Navigating diabetes-related immune epitope data: resources and tools provided by the Immune Epitope Database (IEDB)

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

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)2 Vitamin D3 (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 in vitro 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.

The Autoantigenic Proinsulin B-Chain Peptide B11-23 Synergises with the 70 kDa Heat Shock Protein DnaK in Macrophage Stimulation

BACKGROUND

Heat shock proteins (Hsp) act as intracellular chaperones and in addition are used as adjuvant in vaccines of peptides complexed with recombinant Hsp. By interacting with autologous peptides, Hsp may promote the induction of autoimmune reactivity.

OBJECTIVE

Here, we analysed whether the effect of Hsp on macrophages is modulated by insulin peptides known to interact with Hsp.

RESULTS

Combinations of the 70 kDa Hsp DnaK with peptide B11-23 from the core region of the proinsulin B-chain induced the release of the inflammatory mediators interleukin-6, tumor necrosis factor α, and interleukin-1β from cells of human and murine macrophage lines. In parallel, there was high-affinity binding of B11-23 to DnaK. DnaK mixed with peptides from other regions of the insulin molecule did not stimulate cytokine secretion. DnaK alone induced little cytokine production, and peptides alone induced none.

CONCLUSION

The macrophage-stimulating potential of Hsp70 family proteins when combined with the proinsulin B-chain peptide B11-23 may contribute to the immunodominance of this peptide in the development of beta cell-directed autoimmunity in type 1 diabetes.

A novel mimovirus encoding ChgA10-19 peptide with PD-L1 induces T cell tolerance and ameliorates the severity of diabetes

Related studies demonstrate that type 1 diabetes (T1D) is caused by β-cell antigen specific autoreactive CD8+ T cells. ChgA has recently been identified as the autoantigen in NOD mice and T1D patients. Therefore, attenuating the activation of ChgA specific CD8+ T cells might be a promising target for T1D therapy. The negative co-stimulatory PD-L1 inhibits T cell mediated alloimmunity and induces tolerance. In this experiment, a novel mimovirus encoding ChgA_10-19 peptide with PD-L1 was constructed. The NOD.β2m null HHD mice were administrated with mimovirus transduced DCs. After immunization, the activation and proliferation of CD8+ T cells were detected, diabetes incidence and pancreatic tissue destruction were also analyzed. The results demonstrated that transduced DCs attenuated CD8+ T cell activation and proliferation. In addition, transduced DCs inhibited CD8+ T response to ChgA stimulation, and ameliorated the severity of diabetes. These data suggested that mimovirus transduced DCs might provide novel clues for T1D therapy.

Type 1 diabetes associated HLA-DQ2 and DQ8 molecules are relatively resistant to HLA-DM mediated release of invariant chain-derived CLIP peptides

HLA-DM is essential for editing peptides bound to MHC class II, thus influencing the repertoire of peptides mediating selection and activation of CD4(+) T cells. Individuals expressing HLA-DQ2 or DQ8, and DQ2/8 trans-dimers, have elevated risk for type 1 diabetes (T1D). Cells coexpressing DM with these DQ molecules were observed to express elevated levels of CLIP (Class II associated invariant chain peptide). Relative resistance to DM-mediated editing of CLIP was further confirmed by HPLC-MS/MS analysis of eluted peptides, which also demonstrated peptides from known T1D-associated autoantigens, including a shared epitope from ZnT8 that is presented by all four major T1D-susceptible DQ molecules. Assays with purified recombinant soluble proteins confirmed that DQ2-CLIP complexes are highly resistant to DM editing, whereas DQ8-CLIP is partially sensitive to DM, but with an apparent reduction in catalytic potency. DM sensitivity was enhanced in mutant DQ8 molecules with disruption of hydrogen bonds that stabilize DQ8 near the DM-binding region. Our findings show that T1D-susceptible DQ2 and DQ8 share significant resistance to DM editing, compared with control DQ molecules. The relative resistance of the T1D-susceptible DQ molecules to DM editing and preferential presentation of T1D-associated autoantigenic peptides may contribute to the pathogenesis of T1D.

Metabolic syndrome - Removing roadblocks to therapy: Antigenic immunotherapies

Up to 25 per cent of the world׳s adult population may have the metabolic syndrome, a condition closely associated with central obesity. The metabolic syndrome is a major risk factor for cardiovascular disease and type 2 diabetes and therefore represents an important worldwide health problem. In addition to metabolic abnormalities such as raised fasting plasma glucose, high cholesterol and high blood pressure, there is consensus that obese subjects develop a state of low-grade chronic immune activation. This sustained pro-inflammatory response in fat tissue is thought to worsen insulin resistance and dyslipidemia. Likewise, the immune system contributes to the detrimental cascade of events leading to plaque formation in atherosclerosis. It has long been assumed that the innate arm of the immune system was the only key player, but emerging evidence suggests that there is in fact a sizeable adaptive immune component to obesity and cardiovascular disease. From a therapeutic perspective, it could be envisioned that immune modulation drugs such as cytokine inhibitors, co-stimulation blockers or anti-T cell agents could offer benefit. It is questionable, however, whether chronic treatment with for instance biologicals will have a favorable risk/benefit profile in a silent condition such as the metabolic syndrome. An attractive alternative could be the development of antigen-specific T cell therapies, not unlike those currently in various phases of development for type 1 diabetes. In this article, we will give an overview of antigen-specific treatment modalities in type 1 diabetes, followed by a review of the evidence for T cell involvement in obesity and atherosclerosis.