TNF and psoriasis: Increased oxidative stress and inflammatory mediators including tumor necrosis factor (TNF)-α, interferon gamma (IFN-γ), interleukin (IL)-1β, IL-6, IL-12, IL-17, IL-22 and IL-23, released by activated T-cells subsets, monocytes and dendritic cells, are involved in the pathophysiology of psoriasis [2,3].