PTPN22 R620W Gene Editing in T Cells Enhances Low Avidity TCR Responses

Abstract

AbstractA genetic variant in the genePTPN22(R620W, rs2476601) is strongly associated with increased risk for multiple autoimmune diseases and has been linked to altered TCR regulation. Here, we utilize Crispr/Cas9 gene editing with donor DNA repair templates in human cord blood-derived, naive T cells to generatePTPN22risk edited, non-risk edited (silent modification), or knock out T cells from the same donor.PTPN22risk edited cells exhibited increased activation marker expression following non-specific TCR engagement, findings that mimicked PTPN22 KO cells. Next, using lentiviral delivery of T1D patient-derived islet-antigen specific TCRs, we demonstrate that loss of PTPN22 function led to enhanced signaling in T cells expressing a lower avidity self-reactive TCR. In this setting, loss of PTPN22 mediated enhanced proliferation and Th1 skewing. Importantly, expression of the risk variant in association with a lower avidity TCR also increased proliferation relative to PTPN22 non-risk T cells. Together, these findings suggest that, in primary human T cells,PTPN22rs2476601 contributes to autoimmunity risk by permitting increased TCR signaling in mildly self-reactive T cells, thereby potentially expanding the self-reactive T cell pool and skewing this population toward an inflammatory phenotype.