IL-22BP is regulated by the inflammasome and modulates tumorigenesis in the intestine

Chronic mucosal inflammation and tissue damage predisposes patients to the development of colorectal cancer (CRC)(1). This association could be explained by the hypothesis that the same factors and pathways important for wound healing also promote tumorigenesis. A sensor of tissue damage should induce these factors to promote tissue repair and regulate their action to prevent development of cancer. IL-22, a cytokine of the IL-10 superfamily, plays an important role for colonic epithelial cell repair, and is increased in the blood and intestine of IBD patients(2, 3). This cytokine can be neutralized by the soluble IL-22 receptor, known as the IL-22 binding protein (IL-22BP, IL-22RA2), however the significance of endogenous IL-22BP in vivo and the pathways that regulate this receptor are unknown(4, 5). We describe herein that IL-22BP plays a crucial role in controlling tumorigenesis and epithelial cell proliferation in the colon. IL-22BP is highly expressed by dendritic cells (DC) in the colon in steady state conditions. Sensing of intestinal tissue damage via the NLRP3 or NLRP6 inflammasomes led to an IL-18-dependent down regulation of IL-22BP, thereby increasing the ratio of IL-22/IL-22BP. IL-22, which is induced during intestinal tissue damage, exerted protective properties during the peak of damage, but promoted tumor development if uncontrolled during the recovery phase. Thus the IL-22-IL-22BP axis critically regulates intestinal tissue repair and tumorigenesis in the colon.