TNF and psoriasis: Some studies have shown decreased levels of IL-17A, TNF-α, S100A15, S100A7, S100A9 and IL-6 gene expression in PBMCs after NB-UVB treatment in patients with psoriasis [28, 29] whereas other pro-inflammatory mediators such as sVCAM-1, sICAM-1, sE-selectin, MMP-9, and MPO showed no significant reduction [30].