Oral microbiome associated with asthma and COPD in a multicenter study

Abstract

Oral bacteria may affect respiratory disease, but few studies have explored this in general population samples from different geographical regions. We aimed to explore the association between oral microbial community composition with asthma and COPD in the ECRHS3. Metagenomic sequencing (2x150 bp paired-end sequencing on Illumina platform) was performed on subgingival samples from 330 ECRHS participants in Bergen (NO), Melbourne (AU) and Tartu (EE) (median age: 53 years [range: 40-65] and 50% men). Alpha and beta diversity group differences were tested by Wilcoxon and PERMANOVA tests, respectively, for study centre, age, sex, smoking, COPD and asthma. Overall, 20% reported current asthma (asthma medication use and/or asthma attack last 12 months) and 19% were current smokers. Only 3% reported doctor-diagnosed COPD. Alpha diversity was higher in Tartu than Bergen and Melbourne, and overall composition also differed significantly between centers (R2=6.7%, p=0.001). Current smokers differed in microbial composition from ex-smokers or non-smokers (R2=1.9%, p=0.001). Never asthmatics had higher alpha diversity (richness) compared to those with current (p=0.013) or past asthma (p=0.002). The overall microbial composition also differed by asthma status (R2=1.7%, p=0.001). There was no difference in microbial composition by age or sex (both, p>0.2). Microbial composition variation was mostly explained by study center, smoking and asthma. No association between oral microbiome composition and COPD were observed; but numbers were small. Both asthma and smoking affect the oral microbiome, but smoking was not associated with asthma. Differences by center may indicate that lifestyle also influences the oral microbiome.