interaction may be direct or indirect and / or may be covalent or non- covalent. In some embodiments, the interaction is direct, i.e., a first entity binds directly to a second moiety. In some embodiments, the interaction is indirect, i.e., a first entity binds to a second moiety via a third entity, e.g., a particle is bound to a complement protein and the complement protein binds to a B cell.

[0064] The terms “delivering” or “introducing," or grammatical variations thereof, refers to delivering an agent (e.g., a prophylactic agent or therapeutic agent) to and / or into a cell.

[0065] As used herein, the phrase “sustained delivery” means that a particle described herein continues to deliver an agent over a defined period of time. Sustained delivery may be observed, for example, when an agent continues to be present in the bloodstream up to 24 hours, or longer, after administration.

[0066] The term “contact” or "contacting," and grammatical variations thereof, refers to placing the components of a desired reaction together under conditions suitable for carrying out the desired reaction.

[0067] Grammatical variations of “administer,” “administration,” and “administering” refer any route of providing an agent to a subject. Administration can be carried out by any suitable route, including oral, topical, intravenous, subcutaneous, transcutaneous, transdermal, intramuscular, intra-joint, parenteral, intra-arteriole, intradermal, intraventricular, intracranial, intraperitoneal, intralesional, intranasal, rectal, vaginal, by inhalation, via an implanted reservoir, parenteral (e.g., subcutaneous, intravenous, intramuscular, intra-articular, intra-synovial, intrasternal, intrathecal, intraperitoneal, intrahepatic, intralesional, and intracranial injections or infusion techniques), and the like. “Concurrent administration,” “administration in combination,” “simultaneous administration,” or “administered simultaneously” as used herein, means that the compounds are administered at the same point in time, overlapping in time, or one following the other. In the latter case, the two compounds are administered at times sufficiently close that the results observed are indistinguishable from those achieved when the compounds are administered at the same point in time. “Systemic administration” refers to the introducing or delivering to a subject an agent via a route which introduces or delivers the agent to extensive areas of the subject’s body (e.g., greater than 50% of the body), for example through entrance into the circulatory or lymph systems. By contrast, “local administration” refers to the introducing or delivery to a subject an agent via a route which introduces or delivers the agent to the area or area immediately adjacent to the point of administration and does not introduce the agent systemically in a therapeutically significant amount. For example, locally administered agents are easily detectable in the local vicinity of the point of administration but are undetectable or detectable at negligible amounts in distal parts of the subject's body. Administration includes self-administration and the administration by another.

[0068] As used herein, the term “effective amount” refers to an amount, dose or a concentration of one or more of the compositions described herein used for a period of time (including acute or chronic administration and periodic or continuous administration) that is effective within the context of its administration for causing an intended effect or physiological outcome, e.g., the generation of regulatory B cells, inducing production of IL-10 by B cells, treating an inflammatory or autoimmune disease or condition, or inducing immune tolerance.

[0069] As used herein, "agent" refers to a biological, pharmaceutical, or chemical compound or other moiety. Non-limiting examples include simple or complex organic or inorganic molecule, a peptide, a protein, an oligonucleotide, an antibody, an antibody derivative, antibody fragment, an antigen, a vitamin derivative, a carbohydrate, a toxin, or a chemotherapeutic compound. Various compounds can be synthesized, for example, small molecules and oligomers (e.g., oligopeptides and oligonucleotides), and synthetic organic compounds based on various core structures. In addition, various natural sources can provide compounds for screening, such as plant or animal extracts, and the like. A skilled artisan can readily recognize that there is no limit as to the structural nature of the agents of the present invention.

[0070] “ Treat,” “treating” and similar terms as used herein in the context of treating a subject refer to providing medical and / or surgical management of a subject. Treatment may include, but is not limited to, administering an agent or composition (e.g., a pharmaceutical composition) to a subject. Treatment is typically undertaken in an effort to alter the course of a disease (which term is used to indicate any disease, disorder, syndrome or undesirable condition warranting or potentially warranting therapy) in a manner beneficial to the subject. The effect of treatment may include reversing, alleviating, reducing severity of, delaying the onset of, curing, inhibiting the progression of, and / or reducing the likelihood of occurrence or recurrence of the disease or one or more symptoms or manifestations of the disease. A therapeutic agent may be administered to a subject who has a disease or is at increased risk of developing a disease relative to a member of the general population. In some embodiments a therapeutic agent may be administered to a subject who has had a disease but no longer shows evidence of the disease. The agent may be administered e.g., to reduce the likelihood of recurrence of evident disease. A therapeutic agent may be administered prophylactically, i.e., before development of any symptom or manifestation of a disease. “Prophylactic treatment” refers to providing medical and / or surgical management to a subject who has not developed a disease or does not show evidence of a disease in order, e.g., to reduce the likelihood that the disease will occur, delay the onset of the disease, or to reduce the severity of the disease should it occur. The subject may have been identified as being at risk of developing the disease (e.g., at increased risk relative to the general population or as having a risk factor that increases the likelihood of developing the disease).

[0071] A “subject” may be any vertebrate organism in various embodiments. A subject may be an individual to whom an agent is administered, e.g., for experimental, diagnostic, and / ortherapeutic purposes or from whom a sample is obtained or on whom a procedure is performed. In some embodiments a subject is a mammal, e.g., a human, non-human primate, lagomorph (e.g., rabbit), rodent (e.g., mouse, rat), companion animal (e.g., dog or cat), or livestock (e.g., cow, pig, chicken, turkey). In some embodiments a human subject is a neonate, child, adult or geriatric subject.

[0072] An “inflammatory disease or condition” means any disease, disorder or condition in which undesired inflammation occurs. The terms “inflammatory response” and “inflammation” as used herein indicate the complex biological response of vascular tissues of an individual to harmful stimuli, such as pathogens, damaged cells, or irritants, and includes secretion of cytokines and more particularly of pro-inflammatory cytokines, i.e., cytokines which are produced predominantly by activated immune cells and are involved in the amplification of inflammatory reactions. Exemplary pro-inflammatory cytokines include, but are not limited to, IL-1, IL-6, TNF- a, IL-17, IL21, IL23, and IL27. Exemplary inflammations include acute inflammation and chronic inflammation. Acute inflammation indicates a short-term process characterized by the classic signs of inflammation (swelling, redness, pain, heat, and loss of function) due to the infiltration of the tissues by plasma and leukocytes. An acute inflammation typically occurs as long as the injurious stimulus is present and ceases once the stimulus has been removed, broken down, or walled off by scarring (fibrosis). Chronic inflammation indicates a condition characterized by concurrent active inflammation, tissue destruction, and attempts at repair. Chronic inflammation is not characterized by the classic signs of acute inflammation listed above. Instead, chronically inflamed tissue is characterized by the infiltration of mononuclear immune cells (monocytes, macrophages, lymphocytes, and plasma cells), tissue destruction, and attempts at healing, which include angiogenesis and fibrosis. Inflammation can be inhibited in the sense of the present disclosure by affecting and in particular inhibiting any one of the events that form the complex biological response associated with an inflammation in an individual. Examples of inflammatory diseases or conditions are described elsewhere herein. Additional inflammatory diseases or conditions will be known to those of skill in the art and the invention is not limited in this respect.

[0073] An “autoimmune disease or condition” is any disease where the immune system mounts an undesired immune response against self e.g., one or more autoantigens). In some embodiments, an autoimmune disease comprises an aberrant destruction of cells of the body as part of the selftargeted immune response. In some embodiments, the destruction self-manifests in the malfunctionof an organ, for example, the colon or pancreas. Examples of autoimmune diseases are described elsewhere herein. Additional autoimmune diseases will be known to those of skill in the art and the invention is not limited in this respect.

[0074] As used herein, “immune tolerance” refers to the lack of a specific immune response to an antigen. In some embodiments, immune tolerance is induced to make the immune system unresponsive to self-antigens thereby preventing damage to healthy tissues.

[0075] “Antigen” means a compound, composition, or substance that may be specifically bound by the products of specific humoral or cellular immunity, such as an antibody molecule or T-cell receptor. In some embodiments, antigens may be proteins, polypeptides, peptides, lipoproteins, glycolipids, phospholipids, polynucleotides, polysaccharides, hormones, small molecules, macromolecules, or are contained or expressed in cells. An antigen can be combined with the particle (e.g., hydrophobic microparticle or nanoparticle) in the same form as what a subject is exposed to that causes an undesired immune response but may also be a fragment or derivative thereof. Common categories of antigens include, but are not limited to, viral antigens, bacterial antigens, fungal antigens, protozoa and other parasitic antigens, tumor antigens, antigens involved in autoimmune disease, allergy and graft rejection, toxins, and the like. As used herein, the term “auto-antigen” refers to a sub-type of antigens that are a normal bodily constituent and against which the immune system produces autoantibodies.

[0076] “Pharmaceutical composition” means a mixture of substances suitable for administering to a subject. For example, a pharmaceutical composition may comprise a particle (e.g., a hydrophobic microparticle or nanoparticle), or a B cell bound to the same, in a pharmaceutically acceptable carrier.

[0077] “Pharmaceutically acceptable” or “physiologically tolerable” and grammatical variations thereof, as they refer to compositions, carriers, diluents and reagents, are used interchangeably and represent that the materials are capable of administration to or upon a subject e.g., a mammal such as a mouse, rat, rabbit, or a primate such as a human), without the production of therapeutically prohibitive undesirable physiological effects.

[0078] Applicant has found that particles, in particular hydrophobic microparticles or nanoparticles such as acetalated dextran (Ace-DEX) microparticles or nanoparticles, bind to the surface of B cells without being internalized. In addition, when the Ace-DEX microparticles or nanoparticles are injected into a subject subcutaneously, the microparticles or nanoparticlesassociate with B cells. Notably, Ace-DEX microparticles bound to B cells remain in the blood for at least 3 days following intravenous injection. Further, ex vivo incubation of B cells with Ace- DEX was found to induce Bregs as evidenced by IL- 10 production. Therefore, particles such as Ace-DEX microparticles or nanoparticles can be used by themselves to induce Bregs and / or used as a carrier to deliver therapeutic agents to target tissues where B cells would traffic, e.g., sites of inflammation. Accordingly, this invention relates to compositions and methods for using particles such as Ace-DEX microparticles or nanoparticles for targeting B cells in vivo or ex vivo and treating diseases and conditions where B cells are known to be involved and / or traffic, e.g., to control autoimmune or inflammatory diseases and conditions and / or to treat cancer. In addition, particles targeting B cells may be used for sustained delivery of a therapeutic agent and to upregulate immunodeficient conditions such as common variable immunodeficiency (CVID), wherein B cell depletive therapy has become a standard of therapy for CVID interstitial lung disease.

