Distinctive Serum MicroRNA For Cardiovascular Risk Stratification And Their Clinical Significance

Background/Aims:Cardiovascular disease (CVD) is the leading cause of morbidity and mortality of adults in China. Acute coronary syndrome (ACS) patients exhibited dangerous consequences with a high mortality and high recurrence rate. The stratification and early diagnosis of the populations with different cardiovascular risk may contribute to the decrease in prevalence and mortality of CVD. Micro-ribonucleic acid (miRNA), as a species of small non-coding ribonucleic acid, can negatively regulate gene expression via translational inhibition or mRNA degradation followed by protein synthesis repression. Serum/plasma miRNA can be detected in a stable form and may be the potential biomarker for the associated diseases. Recently, the unique serum/plasma miRNA expression profile was found in patients with coronary artery disease (CAD), especially with ACS, which indicated that distinctive miRNA may be as the novel biomaker for the differential diagnosis of the populations with different cardiovascular risk. In this study, we have determined the serum miRNA expression profile in the patients with high, medium or low cardiovascular risk, and evaluated the clinical diagnosis and monitoring value of the distinctive miRNA.Methods:Serum samples were taken from the patients with different cardiovascular risk, including high-risk (N=175), medium-risk (N=40), low-risk (N=112) and health controls (N=103) with matched age and gender. The patients with high cardiovascular risk included89ACS and86SCAD patients. An initial screen of miRNA expression by TaqMan(?) Low Density Arrays (TLDA) was performed in the mixed serum samples from50ACS,50SCAD,50low-risk patients as well as50controls. A TaqMan probe-based stem-loop reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time polymerase chain reaction (qRT-PCR) assay was employed to validate and confirm the expression levels of miRNA in serum samples of the ACS, SCAD, medium-risk, low-risk patients and controls. The Spearman rank correlation analysis was performed among the distinctive serum miRNA, oxidized lipoproteins, myocardial enzymogram and Gensini scores.Result:According to the results of TLDA, the relative expression levels of82miRNA were found increased in the mixed serum samples of ACS, SCAD and low-risk patients, compared with the controls. Based on the TLDA results and relevant literature, we selected9serum miRNA for the validation, including miR-208b, miR-499, miR-155, miR-134, let-7b, miR-29b, miR-186, miR-146a and miR-320. Subsequently, we have confirmed4distinctive miRNA by RT-PCR and qRT-PCR in the serum of ACS, SCAD, medium-risk and low-risk patients, including miR-208b, miR-499, miR-186and miR-146a. Compared with the controls, the expression of miR-208b, miR-186and miR-146a were found significantly up-regulated in the serum of ACS, SCAD, medium-risk and low-risk patients (P<0.05), and the expression of miR-499were significantly up-regulated in the serum of ACS, SCAD and medium-risk patients (P<0.05). Furthermore, the relative expression levels of serum miR-208b, miR-499and miR-186in ACS, SCAD and medium-risk patients were significantly higher than in low-risk patients (P<0.05). Strikingly, the relative expression levels of serum miR-186and miR-499were found increased significantly in ACS patients, in contrast with SCAD patients (P<0.05). The Spearman correlation analysis showed that the serum relative expression levels of miR-208b, miR-186were positively correlated with the serum levels of oxidized low-density lipoprotein (ox-LDL), oxidized lipoprotein(a)[ox-Lp(a)], and that the serum relative expression levels of miR-499were positively related with ox-Lp(a) in all patients with different cardiovascular risk. Moreover, serum miR-499relative expression levels were found positively correlated with the serum ox-Lp(a), creatine kinase MB isoenzyme (CK-MB), cardiac troponin T (cTNT) levels as well as Gensini scores. Serum miR-186relative expression levels exhibited the positive correlation with the serum levels of ox-LDL, ox-Lp(a), cTNT and Gensini scores in all CAD patients.Conclusions:There were stable and unique serum miRNA expression profiles in the populations with different cardiovascular risk. Serum miR-208b, miR-499, miR-186and miR-146a may be the effective and novel biomarkers for the differential diagnosis and stratification of the populations with different cardiovascular risk. Serum miR-499and miR-186may be used to distinguish ACS from SCAD patients. Furthermore, serum miR-208b, miR-499and miR-186might be correlated with the abnormal lipid metabolism and may contribute to monitoring of the severity of atherosclerotic CVD.