Inverse Association Between the Skin and Oral Microbiota in Atopic Dermatitis.

Previous studies have shown independently that the skin and gut microbiota are closely associated with atopic dermatitis (AD); however, the microbiota across different habitats of AD patients as an integrated community has not been characterized. In the present study, we comparatively analyzed the structure and function of the microbial communities in the skin, oral cavity, and gut of 172 AD patients and 120 healthy controls through 16S ribosomal RNA gene amplicon sequencing. The skin and oral cavity, but not the gut, of AD patients demonstrated differential reduction in the microbial diversity, and these were distinctly correlated with disease severity. Different degrees of shifts in the community structure were found among different habitats, and the lineage distance between the skin and oral microbiota of AD patients was closer than that observed in the controls. The different habitats of AD patients exhibited site-specific alterations at the genus level, and many oral-specific microbes of AD showed opposing directions of enrichment in the skin and oral cavity. Most interestingly, an inverse association in the functional pathways was found between the skin and oral microbiota of AD patients. Additionally, the alterations of the microbiota in different body sites of AD patients were differentially affected by age.