Extracellular vesicle microRNA cargoes from intermittent hypoxia-exposed cardiomyocytes and their effect on endothelium
Abstract Background Intermittent hypoxia (IH), as the crucial pathophysiological feature of obstructive sleep apnea syndrome (OSAS), is an independent risk factor initiating the progression of cardiovascular complications. However, how IH cause cardiovascular injury and initiate inter-organ communication remains unclear. Extracellular vesicle (EV) are reported to be involved in cell-to-cell and organ-to-organ communications through selectively carrying RNA and protein cargos from donor cells and delivering them to recipient cells. By utilizing an unbiased miRNA microarray approach, current study attempted to determine whether IH may alter miRNA profiles in cardiomyocyte-derived extracellular vesicles and whether EVs from IH-treated cardiomyocytes could affect endothelial function. Methods EVs were isolated from culture medium of normoxia- or intermittent hypoxia-treated C57BL/6 mouse primary cardiomyocytes. miRNA array assay was used to identify myocardial EV miRNA. The expression of target miRNAs was validated by qPCR and the enriched function of the target miRNAs were predicted by bioinformatics and western blotting analysis. Moreover, vascular functional study validated whether EVs from IH-exposed cardiomyocytes could influence endothelial function. Results 63 differentially expressed miRNAs, including 32 up-regulated and 31 down-regulated miRNAs were identified in EVs from IH-exposed cardiomyocytes. Among them, 16 miRNAs with homologous sequence in mouse and human were selected and verified by qPCR assay and 11 miRNAs were proved with the same tendency as miRNA array identified. KEGG pathway and western blotting analysis showed the main enriched pathway of differentially expressed miRNA was associated with PI3K/Akt signaling pathway. Of note, EVs from IH-exposed cardiomyocytes dramatically impaired endothelium-dependent relaxation and inhibited Akt/eNOS pathway in endothelial cells. Conclusions This study provides the first evidence that IH causes significant alteration in myocardial EV miRNA composition, which may contribute to IH or OSAS-triggered cardiovascular injury and organ-to-organ communication.