Regulatory T cells targeting a pathogenic MHC class II: Insulin peptide epitope postpone spontaneous autoimmune diabetes

Abstract

IntroductionIn spontaneous type 1 diabetes (T1D) non-obese diabetic (NOD) mice, the insulin B chain peptide 9-23 (B:9-23) can bind to the MHC class II molecule (IAg7) in register 3 (R3), creating a bimolecular IAg7/InsulinB:9-23 register 3 conformational epitope (InsB:R3). Previously, we showed that the InsB:R3-specific chimeric antigen receptor (CAR), constructed using an InsB:R3-monoclonal antibody, could guide CAR-expressing CD8 T cells to migrate to the islets and pancreatic lymph nodes. Regulatory T cells (Tregs) specific for an islet antigen can broadly suppress various pathogenic immune cells in the islets and effectively halt the progression of islet destruction. Therefore, we hypothesized that InsB:R3 specific Tregs would suppress autoimmune reactivity in islets and efficiently protect against T1D.MethodsTo test our hypothesis, we produced InsB:R3-Tregs and tested their disease-protective effects in spontaneous T1D NOD.CD28-/- mice.ResultsInsB:R3-CAR expressing Tregs secrete IL-10 dominated cytokines upon engagement with InsB:R3 antigens. A single infusion of InsB:R3 Tregs delayed the onset of T1D in 95% of treated mice, with 35% maintaining euglycemia for two healthy lifespans, readily home to the relevant target whereas control Tregs did not. Our data demonstrate that Tregs specific for MHC class II: Insulin peptide epitope (MHCII/Insulin) protect mice against T1D more efficiently than polyclonal Tregs lacking islet antigen specificity, suggesting that the MHC II/insulin-specific Treg approach is a promising immune therapy for safely preventing T1D.

High affinity chimeric antigen receptor signaling induces an inflammatory program in human regulatory T cells

“…The application of CAR technology to Tregs to induce or re-establish immune tolerance has been met with cautious optimism. While CAR engineered Tregs have shown promising results in vitro and in murine disease models of GvHD and skin graft rejection 16–19 , their suboptimal efficacy in preclinical models of vascularized organ transplantation and autoimmune disease 20,23,24 , settings where antigen-specific TCR Tregs have demonstrated efficacy 26,75 , exposes the current limitations of CAR Treg-based strategies. This disparity underscores the need for a more complete understanding of how CAR Tregs function at a molecular level compared to their naturally activated (TCR/CD28) counterparts.…”

Genetically engineered CD80–pMHC-harboring extracellular vesicles for antigen-specific CD4+ T-cell engagement

“…In our system, each peptide of interest is covalently bound to the beta chain of the MHC-II molecule, allowing for the presentation of low-affinity peptides. Previously, the presentation of peptides covalently linked to the beta chain of MHC-II was successfully achieved on the cell surface ( Yang et al, 2014 ; Obarorakpor et al, 2023 ). Consequently, the relatively large diameter of HeLa-derived EVs and the high surface concentration of CD80 and pMHCs of interest make EVs capable of individual activation of antigen-specific CD4 + T cells without carrier beads or cells.…”