..Data were available for 100 severe asthma subjects (median age: 55 yrs, 42% males). Two microbiome-driven clusters were identified, characterized by differences in asthma onset, smoking status, residential locations, percentage of blood and/or sputum neutrophils and macrophages, lung spirometry, and concurrent asthma medications (all p-values <.05).
Cluster 2 patients displayed a commensal-deficient bacterial profile which was associated with worse asthma outcomes compared to cluster 1. Longitudinal clusters revealed high relative stability after 12-18 months in the severe asthmatics. Further inclusion of 24 independent mild-to-moderate asthmatics was consistent with the clustering assignments.
Unbiased microbiome-driven clustering revealed two distinct robust severe asthma phenotypes, which exhibited relative overtime stability. This suggests that the sputum microbiome may serve as a biomarker for better characterizing asthma phenotypes.