Do Circulating Extracellular Vesicles Strictly Reflect Bronchoalveolar Lavage Extracellular Vesicles in COPD?

Abstract

Cell-derived extracellular vesicles (EVs) found in the circulation and body fluids contain biomolecules that could be used as biomarkers for lung and other diseases. EVs from bronchoalveolar lavage (BAL) might be more informative of lung abnormalities than EVs from blood, where information might be diluted. To compare EVs’ characteristics in BAL and blood in smokers with and without COPD. Same-day BAL and blood samples were obtained in 9 nonsmokers (NS), 11 smokers w/o COPD (S), and 9 with COPD (SCOPD) (FEV1: 59 ± 3% pred). After differential centrifugation, EVs (200–500 nm diameter) were identified by flow cytometry and labeled with cell-type specific antigens: CD14 for macrophage-derived EVs, CD326 for epithelial-derived EVs, CD146 for endothelial-derived EVs, and CD62E for activated-endothelial-derived EVs. In BAL, CD14-EVs were increased in S compared to NS [384 (56–567) vs. 172 (115–282) events/μL; p = 0.007] and further increased in SCOPD [619 (224–888)] compared to both S (p = 0.04) and NS (p < 0.001). CD326-EVs were increased in S [760 (48–2856) events/μL, p < 0.001] and in SCOPD [1055 (194–11,491), p < 0.001] when compared to NS [15 (0–68)]. CD146-EVs and CD62E-EVs were similar in the three groups. In BAL, significant differences in macrophage and epithelial-derived EVs can be clearly detected between NS, S and SCOPD, while these differences were not found in plasma. This suggests that BAL is a better medium than blood to study EVs in lung diseases.

A heterogenous population of extracellular vesicles mobilize to the alveoli postinjury

“…A prior study obtained BAL to compare smokers versus nonsmokers with COPD. 30 In that study, the authors identified differences in macrophage and epithelial-derived EVs between smokers versus nonsmokers with COPD, while no differences were found in EVs collected from plasma. This further supports that utilizing BAL to obtain EVs from the alveolar space more likely represents the complexity of the lung inflammatory response compared with circulating markers.…”

“…To our knowledge, this is the first study to utilize vFC to evaluate surface markers on EVs in the BAL fluid of severely injured patients. A prior study obtained BAL to compare smokers versus nonsmokers with COPD 30 . In that study, the authors identified differences in macrophage and epithelial-derived EVs between smokers versus nonsmokers with COPD, while no differences were found in EVs collected from plasma.…”

Suppressor of cytokine signaling-3 expression and its regulation in relation to inflammation in Chronic Obstructive Pulmonary Disease

“…Smokers with COPD showed a significant increase in total CD14 + SOCS3 + EVs when compared with those without COPD and non-smokers. We have previously described that alveolar macrophage-derived (CD14 + ) EVs are increased in COPD patients’ BAL when compared to smokers without COPD ( 30 , 31 ), but the presence of SOCS3 + in macrophage-derived EVs in BAL of COPD patients had not been described before. Importantly, the reported increased counts of CD14 + SOCS3 + EVs in COPD are not only due to the increased of total EVs but also due to the larger percentage of EVs expressing SOCS3 on their surface.…”

“…BAL was obtained and immediately processed ( 30 , 31 ) (Group B). According to international guidelines, the BAL collection procedure consisted in positioning the bronchoscope in a wedged position within a bronchial opening.…”

“…Finally, EVs were resuspended in ultrafiltered PBS and stored at −80°C. Flow cytometry analysis of EVs from BAL was performed using a CytoFLEX flow cytometer (Beckman-Coulter, USA) for the characterization and analysis of the EVs as previously reported ( 30 , 31 ). Samples were then incubated with fluorescent-conjugated monoclonal antibodies for analysis.…”