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Original Article, Background: Psoriasis is associated with metabolic syndrome (MetS), and both psoriasis and MetS are associated with abnormal adipokine secretion. Much is unknown regarding the association between adipokine gene expression in subcutaneous adipose tissue (SAT) and levels of circulating adipokines in psoriasis patients with or without MetS. We examined messenger ribonucleic acid (mRNA) expression levels in SAT and circulating levels of 4 major adipokines, namely, tumor necrosis factor α (TNF-α), adiponectin, leptin, and interleukin 6 (IL-6). Methods: Twenty-nine psoriasis patients and 25 control patients were studied; 27 of the psoriasis patients and controls did not undergo systemic therapy. One psoriasis patient was treated with TNF-α antagonist and another was treated with retinoids (etretinate). Among the 29 psoriasis patients, 24 were treated with topical therapies (topical steroids and vitamin D analogues) and 5 were not. The participants were subdivided into 4 groups based on the presence of psoriasis and MetS. Serum concentrations of adipokines were measured in all participants, and SAT samples were collected from 18 psoriasis patients and 9 controls. Topical therapies were avoided for at least 1 week before collecting biopsy specimens. Adipokine mRNA expression in SAT was measured using quantitative real-time reverse transcription polymerase chain reaction (real-time RT-PCR) amplification. Results: Psoriasis Area and Severity Index (PASI) score, serum leptin concentration, and leptin mRNA expression in SAT were significantly higher in psoriasis patients with MetS than in those without MetS. IL-6 mRNA expression in SAT was significantly higher in controls than in psoriasis patients. Conclusions: The association of psoriasis activity, adipokines, and MetS was confirmed. SAT from psoriasis patients was involved in increased leptin and decreased IL-6 mRNA expression. This is the first indication that SAT adipokines are involved in the pathophysiology of psoriasis.

Numerous reports have shown that psoriasis is associated with obesity and leptin. However, few reports are available on the association between serum leptin levels and leptin gene expression in SAT of psoriasis patients. To clarify this point, we examined serum leptin levels and expression levels of leptin messenger RNA (mRNA) in subcutaneous adipose tissue (SAT) of psoriasis patients. 17 psoriasis vulgaris patients and 6 non-obese control patients who underwent skin surgery were enrolled in this study. We measured serum leptin levels. SAT samples in psoriasis patients were taken from beneath the lesional psoriatic skin at the time of skin biopsy. Leptin mRNA expression in SAT was measured using quantitative real-time reverse transcription polymerase chain reaction (real-time RT-PCR) amplification. Leptin mRNA expression showed a positive correlation with serum leptin levels and BMI. We classified psoriasis patients into two groups according to BMI: the group of non-obese psoriasis patients (BMI < 25, n = 7), and the group of obese psoriasis patients (BMI ≥ 25, n = 10). PASI score, serum leptin levels and Leptin mRNA expression in SAT were significantly higher in the obese psoriasis patients than in the non-obese psoriasis patients. Leptin mRNA expression in SAT was correlated with circulating levels of leptin, the severity of psoriasis, and obesity in psoriasis patients. Serum leptin levels and leptin mRNA expression levels in SAT of non-obese psoriasis patients were not significantly different from those of non-obese controls. The altered secretion of leptin by SAT may be related to the severity of psoriasis.