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) &amp; 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 &amp; 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 &amp; 20 NS-COPD subjects. Samples were sequenced using V3 &amp; V4 hypervariable region (Illumina MiSeq Platform) and taxanomic diversity information was obtained with QIIME pipeline, &amp; R script package. Bacterial abundance was significantly higher in NS-COPD subjects compared to H-Nonsmokers, H-Biomass, &amp; TS-COPD subjects (Fig.1A). Exposure to tobacco-smoke caused decrease in bacterial diversity (Fig.1B). <i>Firmicutes</i>, <i>Bacteriodetes</i>, <i>Proteobacteria</i>, <i>Actinobcater</i> &amp; <i>Fusobacter</i> were the most prevalent phyla in our samples. Phylum <i>Proteobacteria</i>, which includes many pathogens showed higher abundance in COPD subjects (Fig.1C) &amp; were negatively associated with lung function (Fig.1D). The impaired lung function observed in COPD is associated with in increased abundance of pathogenic microbiome &amp; a decline in its diversity, which may have implications in COPD pathophysiology.