[0079] In one aspect, the invention provides a method for delivering an agent to a B cell by contacting the B cell with a particle including the agent, thereby delivering the agent to the B cell. In some embodiments, the B cell is in vivo. In other embodiments, the B cell is ex vivo. In some embodiments, the particle does not covalently bind to the B cell. In some embodiments, the particle is a hydrophobic particle. In some embodiments, the particle is a hydrophilic particle. In some embodiments, the particle is a nanoparticle. In some embodiments, the particle is a microparticle. Not wishing to be bound by theory, it is believed that particles having an average size in the range of, e.g., 1-2 micron are not internalized by non-phagocytic cells such as B cells. Instead, the particles remain bound to the surface of the B cells. Thus, upon binding to B cells, the particles release their cargo, e.g., for delivery into the B cells themselves or at the site in which the B cells have trafficked, e.g., sites of inflammation.

[0080] When used ex vivo, B cells may be obtained from any tissue where they reside including, but not limited to, blood (including blood collected by blood banks), spleen, bone marrow, tissues removed and / or exposed during surgical procedures, and tissues obtained via biopsy procedures. B cells can be obtained from a subject in need of therapy or suffering from a disease. Alternatively, B cells can be obtained from a donor, preferably a histocompatibility matched donor. The B cell population may be harvested from the peripheral blood, bone marrow, spleen, or any otherorgan / tissue in which B cells reside in said subject or donor. In a further aspect, the B cells may be isolated from a pool of subjects and / or donors, or from pooled blood.

[0081] When the population of B cells is obtained from a donor distinct from the subject, the donor is preferably syngeneic, but can also be allogeneic, or even xenogeneic, provided the cells obtained are subject-compatible in that they can be introduced into the subject. Allogeneic donor cells are preferably human-leukocyte-antigen (HLA)-compatible. To be rendered subjectcompatible, xenogeneic cells may be subject to gamma irradiation or PEN110 treatment (see, e.g., Fast et al. (2004) Transfusion 44:282-5). In some aspects, an allogenic B cell population from a donor may be used to promote tolerance, and then the adopted allogenic tissue may be transplanted.

[0082] B cells can be enriched, isolated and / or purified from a tissue or population of immune cells (e.g., peripheral blood mononuclear cells (PBMCs)) by selection using automated cell sorting such as fluorescence-activated cell sorting (FACS), solid-phase magnetic beads, etc. To enhance enrichment, positive selection (e.g., selection for the presence of the B cell receptor, CD 19, CD20, etc.) may be combined with negative selection; i.e., by removing cells having surface markers specific to non-B cells and / or those specific to non-regulatory B cells, e.g., T cells, NK cells, monocytes, dendritic cells, granulocytes, platelets, and erythroid cells. By way of illustration, non- B cells can be labeled with one or more biotinylated CD2, CD14, CD16, CD36, CD43, and / or CD235a (glycophorin A) antibodies. Labeled cells are subsequently magnetically labeled with anti-biotin microbeads for depletion. Highly pure B cells are obtained by depletion of magnetically labeled non-B cells. In some embodiments, the B cells are enriched and / or isolated at least 2-fold, e.g., at least 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 20-, 30-, 40-, or 50-fold.

[0083] Particles of use in this invention include, but are not limited to, particles, e.g., nanoparticles or microparticles, prepared from a polymer such as a polysaccharide, a carbohydrate, a polyserine, a polyol, polyvinyl alcohol, and other polymers such as 2- (hydroxyethyl)methacrylate. In some embodiments, the polymer and the particle comprising the same is hydrophilic. In some embodiments, the polymer and the particle comprising the same is hydrophobic. In some embodiments, the particle is comprised of a combination of hydrophilic and hydrophobic polymers. In some embodiments, the polysaccharide used in this invention can include, but is not limited to, dextran, mannan, pullulan, maltodextrin, inulin, starch, cellulose and a cellulose derivative, gum (e.g., xanthan, locust bean), and pectin. In some embodiments, a polymer and the particle comprising the same is unmodified. In some embodiments, the polymerand the particle comprise one or more aldehyde groups on the surface. In some embodiments, a polymer and the particle comprising the same is modified with a hydrophobic moiety. In some embodiments, the particle is comprised of a combination of modified and unmodified polymers. In some embodiments, the modification of a polymer and particle with a hydrophobic moiety includes, but is not limited to, an acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituent, or other hydrolysable modification. In some embodiments, the hydrophobic polymer of the particle is a polysaccharide comprising one or more of an acetal (e.g., a cyclic or acyclic acetal), aromatic acetal, ketal, ester, and / or silyl-ether substituent. In some embodiments, the hydrophobic particle comprises a hydrophobic dextran. In some embodiments, the hydrophobic particle comprises a hydrophobic oxidized dextran. In other embodiments, the hydrophobic polymer is a hydrophobic dextran comprising one or more of an acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituent. In further embodiments, the hydrophobic polymer of the particle is an acetal- derivatized dextran, acetal-derivatized inulin, or acetal -derivatized mannan, singly or in any combination. In still other embodiments, the hydrophobic polymer of the particle is a polysaccharide, a carbohydrate, a polyserine, a polyol, polyvinyl alcohol or 2- hydroxyethylmethacrylate comprising pendant acetals thus providing a polyacetal polymer. In some embodiments, the hydrophobic particle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle. In some embodiments, the hydrophobic polymer is an oxidized dextran comprising one or more of an acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituent. In some embodiments, the hydrophobic particle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle comprising oxidized dextran.

[0084] In some embodiments, the particles (e.g., acetalated dextran microparticles or nanoparticles) are formed by electrohydrodynamic spraying (electrospray). In some embodiments, the particles can be formed by double emulsion, single emulsion, or precipitation processes. In some embodiments, the particles are made via co-axial electrospray. In some embodiments, the particles are made via single axial / monoaxial electrospray. In some embodiments, the particles are made through coacervation. In some embodiments, the particles are made through the salting out method. In some embodiments, the particles are made through nanoprecipitation. In some embodiments, the particles are made through spray drying. In some embodiments, the particles are prepared in the absence of a surfactant. In some embodiments, the particles of the disclosure are devoid of a surfactant. In some embodiments, the particles are made through spray drying orelectrospraying in the absence of a surfactant. In some embodiments the particles are made with a decrease in surfactant compared to what is typically used.

[0085] In some embodiments, a polymer (e.g., a hydrophilic polymer and / or hydrophobic polymer) of this invention may be made into nanoparticles (e.g., hydrophilic nanoparticles or hydrophobic nanoparticles) that are about 1 nm to about 500 nm in size, e.g., about 1 nm, 2 nm, 3 nm, 4 nm, 5 nm 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm, any range therein. In some embodiments, the nanoparticles are about 10 nm to about 500 nm, or more preferably about 100 nm to about 500 nm, or most preferably about 300 nm to 500 nm in size.

[0086] In some embodiments, a polymer (e.g., a hydrophilic polymer and / or hydrophobic polymer) of this invention may be made into microparticles (e.g., hydrophilic microparticles or hydrophobic microparticles) that are about 0.50 pm to about 500 pm in size (e.g., 500 nm to 500 pm in size), e.g., about 0.50 pm, 0.55 pm, 0.60 pm, 0.65 pm, 0.70 pm, 0.75 pm, 0.80 pm, 0.85 pm, 0.90 pm, 0.91 pm, 0.92 pm, 0.93 pm, 0.94 pm, 0.95 pm, 0.96 pm, 0.97 pm, 0.98 pm, 0.99 pm, 1 pm, 2 pm, 3 pm, 4 pm, 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 150 pm, 200 pm, 250 pm, 300 pm, 350 pm, 400 pm, 450 pm, or 500 pm or any range therein. In some embodiments, the microparticles are about 0.90 pm to about 100 pm, or more preferably about 0.95 pm to about 50 pm, or most preferably about 0.99 pm to 10 pm in size. Smaller micro-sized particles can be obtained, for example, by the process of fractionation whereby the larger particles are allowed to settle in an aqueous solution. The upper portion of the solution is then recovered by methods known to those of skill in the art. This upper portion is enriched in smaller size particles. The process can be repeated until a desired average size is generated. In certain embodiments, the particles are not liposomes or viral particles.

[0087] In some embodiments, a polymer (e.g., a hydrophilic polymer and / or hydrophobic polymer) of this invention may be made into particles (e.g., hydrophilic particles or hydrophobic particles) that have a molecular weight of about 3 kDa to about 200 kDa, e.g., about 5 kDa to about 100 kDa, about 10 kDa to about 75 kDa, about 10 kDa to about 100 kDa, about 10 kDa to about 150 kDa, or about 10 to about 200 kDa, or any range therein. In some embodiments, the particles have a molecular weight of about 5 kDa to about 15 kDa, or more preferably about 7 kDa to about 12 kDa, or most preferably about 10 kDa.

[0088] In some embodiments, microparticles or nanoparticles of this invention are used as carriers that encapsulate or are otherwise associated with an agent, e.g., a prophylactic agent or therapeutic agent, to target cell sites, in particular B cells, of the body where the agent provides a prophylactic or therapeutic activity. Agents that may be encapsulated by or within the particle (e.g., hydrophobic microparticle or nanoparticle) include, e.g., an antigen, anti-inflammatory agent, antimicrobial, cytokine, chemokine, chemotherapeutic agent or other drug. In some embodiments, one or more agents may be encapsulated by the particle (e.g., hydrophobic microparticle or nanoparticle). In some embodiments, the agent(s) is(are) encapsulated during the preparation of the particle (e.g., hydrophobic microparticle or nanoparticle).

