IL-22

Interleukin-22 (IL-22) is an IL-10 family cytokine that uniquely targets non-hematopoietic barrier tissues rather than immune cells. Produced by Th22, Th17 and Th1 cells, γδ T cells, NK cells and group 3 innate lymphoid cells, IL-22 signals through a receptor complex of IL-22RA1 paired with IL-10RB, activating JAK1/TYK2-STAT3 and STAT1/STAT5 pathways. In intestinal, skin and airway epithelium, IL-22 strengthens barrier integrity by inducing mucins, antimicrobial peptides (S100A8/A9, RegIIIγ), claudins and fucosyltransferases, and by promoting epithelial proliferation and wound repair-it is essential for host defense against Citrobacter rodentium and Candida. Conversely, excessive IL-22 drives psoriasis-like epidermal hyperplasia, colitis-associated tumorigenesis and metabolic dysfunction; its activity is restrained by the soluble decoy IL-22 binding protein (IL-22BP/IL-22RA2).