Microbiota associations with inflammatory pathways in asthma

BACKGROUND: The airway microbiota plays an important role in asthma pathophysiology. However, the relationship between the airway microbiota and asthma phenotypes is still poorly understood. OBJECTIVE: We aimed to characterize the airway microbiota in asthma patients and determine its correlation with airway inflammatory phenotypes and other phenotypic characteristics. METHODS: The microbial composition of induced sputum specimens collected from asthma patients was determined using 16S rDNA gene sequencing. RESULTS: Patients with asthma had a higher abundance of bacterial taxa associated with Bacteroidetes, Fusobacteria and Proteobacteria and a reduced abundance of Firmicutes and Actinobacteria compared to healthy controls. This study classified the asthma-associated lung microbiota into three community types based on DMM models, which were defined as three pulmotypes (P1, P2 and P3). The lungs of patients with pulmotype 3 (P3) were dominated by Faecalibacterium and Bacteroides, while patients with pulmotype 1 (P1) had a greater abundance of Pasteurellaceae, Streptococcus and Rothia. P1 patients were older (p = .045) and had lower blood TGF levels (p = .028). P3 patients had fewer eosinophils (p = .016) and more neutrophils (p = .039) in induced sputa than P1 patients. CONCLUSIONS: Differences in asthma-associated airway microbiota pulmotypes are associated with and might influence asthma, particularly inflammatory phenotypes.