After treatment with anti-IL-10R mAb, the recipient mice that were reconstituted with WT CBir1 Th1 cells developed more severe colitis compared to IgG-treated mice reconstituted with WT CBir1 Th1 cells, at the level similar to that of mice reconstituted with Gpr43−/− CBir1 Th1 cells (Fig. 4a, b). Here, FFAR2 is linked to colitis.