IL17A and psoriasis: The roles of IL-17 in psoriasis, PsA, and AS are well-established.176–178 CMTM4 is a subunit of the IL-17 receptor and mediates psoriasis.48 In mice and humans, Th17 cells are found in the dermis of psoriatic skin lesions,179 and regulate skin inflammation in response to self-lipid antigens presented by cluster of differentiation 1a (CD1a).180 IL-17 activity connects psoriasis and metabolic-associated fatty liver disease.181