Extracellular vesicles from BALF of pediatric cystic fibrosis and asthma patients increase epithelial sodium channel activity in small airway epithelial cells

Extracellular Vesicles (EVs) are nanosized vesicles derived from all cell types. EV cargo allows for intercellular communication, intracellular signaling, and regulation of proteins in recipient cells. We tested the hypothesis that EVs isolated from the bronchoalveolar-lavage fluid (BALF) of pediatric cystic fibrosis (CF) or pediatric asthma patients increase epithelial sodium channel (ENaC) activity in normal human small airway epithelial cells (SAECs) and the mechanism involves specific EV lipids. We characterized EVs from BALF of pediatric CF and pediatric asthma patients by nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. The CF and asthma pediatric groups were similar in BALF electrolytes concentration and cell count, except for neutrophils, which were higher in the CF group. Lipidomic analyses for each group of EVs were performed using targeted mass spectrometry. Phosphatidylethanolamine, sphingomyelins, and triacylglycerol were enriched in both groups, but phosphatidylcholine and phosphatidylinositol concentrations were greater in the CF group compared to the asthma group, and the opposite trend was found for phosphatidylserine. Endogenous ENaC activity, measured by the single-channel patch-clamp technique, increased in normal human SAECs after challenging SAEC with EVs from either the CF or asthma groups compared to control EVs. In conclusion, EVs isolated from BALF of pediatric patients with CF or asthma have unique lipid profiles. Despite the differences, both types of EVs increase ENaC activity in normal human SAECs compared to control EVs isolated from the conditioned media of these cells.