Alterations in gut microbiome associated with severity of atopic dermatitis in infants

Background: Atopic dermatitis (AD) often arises in infancy, and gut microbial dysbiosis is associated with the development of AD. However, less is known about specific changes in early-life gut microbiome associated with AD and AD severity. This study aims to reveal the gut microbial composition and function profiles associated with the severity of AD in infants. Methods: Sixty-two infants (mean [SD] age, 4.7[1.9] months) with different severities of AD were enrolled and divided into three groups (mild, moderate and severe) according to the Scoring Atopic Dermatitis (SCORAD) index. The profiles of gut microbial composition and function were analysed by sequencing 16S ribosomal RNA amplicons. Quality of life on children and the family was evaluated using published questionnaires. Results: Decreased levels of Clostridium sensu stricto, Collinsella and increased level of Parabacteroides presented in the severe AD group compared with the mild AD group after adjusting potential confounders (p < 0.05). There were strong positive correlations between the Scoring Atopic Dermatitis (SCORAD) index and the relative abundance (RA) of Bacteroides and functional pathways for metabolism of sphingolipids and glycosphingolipids (p < 0.05). The SCORAD index was negatively correlated with the RA of Clostridium sensu stricto (p < 0.05), and was also positively correlated with the index of quality of life on children and the family (p < 0.05). Conclusion: Discrepancies in gut microbial composition and functional pathways were observed in infants with mild-to-severe AD. Alterations in butyrate-producing bacteria (Clostridium sensu stricto), sphingolipid-producing bacteria (Parabacteroides, Bacteroides), and related functional pathways were associated with the severity of AD infants.