[0089] Any antigen from any disease, disorder, or condition may be used in accordance with the invention. Exemplary antigens include but are not limited to bacterial, viral, parasitic, allergens, autoantigens and tumor-associated antigens. The antigen can include, e.g., protein antigens, peptides, polysaccharides, and the like. Specific examples of antigens that can be used in the invention include antigens from hepatitis A, B, C or D, influenza virus, Listeria, Clostridium botulinum, tuberculosis, tularemia, Variola major (smallpox), viral hemorrhagic fevers, Yersinia pestis (plague), HIV, herpes, papilloma virus, and other antigens associated with infectious agents. Allergens include, e.g., milk, egg, tree nut, peanut, shellfish, fish, grass, wheat, pet, soy or fruit allergens. Other antigens include antigens associated with autoimmune conditions, inflammatory conditions, allergy, and asthma. Non-limiting examples of such autoantigens include, e.g., Carboxypeptidase H, Chromogranin A, Glutamate decarboxylase, Tyrosine Phosphatase-Related Islet Antigen 2, Imogen-38, Insulin, Insulinoma antigen-2 (IA-2) and 2b, Islet-specific glucose-6- phosphatase catalytic subunit related protein (IGRP), Proinsulin, Preproinsulin, Glutamate Decarboxylase (GAD), Zinc-Transporter 8 (ZnT8), Chromogranin A, a-enolase, Aquaporin-4, P- arrestin, Myelin basic protein (MBP), Myelin Oligodendrocytic Glycoprotein (MOG), Myelin Proteolipid Protein (PLP), Myelin Associated Glycoprotein (MAG), Myelin-associated Oligodendrocyte Basic Protein (MOBP), 2',3'-Cyclic-nucleotide 3 '-phosphodiesterase (CNPase), nAChR, MuSK, LRP4, Citrullinated antigen, Carbamylated antigen, Collagen such as Collagen type I, Collagen type II, Collagen type III, Collagen type IV, Heat shock proteins, Human cartilage glycoprotein 39, Double-stranded DNA, La antigen, Nucleosomal histones and ribonucleoproteins (snRNP), P-2 glycoprotein, Poly(ADP -ribose) polymerase, Sm antigens of U-l small ribonucleoprotein complex, Transaldolase, Fc-part of immunoglobulins, Aggrecan, Aquaporin 4(AQP-4), NMDA-receptor, AMPA-receptor, GABA receptor, Gly-receptor, Dipeptidyl aminopeptidase-like Protein 6 (DPPX), GluR5, VGKC-complex, HU, Jo, Ri, Mai, Ma2, Zic4, CRMP5, Amphiphysin; or an immunologically active fragment thereof. Antigens also include those associated with organ or tissue rejection. Examples of such antigens include, but are not limited to, antigens from allogeneic cells, e.g., antigens from an allogeneic cell extract and antigens from other cells, such as endothelial cell antigens.

[0090] Anti-inflammatory agents refer to compounds that reduce inflammation or inflammatory responses in an animal. Examples of anti-inflammatory agents include, but are not limited to, a statin, sulindac, sulfasalazine, naroxyn, diclofenac, indomethacin, ibuprofen, flurbiprofen, ketoprofen, aclofenac, aloxiprin, aproxen, aspirin, diflunisal, fenoprofen, mefenamic acid, naproxen, phenylbutazone, piroxicam, meloxicam, salicylamide, salicylic acid, desoxysulindac, tenoxicam, ketoralac, flufenisal, salsalate, triethanolamine salicylate, aminopyrine, antipyrine, oxyphenbutazone, apazone, cintazone, flufenamic acid, clonixeril, clonixin, meclofenamic acid, flunixin, colchicine, demecolcine, allopurinol, oxypurinol, benzydamine hydrochloride, dimefadane, indoxole, intrazole, mimbane hydrochloride, paranylene hydrochloride, tetrydamine, benzindopyrine hydrochloride, fluprofen, ibufenac, naproxol, fenbufen, cinchophen, diflumidone sodium, fenamole, flutiazin, metazamide, letimide hydrochloride, nexeridine hydrochloride, octazamide, molinazole, neocinchophen, nimazole, proxazole citrate, tesicam, tesimide, tolmetin, triflumidate, fenamates (mefenamic acid, meclofenamic acid), nabumetone, celecoxib, etodolac, nimesulide, apazone, gold, tepoxalin; dithiocarbamate, naproxen; diclofenac; celecoxib; sulindac; diflunisal; piroxicam; indomethacin; etodolac; meloxicam; ibuprofen; ketoprofen; r-flurbiprofen; mefenamic; nabumetone; tolmetin; ketorolac bromethamine; ketorolac tromethamine; ketorolac acid; choline magnesium tri salicylate; rofecoxib; valdecoxib; lumiracoxib; etoricoxib; aspirin; salicylic acid and its sodium salt; tocopherols and tocotrienols; tenoxicam; aceclofenac; nimesulide; nepafenac; amfenac; bromfenac; flufenamate; phenylbutazone; calcitriol; rapamycin; all-trans retinoic acid; vitamin D3, calcitriol, or a combination thereof. Anti-inflammatory agents also include other compounds such as steroids, such as for example, fluocinolone, cortisol, cortisone, hydrocortisone, fludrocortisone, prednisone, prednisolone, methylprednisolone, triamcinolone, betamethasone, dexamethasone, beclomethasone, fluticasone interleukin- 1 receptor antagonists, thalidomide (a TNF-a release inhibitor), thalidomide, bone morphogenetic protein (BMP) type 2 or BMP-4, quinapril, interferons such as IL-11 (which modulate TNF-areceptor expression), and aurin-tricarboxylic acid (which inhibits TNF-a), guanidinoethyldisulfide, or a combination thereof.

[0091] As used herein, an antimicrobial agent is intended to include antibacterial, antiviral, antiparasitic, and antifungal agents. Antimicrobial agents include, e.g., penicillins such as ampicillin, augmentin and amoxycillin; cephalosporins such as ceftriaxone; chloramphenicols; macrolides such as erythromycin and azithromycin; aminoglycosides such as gentamycin and streptomycin; tetracyclines such as oxytetracycline; quinolones such as nalidixicacid and ciprogloxacin; sulfonamides such as sulfamethazine and trimethoprim; protease inhibitors; nucleoside analogs such as acyclovir; neuraminidase inhibitors such as oseltamivir; or a combination thereof.

[0092] Cytokines refer to a general class of biological molecules that affect / influence cells of the immune system. Cytokines include interferons (IFNs), interleukins (ILs), and growth factors. Examples of cytokines include, but are not limited to, IL-2, IL-4, IL-10, IL-12, IL-15, IL-18, IL- 22, IFN-y, TGF-P, granulocyte-macrophage colony stimulating factor (GM-CSF), and variants or prodrugs thereof, e.g., THOR-707, ProIL2, and the like.

[0093] Chemokines are a class of cytokines that direct immune cell migration and positioning. Examples of chemokines include, but are not limited to, CC-chemokine ligand 2 (CCL2), CC Chemokine Receptor 4 (CCR4), CCR1, CCR7, C-X-C Chemokine Receptor 2 (CXCR2), and CXCR4.

[0094] Chemotherapeutic agents include any agent useful in the treatment of a neoplastic condition. Examples of chemotherapeutic agents include, e.g., aminoglutethimide, amsacrine, anastrozole, asparaginase, bicalutamide, bleomycin, buserelin, busulfan, campothecin, capecitabine, carboplatin, carmustine, chlorambucil, cisplatin, cladribine, clodronate, colchicine, cyclophosphamide, cyproterone, cytarabine, dacarbazine, dactinomycin, daunorubicin, dienestrol, diethylstilbestrol, docetaxel, doxorubicin, epirubicin, estradiol, estramnustine, etoposide, exemestane, filgrastim, fludarabine, fludrocortisone, fluorouracil, fluoxymesterone, flutamide, gemcitabine, genistein, goserelin, hydroxyurea, idarubicin, ifosfamide, imatinib, interferon, irinotecan, ironotecan, letrozole, leucovorin, leuprolide, levamisole, lomustine, mechlorethamine, medroxyprogesterone, megestrol, melphalan, mercaptopurine, mesna, methotrexate, mitomycin, mitotane, mitoxantrone, nilutamide, nocodazole, octreotide, oxaliplatin, paclitaxel, pamidronate, pentostatin, plicamycin, porfimer, procarbazine, raltitrexed, rituximab, streptozocin, suramin,tamoxifen, temozolomide, teniposide, testosterone, thioguanine, thiotepa, titanocene dichloride, topotecan, trastuzumab, tretinoin, vinblastine, vincristine, vindesine, vinorelbine, and any combinations thereof.

[0095] IL-10 is capable of inhibiting ischemia / reperfusion injury (Deng et al. (2001) Kidney Int. 60:2118-28), graft-versus-disease, and transplant-related mortality (Baker et al. (1999) Bone Marrow Transplant 23: 1123-9; Holler et al. (2000) Bone Marrow Transplant 25:237-41). As demonstrated herein, B cells contacted with particles, in particular hydrophobic particles, exhibit an increase in IL- 10 production. Thus, this invention also provides a method for inducing IL- 10 production by B cells. According to this method, B cells are contacted with an effective amount of a particle, thereby inducing IL-10 production by the B cells. In some embodiments, the particle is a hydrophobic microparticle or nanoparticle, e.g., dextran microparticle or nanoparticle. In some embodiments, the hydrophobic microparticles or nanoparticles comprise dextran, wherein one or more of the hydroxyl groups of the dextran have been converted into esters. In some embodiments, the hydrophobic microparticle or nanoparticle comprises acetal, aromatic acetal, and / or ketal substituents. In some embodiments, the hydrophobic microparticle or nanoparticle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran that is converted into acetalated dextran. In some embodiments, the B cells are ex vivo, e.g., in a cell culture medium. In other embodiments, the B cells are in vivo.

