TNF and psoriasis vulgaris: A central role in the pathogenesis of psoriasis vulgaris has been ascribed to the proinflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-23, and IL-17, with upregulation of the Th1 and Th17 subsets and dysfunction of the regulatory T cells [34,35,36,37,38].