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Distinct nasal airway bacterial microbiotas differentially relate to exacerbation in pediatric patients with asthma
Kathryn McCauley1, Juliana Durack1, Ricardo Valladares1
1Department of Medicine, University of California, San Francisco, Calif.
Insights
Distinct nasal bacteria in children with asthma impact respiratory illness severity and exacerbation risk. Specific bacterial communities, like Moraxella, are linked to higher exacerbation risk, while others may offer protection.
Area of Science:
- Microbiology
- Immunology
- Pediatric Respiratory Medicine
Background:
- Infant nasopharyngeal bacterial communities are linked to respiratory infections and asthma development.
- The role of nasal microbiota in children with asthma requires further investigation.
Purpose of the Study:
- To investigate the association between distinct nasal airway microbiota structures in children with asthma and clinical outcomes.
- To determine if nasal microbiota composition relates to asthma exacerbations, rhinovirus infections, and respiratory illnesses.
Main Methods:
- 16S rRNA profiling of nasal secretion samples from 413 children with asthma (aged 6-17 years).
- Statistical analysis correlating microbiota composition with exacerbations, rhinovirus infections, and respiratory illnesses.
- In vitro assessment of bacterial isolates (Moraxella, Staphylococcus, Corynebacterium) for epithelial damage and inflammatory responses.
Main Results:
- Six distinct nasal microbiota assemblages were identified, dominated by Moraxella, Staphylococcus, Corynebacterium, Streptococcus, Alloiococcus, or Haemophilus.
- Moraxella-dominated microbiotas were associated with increased exacerbation risk and eosinophil activation.
- Staphylococcus or Corynebacterium-dominated microbiotas correlated with reduced respiratory illness and exacerbations, while Streptococcus-dominated ones increased rhinovirus infection risk.
- Moraxella catarrhalis induced greater epithelial damage and inflammatory responses in vitro compared to other tested isolates.
Conclusions:
- Distinct nasal airway microbiotas in children with asthma are associated with the likelihood of exacerbations, rhinovirus infections, and respiratory illnesses.
- Nasal microbiota composition shows relative stability despite infections or exacerbations, with minor fluctuations in dominant taxa.
Background:
In infants, distinct nasopharyngeal bacterial microbiotas differentially associate with the incidence and severity of acute respiratory tract infection and childhood asthma development.
Objective:
We hypothesized that distinct nasal airway microbiota structures also exist in children with asthma and relate to clinical outcomes.
Methods:
Nasal secretion samples (n = 3122) collected after randomization during the fall season from children with asthma (6-17 years, n = 413) enrolled in a trial of omalizumab (anti-IgE) underwent 16S rRNA profiling. Statistical analyses with exacerbation as the primary outcome and rhinovirus infection and respiratory illnesses as secondary outcomes were performed. Using A549 epithelial cells, we assessed nasal isolates of Moraxella, Staphylococcus, and Corynebacterium species for their capacity to induce epithelial damage and inflammatory responses.
Results:
Six nasal airway microbiota assemblages, each dominated by Moraxella, Staphylococcus, Corynebacterium, Streptococcus, Alloiococcus, or Haemophilus species, were observed. Moraxella and Staphylococcus species-dominated microbiotas were most frequently detected and exhibited temporal stability. Nasal microbiotas dominated by Moraxella species were associated with increased exacerbation risk and eosinophil activation. Staphylococcus or Corynebacterium species-dominated microbiotas were associated with reduced respiratory illness and exacerbation events, whereas Streptococcus species-dominated assemblages increased the risk of rhinovirus infection. Nasal microbiota composition remained relatively stable despite viral infection or exacerbation; only a few taxa belonging to the dominant genera exhibited relative abundance fluctuations during these events. In vitro, Moraxella catarrhalis induced significantly greater epithelial damage and inflammatory cytokine expression (IL-33 and IL-8) compared with other dominant nasal bacterial isolates tested.
Conclusion:
Distinct nasal airway microbiotas of children with asthma relate to the likelihood of exacerbation, rhinovirus infection, and respiratory illnesses during the fall season.
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