IL7 and colitis: Overall, B. fragilis may indirectly motivate ILC3 (Meanwhile B. fragilis promote the maturation and development of ILC3 through IL-7 signaling) to secrete IL-22, followed by IL-22-induced STAT3 phosphorylation in the colonic mucosa, hence promoting colonic mucosa regeneration including cell proliferation and mucus secretion, and modulating intestinal microbiota in a DSS-induced colitis mouse model (Figure 7).