Fig. 1
From: Interleukin-22 and connective tissue diseases: emerging role in pathogenesis and therapy
IL-22R downstream signal transduction pathways. IL-22 binds to IL-22R1, then IL-10R2 binds to the IL22-IL22R1 complex, which activates a cascade of downstream signal transduction pathways. IL-22 stimulation activates JAK1 and TYK2, such as the MAPK pathways (i.e., ERK1/2, MEK1/2, JNK, and p38 kinase depending on the cell type), STAT1, STAT3, and STAT5. Among them, STAT3 is the main activated pathway. The above signalling pathways are phosphorylated depending on the IL-22 stimulation. Several mediators are produced after STAT3 phosphorylation, including inflammatory factors, tissue repair molecules, chemokines and antimicrobial peptides, which are involved in many diverse processes in innate immunity and adaptive immunity at barrier surfaces (i.e., skin, intestine and lung). Thus, IL-22 can regulate the process of inflammation, tissue repair, chemotaxis and antimicrobial peptides production depending on the mediators generated and the tissues where it is expressed