Table 5 Summary of studies on bacterial EVs and COPD

Kim et al., 2015 [41]

Extracellular vesicles derived from gram-negative bacteria, such as Escherichia coli, induce emphysema mainly via IL-17A-mediated neutrophilic inflammation

Investigate whether E. coli EVs are casually related to the pathogenesis of emphysema, and determine the immunologic mechanisms of emphysema induced by E. coli EVs

In vivo

Mice

In vitro

Airway exposure of EVs derived from Gram-negative bacteria, especially E. coli, can induce neutrophilic inflammation and thereby emphysema mainly in an IL-17A–dependent manner. TLR4 signaling is important in the uptake of E. coli EVs and the production of proinflammatory cytokines induced by interaction with LPS on E. coli EVs

Kim et al., 2017 [42]

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

Investigate whether the microbiome of lung EVs might have distinct characteristics depending on the presence of COPD and smoking status

Ex vivo

Human

Bacteria-derived EVs have distinctive characteristics in the lungs of non-smokers, healthy smokers and patients with COPD. According to the Shannon index, non-smokers demonstrated most diversity in lung tissue compared to COPD patients which were least diverse. Also, diversity index for lung EVs showed most diversity in COPD patients and least in the non-smoker group. The Simpson index was highest in COPD group, indicative of dominant organisms

Kim et al., 2016 [43]

IgG sensitization to extracellular vesicles in indoor dust is closely associated with the prevalence of non-eosinophilic asthma, COPD, and lung cancer

To evaluate whether sensitization to indoor dust EVs is a risk for the development of COPD

To determine whether serum antibodies against dust EVs associate with the increased risk of COPD

Ex vivo

Human

Serum anti-dust EV IgG levels were significantly higher in patients with COPD than in the control subjects. Thus, IgG sensitization to dust EVs may increase the risk of COPD expression and/or development, providing an insight into the pathogenesis of COPD

Yang et al., 2020 [44]

Lung disease diagnostic model through IgG sensitization to microbial extracellular vesicles

To investigate whether exposure to bacterial EVs in indoor dust might be associated with the risk of asthma, COPD and lung cancer

Ex vivo

Human

The specific bacterial EVs affecting pulmonary diseases in indoor dust, such as S. aureus, A. baumannii, E. cloacae and P. aeruginosa. Anti-core indoor dust bacterial EV IgG, IgG1 and IgG4 antibodies titres in serum were significantly higher in patients with COPD compared to the healthy control group