Induced sputum microbiome in smoker and non-smoker COPD subjects and its association with lung function in Indian subjects

Culture independent techniques have allowed a better understanding of association between tobacco-smoke exposed COPD (TS-COPD) & lung microbiome, but there is limited knowledge about lung microbiome in non-smoker COPD (NS-COPD) subjects. We aimed to study lung microbiome in smoker & non-smoker COPD subjects and its association with lung function in rural Indian subjects. Induced sputum samples were obtained from 11 healthy-nonsmokers (H-Nonsmokers), 10 healthy-smokers (H-Smokers), 18 biomass-smoke exposed healthy (H-Biomass), 15 TS-COPD & 20 NS-COPD subjects. Samples were sequenced using V3 & V4 hypervariable region (Illumina MiSeq Platform) and taxanomic diversity information was obtained with QIIME pipeline, & R script package. Bacterial abundance was significantly higher in NS-COPD subjects compared to H-Nonsmokers, H-Biomass, & TS-COPD subjects (Fig.1A). Exposure to tobacco-smoke caused decrease in bacterial diversity (Fig.1B). Firmicutes, Bacteriodetes, Proteobacteria, Actinobcater & Fusobacter were the most prevalent phyla in our samples. Phylum Proteobacteria, which includes many pathogens showed higher abundance in COPD subjects (Fig.1C) & were negatively associated with lung function (Fig.1D). The impaired lung function observed in COPD is associated with in increased abundance of pathogenic microbiome & a decline in its diversity, which may have implications in COPD pathophysiology.