Gut microbiota relationships to lung function and adult asthma phenotype: a pilot study

INTRODUCTION: Despite strong evidence that maturation patterns of the gut microbiome in early life influence the risk for childhood asthma, very little is known about gut microbiota patterns in adults with established asthma, and of greater interest relationships to phenotypic features that characterise asthma heterogeneity. METHODS: Fifty-eight faecal samples from 32 adults with (n=24) and without (n=8) asthma were analysed using 16S ribosomal RNA gene sequencing methods to characterise intestinal bacterial composition. Compositional stability of paired samples was evaluated and features of gut bacterial community structure analysed in relation to extensive clinical characterisation data collected from subjects, who were enrolled in a prospective observational cohort study at the University of Michigan. RESULTS: Differences in gut bacterial community structure were associated with aeroallergen sensitisation and lung function as assessed by forced expiratory volume in 1 s (FEV(1)) %predicted. Associations with FEV(1) were consistently observed across independent analytic approaches. k-means clustering of the gut microbiota data in subjects with asthma revealed three different clusters, distinguished most strongly by FEV(1) (p<0.05) and trends in differences in other clinical and inflammatory features. CONCLUSION: In this pilot study of asthmatic and non-asthmatic subjects, significant relationships between gut microbiota composition, aeroallergen sensitisation and lung function were observed. These preliminary findings merit further study in larger cohorts to explore possible mechanistic links to asthma phenotype.