Association between hypertension and circulating vascular-related microRNAs

microRNAs (miRNAs) have a key role in regulating inflammation, vascular health and in turn, cardiovascular disease. Specifically, altered circulating expression of miR-17, miR-21, miR-34a, miR-92a, miR-126, miR-145, miR-146a, and miR-150 has been linked with the pathogenesis and progression of cardiovascular disease. The aim of this study was to determine whether the circulating profile of these vascular-related miRNAs is disrupted with hypertension. Thirty sedentary, middle-aged adults were studied: 15 normotensive (10M/5F; age: 56 +/- 1 year; BP: 113/71 +/- 2/1 mmHg) and 15 hypertensive (10M/ 5F; 56 +/- 2 year; 140/87 +/- 2/2 mmHg). All subjects were non-obese and free of other cardiometabolic disorders. Circulating miRNAs were determined in plasma using standard RT-PCR techniques with miRNA primers of interest. Expression was normalized to exogenous C. elegans miR-39 and reported as relative expression in arbitrary units (AU). Circulating expression of miR-34a (9.18 +/- 0.94 vs 5.33 +/- 0.91 AU) was higher (similar to 170%; P<0.01) whereas the expression of miR-21 (1.32 +/- 0.25 vs 2.50 +/- 0.29 AU), miR-126 (0.85 +/- 0.10 vs 1.74 +/- 0.27 AU) and miR-146a (1.50 +/- 0.20 vs 3.10 +/- 0.50 AU) were markedly lower (similar to 50%, similar to 55%, and similar to 55% respectively; P< 0.05) in the hypertensive vs normotensive groups. Moreover, circulating levels of miR-34a, miR-21, and miR-126 were significantly related to systolic blood pressure (r = 0.48, r = -0.38; r= -0.48); whereas, miR-146a was significantly related to both systolic (r= -0.58) and diastolic (r = -0.55) blood pressure. There were no significant group differences in circulating miR-17, miR-92a, miR-145, and miR-150. In summary, these results suggest that hypertension, independent of other cardiometabolic risk factors, adversely affects the circulating profile of a subset of vascular-related miRNAs that have been link to CVD risk and development.