Extracellular vesicles produced by airway epithelial cells in response to oxidative stress contain microRNAs associated with cellular senescence

COPD is associated with elevated cellular senescence. COPD patients have increased markers of oxidative stress, which can drive cellular senescence. MiR34a is involved in the induction of cellular senescence by inhibiting the anti-aging molecules sirtuin1/-6. Extracellular vesicles (EV), including microvesicles and exosomes, can contain miRNA involved in the induction of cellular senescence. In response to oxidative stress and in senescent cells, EVs cargo is modified. However, the involvement of EVs in epithelial cell senescence remains unclear. The aim is to characterise EV released by airway epithelial cells in response to oxidative stress and to assess their effect on epithelial cell senescence. BEAS2B cells and primary small airway epithelial cells (SAEC) were stimulated with H₂O₂ (100μM) for 48h. EV were isolated and characterised by Western blot and micro-BCA. miRNA expression in EV and cells treated with EVs was determined by qRT-PCR. In response to H₂O₂, epithelial cells release significantly more microvesicles (4.25μg/ml in medium condition and 6.42 μg/ml) in response to H₂O₂ and exosomes (1.89μg/ml in medium vs 4.13μg/ml) in response to H₂O₂. Microvesicles and exosomes produced by BEAS2B stimulated with H₂O₂ showed increased expression of miR34a (1.44 fold, n=4). Microvesicles produced by SAEC from COPD patients exhibit increased expression of miR34a compared to non-smokers (n=7 non-smoker, n=6 COPD). These data suggest that epithelial cells produce extracellular vesicles enriched in miRNA involved in cellular senescence. Further exploration of EVs in senescence may provide useful biomarkers and targets for future COPD therapy.