Plasma adiponectin and leptin levels in Japanese patients with psoriasis

Conflicts of interest: none declared. Sir, Psoriasis is a hyperproliferative inflammatory skin disorder with microvessel dilation. Although the precise pathomechanism remains unknown, various cytokines and growth factors are involved in this disease.1, 2 Tumour necrosis factor (TNF)‐α is a pleiotropic inflammatory cytokine, and recent studies indicate that TNF‐α plays a critical role in the development of psoriasis. Now anti‐TNF‐α biologic agents are available for the treatment of psoriasis with remarkable efficacy.3 Adiponectin is an adipocyte‐specific secretory protein abundantly present in the circulation. Plasma levels of adiponectin are decreased in obesity, insulin resistance and type 2 diabetes,4 and hypoadiponectinaemia is assumed to be closely associated with the metabolic syndrome.5 Leptin is another adipocyte‐specific secretory protein, which acts primarily through specific receptors in the hypothalamus.6 It decreases appetite and increases energy expenditure, and serum leptin levels reflect the body fat mass. A recent study indicates that adiponectin inhibits TNF‐α production and TNF‐α inhibits adiponectin production, antagonizing each other’s function.6