IL17A and psoriasis: Elevated levels of IL-23 and Th17-associated cytokines in the serum and in cutaneous lesions of psoriatic patients indicate an important role of the IL-23/IL-17 Axis in the pathogenesis of psoriasis, Including IL-23, IL-17, IL-18, IL-22, IL-1β, IL-6 and TNF-α [5].