In addition to IL-17A and IL-17F, various studies have reported an increased production of other Th17 cytokines in the inflamed gut of IBD patients, such as IL-22 and IL-26 [48], or IL-21 and IL-23, which in turn exacerbate inflammation by promoting Th1 and Th17 responses [49]. Here, IL21 is linked to inflammatory bowel disease.