Metagenomic analysis of the induced sputum samples from non-smoker COPD, smoker-COPD, and healthy rural Indian subjects. COPD Lung Microbiome

Chronic obstructive pulmonary disease (COPD) is a chronic, progressive, degenerative, inflammatory lung disease. Culture independent techniques have allowed a better understanding of association between tobacco-smoke exposed COPD (TS-COPD) and lung microbiome, but there is limited knowledge about lung microbiome in non-smoker COPD (NS-COPD) subjects. We aimed to study lung microbiome in TS-COPD and biomass-smoke exposed associated COPD (NS-COPD)subjects and its association with lung function in rural Indian subjects. Induced sputum samples were obtained from 74 subjects involving: 14 healthy-nonsmokers (H-Nonsmokers), 10 healthy-smokers (H-Smokers), 15 biomass-smoke exposed healthy (H-Biomass), 15 TS-COPD and 20 NS-COPD subjects. Samples were sequenced using V3 and V4 hypervariable region (Illumina MiSeq Platform) and taxanomic diversity information was obtained with QIIME pipeline, MOTHUR, R scripts package and GraphPad Prism. Bacterial abundance was significantly higher in NS-COPD subjects compared to H-Nonsmokers, H-Biomass, and TS-COPD subjects. Exposure to tobacco-smoke caused decrease in bacterial diversity. Firmicutes, Bacteriodetes, Proteobacteria, Actinobcater and Fusobacter were the most prevalent phyla in our samples. Phylum Proteobacteria, which includes many pathogens showed higher abundance in COPD subjects and were negatively associated with lung function. The impaired lung function observed in COPD is associated with increased abundance of pathogenic microbiome and a decline in its diversity, which may have implications in the pathophysiology of COPD. This study further helps in the understanding of lung microbiome dynamics in COPD patients and highlights its potential as a biomarker, and possibly a target, for future therapeutics.