A post-translational cysteine-to-serine conversion in human and mouse insulin generates a diabetogenic neoepitope.

Type 1 diabetes (T1D) affects a genetically susceptible population that develops autoreactive T cells attacking insulin-producing pancreatic β cells. Increasingly, neoantigens are recognized as critical drivers of this autoimmune response. Here, we report a novel insulin neoepitope generated via post-translational cysteine-to-serine conversion (C>S) in human patients, which is also seen in the autoimmune-prone non-obese diabetic (NOD) mice.

Crinophagic granules in pancreatic β cells contribute to mouse autoimmune diabetes by diversifying pathogenic epitope repertoire.

Autoimmune attack toward pancreatic β cells causes permanent loss of glucose homeostasis in type 1 diabetes (T1D). Insulin secretory granules store and secrete insulin but are also thought to be tissue messengers for T1D. Here, we show that the crinophagic granules (crinosome), a minor set of vesicles formed by fusing lysosomes with the conventional insulin dense-core granules (DCG), are pathogenic in T1D development in mouse models.

Synthesis of propargyl glycosides of serotypes 6A and 6B for glycoconjugate vaccines.

We developed a method for making immune responses to bacterial glycans T cell-dependent, which involves attachment of short, synthetic glycans to a virus-like nanoparticle (VLP). This strategy enhances immune responses to glycans by facilitating cognate T cell help of B cells, leading to antibody class switching and affinity maturation yielding high-affinity, anti-glycan antibodies. This method requires synthesis of bacterial glycans as propargyl glycosides for covalent attachment to VLPs, and the resulting short linker between the VLP and glycan is important for optimal T cell receptor recognition.

Repositioning the Early Pathology of Type 1 Diabetes to the Extraislet Vasculature.

Type 1 diabetes (T1D) is a prototypic T cell-mediated autoimmune disease. Because the islets of Langerhans are insulated from blood vessels by a double basement membrane and lack detectable lymphatic drainage, interactions between endocrine and circulating T cells are not permitted. Thus, we hypothesized that initiation and progression of anti-islet immunity required islet neolymphangiogenesis to allow T cell access to the islet.

Hyperglycosylation of prosaposin in tumor dendritic cells drives immune escape.

Tumors develop strategies to evade immunity by suppressing antigen presentation. In this work, we show that prosaposin (pSAP) drives CD8 T cell-mediated tumor immunity and that its hyperglycosylation in tumor dendritic cells (DCs) leads to cancer immune escape. We found that lysosomal pSAP and its single-saposin cognates mediated disintegration of tumor cell-derived apoptotic bodies to facilitate presentation of membrane-associated antigen and T cell activation.

Targeting the tissue factor coagulation initiation complex prevents antiphospholipid antibody development.

Antiphospholipid antibodies (aPL) in primary or secondary antiphospholipid syndrome (APS) are a major cause for acquired thrombophilia, but specific interventions preventing autoimmune aPL development are an unmet clinical need. Although autoimmune aPL cross react with various coagulation regulatory proteins, lipid-reactive aPL, including those derived from patients with COVID-19, recognize the endolysosomal phospholipid lysobisphosphatidic acid presented by the cell surface-expressed endothelial protein C receptor. This specific recognition leads to complement-mediated activation of tissue factor (TF)-dependent proinflammatory signaling and thrombosis.

A vascularized 3D model of the human pancreatic islet forstudy of immune cell-islet interaction.

Insulin is an essential regulator of blood glucose homeostasis that is produced exclusively bycells within the pancreatic islets of healthy individuals. In those affected by diabetes, immune inflammation, damage, and destruction of isletcells leads to insulin deficiency and hyperglycemia. Current efforts to understand the mechanisms underlyingcell damage in diabetes rely on-cultured cadaveric islets.

A practitioner's view of spectral flow cytometry.

Spectral flow cytometry allows the simultaneous analysis of a large number of cell surface markers at the single cell level

Measuring anti-islet autoimmunity in mouse and human by profiling peripheral blood antigen-specific CD4 T cells.

