IL-22 is produced by activated Th1 and NK cells acting primarily on epithelial cells and is involved in inflammatory responses. Neither resting nor activated immune cells express IL-22 receptor, and IL-22 does not have any effects on these cells in vitro and in vivo. In contrast, cells of the skin and the digestive and respiratory systems represent putative targets of this cytokine. Thus IL-22 does not serve the communication between immune cells but is a T cell mediator that directly promotes the innate, nonspecific immunity of tissues. IL-22 serves as a protective molecule to counteract the destructive nature of the immune response to limit tissue damage. Interleukin-22 (IL-22) is a cytokine that regulates the production of acute phase proteins of the immunological response. On binding to its cognate receptor (IL-22R1), which is associated to the interleukin-10 receptor 2 (IL-10R2), IL-22 promotes activation of signal transducer and activator of transcription (STAT) pathway and several other cellular responses. A soluble receptor termed interleukin-22 binding protein (IL-22BP) is also able to bind to IL-22 as a natural protein antagonist, and probably provides systemic regulation of IL-22 activity. IL-22, in contrast to its relative IFN-gamma, regulates the expression of only a few genes in keratinocytes. This is due to varied signal transduction. The IL-22 effects are transcriptional and either independent of protein synthesis and secretion, or mediated by a secreted protein. Inflammatory conditions, but not keratinocyte differentiation, amplify the IL-22 effects. IL-22 application in mice enhances cutaneous S100A9 and MMP1 expression. Psoriatic patients show strongly elevated IL-22 plasma levels, which correlated with the disease severity. IL-22 plays a protective role in T cell-mediated hepatitis induced by Concanavalin A (Con A), acting as a survival factor for hepatocytes. IL-22 is present in high quantities in the blood of Crohn's disease patients in contrast to IFN-gamma and IL-17.
Synonyms: ILD110, ILTIF, Interleukin 10 related T cell derived inducible factor