Compositional and Functional Profile of Gut Microbiota in a Cohort of Adult Spanish Patients with Atopic Dermatitis Using Metagenomics: A Cross-Sectional Study

<u><b><i></i></b></u> <u><b><i>Background:</i></b></u> The role of gut dysbiosis in the pathophysiology of atopic dermatitis (AD) through immune system (IS) imbalance is a novel line of investigation currently under discussion. This study aimed to characterize compare the composition and functional profile of the gut microbiota (GM) between adults with AD and healthy individuals. <u><b><i>Methods:</i></b></u> Observational cross-sectional study, where fecal samples from 70 adults (38 patients and 32 controls) were analyzed using metagenomics and bioinformatics. <u><b><i>Results:</i></b></u> Differences between the GM of patients with AD and healthy individuals were demonstrated. Reduced microbial diversity was found in subjects with AD. Bacterial species with lower abundance primarily belonged to the families Ruminococcaceae, Akkermansiaceae, and Methanobacteriaceae. Several microbial metabolic pathways were found to be decreased in patients with AD, including amino acid biosynthesis, vitamin biosynthesis, fatty acids and lipids biosynthesis, and energy metabolism. <u><b><i>Conclusion:</i></b></u> Adults with AD exhibited a distinct GM compared to healthy individuals. Changes were demonstrated both compositionally and functionally. Further investigation is mandatory to elucidate the potential link and causal relationship between gut dysbiosis and AD, which may be crucial for a deeper understanding of the disease's pathophysiology and the development of novel therapeutic approaches.