High-fat diet exacerbates atopic dermatitis through alterations in the gut microbiome

Atopic dermatitis (AD) is a chronic, relapsing skin disorder characterized by pruritic eczema. In addition to genetic predispositions, environmental factors such as diet are thought to contribute to the exacerbation of AD. The aim of this study was to provide scientific evidence on how environmental factors, particularly a high-fat diet (HFD), influence the pathogenesis of AD. AD was induced in NC/Nga mice fed an HFD through the application of 2,4-dinitrochlorobenzene. In the AD-HFD group, the expression levels of inflammatory markers (Tnfa, Il1b, Ptgs2, and Nos2) and AD-related factors (Il4, Ccl17, and Tslp) in the skin were significantly elevated compared with those in the AD group (mice fed a normal diet). Alteration of gut microbiota was observed in the AD-HFD group, characterized by a reduction in the abundances of Bacteroides acidifaciens and Parabacteroides distasonis, bacteria involved in short-chain fatty acid (SCFA) production. Moreover, the levels of acetate, propionate, and butyrate in the cecal contents were significantly decreased in the AD-HFD group. Fecal microbiota transplantation experiments revealed that alterations in the gut microbiota were associated with the exacerbation of AD symptoms. Furthermore, the administration of acetate alleviated the increase in the expression of skin inflammation markers and AD-related factors and the overall exacerbation of AD-like symptoms induced by the HFD. HFD intake exacerbates AD-like symptoms, and this exacerbation is linked to alteration of gut microbiota and a decrease in SCFA levels. These results suggest that acetate and acetate-producing bacteria may serve as potential tools for the prevention and treatment of AD.