Following our previous demonstration that T cell-specific Pep overexpression alleviates insulitis and diabetes in NOD mice,27 we further explored whether the transgenic overexpression of Pep to downregulate TCR signaling could restore the impaired suppressive function of Blimp-1-deficient Tregs and subsequently ameliorate colitis in autoimmune diabetes-prone Blimp-1-deficient NOD mice. Here, PTPN22 is linked to diabetes mellitus.