Gastric bypass surgery: improving psoriasis through a GLP-1-dependent mechanism?

Psoriasis is a common inflammatory skin disease and obesity constitutes a risk factor for the disease. Obese patients with psoriasis are often more difficult to treat and are at increased risk for dyslipidemia, diabetes, hypertension and cardiovascular disease. Case reports suggest that gastric bypass surgery in patients with psoriasis may result in complete remission of the disease. A substantial weight loss is achieved in the months following surgery, which is likely to reduce psoriasis symptoms and risk of comorbidities. Interestingly, however, it has been described that improvement of psoriasis is initiated immediately following surgery before any weight loss could have happened. We hypothesize that the glucose-lowering gut incretin hormone glucagon-like peptide-1 (GLP-1) is responsible for this effect. The levels of GLP-1 have been shown to increase up to 20 times after gastric bypass surgery. This most likely contributes importantly to the acute remission of type 2 diabetes, which is often induced by gastric bypass operations. The hormone is not hypersecreted after the purely restrictive bariatric procedure gastric banding and no case reports exist on improvement in psoriasis following gastric banding. Intriguingly, recent studies describe that GLP-1 may convey anti-inflammatory effects in addition to its effects on glucose homeostasis. Also, GLP-1 reduces appetite and gastrointestinal motility including gastric emptying, which reduces food intake and leads to weight loss. Thus, both a direct anti-inflammatory effect of GLP-1 as well as an indirect effect through weight loss could contribute to improvement in psoriasis. A potential involvement of GLP-1 in the remission of psoriasis observed after bariatric surgery offers exciting possibilities for research and eventually perhaps new ways of anti-psoriatic treatment.