Airway microbiome, host immune response and recurrent wheezing in infants with severe respiratory syncytial virus bronchiolitis

Abstract

Early interactions between respiratory viruses and microbiota might modulate host immune responses and subsequently contribute to later development of recurrent wheezing and asthma in childhood. We aimed to study the possible association between respiratory microbiome, host immune response, and the development of recurrent wheezing in infants with severe respiratory syncytial virus (RSV) bronchiolitis. Seventy-four infants who were hospitalized at Beijing Children's Hospital during an initial episode of severe RSV bronchiolitis at 6months of age or less were included and followed up until the age of 3years. Sputum samples were collected, and their microbiota profiles, LPS, and cytokines were analyzed by 16S rRNA-based sequencing, ELISA, and multiplex immunoassay, respectively. Twenty-six (35.1%) infants developed recurrent wheezing by the age of 3years, and 48 (64.9%) did not. The relative abundance of Haemophilus, Moraxella, and Klebsiella was higher in infants who later developed recurrent wheezing than in those who did not (LDA score >3.5). Airway levels of LPS (P=.003), CXCL8 (P=.004), CCL5 (P=.029), IL-6 (P=.004), and IL-13 (P<.001) were significantly higher in infants who later developed recurrent wheezing than in those who did not. Moreover, high airway abundance of Haemophilus was associated with CXCL8 (r=0.246, P=.037) level, and that of Moraxella was associated with IL-6 level (r=0.236, P=.046) and IL-10 level (r=0.266, P=.024). Our study suggests that higher abundance of Haemophilus and Moraxella in airway microbiome might modulate airway inflammation during severe RSV bronchiolitis in infancy, potentially contributing to the development of subsequent recurrent wheezing in later childhood.