IL17A and psoriasis: These cytokines promote T cell differentiation into Th1 and Th17, which produce more TNF-α and other proinflammatory cytokines such as IL-17 and IFN-γ, leading to the pathologic manifestations of psoriasis, i.e., keratinocyte hyperproliferation, acanthosis, parakeratosis, and hypogranulosis (Conrad and Gilliet, 2018; Ogawa et al., 2018).