[0096] In embodiments, IL- 10 production is induced in regulatory B cells. In some embodiments, the levels of endogenous IL-10 are induced in a subject, e.g., a subject receiving an organ transplant, by administration of a regulatory B cell subset. In one embodiment, the regulatory B cell population is isolated from the patient themselves, i.e., the subject is the donor. In another embodiment, the regulatory B cell population is isolated from a donor that is not the subject. The donor of the regulatory B cells may be the same as the organ donor. In another embodiment, the regulatory B cell population is pooled from several donors.

[0097] Production of IL-10 by the cells can be assessed by assaying for IL-10 in cell culture supernatant. In addition, production of IL- 10 can be verified directly by intracellular cytokine staining or by RT-PCR. Standard immunoassays known in the art can be used for such purpose.Examples of assays for TL-10 production are known in the art and kits for detecting IL-10 are commercially available, e.g., IL-10 OptEIA™ ELISA kits (BD PharMingen). In some embodiments, IL- 10 production is increased by at least 2-fold, e.g., at least 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 20-, 30-, 40-, or 50-fold, as compared to a B cell that has not been contacted with a particle, e.g., a hydrophobic microparticle or nanoparticle.

[0098] The invention also provides a method for treating an inflammatory or autoimmune disease or condition in a subject, comprising administering to the subject an effective amount of a particle (e.g., a hydrophobic microparticle or nanoparticle), or a B cell bound to the same, thereby treating the subject’s inflammatory or autoimmune disease or condition. In some embodiments, the particle is a hydrophobic microparticle or nanoparticle such as a dextran microparticle or nanoparticle. In some embodiments, the hydrophobic microparticles or nanoparticles comprise dextran, wherein one or more of the hydroxyl groups of the dextran have been converted into esters. In some embodiments, the hydrophobic microparticle or nanoparticle comprises acetal, aromatic acetal, and / or ketal substituents. In some embodiments, the hydrophobic microparticle or nanoparticle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran that is converted into acetalated dextran. In some embodiments, the particle (e.g., dextran microparticle or nanoparticle optionally comprising oxidized dextran) has a molecular weight in the range of about 3 kDa to about 200 kDa. In some embodiments, the particle (e.g., hydrophobic microparticle or nanoparticle) further includes an agent, e.g., an agent encapsulated by or within the particle. In embodiments, the agent is an antigen, anti-inflammatory agent, antimicrobial, cytokine, chemokine, chemotherapeutic agent or other drug as described herein. In some embodiments, the particle, e.g., hydrophobic microparticle or nanoparticle, is an Ace-DEX microparticle or nanoparticle with an antigen, anti-inflammatory agent, antimicrobial, cytokine, chemokine, and / or chemotherapeutic agent encapsulated therein.

[0099] A particle (e.g., hydrophobic microparticle or nanoparticle) bound to a B cell may be prepared ex vivo by isolating and / or purifying a B cell, as described elsewhere herein, and contacting the isolated and / or purified B cell with the particle. In some embodiments, the B cells are obtained from the subject being treated. In other embodiments, the B cells are obtained from adonor, preferably a histocompatibility matched donor. In some aspects, the donor is a syngeneic or allogeneic.

[0100] Any type of autoimmune disease or condition can be treated in accordance with this method of the invention. Non-limiting examples of autoimmune diseases or conditions include, but are not limited to, multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, an idiopathic inflammatory myopathy, Sjogren's syndrome, systemic vasculitis, autoimmune hemolytic anemia, autoimmune thrombocytopenia, diabetes (Type I or immune- mediated diabetes mellitus), Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, autoimmune hepatitis, primary biliary cirrhosis, inflammatory bowel disease (e. ., Crohn’s disease or ulcerative colitis), polymyalgia rheumatica, alopecia, vasculitis, celiac disease, a bullous skin disease, psoriasis, asthma, uveitis or autoimmune retinopathy.

[0101] Any type of inflammatory disease or condition can be treated in accordance with this method of the invention. Non-limiting examples of inflammatory diseases include, but are not limited to, sepsis, cancer, colitis, osteoarthritis, sarcoidosis, thyroiditis, Alzheimer's disease, myocarditis, kidney disease, obesity, cardiovascular disease (e.g., coronary artery disease), neuropathy, hepatitis, Whipple's disease, erythema multiforme, contact dermatitis, allergic rhinitis, atopic dermatitis, food hypersensitivity, urticaria, chronic obstructive pulmonary disease, eosinophilic pneumonia, idiopathic pulmonary fibrosis, or graft rejection. Some autoimmune diseases or conditions are associated with an inflammatory condition. Thus, there is overlap between what is considered an autoimmune disease or condition and an inflammatory disease or condition. Therefore, some autoimmune diseases or conditions may also be characterized as inflammatory diseases or conditions.

[0102] In some embodiments, the autoimmune condition is multiple sclerosis and the subject is treated with an Ace-DEX microparticle or nanoparticle, or a B cell bound to the same, wherein the Ace-DEX microparticle or nanoparticle comprises the MOG autoantigen or a fragment thereof.

[0103] In some embodiments, the autoimmune condition is Type I diabetes and the subject is treated with an Ace-DEX microparticle or nanoparticle, or a B cell bound to the same, wherein the Ace-DEX microparticle or nanoparticle comprises the IGRP, Insulin, GAD or IA-2 protein, or a fragment thereof.

[0104] IL-10 has been shown to promote tumor growth and overexpression of IL-10 has been demonstrated in certain cancers (Matsuda et al. (1994) J. Exp. Med. 180:2371-6; Salazar-Onfrayet al. (1997) J. Jmmunol. 159:3195-3202; Hagenbaugh et al. (1997) J. Exp. Med. 185:2101-110; Kruger-Kraskagakes et al. (1994) Br. J. Cancer 70: 1182-5). As such, in one embodiment, the inflammatory condition is cancer (e.g., a carcinoma, solid tumor, mesothelioma, sarcoma, hematological cancer, leukemia, lymphoma, or neuroma) and the cancer is treated by ablation of the IL- 10 producing regulatory B cell subset. In some embodiments, the cancer is a B cell cancer (e.g., lymphoma or ALL) and the cancer is treated by ablation of the cancerous B cells. In accordance with these embodiments, the invention provides a method for treating cancer in a subject, comprising administering to the subject an effective amount of a particle, e.g., a hydrophobic microparticle or nanoparticle, that encapsulates one or more cytotoxic agents, thereby treating the subject’s cancer. In some embodiments, the particle encapsulates one or more cytotoxic agents, which upon binding to regulatory B cells, selectively deplete the regulatory B cell population in the subject. Non-limiting examples of cytotoxic agents include chemotherapeutic agents such as antimetabolites (e.g., cytosine arabinoside, aminopterin, methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, and 5-fluorouracil decarbazine); alkylating agents (e.g., mechlorethamine, thiotepa chlorambucil, melphalan, carmustine (BCNU) and lomustine (CCNU), cyclophosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, cis-dichlorodiammine-platinum (II) (CDDP), and cisplatin); mTOR inhibitors (e.g., everolimus); MEK inhibitors (e.g., Tramitinib); BRAF inhibitors (e.g., Buparlisib); EGFR inhibitors (e.g., Erlotinib); PDGFR / VEGFR inhibitors (e.g., Sorafinib); vinca alkaloid; anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorubicin); antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)); calicheamicin; CC-1065 and derivatives thereof; auristatin molecules (e.g., auristatin PHE, bryostatin-1, and dolastatin-10; DNA-repair enzyme inhibitors (e.g., etoposide or topotecan); kinase inhibitors (e.g., compound ST 1571, imatinib mesylate; demecolcine; and other cytotoxic agents (e.g., paclitaxel, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicine, doxorubicin, or daunorubicin) and analogs or homologues thereof.

[0105] In another aspect, this invention provides a method for inducing immune tolerance in a subject, comprising administering to the subject an effective amount of a particle (e.g., a hydrophobic microparticle or nanoparticle), or a B cell (e.g., a regulatory B cell) bound to the same, wherein the particle comprises an autoantigen as described herein. In some embodiments,the particle is a hydrophobic microparticle or nanoparticle such as a dextran microparticle or nanoparticle. In some embodiments, the hydrophobic microparticles or nanoparticles comprise dextran, wherein one or more of the hydroxyl groups of the dextran have been converted into esters. In some embodiments, the hydrophobic microparticle or nanoparticle comprises acetal, aromatic acetal, and / or ketal substituents. In some embodiments, the hydrophobic microparticle or nanoparticle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran that is converted into acetalated dextran. In some embodiments, the particle (e.g., dextran microparticle or nanoparticle optionally comprising oxidized dextran) has a molecular weight in the range of about 3 kDa to about 200 kDa. This method of the invention can be used in the prophylaxis and / or treatment of diseases, disorders or conditions in which a tolerogenic immune response would confer a treatment benefit. Such diseases, disorders or conditions include inflammatory diseases, autoimmune diseases, and allergies as described herein. The method can also be used in subjects who have received, are receiving or will receive a therapeutic protein against which they have generated or are expected to generate an undesired immune response. The method can also be used in subjects who have undergone or will undergo transplantation, e.g., cell, tissue or organ transplantation. In addition, the method can be used in the treatment of graft versus host disease. Graft versus host disease (GVHD) is a complication that can occur after a pluripotent cell (e.g., stem cell) or bone marrow transplant in which the newly transplanted material results in an attack on the transplant recipient's body. In some instances, GVHD takes place after a blood transfusion. Graft-versus-host-disease can be divided into acute and chronic forms. The acute or fulminant form of the disease (aGVHD) is normally observed within the first 100 days post-transplant, and is a major challenge to transplants owing to associated morbidity and mortality. The chronic form of graft-versus-host-disease (cGVHD) normally occurs after 100 days. The appearance of moderate to severe cases of cGVHD adversely influences long-term survival.

