Distinct nasal microbiota increase asthma exacerbation and rhinovirus-infection risk
Published online: June 12, 2019
Perturbations to the communities of mixed species microbes that inhabit the human body - the human microbiome – have emerged as a critical driver of inflammatory disease. Recently, a large population-based infant cohort study demonstrated that six distinct upper airway microbiota exist and relate to significant differences in risk of virus-associated acute respiratory illness in infancy and subsequent asthma development in childhood. Thus, there is growing interest in the role of the airway microbiome as a potential modulator of asthma outcomes and a contributor to the clinical heterogeneity observed in patient populations.
In their study recently published in The Journal of Allergy & Clinical Immunology (JACI), McCauley and colleagues hypothesized that compositionally distinct microbiota also exist in the nasal airways of children with asthma and are related to differences in asthma exacerbation outcomes and rhinovirus (RV) infection. The researchers leveraged longitudinally sampled nasal secretions collected post-randomization from more than four hundred children with asthma (ages 6-17 years) participating in the Preventative Omalizumab (Xolair® anti-IgE antibody) or Step-up Therapy for Severe Fall Exacerbations (PROSE) randomized controlled trial.
Analyzing nasal microbiota profiles generated on over 3,000 samples, the authors found that six airway microbiota, dominated by Moraxella, Staphylococcus, Corynebacterium, Streptococcus, Alloiococcus or Haemophilus, existed in this population of pediatric patients with asthma. Moraxella- and Staphylococcus-dominated microbiota were stably maintained in the upper airways of children with asthma. Relating these nasal microbiota types to asthma exacerbation, rhinovirus infection (RV) and respiratory illnesses revealed that Moraxella-dominated nasal airway microbiota were associated with increased asthma exacerbation risk. Staphylococcus- or Corynebacterium-dominated microbiota were relatively protective and associated with reduced respiratory illnesses and exacerbations, while Streptococcus-dominated assemblages were associated with increased the risk of RV infection.
The authors findings indicate that the presence of specific nasal microbiota modulate risk of asthma exacerbations, RV infections, and respiratory illnesses and that microbiota associated with increased risk of asthma exacerbation are stably maintained in the upper airways. Although causal mechanisms have not been elucidated, and identification of germs at species level e.g. for S. aureus is not provided, these observations may help explain why some children with asthma are exacerbation-prone and could lead to targeted strategies to promote appropriate nasal airway mucosal colonization and potentially reduce exacerbation risk or modulate response to viral respiratory infections.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.
Graphical Abstract