Gut Microbiome Characteristics Associate with Clinical and Immunologic Features of Adult Asthma Phenotype

While there is strong evidence that alterations in the gut microbiome influence childhood atopic diseases, such as asthma, little is known regarding potential associations between gut microbiota patterns and phenotypic features of adult asthma. Fecal samples from 65 adults enrolled in a prospective observational cohort study (CAARS) at the University of Michigan were analyzed using 16S ribosomal RNA gene sequencing methods to characterize gut microbiota composition. QIIME2 and R analysis software were used to determine fecal microbiota patterns associated with clinical and immunologic features. Differences in gut bacterial community diversity were associated with asthma and atopic status, related clinical features, as well as age, gender, and obesity (p<0.05). Asthmatic and obese subjects had lower microbiota richness compared to non-asthmatic and non-obese subjects (p<0.05). Asthmatics had higher relative abundance of Blautia, whereas healthy subjects had higher relative abundance of Prevotella, among other differentially abundant taxa. Gut bacterial diversity correlated negatively with sensitization to aeroallergens (#positive sIgE, padj 0.03) but positively with measures of bronchial hyperresponsiveness (methacholine PC20, padj 0.04). Inhaled corticosteroid (ICS) use was associated with higher relative abundance of several taxa including Alistipes, Parabacteroides and Ruminococcaceae. Gut bacterial diversity and richness were positively associated with serum adiponectin (rho =0.4, padj=0.<0.01), and inversely related to PAI-1 (rho = -0.3, p=0.05). In this cohort inclusive of subjects with mild-moderate asthma, significant relationships exist between gut microbiota composition, atopy, ICS use, and blood cytokines. Findings support further studies to understand mechanisms of gut microbiome influence on adult asthma phenotypes.