IL17A and colitis: As shown in Fig. 5, the level of Th1 cytokine-IFN-γ was significantly higher, but the levels of Th2 cytokine-IL-4, IL-5 or IL-13, and Th17 cytokine-IL-17A were greatly lower in colonic LP of IL-21RKO mice after DSS-induced colitis as compared with those in C57BL/6 mice (**P < 0.01 or ***P < 0.001).