MicroRNA-17-3p blunts endothelial responses to inflammatory stimuli

Abstract

Introduction: Micro-ribonucleic acids (miRNAs) are small endogenous non-coding RNAs which play an important role in vascular inflammation. Previous studies demonstrate that miRNA-17-3p reduces inflammatory responses of human endothelial cells to the bacterial endotoxin lipopolysaccharide (LPS). Vascular inflammation is a risk factor for cardiovascular diseases, and is associated with endothelial dysfunction. Aims: To determine whether or not miRNA-17-3p protects against impairment of endothelial function during inflammation, and, if so, whether or not its anti-inflammatory effect is selective for LPS. Methods: Human aortic and umbilical vein endothelial cells, without or with transfection with miRNA-17-3p agomir (synthetic RNA duplexes stimulating miRNA-17-3p activity) or its negative control, were exposed to the inflammatory stimuli LPS or human immunodeficiency virus (HIV) proteins gp-120. After treatment, the level of miRNA-17-3p was assessed with quantitative reverse transcription-polymerase chain reaction. The levels of inflammatory mediators [interleukin (IL)-6 and monocyte chemotactic protein-1 (MCP-1)], and the protein levels of endothelial nitric oxide synthase (eNOS) and cyclooxygenases (COXs), enzymes responsible for the generation of endothelium-derived nitric oxide and vasoactive prostanoids, were measured with enzyme immunoassays and Western immunoblotting, respectively. Results: In human endothelial cells treated with LPS or gp-120, the amounts of IL-6 and MCP-1, and the protein levels of COX-1 were increased. LPS increased the expression level of miRNA-17-3p; this upregulation was paralleled by reduced levels of the inflammatory mediators induced by LPS. In endothelial cells transfected with miRNA-17-3p agomir, the protein level of eNOS was augmented while that of COX-2 was reduced. Conclusion: These findings suggest that miRNA-17-3p reduces the inflammatory responses of endothelial cells to different inflammatory stimuli, LPS and HIV proteins. Upregulation of miRNA-17-3p may enhance endothelial function in terms of regulation of vascular tone, as demonstrated by the increased eNOS (favoring the production of NO) level and the reduced COX-2 presence (blunting the release of vasoconstrictor prostanoids).