Gut Streptococcus species affect persistence and severity of atopic dermatitis during infancy

Abstract

Perturbations of gut microbiota in early life can disrupt the development of immune system and directly associated with the risk of atopic dermatitis (AD). This study evaluated the association between persistence and severity of AD and the composition of gut microbiota at 6 months of age. The composition of gut microbiota was analyzed in fecal samples from 116 infants (6-month-old) by pyrosequencing, including 58 healthy infants and 58 infants with AD from Cohort for Childhood Origin of Asthma and Allergic Diseases (COCOA). AD in infants was diagnosed by a pediatric allergists at 6 months and 1 year of age, and severity of physical symptoms assessed by the SCORAD (Scoring Atopic Dermatitis) index at 6 months. Persistence was defined as AD symptom up to 12 months. The OTUs (P = 0.027) and Simpson index (P = 0.006) of diversity in gut microbiota were lower in healthy infants than those in persistent AD infants. The composition of Streptococcus was enriched in persistence AD infants than healthy infants (P = 0.001). The composition of Streptococcus pseudopneumoniae, Streptococcus mitis and Streptococcus salivarius were enriched in infants with persistent AD, compared to healthy infants. The relative abundance of S. pseudopneumoniae was increased in persistence AD infants compared with non-persistence AD. The relative abundance of gut S. mitis and S. pseudoneumoniae were positively correlated with serum IgE in infants with AD. S. pseudoneumoniae was positively correlated with SCORAD. Gut Streptococcus may affect persistence and severity of AD via IgE mediated allergic inflammation.