Additionally, the length of the colon was longer without signs of inflammation (Fig. 5d) and colonic sections at 15 weeks old showed reduced inflammatory cell infiltration with more preserved goblet cells in NOD.LckPtpn22LckCrePrdm1F/F mice compared with NOD.LckCrePrdm1F/F mice (Fig. 5e), suggesting that Pep overexpression rendered significant protection from Blimp-1 deficiency-mediated colitis. Here, PTPN22 is linked to colitis.