Influenza infection of epithelial cells alters extracellular vesicle microRNA involved in viral replication and the immune response

Abstract

Influenza A virus (IAV) is a major health threat both in terms of seasonal epidemics and global pandemics. Recent studies have demonstrated epithelial cells release lipid bilayer particles, termed extracellular vesicles (EVs) that are selectively packaged with microRNA (miR) which regulate gene expression. We investigated changes in the miR profile of EVs released from bronchial epithelial cells in response to infection with IAV.

EVs were isolated by size exclusion chromatography from the apical surface wash of air-liquid interface differentiated bronchial epithelial cells (BCi-NS1.1) either uninfected (n=5) or infected (n=5) with IAV (Wisconsin/67/2005). EV miR was then sequenced and reads were mapped to miRBase and the human genome.

Differential expression analyses identified 6 miR that were significantly altered in EVs released from IAV infected BCi compared to uninfected BCi (Bonferroni p<0.05). Of these, 5 were upregulated (fold change >1.5): miR-155-5p, miR-122-5p, miR-378a-3p, miR-7-5p and miR-146a-5p and 1 was downregulated (fold change <−1.5): miR-505-5p. MiR target prediction and functional analysis was performed using miRNet. Influenza A KEGG pathway was identified to be significantly enriched. Furthermore, Gene Ontology revealed relevant biological processes, such as apoptosis, cell death, cell cycle, nuclear transport, NF-κB cascade, cytokine-mediated signalling and viral reproductive process to be regulated by these miRs. Future in vitro modelling will validate these findings.

EV miRs may be a key mechanism in modulating the response to IAV and therefore are potential novel targets for future anti-viral therapies.