ena-STUDY-UNIVERSITY OF CALIFORNIA - SAN FRANCISCO-16-03-2018-22:32:58:288-2012
Distinct Nasal Airway Bacterial Microbiota Differentially Relate to Exacerbation in Pediatric Asthma
Background: In infants, distinct nasopharyngeal bacterial microbiota differentially associate with incidence and severity of acute respiratory 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=3,122) collected post-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 RV infection and respiratory illnesses as secondary outcomes were performed. Using A549 epithelial cells, we assessed nasal isolates of Moraxella, Staphylococcus and Corynebacterium 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 were observed. Moraxella and Staphylococcus-dominated microbiota were most frequently detected and exhibited temporal stability. Nasal microbiota dominated by Moraxella associated with increased exacerbation risk and eosinophil activation. Staphylococcus- or Corynebacterium-dominated microbiota associated with reduced respiratory illness and exacerbation events, while Streptococcus-dominated assemblages increased the risk of RV 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, M. catarrhalis induced significantly greater epithelial damage and inflammatory cytokine expression (IL33 and IL8), compared with other dominant nasal bacterial isolates tested.  Conclusion: Nasal airway microbiota of children with asthma relate to the likelihood of exacerbation, RV infection, and respiratory illnesses during the fall season.
Background: In infants, distinct nasopharyngeal bacterial microbiota differentially associate with incidence and severity of acute respiratory 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=3,122) collected post-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 RV infection and respiratory illnesses as secondary outcomes were performed. Using A549 epithelial cells, we assessed nasal isolates of Moraxella, Staphylococcus and Corynebacterium 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 were observed. Moraxella and Staphylococcus-dominated microbiota were most frequently detected and exhibited temporal stability. Nasal microbiota dominated by Moraxella associated with increased exacerbation risk and eosinophil activation. Staphylococcus- or Corynebacterium-dominated microbiota associated with reduced respiratory illness and exacerbation events, while Streptococcus-dominated assemblages increased the risk of RV 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, M. catarrhalis induced significantly greater epithelial damage and inflammatory cytokine expression (IL33 and IL8), compared with other dominant nasal bacterial isolates tested.  Conclusion: Nasal airway microbiota of children with asthma relate to the likelihood of exacerbation, RV infection, and respiratory illnesses during the fall season.