High-fat diet exacerbates imiquimod-induced psoriasis-like dermatitis in mice

Psoriasis, a chronic inflammatory skin disease, is closely related to systemic metabolism. An elevated body mass index (BMI) is a risk factor for psoriasis; inflammasomes are activated by adipose tissue macrophages in obese subjects. We hypothesized that hyperlipidaemia is involved in the pathogenesis of psoriasis and examined the role of a high-fat diet (HFD) in the development of psoriasis in imiquimod (IMQ)-treated mice. The body weight and serum level of cholesterol were significantly higher in mice fed an HFD than in a regular diet (RD). HFD mice had higher psoriasis skin scores, and the number of neutrophils infiltrating into the lesional skin was elevated. IL-17A mRNA expression was significantly increased in the skin of IMQ-treated HFD mice; the expression of IL-22, IL-23 and TNF-α mRNA was not enhanced. Caspase-1 and IL-1β were activated in the skin of IMQ-treated HFD mice, and their serum level of IL-17A, TNF-α and IL-1β was significantly upregulated. Our findings strongly suggest that hyperlipidaemia is involved in the development and progression of psoriasis via systemic inflammation and inflammasome activation.