Atopic dermatitis regional fecal microbiomes
Atopic dermatitis (AD) has been associated with microbial gut dysbiosis, but data in adults is scarce. We sought to explore the fecal microbiome composition in AD patients versus healthy controls (HC) and investigate the impact of environmental aspects such as the geographical location and dietary habits. In this case control study, a total of 140 fecal samples from 69 AD patients and 71 HC from Tanzania (TZ) and Switzerland (CH) were analysed. Illumina shotgun metagenomics sequencing was performed followed by taxonomic profiling, calculation of alpha and beta diversity, and permutational multivariate analysis of variance. Differentially abundant species and genera between AD and HC were evaluated. Alpha diversity (Shannon Index) did not significantly differ between AD and HC. Beta diversity (Bray-Curtis) analysis showed larger variations within TZ samples. The presence of AD, sex, dietary habits (nut consumption), and BMI were identified as significant sources of fecal microbiome variation. On a species level, Faecalibacterium taiwanense was more abundant in AD, and Vescimonas sp000435555 was more abundant in HC. On a genus level, CAG-302 (NCBI: Clostridium) was more abundant in HC. AD severity or the presence of atopic comorbidities did not significantly influence microbiome variation. The presence of AD significantly impacted the fecal microbiome variation. It was associated with a particular microbial composition. Environmental factors associated with microbial changes included nutritional habits and BMI. Our data underline the need to further decipher the impact of environmental factors on the gut microbiome in AD and how this may impact potential clinical interventions on the latter.