NOS2 and colitis: As expected, lentiviral Nox4 shRNA, but not control shRNA, markedly decreased DSS‐induced colonic Nox4 expression (Figure 3F) and mimicked the effects of DSC on alleviating DSS‐induced colitis, as evidenced by attenuated colon length shortening (Figure 3G), improved histological score (Figure 3H), reduced inflammatory mediator (COX‐2 and iNOS) expression, weight loss and MPO activities (Figure S5) and restored TJP (ZO‐2 and claudin‐1) expression (Figure 3I).