Considerations for Systemic Treatment of Psoriasis in Obese Patients.

Psoriasis is an immune-mediated inflammatory skin disease frequently associated with metabolic disorders, including diabetes, dyslipidaemia and metabolic syndrome. Moreover, a growing number of studies confirm the association between psoriasis and obesity. It has been found that obesity, as measured by body mass index >30 kg/m2, can double the risk of incident psoriasis. A positive correlation between different measures of adiposity and the severity of psoriasis has also been reported. Epidemiologic studies have also provided robust evidence confirming the association between obesity and psoriatic arthritis. Genetic, metabolic and environmental factors are all likely to contribute to these associations. Adipose tissue is an active endocrine and paracrine organ that has a key role in lipid and glucose metabolism as well as inflammation. Fat tissue is traditionally distributed into two main compartments with different metabolic characteristics, i.e. the subcutaneous and visceral adipose tissue. Particular attention has been devoted to visceral adiposity because of its contribution to inflammation and atherosclerosis. The association between psoriasis and obesity should be properly considered when choosing a systemic treatment, because it could exert negative effects on metabolic parameters, including liver enzymes, serum lipids and renal function. Obesity may increase the risk of liver and renal toxicity from methotrexate and cyclosporine. Moreover, obesity can compromise the effectiveness of systemic treatments for psoriasis (conventional and biological therapies). Dermatologists are also expected to promote a healthy lifestyle and weight loss for obese patients because they could improve metabolic parameters and responsiveness to psoriasis therapies.