Use of CART cells to selectively target autoantigen-specific T cells for the treatment of autoimmune diabetes

Abstract Previous clinical trials using biologics-based broad-spectrum T cell- and B cell-depleting molecules for the treatment of autoimmune diabetes have shown promising, yet mixed, results. Their varied extent of success may be due to their non-specific action and failure to permanently and completely remove the pathogenic subpopulations. As CD8+ T cells, the most dominant cell type in human insulitis, are thought to be the primary mediator of β-cells damage, we thus designed a strategy by adapting chimeric antigen receptor engineered T (CART) technology to directly target these pathogenic T cells. The newly generated CAR construct maintains original transmembrane and intracellular components, while the extracellular scFv antigen-binding domain was replaced with HLA-A2/β2-microglobulin (B2M) complex that is linked with either diabetes-associated immunodominant peptide zinc transporter 8(ZnT8)186–194 or negative control peptide HIV Gag77–85. We have shown that HLA-A2/B2M complexes were correctly folded and presenting right peptide epitopes on CART cells. The CAR signaling was also sustained, as the expression levels of CD25 and CD69 were significantly elevated only on CAR-transduced Jurkat cells presenting ZnT8186–194 peptide co-cultured with a T-cell line that expresses TCRs recognizing the same peptide. To determine the killing ability of CART cells, we further engineered primary human T cells to express our CAR construct and demonstrated that CART cells can selectively deplete human antigen-specific CD8+ T cells in vitro. Therefore, our results have provided proof-of-principle for the development of a novel immunotherapy for disease treatment.