IL17A and colitis: Evidence-based research has revealed a crucial role for the immune balance maintained by CD4+ T-cell differentiation into Th17 and Treg cells through the secretion of cytokines; for example, secretion of IL-10 and TGF-β promotes the differentiation of CD4+ T cells into Treg cells and attenuates the progress of colitis promoted by the IL-17 signaling pathway [37, 38].