IL22 and psoriasis: In this study, we used HaCaT keratinocytes stimulated with M5, a cocktail of five inflammatory cytokines (TNF-α, oncostatin M, IL-1α, IL-17A, and IL-22), as an in vitro model of psoriasis with typical upregulation in the production of cytokines, chemokines, and antimicrobial peptides [20,32].