Background. Although the precise pathomechanism of psoriasis is still unknown, various cytokines and growth factors derived from T cells, dendritic cells or keratinocytes, are critically involved in this disease. There have been several studies determining the serum levels of cytokines in patients with psoriasis, but with conflicting results. The levels of various cytokines and growth factors were measured in the sera of patients with psoriasis and compared with those of healthy controls. The correlation with disease severity was also determined.
Methods. Sera were collected from 122 patients with psoriasis and 78 healthy controls for ELISA analysis to evaluate the levels of cytokines and growth factors. The severity of psoriasis was determined by the Psoriasis Area and Severity Index (PASI).
Results. Serum levels of tumour necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-2, IL-6, IL-7, IL-8, IL-12, IL-17, IL-18 and vascular endothelial growth factor (VEGF) were significantly increased in patients with psoriasis compared with those of healthy controls. The serum levels of IL-2, soluble intercellular adhesion molecule-1, epidermal growth factor, hepatocyte growth factor and amphiregulin were not significantly different from those of healthy controls. Increased serum levels of TNF-α, IFN-γ, IL-12, IL-17, IL-18 and VEGF correlated with PASI. Furthermore, these cytokine levels were decreased after psoriasis treatment. In contrast, serum levels of IL-10 were decreased in psoriasis and negatively correlated with PASI.
Discussion. Serum levels of TNF-α, IFN-γ, IL2, IL-6, IL-7, IL-8, IL-12, IL-17, IL-18 and VEGF were positively correlated and that of IL-10 was negatively correlated with PASI in Japanese patients with psoriasis. These parameters might be useful for determining the disease activity of psoriasis.