The microbiome of the lung and its extracellular vesicles in nonsmokers, healthy smokers and COPD patients

Abstract

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease, and bacterial infection plays a role in its pathogenesis. Bacteria secrete nanometer-sized extracellular vesicles (EVs), which may induce more immune dysfunction and inflammation than the bacteria themselves. We hypothesized that the microbiome of lung EVs might have distinct characteristics depending on the presence of COPD and smoking status. We analyzed and compared the microbiomes of 13 nonsmokers with normal spirometry, 13 smokers with normal spirometry (healthy smokers) and 13 patients with COPD by using 16S ribosomal RNA gene sequencing of surgical lung tissue and lung EVs. Subjects were matched for age and sex in all groups and for smoking levels in the COPD and healthy smoker groups. Each group included 12 men and 1 woman with the same mean age of 65.5 years. In all groups, EVs consistently showed more operational taxonomic units (OTUs) than lung tissue. In the healthy smoker and COPD groups, EVs had a higher Shannon index and a lower Simpson index than lung tissue and this trend was more prominent in the COPD group. Principal component analysis (PCA) showed clusters based on sample type rather than participants' clinical characteristics. Stenotrophomonas, Propionibacterium and Alicyclobacillus were the most commonly found genera. Firmicutes were highly present in the EVs of the COPD group compared with other samples or groups. Our analysis of the lung microbiome revealed that the bacterial communities present in the EVs and in the COPD group possessed distinct characteristics with differences in the OTUs, diversity indexes and PCA clustering.

Airway Epithelial Barrier Dysfunction in Chronic Obstructive Pulmonary Disease: Role of Cigarette Smoke Exposure

“…in the nasopharynx of smokers compared with nonsmokers. In COPD, an overrepresentation of the Proteobacteria phylum (131,132) and the Firmicutes phylum (133)(134)(135) has been observed. As far as we know, there are no studies available assessing the effect of Firmicutes on human airway epithelial barrier function, whereas various studies have shown adverse effects of respiratory pathogens on cultured airway epithelial cells.…”

16S rDNA microbiome composition pattern analysis as a diagnostic biomarker for biliary tract cancer

“…Moreover, recent studies investigated and revealed that there is extremely active interaction and synergistic effect between the microbiota and human host cells by EVs. This mechanism has been recently spotlighted as a pathogenetic mechanism of various diseases [14,15,[27][28][29].…”

Urine Bacteria-Derived Extracellular Vesicles and Allergic Airway Diseases in Children

“…A study on lung tissue microbiota and EVs in chronic obstructive pulmonary disease patients, healthy smokers, and healthy nonsmokers found Methylobacterium to be one of the most predominant genera, indicating its importance in airway microbiota composition [3]. In addition, Methylobacterium was found to be abundant in bronchoalveolar lavage of clinically well infants with cystic fibrosis [30].…”

“…Recent airway studies have analyzed both microbiota and EVs in nasal lavage and lung tissue samples [2, 3]. EVs have distinct characteristics in relation to chronic rhinitis and chronic obstructive pulmonary diseases, and hence they have been proposed to play essential roles in immune dysfunction and inflammation in the airway diseases.…”