Interleukin-22 (IL22) is also known as cytokine Zcyto18, IL-10-related T-cell-derived-inducible factor (IL-TIF), which is belongs to the IL-10 family or IL-10 superfamily (including IL-19, IL-20, IL-24, and IL-26), a class of potent mediators of cellular inflammatory responses. IL-22 is produced by activated DC and T cells and initiates innate immune responses against bacterial pathogens especially in epithelial cells such as respiratory and gut epithelial cells. IL-22 biological activity is initiated by binding to a cell-surface complex composed of IL-22R1 and IL-10R2 receptor chains and further regulated by interactions with a soluble binding protein IL-22BP. IL-22 also promotes hepatocyte survival in the liver and epithelial cells in the lung and gut similar to IL-10.