Serum IL-33 levels are increased in patients with psoriasis

BackgroundInterleukin (IL)-33 is a recently identified cytokine, which is a member of the IL-1 family and binds to a heterodimeric receptor comprising ST2 (suppression of tumorigenicity 2) and IL-1 receptor accessory protein. Serum levels of IL-33 have been reported to be upregulated in various T helper (Th)1/Th17-mediated diseases, such as rheumatoid arthritis and inflammatory bowel disease. IL-33 expression is increased in lesional skin in patients with psoriasis, but serum levels in patients with psoriasis have not yet been studied. AimTo study serum IL-33 levels in patients with psoriasis, a Th1/Th17-mediated skin disease, before and after anti-tumour necrosis factor (TNF)- therapy. MethodsSerum IL-33 levels were measured in patients with psoriasis vulgaris (PV), psoriatic arthritis (PsA) or pustular psoriasis (PP), and compared with those of healthy controls. Associations between serum IL-33 levels and serum TNF-, IL-6, vascular endothelial growth factor and C-reactive protein levels were also studied. In addition, the effect of IL-33 stimulation on IL-6, IL-8, TNF- and VEGF secretion by human keratinocyte was analysed. ResultsSerum IL-33 levels in patients with PV, PsA and PP were significantly higher than those in healthy controls. Serum IL-33 levels correlated with serum TNF- levels in patients with psoriasis, and decreased after anti-TNF- therapy. IL-33 stimulated IL-6 and IL-8 secretion by human keratinocytes. ConclusionsThese results suggest that serum IL-33 levels generally reflect increased inflammation in patients with psoriasis.