Gut microbiome of patients with nonatopic chronic hand eczema (CHE) is distinct and enriched in immunomodulatory bacteria species compared with patients with atopic CHE and healthy individuals

The gut microbiome of patients with chronic hand eczema (CHE) is different from healthy individuals and enriched in bacteria with immunomodulatory properties. These differences are more important for patients with nonatopic CHE, opening the door to microbiome-based therapeutic strategies in this patient population. Dear Editor, Chronic hand eczema (CHE) is a common, multifactorial and debilitating inflammatory skin disorder.1 A history of atopic dermatitis (AD) is found in only one-third of patients with CHE. Nonatopic CHE presents with distinct immunological features compared with atopic CHE.1,2 In recent years, the concept of the ‘gut–skin axis’ has emerged, in which the gut microbiome could trigger or exacerbate inflammation in the skin by influencing the levels of metabolites, such as short-chain fatty acids (SCFA), bile acids, kynurenine, indoles and trimethylamine N-oxide, that can affect distant sites.3,4 The gut microbiome can also impair intestinal barrier integrity, leading to systemic immune activation through T helper (Th)1 and Th17 pathways.3 Disruption of the gut microbiome, also termed dysbiosis, has been associated with several inflammatory skin diseases, including AD, psoriasis, alopecia areata and hidradenitis suppurativa.4,5 However, composition of the gut microbiome has not yet been investigated in patients with CHE.