Distinct nasal airway bacterial microbiotas differentially relate to exacerbation in pediatric patients with asthma.
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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D000072283:A549 Cells D000293:Adolescent D001249:Asthma D016923:Cell Death D002648:Child D018450:Disease Progression D004804:Eosinophils D005260:Female D006801:Humans D007223:Infant D007249:Inflammation D008297:Male D064307:Microbiota D009297:Nasal Mucosa D012336:RNA, Ribosomal, 16S D012137:Respiratory System D012141:Respiratory Tract Infections
airway Microbiota exacerbation asthma 16S rRNA rhinovirus Moraxella species Staphylococcus species