Pro-viral miRNAs detected in BALF extracellular vesicles of patients with influenza virus-induced ARDS

Influenza A virus (IAV) causes severe respiratory infections and alveolar epithelial damage resulting in acute respiratory distress syndrome (ARDS). Extracellular vesicles (EV) have been shown to mediate cellular crosstalk in inflammation by transfer of microRNAs. In this study, we found significant changes in the miRNA composition of EVs in the broncho-alveolar lavage fluid (BALF) from patients with IAV-induced ARDS. Among the nine significantly deregulated microRNAs, miR-17-5p was upregulated in patients` BALF, and in EVs of IAV-infected lung epithelial cells (A549). In these cells, transfer of miR-17-5p strongly downregulated expression of the antiviral factor Mx1 and significantly enhanced IAV replication.