Aim: To investigate the possible mechanisms and association of increased complexes of β₂-glycoprotein I with lipoprotein(a) [β₂-GPI-Lp(a)] levels with the presence and extent of coronary artery disease (CAD). Methods: β₂-GPI-Lp(a) levels were measured in 116 patients with acute coronary syndromes (ACS), 72 patients with stable CAD and 100 control subjects. Results: Compared to the control, β₂-GPI-Lp(a) levels (expressed after logarithmically transformation: ACS, 0.22±0.45 U/mL; stable CAD, 0.05±0.55 U/mL; control, −0.31±0.61 U/mL) significantly increased in both patients with ACS (p <0.001) and stable CAD (p <0.001). Univariate logistic regression analysis of risk factors revealed that the presence of β₂-GPI-Lp(a), ox-Lp(a) or Lp(a) was a strong risk factor for stable CAD [β₂GPI-Lp(a), OR 3.17, 95% CI 1.65, 6.07; ox-Lp(a), OR 2.54, 95% CI 1.33, 4.85; Lp(a), OR 3.00, 95% CI 1.56, 5.75; respectively], and especially for ACS [β₂-GPI-Lp(a), OR 5.38, 95% CI 2.97, 9.74; ox-Lp(a), OR 7.55, 95% CI 4.12, 13.84; Lp(a), OR 4.33, 95% CI 2.40, 7.80; respectively]. In multivariate analysis, adjusting for age, sex and plasma lipid levels, the presence of β₂-GPI-Lp(a) or Lp(a) was a risk factor for both stable CAD and ACS. Ox-Lp(a) was a risk factor only for ACS, while not for stable CAD. β₂-GPI-Lp(a) levels were found to be positively associated with Lp(a), ox-Lp(a), maximal stenosis and a number of vessel diseases in patients with ACS or stable CAD, respectively. Multiple linear regression analysis found that ox-Lp(a) and maximal stenosis accounted for 46.2% of the variation in β₂-GPI-Lp(a) levels. Conclusions: Elevated levels of β₂-GPI-Lp(a) are associated with the presence and severity of CAD, and may be a strong risk factor for atherosclerosis.

In atherosclerosis, DNA methylation plays a key regulatory role in the expression of related genes. However, the molecular mechanisms of these processes in human umbilical vein endothelial cells (HUVECs) are unclear. Here, using high-throughput sequencing from the Infinium HumanMethylation450 assay, we manifested that the cg19564375 methylation of miR-520e promoter region in the peripheral blood of acute coronary syndrome (ACS) patients was higher than that of healthy controls. As shown by RQ-MSP, the upstream DNA methylation level of the miR-520e promoter region was considerably increased in ACS patients. miR-520e was markedly downregulated in ACS patients compared with healthy controls. In the oxidized low-density lipoprotein (ox-LDL)-induced HUVECs injury model, DNA methylation of the upstream region of miR-520e was significantly increased. With increasing concentrations of the methylase inhibitor 5-Aza, miR-520e expression was upregulated. The silence of methyltransferase DNMT1, rather than DNMT3a or DNMT3b, abolished the influence of miR-520e expression by ox-LDL treatment in HUVECs. A dual luciferase reporter assay revealed that miR-520e regulated the TGFBR2 3′-untranslated region region. After silencing TGFBR2, the promoting effect of miR-520e inhibitor on cell proliferation and migration may be attenuated. In conclusion, the expression of miR-520e is modified by its promoter region DNA methylation, and miR-520e and its promoter region DNA methylation may be potential biomarkers in atherosclerosis.