IL17F and psoriasis: Second, POE was also able to inhibit, in lesional skin of IMQ mice, protein expression of the major inflammatory cytokines implicated in the pathogenesis of psoriasis, such as the Th1 hallmark cytokine TNF-α and IFN-γ and the Th17 product IL-17A and IL-17F, and the cytokine IL-23 secreted by dendritic cells, which activates Th1 and Th17 cells to produce IL-17, IFN-γ, and TNF-α.