Skin microbiome and its association with host cofactors in determining atopic dermatitis severity

BackgroundAtopic dermatitis (AD) is a heterogeneous, chronic inflammatory skin disease linked to skin microbiome dysbiosis with reduced bacterial diversity and elevated relative abundance of Staphylococcus aureus (S. aureus). ObjectivesWe aimed to characterize the yet incompletely understood association between the skin microbiome and patients' demographic and clinical cofactors in relation to AD severity. MethodsThe skin microbiome in 48 adult moderate-to-severe AD patients was investigated using next-generation deep sequencing (16S rRNA gene, V1-V3 region) followed by denoising (DADA2) to obtain amplicon sequence variant (ASV) composition. ResultsIn lesional skin, AD severity was associated with S. aureus relative abundance (r(S) = 0.53, p < 0.001) and slightly better with the microbiome diversity measure Evenness (r(S) = -0.58, p < 0.001), but not with Richness. Multiple regression confirmed the association of AD severity with microbiome diversity, including Shannon (in lesional skin, p < 0.001), Evenness (in non-lesional skin, p = 0.015) or S. aureus relative abundance (p < 0.012), and with patient's IgE levels (p < 0.001), race (p < 0.032), age (p < 0.034) and sex (p = 0.012). The lesional model explained 62% of the variation in AD severity, and the non-lesional model 50% of the variation. ConclusionsOur results specify the frequently reported reduced diversity of the AD-related skin microbiome to reduced Evenness, which was in turn mainly driven by S. aureus relative abundance, rather than to a reduced microbiome Richness. Finding associations between AD severity, the skin microbiome and patient's cofactors is a key aspect in developing new personalized AD treatments, particularly those targeting the AD microbiome.

Automated summary

This study investigated the skin microbiome of 48 adult patients with moderate-to-severe atopic dermatitis (AD) and found that the diversity of the skin microbiome is associated with patients' demographic and clinical cofactors, as well as disease severity. Specifically, the relative abundance of Staphylococcus aureus and the evenness of the microbiome were associated with AD severity. These findings are important for the development of personalized treatments for AD.