The endocrine pancreas is one of the most inaccessible organs of the human body. Its autoimmune attack leads to type 1 diabetes (T1D) in a genetically susceptible population and a lifelong need for exogenous insulin replacement. Monitoring disease progression by sampling peripheral blood would provide key insights into T1D immune-mediated mechanisms and potentially change preclinical diagnosis and the evaluation of therapeutic interventions.

Hyperglycosylation of prosaposin in tumor DCs promotes immune escape in cancer.

Unlabelled: Tumors develop strategies to evade immunity by suppressing antigen presentation. Here, we show that prosaposin drives CD8 T cell-mediated tumor immunity and that its hyperglycosylation in tumor DCs leads to cancer immune escape. We found that lysosomal prosaposin and its single saposin cognates mediated disintegration of tumor cell-derived apoptotic bodies to facilitate presentation of membrane-associated antigen and T cell activation.

Syntheses of Propargyl Glycosides of Disaccharides of the Capsular Polysaccharides from Serotypes 4, 7F, and 9V Useful for Glycoconjugate Vaccines.

We have developed a means of presenting relatively small glycans in a context to make them T cell-dependent antigens. This approach requires synthesis of glycans that remain close to carrier proteins upon conjugation, allowing T cell recognition and generation of B cells that produce high-affinity antibodies and memory toward target pathogens. In this work, we describe the syntheses of three disaccharides of the capsular polysaccharides from serotypes 4, 7F and 9V () as propargyl glycosides for use in this vaccine strategy.

Preventing type 1 diabetes in late-stage pre-diabetic NOD mice with insulin: A central role for alum as adjuvant.

Background: Restoration of immune tolerance to disease-relevant antigens is an appealing approach to prevent or arrest an organ-specific autoimmune disease like type 1 diabetes (T1D). Numerous studies have identified insulin as a key antigen of interest to use in such strategies, but to date, the success of these interventions in humans has been inconsistent. The efficacy of antigen-specific immunotherapy may be enhanced by optimising the dose, timing, and route of administration, and perhaps by the inclusion of adjuvants like alum.

Demonstration of the Antitumor Activity of the iNKT Agonist ABX196, a Novel Enhancer of Cancer Immunotherapy, in Melanoma and Hepatocarcinoma Mouse Models.

Unlabelled: Immune checkpoint blockers (ICB) provide a promising approach to antitumor immunotherapy through blockade of immunosuppressive pathways. The synthetic glycolipid, ABX196, is a potent stimulator of invariant natural killer T cells (iNKT), a small subset of regulatory lymphocytes, which are powerful enhancers of immunity when activated. ABX196 was investigated alone and in combination with chemotherapy and ICBs in a melanoma B16F10 tumor cell-bearing and an orthotopic Hepa 1-6 hepatocarcinoma (HCC) cell-bearing C57BL/6 mice model.

Identification of T cell antigens in the 21st century, as difficult as ever.

Identifying antigens recognized by T cells is still challenging, particularly for innate like T cells that do not recognize peptides but small metabolites or lipids in the context of MHC-like molecules or see non-MHC restricted antigens. The fundamental reason for this situation is the low affinity of T cell receptors for their ligands coupled with a level of degeneracy that makes them bind to similar surfaces on antigen presenting cells. Herein we will describe non-exhaustively some of the methods that were used to identify peptide antigens and briefly mention the high throughput methods more recently proposed for that purpose.

Chromogranin A Deficiency Confers Protection From Autoimmune Diabetes via Multiple Mechanisms.

Recognition of β-cell antigens by autoreactive T cells is a critical step in the initiation of autoimmune type1 diabetes. A complete protection from diabetes development in NOD mice harboring a point mutation in the insulin B-chain 9-23 epitope points to a dominant role of insulin in diabetogenesis. Generation of NOD mice lacking the chromogranin A protein (NOD.

Pathogenic lipid-binding antiphospholipid antibodies are associated with severity of COVID-19.

