Immunomodulatory Dual-Sized Microparticle System Conditions Human Antigen Presenting Cells Into a Tolerogenic Phenotype In Vitro and Inhibits Type 1 Diabetes-Specific Autoreactive T Cell Responses

• Published in: Frontiers in immunology 2020-10, Vol.11, p.574447
• Main Authors: Brusko, Maigan A, Stewart, Joshua M, Posgai, Amanda L, Wasserfall, Clive H, Atkinson, Mark A, Brusko, Todd M, Keselowsky, Benjamin G
• Format: Article
• Language: English
• Subjects: Antigen Presentation - drug effects; Autoantigens - immunology; autoimmunity; Calcitriol - chemistry; Calcitriol - pharmacology; combination therapy; Dendritic Cells - drug effects; Dendritic Cells - immunology; Diabetes Mellitus, Type 1 - immunology; Drug Carriers - chemistry; Drug Carriers - pharmacology; Granulocyte-Macrophage Colony-Stimulating Factor - chemistry; Granulocyte-Macrophage Colony-Stimulating Factor - pharmacology; Humans; Immune Tolerance - drug effects; Immunology; Immunomodulation; immunoregulation; Lymphocyte Activation; microparticle; Monocytes - drug effects; Particle Size; Phenotype; poly-lactic-co-glycolic acid; Polylactic Acid-Polyglycolic Acid Copolymer - chemistry; Polylactic Acid-Polyglycolic Acid Copolymer - pharmacology; Receptors, Antigen, T-Cell - immunology; T-Lymphocytes - drug effects; T-Lymphocytes - immunology; Transforming Growth Factor beta1 - chemistry; Transforming Growth Factor beta1 - pharmacology; type 1 diabetes
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2020.574447

Current monotherapeutic agents fail to restore tolerance to self-antigens in autoimmune individuals without systemic immunosuppression. We hypothesized that a combinatorial drug formulation delivered by a poly-lactic-co-glycolic acid (PLGA) dual-sized microparticle (dMP) system would facilitate tunable drug delivery to elicit immune tolerance. Specifically, we utilized 30 µm MPs to provide local sustained release of granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor β1 (TGF-β1) along with 1 µm MPs to facilitate phagocytic uptake of encapsulated antigen and 1α,25(OH) Vitamin D (VD3) followed by tolerogenic antigen presentation. We previously demonstrated the dMP system ameliorated type 1 diabetes (T1D) and experimental autoimmune encephalomyelitis (EAE) in murine models. Here, we investigated the system's capacity to impact human cell activity to advance clinical translation. dMP treatment directly reduced T cell proliferation and inflammatory cytokine production. dMP delivery to monocytes and monocyte-derived dendritic cells (DCs) increased their expression of surface and intracellular anti-inflammatory mediators. In co-culture, dMP-treated DCs (dMP-DCs) reduced allogeneic T cell receptor (TCR) signaling and proliferation, while increasing PD-1 expression, IL-10 production, and regulatory T cell (Treg) frequency. To model antigen-specific activation and downstream function, we co-cultured TCR-engineered autoreactive T cell "avatars," with dMP-DCs or control DCs followed by β-cell line (ßlox5) target cells. For G6PC2-specific CD8 avatars (clone 32), dMP-DC exposure reduced Granzyme B and dampened cytotoxicity. GAD65-reactive CD4 avatars (clone 4.13) exhibited an anergic/exhausted phenotype with dMP-DC presence. Collectively, these data suggest this dMP formulation conditions human antigen presenting cells toward a tolerogenic phenotype, inducing regulatory and suppressive T cell responses.