Converse to its protective effects, IL-22 also promotes the expression of proinflammatory cytokines tumor necrosis factor (TNF)-α and IL-8 in IECs and these cytokines in turn increase IL-22R1 expression, which may further strengthen the proinflammatory effect of IL-22 in inducing Crohn's disease [9]. The gene discussed is TNF; the disease is Crohn disease.