IL17A and psoriasis: IL-17, in turn,is a pro-inflammatory cytokine that stimulates fibroblasts, endothelialcells, macrophages, and epithelial cells to release several otherinflammatory mediators, such as IL-6, TNF-α, nitric oxide synthase,metalloproteases and chemokines.49,50 In the pastfew years, there has been a significant improvement in psoriasis treatment,mainly due to the development of immunobiological drugs, such as TNF-αinhibitors, including infliximab, adalimumab, and etanercept, as wellas ustekinumab, an IL-12/IL-23 inhibitor.