Circulating miR-21 and eNOS in subclinical atherosclerosis in patients with hypertension

The aim of this study is to evaluate the relationship of miR-21, nitric oxide (NOx) and endothelial nitric oxide synthase (eNOS) with subclinical atherosclerosis in carotid arteries by measuring carotid intima media thickness (CIMT) in patients with hypertension and healthy controls.

A total of 28 hypertensive and 28 healthy controls were enrolled. MiR-21 expression was analyzed by quantitative reverse transcription-PCR and NOx, and eNOS levels were measured by ELISA assay. CIMT was evaluated by ultrasonography and CIMT ≥ 0.8 mm was accepted as increased CIMT (iCIMT).

C-reactive protein (CRP) level, plasma miR-21 expression level and CIMT were found to be significantly higher in the hypertension group when compared to the control group (p = 0.009, p = 0.002 and p < 0.001, respectively). NOx and eNOS levels were significantly lower in the hypertension group compared to the control group (p < 0.001, both). MiR-21 level was positively correlated with the clinical systolic blood pressure, clinical diastolic blood pressure, CRP and CIMT. MiR-21 was also negatively correlated with NOx and eNOS. Eighteen patients with hypertension had iCIMT. MiR-21 and CRP levels were significantly higher (p < 0.001 and p = 0.001), whereas NOx and eNOS levels were significantly lower in patients with iCIMT (p < 0.001, both).

The decreased levels of NOx and eNOS found in this study indicate the co-existence of endothelial dysfunction and hypertension once more. In the absence of microalbuminuria, the increased miR-21 expression in patients with iCIMT made us conclude that this miRNA might be involved in the early stages of atherosclerotic process in hypertensive patients.