The skin disease psoriasis has been associated with higher levels of the protein leptin, according to an article released on December 15, 2008 in Archives of Dermatology, one of the JAMA/Archives journals.

Psoriasis is a chronic autoimmune disease whose primary symptom is the presence of a persistent red, scaly rash. Its causes are not fully understood, but many associations have been investigated: “Associations among psoriasis, obesity, hypertension, cardiovascular diseases, diabetes mellitus and metabolic syndrome have been reported,” write the authors. “Although the underlying mechanisms may be complex, the ‘obesity of psoriasis’ is thought to be a key link to cardiovascular diseases, including diabetes mellitus, stroke, heart disease, hypertension and myocardial infarction [heart attack].” One factor associated with obesity, in particular, is the protein hormone leptin, which fat cells produce. This substance  helps control food intake, body weight, and fat stores, and has been linked to immune and inflammatory processes.

To investigate the association between leptin production and psoriasis, Yi-Ju Chen, M.D., of the Taichung Veterans General Hospital and National Chung Hsing University, Taiwan, and colleagues investigated 77 patients with psoriasis in comparison with 81 controls, matched by age and sex. The clinical characteristics of each participant were observed, including age, sex, height, weight, other diseases, and the severity of psoriasis. Additionally, the researchers examined blood samples for the levels of leptin.

In comparison with the controls, participants with psoriasis were more likely to be obese and hypertensive, and to have elevated blood glucose levels or to have diabetes. Leptin levels were higher in participants who were obese, female, or had high blood pressure, metabolic syndrome, or psoriasis.

The authors summarize their results: “After adjustment for sex, body mass index and conventional cardiovascular risk factors (including hypertension and metabolic syndrome), psoriasis was independently associated in our study with hyperleptinemia [high leptin levels].” They continue: “In addition, hyperleptinemia in psoriasis is associated with higher risk of developing metabolic syndrome. This novel finding links the chronic inflammation status of psoriasis with metabolic disturbances.”

The authors hypothesize that the elevated leptin levels may have more than one source: “Body weight loss has been reported to significantly decrease leptin levels and improve insulin sensitivity and may reduce the likelihood of developing metabolic syndrome and adverse cardiovascular diseases,” they write. “Body weight loss could potentially become part of the general treatment of psoriasis, especially in patients with obesity.”

Psoriasis Independently Associated With Hyperleptinemia Contributing to Metabolic Syndrome
Yi-Ju Chen, MD; Chun-Ying Wu, MD, PhD, MPH; Jui-Lung Shen, MD; Szu-Ying Chu, MD; Chih-Kang Chen, MD; Yun-Ting Chang, MD, PhD; Chuan-Mu Chen, PhD
Arch Dermatol. 2008;144(12):1571-1575.
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Written by Anna Sophia McKenney