Role of miRNAs induced by oxidized low-density lipoproteins in coronary artery disease: the REGICOR Study.

Aims: Current risk prediction tools are not accurate enough to identify most individuals at high coronary risk. On the other hand, oxidized low-density lipoproteins (ox-LDLs) and miRNAs are actively involved in atherosclerosis. Our aim was to examine the association of ox-LDL-induced miRNAs with coronary artery disease (CAD), and to assess their predictive capacity of future CAD. Methods and results: Human endothelial and vascular smooth muscle cells were treated with oxidized or native LDLs (nLDL), and their miRNA expression was measured with the miRNA 4.0 array, and analyzed with moderated t-tests. Differently expressed miRNAs and others known to be associated with CAD, were examined in serum samples of 500 acute myocardial infarction (AMI) patients and 500 healthy controls, and baseline serum of 117 incident CAD cases and c 485 randomly-selected cohort participants (case-cohort). Both were developed within the REGICOR AMI Registry and population cohorts from Girona. miRNAs expression in serum was measured with custom OpenArray plates, and analyzed with fold change (age and sex-paired case-control) and survival models (case-cohort). Improvement in discrimination and reclassification by miRNAs was assessed. Twenty-one miRNAs were up- or down-regulated with ox-LDL in cell cultures. One of them, 1 (has-miR-122-5p, fold change=4.85) was upregulated in AMI cases. Of the 28 known CAD-associated miRNAs, 11 were upregulated in AMI cases, and 1 (hsa-miR-143-3p, hazard ratio=0.56 [0.38-0.82]) was associated with CAD incidence and improved reclassification. Conclusion: We identified 2 novel miRNAs associated with ox-LDLs (hsa-miR-193b-5p and hsa-miR-1229-5p), and 1 miRNA that improved reclassification of healthy individuals (hsa-miR-143-3p).