Background: Coronavirus disease 19 (COVID-19)-associated coagulopathy is a hallmark of disease severity and poor prognosis. The key manifestations of this prothrombotic syndrome-microvascular thrombosis, stroke, and venous and pulmonary clots-are also observed in severe and catastrophic antiphospholipid syndrome. Antiphospholipid antibodies (aPL) are detectable in COVID-19 patients, but their association with the clinical course of COVID-19 remains unproven.

Lipid presentation by the protein C receptor links coagulation with autoimmunity.

Antiphospholipid antibodies (aPLs) cause severe autoimmune disease characterized by vascular pathologies and pregnancy complications. Here, we identify endosomal lysobisphosphatidic acid (LBPA) presented by the CD1d-like endothelial protein C receptor (EPCR) as a pathogenic cell surface antigen recognized by aPLs for induction of thrombosis and endosomal inflammatory signaling. The engagement of aPLs with EPCR-LBPA expressed on innate immune cells sustains interferon- and toll-like receptor 7-dependent B1a cell expansion and autoantibody production.

Intestinal Delivery of Proinsulin and IL-10 via Combined With Low-Dose Anti-CD3 Restores Tolerance Outside the Window of Acute Type 1 Diabetes Diagnosis.

A combination treatment (CT) of proinsulin and IL-10 orally delivered via genetically modified bacteria combined with low-dose anti-CD3 (aCD3) therapy successfully restores glucose homeostasis in newly diagnosed non-obese diabetic (NOD) mice. Tolerance is accompanied by the accumulation of Foxp3 regulatory T cells (Tregs) in the pancreas. To test the potential of this therapy outside the window of acute diabetes diagnosis, we substituted autoimmune diabetic mice, with disease duration varying between 4 and 53 days, with syngeneic islets at the time of therapy initiation.

PLA2G1B is involved in CD4 anergy and CD4 lymphopenia in HIV-infected patients.

The precise mechanism leading to profound immunodeficiency of HIV-infected patients is still only partially understood. Here, we show that more than 80% of CD4+ T cells from HIV-infected patients have morphological abnormalities. Their membranes exhibited numerous large abnormal membrane microdomains (aMMDs), which trap and inactivate physiological receptors, such as that for IL-7.

Single-Cell Analysis of CD4 T Cells in Type 1 Diabetes: From Mouse to Man, How to Perform Mechanistic Studies.

Type 1 diabetes is the prototypical CD4 T cell-mediated autoimmune disease. Its genetic linkage to a single polymorphism at position 57 of the HLA class II DQβ chain makes it unique to study the molecular link between HLA and disease. However, investigating this relationship has been limited by a series of anatomical barriers, the small size and dispersion of the insulin-producing organ, and the scarcity of appropriate techniques and reagents to interrogate antigen-specific CD4 T cells both in man and rodent models.

Position β57 of I-A controls early anti-insulin responses in NOD mice, linking an MHC susceptibility allele to type 1 diabetes onset.

The class II region of the major histocompatibility complex (MHC) locus is the main contributor to the genetic susceptibility to type 1 diabetes (T1D). The loss of an aspartic acid at position 57 of diabetogenic HLA-DQβ chains supports this association; this single amino acid change influences how TCRs recognize peptides in the context of HLA-DQ8 and I-A using a mechanism termed the P9 switch. Here, we built register-specific insulin peptide MHC tetramers to examine CD4 T cell responses to Ins and Ins peptides during the early prediabetic phase of disease in nonobese diabetic (NOD) mice.

High-affinity anti-glycan antibodies: challenges and strategies.

High-affinity binding of antibodies provides for increased specificity and usually higher effector functions in vivo. This goal, well documented in cancer immunotherapy, is very relevant to vaccines as well, and has particularly significant application toward glycan antigens. The inability to elicit high-affinity antibodies has limited potential applications of glycan-based immunogens, giving rise to insufficient population coverage due to low titers and short duration of protection.