Human T Cells Expressing A Cd19 Car-T Receptor Provide Insights Into Mechanisms Of Human Cd19-Positive Beta Cell Destruction

Autoimmune destruction of pancreatic beta cells underlies type 1 diabetes (T1D). To understand T cell-mediated immune effects on human pancreatic beta cells, we combine beta cell-specific expression of a model antigen, CD19, and anti-CD19 chimeric antigen receptor T (CAR-T) cells. Coculturing CD19-expressing beta-like cells and CD19 CAR-T cells results in T cell-mediated beta-like cell death with release of activated T cell cytokines. Transcriptome analysis of beta-like cells and human islets treated with conditionedmediumof the immune reaction identifies upregulation of immune reaction genes and the pyroptosismediator GSDMD as well as its activator CASP4. Caspase-4-mediated cleaved GSDMD is detected in beta-like cells under inflammation and endoplasmic reticulum (ER) stress conditions. Among immune-regulatory genes, PDL1 is one of themost upregulated, and PDL1 overexpression partially protects human beta-like cells transplanted into mice. This experimental platform identifies potential mechanisms of beta cell destruction and may allow testing of therapeutic strategies.