As shown in Fig. 7, transfer of CECs from TNBS colitis mice exacerbated colitis and increased the activity of Th1 cells in recipient mice, while co-transfer of these cells and IL-17A inhibited colitis by inhibiting Th1 cell function in recipient mice further demonstrating that CECs are critical target cells in IL-17A-mediated negative regulation. Here, IL17A is linked to colitis.