Cell-surface ZnT8 antibody prevents and reverses autoimmune diabetes in mice

Type 1 diabetes (T1D) is an autoimmune disease where pathogenic lymphocytes target autoantigens expressed in the pancreatic islets, leading to the destruction of insulin-producing β-cells. Zinc transporter 8 (ZnT8) is a major autoantigen abundantly present on the β-cell surface. This unique molecular target offers the potential to shield β-cells against autoimmune attacks in T1D. Our previous work showed that a monoclonal antibody (mAb43) against cell-surface ZnT8 can home in on the pancreatic islets and prevent autoantibodies from recognizing β-cells. This study demonstrates that mAb43 binds to exocytotic sites on the β-cell surface, masking the antigenic exposure of ZnT8 and insulin following glucose-stimulated insulin secretion. In vivo administration of mAb43 to nonobese diabetic (NOD) mice selectively increased the proportion of regulatory T-cells (Tregs) in the islet, resulting in complete and sustained protection against T1D onset as well as reversal of new-onset diabetes. The mAb43-induced self-tolerance was reversible after treatment cessation and exhibited no adverse effects during long-term monitoring. Our findings suggest that mAb43 masking of the antigenic exposure of β-cells suppresses the immunological cascade from B-cell antigen presentation to T-cell mediated β-cell destruction, providing a novel islet-targeted and antigen-specific immunotherapy to prevent and reverse clinical T1D.