[0106] Immune tolerance includes any reduction, delay or inhibition in CD4+T cell or CD8+T cell proliferation and / or activity. Immune tolerance can also include a reduction in antigen-specific antibody production. Immune tolerance can also include any response that leads to the stimulation, induction, production or recruitment of regulatory cells, such as CD4+Treg cells, CD8+Treg cells,etc. CD4+Treg cells can express the transcription factor FoxP3 and inhibit inflammatory responses and autoimmune inflammatory diseases (Cvetanovich & Hafler (2010) Curr. Opin. Immunol. 22(6):753-60; Vila et al. (2009) Curr. Opin. Hematol. 16(4):274-9). Such cells also suppress T- cell help to B-cells and induce tolerance to both self and foreign antigens (Miyara et al. (2009) J. Allergy Clin. Immunol. 123(4):749-55). CD4+Treg cells recognize antigen when presented by Class II proteins on APCs. CD8+Treg cells, which recognize antigen presented by Class I can also suppress T-cell help to B-cells and result in activation of antigen-specific suppression inducing tolerance to both self and foreign antigens. CD8+Treg cells have also been shown to inhibit models of autoimmune inflammatory diseases including rheumatoid arthritis and colitis (Oh et al. (2010) Immunol. Rev. 233(1): 97- 111; Boden & Snapper (2008) Curr. Opin. Gastroenterol. 24(6):733-41). In some embodiments, the compositions provided can effectively result in both types of responses (CD4+Treg and CD8+Treg). Immune tolerance also includes, but is not limited to, the induction of regulatory cytokines, such as Treg cytokines; induction of inhibitory cytokines; the inhibition of inflammatory cytokines (e.g., IL-4, IL-1 , IL-5, IL-6, GM-CSE, IFN-y, IL-2, IL-9, IL-12, IL- 17, IL-18, IL-21, IL-22, IL-23, M-CSF, C reactive protein, acute phase protein, chemokines {e.g., MCP-1, RANTES, MIP-loc, MIP-I0, MIG, ITAC or IP-10), the production of anti-inflammatory cytokines {e.g., IL-4, IL-13, IL-10, etc.), chemokines {e.g., CCL-2, CXCL8), proteases {e.g., MMP-3, MMP-9), leukotrienes {e.g., CysLT-1, CysLT-2), prostaglandins (e.g., PGE2) or histamines; the inhibition of polarization to a Thl7, Thl or Th2 immune response; the inhibition of effector cell-specific cytokines: Thl7 {e.g., IL-17, IL-25), Thl (IFN-y), Th2 {e.g., IL-4, IL-13); the inhibition of Thl-, Th2- or TH17-specific transcription factors; the inhibition of proliferation of effector T cells; the induction of apoptosis of effector T cells; the induction of tolerogenic dendritic cell-specific genes, the induction of FoxP3 expression, the inhibition of IgE induction or IgE- mediated immune responses; the inhibition of antibody responses {e.g., antigen-specific antibody production); the inhibition of T helper cell response; the production of TGF-0 and / or IL- 10; the inhibition of effector function of autoantibodies {e.g., inhibition in the depletion of cells, cell or tissue damage or complement activation); etc.

[0107] Another aspect of the invention provides for a method of transplanting B cells to a subject comprising contacting the B cells with an effective amount of a particle so that the particle binds to the B cells and transplanting the B cells bound to the particle to the subject. In some aspects, the particle is a microparticle or nanoparticle. In some aspects, the particle is a hydrophobicmicroparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle. In some aspects, the dextran microparticle or dextran nanoparticle comprises one or more aldehyde group, e.g., the dextran microparticle or dextran nanoparticle comprises oxidized dextran. In some aspects, the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents. In some aspects, the particle has a molecular weight in the range of about 3 kDa to about 200 kDa. In some aspects, the particle is prepared by spray-drying or electrospraying, e.g., in the absence of a surfactant. In one aspect, the B cells are autologous B cells. In another aspect, the B cells are allogeneic B cells.

[0108] Another aspect of this invention provides for a method of generating regulatory B cells by contacting a population of immune cells with an effective amount of a particle, e.g., a hydrophobic microparticle or nanoparticle, thereby generating regulatory B cells. In some embodiments, the immune cells are in vivo. In other embodiments, the immune cells are ex vivo. In some embodiments, the particle is a hydrophobic microparticle or nanoparticle such as a dextran microparticle or nanoparticle. In some embodiments, the hydrophobic microparticles or nanoparticles comprise dextran, wherein one or more of the hydroxyl groups of the dextran have been converted into esters. In some embodiments, the hydrophobic microparticle or nanoparticle comprises acetal, aromatic acetal, and / or ketal substituents. In some embodiments, the hydrophobic microparticle or nanoparticle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran that is converted into acetalated dextran. In some embodiments, the particle (e.g., dextran microparticle or nanoparticle optionally comprising oxidized dextran) has a molecular weight in the range of about 3 kDa to about 200 kDa.

[0109] Immune cells may include, but are not limited to, those present in blood, e.g., PBMCs (including blood collected by blood banks), spleen, bone marrow, tissues removed and / or exposed during surgical procedures, and tissues obtained via biopsy procedures. Immune cells can be obtained from a subject in need of therapy or suffering from a disease or condition as described herein. Alternatively, immune cells can be obtained from a donor, preferably a histocompatibility matched donor. The immune cell population may be harvested from the peripheral blood, bone marrow, spleen, or any other organ / tissue in said subject or donor. The generation of regulatory Bcells can be assessed by, e.g., the production of IL-10 and / or one or more of the surface markers described herein.

[0110] Regulatory B cells are believed to modulate immune responses, for example, in that IL- 10 release from regulatory B cells exerts anti-inflammatory and immunosuppressive effects on most hematopoietic cells. IL-10 also suppresses pro-inflammatory cytokine production by monocytes and macrophages and the proliferation of antigen-specific CD4+T cells. Thus, the particles of the invention (e.g., hydrophobic microparticles or nanoparticles) preferably result in the generation, recruitment or activation of regulatory B cells that produce and secrete IL- 10. Some regulatory B cells are CDld+or CDldhlgh. Some regulatory B cells are CD5+and / or CD19+. For example, some regulatory B cells are CDld+CD5+CD19+. Some regulatory B cells are CD24+or CD24hlgh; and / or CD38+or CD38hlgh. For example, some regulatory B cells are CD19+CD24+CD38L Additional surface markers and chemokine secretion profiles that can be used to identify regulatory B cells are known to those of skill in the art. Based on the knowledge of surface markers useful for the identification of various regulatory B cell populations, those of skill in the art are able to identify and enumerate regulatory B cells in a heterogeneous population of cells, for example, in a population of immune cells in culture or in a population of immune cells obtained from a subject.[0U1] The invention also provides a cellular composition, comprising B cells bound to particles such as hydrophobic microparticles or nanoparticles. In some embodiments, the B cells are regulatory B cells. In some embodiments, the particles are hydrophobic microparticles or nanoparticles such as dextran microparticles or nanoparticles. In some embodiments, the hydrophobic microparticles or nanoparticle comprise acetal, aromatic acetal, and / or ketal substituents. In some embodiments, the hydrophobic microparticles or nanoparticles comprise dextran, wherein one or more of the hydroxyl groups of the dextran have been converted into esters. In some embodiments, the hydrophobic microparticles or nanoparticles are acetalated dextran (Ace-DEX) microparticles or nanoparticles. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran that is converted into acetalated dextran. In some embodiments, the particle (e.g., dextran microparticle or nanoparticle optionally comprising oxidized dextran) has a molecular weight in the range of about 3 kDa to about 200kDa. In embodiments, the particles further comprise an agent, e.g., an antigen, anti-inflammatory agent, antimicrobial, cytokine, chemokine, chemotherapeutic agent or other drug as described herein.

[0112] Further provided herein is a method for sustained delivery of an agent to a subject, comprising administering to the subject a dextran microparticle or dextran nanoparticle encapsulating the agent or otherwise associate with the agent thereby providing sustained delivery of the agent to the subject. In some embodiments, the hydrophobic microparticles or nanoparticles comprise dextran, wherein one or more of the hydroxyl groups of the dextran have been converted into esters. In some embodiments, the dextran microparticle or nanoparticle comprises acetal, aromatic acetal, and / or ketal substituents. In some embodiments, the dextran microparticle or nanoparticle comprises oxidized dextran. In some embodiments, the hydrophobic microparticle or nanoparticle may be a dextran microparticle or nanoparticle comprising oxidized dextran that is converted into acetalated dextran. In some embodiments, the dextran microparticle or nanoparticle, optionally comprising oxidized dextran, has a molecular weight in the range of about 3 kDa to about 200 kDa. In some embodiments, the dextran microparticle or nanoparticle is an acetalated dextran (Ace-DEX) microparticle or nanoparticle. In embodiments, the agent of the dextran microparticle or nanoparticle is a therapeutic agent, e.g., an antigen, anti-inflammatory agent, antimicrobial, cytokine, chemokine, chemotherapeutic agent or other drug as described herein. In some embodiments, delivery of the agent is sustained for at least about 3 days. For example, a particle for sustained delivery may continue to deliver an agent after the first 3 days after administration. In some embodiments, at least about 30% of the agent is present in the blood stream of the subject for a period of at least 3 days. Depending on the dextran microparticle or nanoparticle and the agent, this may constitute at least about 30%, e.g., at least about 35%, about 40%, about 45%, about 50%, about 55%, or about 60%, of the agent being present in the blood stream of the subject for a period of at least 3 days. In some embodiments, the dextran microparticle or dextran nanoparticle encapsulating the agent is administered subcutaneously, intravenously, intramuscularly, intraperitoneally, intraocularly, intraarticularly, through an epidural, or intrathecally. In some embodiments, the dextran microparticle or dextran nanoparticle encapsulating the agent is administered intravenously and at least about 1% of the agent, at least about 5% of the agent, at least about 10% of the agent, at least about 20% of the agent, or preferably at least about 30%, or more preferably at least about 40%, or most preferably at least about 50%of the agent is present in the blood stream of the subject for a period of at least 3 days. In some embodiments, the dextran microparticle or dextran nanoparticle encapsulating the agent is administered intravenously, binds to B cells, and increases the circulation of the agent, e.g., for a period of at least 3 days.

[0113] In some aspects, the compositions of the invention, e.g., a particle such as a hydrophobic microparticle or nanoparticle, or a B cell bound to the same, are provided as an admixture with a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers are determined in part by the particular composition being administered, as well as by the particular method used to administer the composition. Accordingly, there is a wide variety of suitable formulations of pharmaceutical compositions available (see, for example, Remington, The Science and Practice of Pharmacy (latest edition)).

