IL17A and psoriasis: Specifically, CD8 T-cells; CD4+ Th17 cells, responsible for producing IL-17 and IL-22; type 3 innate lymphoid cells, responsible for producing IL-17 and IL-22; and γδ T cells, responsible for producing IL-17 and TNF- α, are implicated in the pathogenesis of psoriasis [37,41,43].