The Nasal Microbiome in Asthma

Abstract

Lower respiratory tract microbiota have been associated with asthma development and severity. We hypothesized that the nasal microbiome differs between healthy and asthmatic individuals. Nasal swabs were obtained from 73 subjects recruited from the Mount Sinai Health System (New York, NY), including 22 with exacerbated asthma, 31 with stable asthma, and 20 non-asthmatic controls. The nasal microbiome was profiled by 16S rRNA sequencing and analyses were performed using QIIME (Quantitative Insights into Microbial Ecology), PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States), and STAMP (Statistical Analysis of Metagenomic Profiles). Mean age of the cohort was 35.7 years (standard deviation 15.9) with 66% female. Seventy five percent of subjects with exacerbated asthma, 45% of subjects with stable asthma, and 0% of controls had ≥1 hospitalization for asthma in the past year. Nasal bacterial compositions between the classes were significantly different (PERMANOVA η2=5%; P=2.2x10-2). Relative to controls, the nasal microbiota of subjects with asthma were enriched with Bacteroidetes (Wilcoxon-Mann-Whitney |r|=0.33, P=5.1x10-3) and Proteobacteria (|r|=0.29; P=1.4x10-2). qPCR confirmed these findings (Prevotella buccalis fold change=130, P=2.1x10-4). Metagenomic inference revealed lower glycerolipid metabolism in exacerbated and stable asthmatic patients compared to controls (Kruskal-Wallis P=1.9x10-4). The nasal microbiome differs by asthma status, with enrichment of Proteobacteria and Bacteroidetes in subjects with asthma that is associated with lower glycerolipid metabolism. Our findings of these enriched taxa in nasal samples are consistent with lower airway findings, suggesting that microbiome profiling of easily-accessible nasal samples may be used to understand lower airway microbiota in asthma.