[0114] Formulations suitable for parenteral administration, such as, for example, by intravenous, intramuscular, intradermal, and subcutaneous routes, include aqueous and non-aqueous, isotonic sterile injection solutions, which may contain antioxidants, buffers, bacteriostats, and solutes that render the formulation isotonic with the blood of the intended recipient, and aqueous and nonaqueous sterile suspensions that can include suspending agents, solubilizers, thickening agents, stabilizers, and preservatives. The formulations of compositions can be presented in unit-dose or multi-dose sealed containers, such as ampules and vials.

[0115] The compositions of the invention, e.g., a particle such as a hydrophobic microparticle or nanoparticle, or a B cell bound to the same, may be administered by a variety of routes, including but not limited to subcutaneous, intranasal, oral, intravenous, intraperitoneal, intramuscular, transmucosal, sublingual, rectal, ophthalmic, pulmonary, transdermal, transcutaneous or intradermal or by a combination of these routes. Routes of administration also include administration by inhalation or pulmonary aerosol. Techniques for preparing aerosol delivery systems are well known to those of skill in the art.

[0116] In some embodiments providing for the administration of a B cell-based therapy, the B cells may be administered by subcutaneous, intravenous, or intraperitoneal administration or by local administration to an organ or tissue of interest. In other embodiments, a particle such as a hydrophobic microparticle or nanoparticle, or a B cell bound to the same, can be administered subcutaneously, intravenously, intramuscularly, intraperitoneally, intraocularly, intraarticularly, through an epidural, or intrathecally.

[0117] The compositions of the invention may be administered in effective amounts, such as the effective amounts described elsewhere herein. Doses of dosage forms contain varying amounts of particles and / or varying amounts of agents and / or varying amounts of B cells, according to the invention. The amount of particles and / or agents and / or B cells present in the inventive dosage forms may be varied according to the nature of the composition, the therapeutic benefit to be accomplished, and other such parameters. In embodiments, dose ranging studies can be conducted to establish optimal therapeutic amounts of the particles and / or agents and / or B cells to be present in the dosage form. In embodiments, the particles (e.g., hydrophobic microparticles or nanoparticles) are present in the dosage form in an amount effective to induce IL-10 production by B cells upon administration to a subject. In embodiments, the particles (e.g., hydrophobic microparticles or nanoparticles) are present in the dosage form in an amount effective to generate B cells upon administration to a subject. In some embodiments the particles (e.g., hydrophobic microparticles or nanoparticles) and / or agents and / or B cells are present in the dosage form in an amount effective to treat an inflammatory or autoimmune disease or any condition in a subject. In some embodiments the particles (e.g., hydrophobic microparticles or nanoparticles) and / or autoantigens and / or B cells are present in the dosage form in an amount effective to generate a tolerogenic immune response to the autoantigens upon administration to a subject.

[0118] Dosage forms of the invention can be administered at a variety of frequencies. In some embodiments, at least one administration of the dosage form is sufficient to generate a biologically relevant response. In some embodiments, at least two administrations, at least three administrations, or at least four administrations of the dosage form are used to ensure a biologically relevant response. In other embodiments the dosages will be given as needed.

[0119] Exemplary, non-limiting doses of B cells, including regulatory B cells, that could be used in the treatment of human subjects range from at least 1 x 104, at least 1 * 105, at least 1 x 106, at least 1 x 107, at least 1 x 108, at least 1x109, or at least 1xIO10B cells / m2. In some embodiments, the dose used in the treatment of human subjects ranges from about l x l09to about l x lOloB cells / m2.

[0120] Prophylactic administration of the compositions of the invention can be initiated prior to the onset of disease, disorder or condition or therapeutic administration can be initiated after a disorder, disorder or condition is established.

[0121] In some embodiments, a maintenance dose (e.g., of a particle such as a hydrophobic microparticle or nanoparticle or a B cell bound to the same) is administered to a subject after aninitial administration. By way of illustration, a maintenance dose of a particle e.g., a hydrophobic microparticle or nanoparticle) or a B cell bound to the same is administered to a subject after an initial administration has resulted in a tolerogenic response in the subject, for example to maintain the tolerogenic effect achieved after the initial dose, to prevent an undesired immune reaction in the subject, or to prevent the subject becoming a subject at risk of experiencing an undesired immune response or an undesired level of an immune response. In some embodiments, the maintenance dose is the same dose as the initial dose the subject received. In some embodiments, the maintenance dose is a lower dose than the initial dose. For example, in some embodiments, the maintenance dose is about 3 / 4, about 2 / 3, about 1 / 2, about 1 / 3, about 1 / 4, about 1 / 8, about 1 / 10, about 1 / 20, about 1 / 25, about 1 / 50, about 1 / 100, about 1 / 1,000, about 1 / 10,000, about 1 / 100,000, or about 1 / 1,000,000 (weight / weight) of the initial dose.EXAMPLESEXAMPLE 1: Acetalated Dextran Microparticles Bind B Cells

[0122] Acetalated dextran (Ace-DEX, FIG. 1) was made into microparticles (MPs) and was labeled with a fluorescent dye (DiD) by encapsulating the dye through spray drying. The MPs were then injected subcutaneously (SC) into a mouse and the highest signal was unexpectedly found to be associated with B cells (FIGS. 2A-2C). This was mostly in the spleen, but also in the local draining lymph node. It was expected that there would be uptake in phagocytic cells (neutrophils, dendritic cells, macrophages, monocytes) as the particles are 1-2 micron in size and cannot be internalized by non-phagocytic cells (e.g., B cells, T cells). This effect was shown to be somewhat drug-dependent and occurred with blank particles (FIG. 2A). Similar results were observed when ALEXA FLUOR® dye-labeled dextran particles were used in this analysis. Thus, binding of Ace-DEX MPs to B cells is not dye-dependent.EXAMPLE 2: B Cells Bind Ace-DEX MPs on the Surface

[0123] Dendritic cells (DCs) and B cells were isolated from a mouse via magnetic bead isolation. These cells were cultured with DiD-labeled Ace-DEX MPs. As expected, the DCs internalized the MPs (FIGS. 3A-3B). However, the Ace-DEX MPs bound to the surface of the B cells (FIGS. 3A- 3B). Computer rendering of the data from FIG. 3B showed that the particles were not taken up bythe B cells, as they are too big for the cells to internalize them (FIG. 3C). Unexpectedly, the Ace- DEX MPs non-specifically associated with the B cells and resided on the surface.EXAMPLE 3: Ace-DEX MPs Associate with B cells at the Injection Site

[0124] FIGS. 4A-4D provide data showing that when DiD labeled (with or without drug) Ace- DEX MPs are injected SC, the Ace-DEX MPs can be found to associate with B cells isolated from the injection site for several days. The data indicated that MP+ cells are cells that have the DiD Ace-DEX MPs associated with them.

[0125] FIGS. 5A-5C show that B cells are most of the MP -positive cells (MP+) at the depot site after injection, out to 20+ days. It is likely that phagocytic cells take up the particles and degrade the particles and DiD in the phagosome. With B cells, the Ace-DEX MPs are surface-associated such that the DiD dye stays associated with the B cells.EXAMPLE 4: Hydrophobic Microparticles Bind B Cells

[0126] It was subsequently determined whether B cell binding was polymer specific. B cells were isolated from mice and subsequently cultured with Ace-DEX MPs, PLGA MPs or free labeled dextran. There was approximately double the association of Ace-DEX MPs with the B cells as compared to PLGA particles, and dextran did not associate with the B cells (FIG. 6A).

[0127] To determine binding to human B cells, human peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation from human blood sample buffy coats. Human PBMCs were resuspended in 1640 RPMI base media (supplemented with 1% Penicillin- Streptomycin, 1% non-essential amino acids, 10% heat-inactivated fetal bovine serum, and lx beta-mercaptoethanol) and seeded in 96-well plate at 1 million cells / well. PBMCs were treated with spray dried Ace-DEX and PLGA microparticles encapsulating DiD fluorophore and incubated at 37°C for 2 hours. After incubation, samples were stained for flow cytometry analysis with anti-human CD19-FITC antibody, e506 viability dye, fixed with 1% paraformaldehyde, and stored at 4°C in the dark until acquisition on an Attune NxT flow cytometer. B cell affinity was determined by measuring the frequency of DiD+ events on CD 19+ cells. The frequency of DiD+ events on all live PBMC cells was recorded to assess relative particle affinity for B cells. As observed with B cells from mice, there was approximately double the association of Ace-DEX MPs with human B cells as compared to PLGA particles (FIG. 6B).EXAMPLE 5: Complement Mediates Ace-DEX MPs Binding to B Cells

[0128] It was posited that it may be a serum factor binding to the particle surface and facilitating B cell association. A lot of serum factors, including complement should be inactivated by heating the serum. Thus, B cells were isolated from mice and heat inactivated (HI) serum or non-HI serum was used to determine the potential effect of complement. Again, an increased association of B cells with Ace-DEX MPs was found (FIG. 7). Notably, higher binding was observed with non-HI FBS and some of this effect could be blocked with BSA pre-treatment (FIG. 7).EXAMPLE 6: Ace-DEX MPs Induce Regulatory B Cells

[0129] Ace-DEX MPs have been used to induce antigen-specific tolerance in an experimental model of multiple sclerosis (Peine et al. (2014) Mol. Pharm. 11 (3): 828-35) and diabetes (Chen et al. (2018) Adv. Healthc. Mater. 7(18):el800341). In prior studies, Ace-DEX MPs have been prepared by dissolving Ac-DEX in a solvent and subsequently mixing the solution with a surfactant such as polyvinyl alcohol (PVA) to form emulsion particles.

[0130] In contrast to the prior studies, Ace-DEX MPs were prepared by spray drying. In this respect, no surfactant was needed to prepare the MPs. Using the C57B1 / 6 EAE Model (MS model), data was collected for treatment with Ace-DEX MPs at peak disease. Here, a greater impact on treatment was observed using MPs prepared via spray drying compared to previous studies using emulsion particles (FIG. 8). Notably, the PVA of the emulsion particles appeared to diminish Ace- DEX’ s effect on B cells.

