Serum levels of TNF-α showed a trend for higher expression in thick plaque psoriasis compared to thin plaque psoriasis (p = 0.11), and its downstream cytokines, IL-6 and IL-8, were significantly higher in thick plaque psoriasis in comparison to thin plaque psoriasis (p = 0.0035 for IL-6, p = 0.0036 for IL-8; Fig 5). Here, IL6 is linked to psoriasis vulgaris.