Of note, knowledge on IL-22 cellular sources, receptor signaling, cytokine induction and feedback regulation of its production, as well as IL-22 stimulatory functions on antimicrobial molecules has greatly promoted our understanding of this crucial cytokine in intestinal epithelium regeneration and barrier protection, as well as pathobiology in human diseases, such as rheumatoid arthritis, psoriasis, interstitial lung diseases and colon cancer (5). This evidence concerns the gene IL22 and psoriasis.