[0131] Accordingly, binding of B cells with Ace-Dex MPs prepared by different methods was compared. Fluorescent acetalated dextran microparticles (Ace-DEX MPs) were formed by dissolving acetalated dextran (2.5 mg / mL) in 99% ethanol and 1% DMSO. DiD perchlorate was dissolved in ethanol before adding it to the acetalated dextran / ethanol solution. The feed solution was spray-dried using a B-290 spray-dryer (Buchi, New Castle, DE) with 10 mL / min feed flow rate, 75°C inlet temperature, and 55 mm Q-flow meter. MPs were sprayed into a 50 mL tube, suspended in a sucrose solution, aliquoted, lyophilized, and stored at -20°C. Emulsion Ace-DEX MPs were synthesized by a water-in-oil-in-water emulsion method. Ace-DEX and DiD were dissolved in dichloromethane. PBS was added to form the primary emulsion, which was probe homogenized at 21,000 rpm. After this, PBS containing 3% PVA was added to create thesecondary emulsion and also was probe homogenized at 21 ,000 rpm. The secondary emulsion was stirred in 0.3% PVA in PBS for 2 hours. Emulsion MPs were washed, frozen, and lyophilized for use. Fluorescent dextran iron oxide nanoparticles were purchased from Luna Nanotech. To test association to B cells, B were isolated via magnetic separation from 8-12-week-old C57BL / 6 (Jackson Labs; Bar Harbor, ME) murine spleens postmortem. B-cells (50,000) were plated in 100 mL and treated with MPs in 100 mL media (RMPI containing 10% heat-inactivated FBS) for 2 hours in a 96 well plate. Cells were stained for flow cytometry with a viability dye and a CD 19 marker. This analysis demonstrated that spray-dried Ace-DEX MPs specifically bound to B cells (FIG. 9)

[0132] From this work, it is believed that Ace-DEX is inducing an immune regulatory mechanism that, in addition to regulatory T cells (Tregs), includes an induction of regulatory B cells (Bregs).EXAMPLE 7: Ace-DEX MPs Induce IL-10 Production by Regulatory B Cells

[0133] Bregs are an emerging regulatory cell that have been classified by a number of markers. However, one notable marker is the production of the anti-inflammatory cytokine IL- 10. In FIG. 10, it is shown that isolated B cells, when cultured with Ace-DEX MPs, produce high levels of IL- 10, significantly greater than B cells cultured with PLGA MPs or untreated cells. Sometimes IL- 10 can also be produced because it is regulating pro-inflammatory cytokines (as a feedback loop). It can be seen in FIG. 11 that only low levels of the pro-inflammatory cytokine IFNy are being produced by any of the experimental groups. This indicates that the IL- 10 being produced provides a tolerogenic and regulatory response.EXAMPLE 8: Regulatory B Cells Bound With Ace-DEX MPs Induce Immune Tolerance

[0134] It was believed that Bregs generated by Ace-DEX MPs could result in immune tolerance. To examine this, the EAE model of MS was used. B cells were isolated from mice and in vitro treated with Ace-DEX microparticles that contained MOG. Subsequently, the Ace-DEX MP- bound B cells were injected IP in the mouse at peak disease (FIG. 12A). Animals in FIG. 12B received blank MPs. The results of this analysis showed that mice with full hind limb paralysis, when treated with Ace-DEX MP -bound B cells, exhibited a significant decrease in symptoms as evidenced by only a very partially limp tail (FIG. 12A). These data indicate that, in addition toinducing a tolerogenic response when Ace-DEX MPs are given SC, when B cells are taken out, cultured with particles ex vivo and injected into a diseased mouse, a significant therapeutic effect is observed (FIG. 12A).

[0135] To determine the cell populations associated with the observed response, spleen and spinal cords were isolated from the mice in FIGS. 12A-12B and flow cytometry of cells therefrom was performed. This analysis indicated that treatment (although only through the addition of B cells) induced significantly greater Tregs (FoxP3+ cells) in the spleen and spinal cord (FIG. 13A). Further, increased Bregs were observed in the mice in both the spleen and site of inflammation (spinal cord) (FIG. 13B). Additional studies are carried out to determine whether the Bregs are the introduced cells or Bregs generated in the host.Example 9: Ace-DEX MPs are specific for B cells in vivo

[0136] Ace-DEX MPs (4 mg) encapsulating DiD fluorophore were suspended in 100 pL PBS and administered to 10-12-week-old BALB / c mice by tail vein intravenous injection. Blood was taken from animals by submandibular bleed 3 days after injection. Blood was processed into a single-cell suspension for flow cytometry analysis, removing red blood cells by Ammonium- Chloride-Potassium (ACK) lysis buffer. Cells were stained for viability and for B cell, T cell, and NK cell markers. These results indicated that ~7% of all B cells in the blood are particle positive (FIG. 14A) 3 days after injection. In FIG. 14B we show the selectivity of Ace-DEX MPs; of all the cells in the blood nearly 100% of the cells that are positive for Ace-DEX MPs are B cells. This shows that Ace-DEX has high selectivity in binding to B cells.EXAMPLE 10: Effect of Ace-DEX particle molecular weight of on binding to B cells

[0137] We wanted to explore the effect of molecular weight of the Ace-DEX particles in binding to B cells. B cells were isolated from C57BL / 6 spleens using Miltenyi negative magnetic isolation kits. B cells were seeded at 50K cells per well and treated for 2 hours with different concentrations (0.1, 0.05, 0.01 mg / ml) of 10k, 71k, and 500k DiD MPs in 96-well plate. After incubation, the samples were prepped for flow cytometry by adding 50 pL of e506 for a live / dead stain and the culture was incubated for 15 minutes at 25°C. After 15 minutes, the cells were stained for CD 19 with 50 pL of FITC. As shown in FIG. 15, on average the molecular weight of 10K had the highest affinity to B cells.EXAMPLE 11: Oxidized Dextran

[0138] To increase the number of available aldehydes, the dextran is oxidized then acetalated. Dextran (10 kDa, 5.0 g) was dissolved in 20 mL of Milli-Q water in a glass beaker under constant magnetic stirring. Once fully dissolved, sodium periodate (1.1 g) was gradually added to the solution while stirring continuously. The oxidation reaction was carried out at room temperature for 5 hours, maintaining constant agitation with a magnetic stir bar. After the reaction period, the solution was transferred into a dialysis membrane (3500 MWCO) and dialyzed against Milli-Q water for 12 hours. The dialysis water was replaced twice: once at 12-hour mark and once at 17- hour mark to ensure thorough removal of residual reagents. At the end of the second dialysis day, the oxidized dextran solution was transferred into a pre-weighed 50 mL centrifuge tube and frozen at -80°C for 30 minutes. The frozen sample was then subjected to lyophilization overnight.

[0139] After oxidation, acetalated dextran was synthesized. To eliminate endotoxin contamination before the synthesis process, glassware was conditioned in 1.0 M sodium hydroxide. The 10 kDa dextran was mixed with pyridinium p-toluenesulfonate catalyst and dissolved in dimethyl sulfoxide (DMSO). While maintaining anhydrous conditions, a reaction was performed between the oxidized dextran and 2-ethoxypropene (Matrix Scientific; Montgomery, AL). After 15 minutes, the reaction was terminated by adding triethylamine (TEA). Using 0.1% TEA water the product was precipitated, and then collected by vacuum filtration. The product was then dried by lyophilized overnight. The following day, the product underwent an additional filtration via centrifugation (21,000g for 20 minutes) was then precipitated again using 0.1% TEA water. The product was subj ect to another centrifugation (21 ,000g for 20 minutes). The supernatant was discarded and the product was then dried and lyophilized again. NMR analysis revealed the cyclic acetal coverage to be 56%.EXAMPLE 12: Electrosprayed particle fabrication

[0140] Electrosprayed MPs are prepared from Ace-DEX by a monoaxial electrospray method. Ace-DEX is first dissolved in absolute ethanol to a final concentration of 20 mg / mL. The polymer solution is loaded into a 2.5 mL glass syringe equipped with a 20-gauge stainless-steel blunt needle (Hamilton Company; Reno, NV). The syringe is then mounted on a syringe pump (Harvard Apparatus; Holliston, MA) and positioned vertically above a stainless-steel collection plate. Thepump sprayed at a constant rate of 0.2 mL / h, with a -5 kV potential applied to the needle and a +2.5 kV potential applied to the plate. The resulting MPs are collected, frozen, lyophilized, and stored at -20 °C until use.EXAMPLE 13: In vitro Treatment of Immune Cells with Ace-DEX MPs

[0141] B cells were isolated from NOD mice and CD4 T cells (BDC2.5) were isolated from transgenic mice using Miltenyi negative magnetic isolation kits. B cells were seeded at 200K cells per well with treatment for 2 hours with different doses of spray-dried P31 MPs in a 96-well plate. After incubation, 50K T cells were added to the culture and incubated for 72 hours. After 72 hours, cells were stained for flow cytometry with markers for CD4, CD 19, Lag3 and CTLA4. MP-treated T cells had co-expression of Lag3 and CTLA4, while a population of B cells had Lag3 expression (FIGS. 16A-16C). These data are of relevance as CTLA4 is expressed on Tregs and helps suppress autoimmune diseases (Kim & Choi (2022) Mol. Cells 45(8):513-521). In addition, it has been suggested that LAG3 is expressed on Tregs (Huang et al. (2004) Immunity 21(4):503-513). Furthermore, immunosuppressive B cells have been defined in the literature for expressing LAG3 (Lino et al. (2Q\8) Immunity 49(1): 120-133).

[0142] The foregoing examples are illustrative of the present invention, and are not to be construed as limiting thereof. Although the invention has been described in detail with reference to preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method for delivering an agent to a B cell, comprising contacting the B cell with a particle comprising the agent, thereby delivering the agent to the B cell.

2. The method of claim 1, wherein the B cell is in vivo.

3. The method of claim 1, wherein the B cell is ex vivo.

4. The method of any one of claims 1-3, wherein the particle is a microparticle or nanoparticle.

5. The method of any one of claims 1-4, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

6. The method of claim 5, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

7. The method of claim 5 or claim 6, wherein the microparticle or nanoparticle comprises oxidized dextran.

8. The method of any one of claims 5-7, wherein the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

9. The method of any one of claims 1-8, wherein the particle has a molecular weight in the range of about 3 kDa to about 200 kDa.

10. The method of any one of claims 1-9, wherein the particle is prepared by spray-drying or electrospraying.11 . The method of any one of claims 1-10, wherein the particle is prepared in the absence of a surfactant.

12. The method of any one of claims 1-11, wherein the agent comprises an antigen, antiinflammatory agent, antimicrobial, cytokine, chemokine, or chemotherapeutic agent.

13. A method for inducing IL- 10 production by B cells, comprising contacting the B cells with an effective amount of a particle, thereby inducing IL- 10 production by the B cells.

14. The method of claim 13, wherein the B cells are in vivo.

15. The method of claim 13, wherein the B cells are ex vivo.

16. The method of any one of claims 13-15, wherein the particle is a microparticle or nanoparticle.

17. The method of any one of claims 13-16, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

18. The method of claim 17, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

19. The method of claim 17 or claim 18, wherein the microparticle or nanoparticle comprises oxidized dextran.

20. The method of any one of claims 17-19, wherein the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.21 . The method of any one of claims 13-20, wherein the particle has a molecular weight in the range of about 3 kDa to about 200 kDa.

22. The method of any one of claims 13-21, wherein the particle is prepared by spray-drying or electrospraying.

23. The method of any one of claims 13-22, wherein the particle is prepared in the absence of a surfactant.

24. The method of any one of claims 13-23, wherein the B cells are regulatory B cells.

25. A method for treating an inflammatory or autoimmune disease or condition in a subject, comprising administering to the subject an effective amount of a particle, or a B cell bound to the same, thereby treating the subject’s inflammatory or autoimmune disease or condition.

26. The method of claim 25, wherein the B cell is a regulatory B cell.

27. The method of claim 25 or claim 26, wherein the particle is a microparticle or nanoparticle.

28. The method of any one of claims 25-27, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

29. The method of claim 28, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

30. The method of claim 28 or claim 29, wherein the microparticle or nanoparticle comprises oxidized dextran.

31. The method of any one of claims 28-30, wherein the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

32. The method of any one of claims 25-31, wherein the particle has a molecular weight in the range of about 3 kDa to about 200 kDa.

33. The method of any one of claims 25-32, wherein the particle is prepared by spray-drying or electrospraying.

34. The method of any one of claims 25-33, wherein the particle is prepared in the absence of a surfactant.

35. The method of any one of claims 25-34, wherein the particle further comprises an agent, e.g., a therapeutic agent.

36. The method of claim 35, wherein the agent comprises an antigen, anti-inflammatory agent, antimicrobial, cytokine, chemokine, or chemotherapeutic agent.

37. The method of any one of claims 25-36, wherein the B cell bound to the particle is administered subcutaneously, intravenously, or intraperitoneally.

38. The method of any one of claims 25-37, wherein the inflammatory disease or condition comprises sepsis, cancer, colitis, osteoarthritis, sarcoidosis, thyroiditis, Alzheimer's disease, myocarditis, kidney disease, obesity, cardiovascular disease, neuropathy, neuroinflammation, hepatitis, Whipple's disease, erythema multiforme, contact dermatitis, allergic rhinitis, atopic dermatitis, food hypersensitivity, urticaria, chronic obstructive pulmonary disease, eosinophilic pneumonia, idiopathic pulmonary fibrosis, or graft rejection.

39. The method of any one of claims 25-37, wherein the autoimmune disease or condition comprises multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, systemicsclerosis, an idiopathic inflammatory myopathy, Sjogren's syndrome, systemic vasculitis, autoimmune hemolytic anemia, autoimmune thrombocytopenia, diabetes, Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, autoimmune hepatitis, primary biliary cirrhosis, inflammatory bowel disease, polymyalgia rheumatica, alopecia, vasculitis, celiac disease, a bullous skin disease, psoriasis, asthma, uveitis or autoimmune retinopathy.

40. A method for inducing immune tolerance in a subject, comprising administering to the subject an effective amount of a particle, or a B cell bound to the same, wherein the particle comprises an autoantigen, thereby inducing immune tolerance in the subject.

41. The method of claim 40, wherein the B cell is a regulatory B cell.

42. The method of claim 40 or claim 41, wherein the particle is a microparticle or nanoparticle.

43. The method of any one of claims 40-42, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

44. The method of claim 43, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

45. The method of claim 43 or claim 44, wherein the microparticle or nanoparticle comprises oxidized dextran.

46. The method of any one of claims 43-45, wherein the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

47. The method of any one of claims 40-46, wherein the particle has a molecular weight in the range of about 3 kDa to about 200 kDa.

48. The method of any one of claims 40-47, wherein the particle is prepared by spray-drying or electrospraying.

49. The method of any one of claims 40-48, wherein the particle is prepared in the absence of a surfactant.

50. The method of any one of claims 40-49, wherein the particle, or the B cell bound to the same, is administered subcutaneously, intravenously, intramuscularly, intraperitoneally, intraocularly, intraarticularly, through an epidural, or intrathecally.

51. A method of generating regulatory B cells comprising contacting a population of immune cells with an effective amount of a particle, thereby generating regulatory B cells.

52. The method of claim 51, wherein the immune cells are in vivo.

53. The method of claim 51, wherein the immune cells are ex vivo.

54. The method of any one of claims 51-53, wherein the particle is a microparticle or nanoparticle.

55. The method of any one of claims 51-54, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

56. The method of claim 55, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

57. The method of claim 55 or claim 56, wherein the microparticle or nanoparticle comprises oxidized dextran.

58. The method of any one of claims 56-57, wherein the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

59. The method of any one of claims 51-58, wherein the particle has a molecular weight in the range of about 3 kDa to about 200 kDa.

60. The method of any one of claims 51-59, wherein the particle is prepared by spray-drying or electrospraying.

61. The method of any one of claims 51-60, wherein the particle is prepared in the absence of a surfactant.

62. A cellular composition, comprising B cells bound to particles.

63. The cellular composition of claim 62, wherein the particles are hydrophobic microparticles or hydrophobic nanoparticles, optionally dextran microparticles or dextran nanoparticles.

64. The cellular composition of claim 63, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

65. The cellular composition of claim 63 or claim 64, wherein the microparticles or nanoparticles comprise oxidized dextran.

66. The cellular composition of any one of claims 63-65, wherein the hydrophobic microparticles or hydrophobic nanoparticles comprise acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

67. The cellular composition of any one of claims 62-66, wherein the particles have a molecular weight in the range of about 3 kDa to about 200 kDa.

68. The cellular composition of any one of claims 62-67, wherein the particle is prepared by spray-drying or electrospraying.

69. The cellular composition of any one of claims 62-68, wherein the particle is prepared in the absence of a surfactant.

70. The cellular composition of any one of claims 62-69, wherein the particles further comprise an agent, e.g., a therapeutic agent.

71. The cellular composition of claim 70, wherein the agent comprises an antigen, antiinflammatory agent, antimicrobial, cytokine, chemokine, or chemotherapeutic agent.

72. A method for sustained delivery of an agent (e.g., a therapeutic agent) to a subject, comprising administering to the subject a particle encapsulating the agent thereby providing sustained delivery of the agent to the subject.

73. The method of any one of claims 72, wherein the particle is a microparticle or nanoparticle.

74. The method of claim 72 or claim 73, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

75. The method of claim 74, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

76. The method of claim 74 or claim 75, wherein the microparticle or nanoparticle comprises oxidized dextran.

77. The method of any one of claims 74-76, wherein the dextran microparticle or dextran nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

78. The method of any one of claims 72-77, wherein the dextran microparticle or dextran nanoparticle has a molecular weight in the range of about 3 kDa to about 200 kDa.

79. The method of any one of claims 72-78, wherein the particle is prepared by spray-drying or electrospraying.

80. The method of any one of claims 72-79, wherein the particle is prepared in the absence of a surfactant.

81. The method of any one of claims 72-80, wherein the agent comprises an antigen, antiinflammatory agent, antimicrobial, cytokine, chemokine, or chemotherapeutic agent.

82. The method of any one of claims 72-81, wherein the dextran microparticle or dextran nanoparticle is administered subcutaneously, intravenously, intramuscularly, intraperitoneally, intraocularly, intraarticularly, through an epidural, or intrathecally.

83. The method of any one of claims 72-82, wherein at least about 30% of the agent is present in the blood stream of the subject for a period of at least about 3 days.

84. A method of transplanting B cells to a subject comprising contacting the B cells with an effective amount of a particle so that the particle binds to the B cells and transplanting the B cells bound to the particle to the subject.

85. The method of claim 84, wherein the particle is a microparticle or nanoparticle.

86. The method of claim 84 or claim 85, wherein the particle is a hydrophobic microparticle or hydrophobic nanoparticle, optionally a dextran microparticle or dextran nanoparticle.

87. The method of claim 86, wherein the microparticle or nanoparticle comprises one or more aldehyde groups.

88. The method of claim 86 or claim 87, wherein the microparticle or nanoparticle comprises oxidized dextran.

89. The method of any one of claims 86-88, wherein the hydrophobic microparticle or hydrophobic nanoparticle comprises acetal, aromatic acetal, ketal, ester, and / or silyl-ether substituents.

90. The method of any one of claims 84-89, wherein the particle has a molecular weight in the range of about 3 kDa to about 200 kDa.

91. The method of any one of claims 84-90, wherein the particle is prepared by spray-drying or electrospraying.

92. The method of any one of claims 84-91, wherein the particle is prepared in the absence of a surfactant.

93. The method of any one of claims 84-92, wherein the B cells are autologous B cells.

94. The method of any one of claims 84-92, wherein the B cells are allogeneic B cells.

95. Use of a particle, or a B cell bound to the same, in the preparation of a medicament for the treatment of an inflammatory or autoimmune disease or condition in a subject.

96. A particle, or a B cell bound to the same, for use in treating an inflammatory or autoimmune disease or condition in a subject.