MiR-4291 stabilized the vulnerable atherosclerotic plaques by degrading the MAPK1/ERK2 in ApoE-/- mice

Background: This study sought to explore the mechanism of action of the micro ribonucleic acid (miR)-4291 in stabilizing atherosclerotic (AS) plaques.Methods: An AS model of apolipoprotein E-deficient (ApoE-/-) mice fed a high-fat diet (HFD) was established. Oxidized low-density lipoprotein (ox-LDL) was used to induce an inflammatory response of RAW264.7 macrophages. The mice were divided into the normal diet (ND) + miR-4291 negative control (NC) group, the ND + miR-4291 mimic group, the HFD + miR-4291 NC group, and the HFD + miR-4291 mimic group. They were also classified into the miR-4291 NC group, the miR-4291 mimic group, the ox-LDL + miR-4291 NC group, and the ox-LDL + miR-4291 mimic group. The arterial plaque burden of the mice was assessed by hematoxylin-eosin staining and immunohistochemistry, and the expression of phosphorylated-extracellular signal-regulated kinase 2 (p-ERK2) and related proteins in the arterial plaques and RAW264.7 macrophages of the mice were detected by Western blotting.Results: Obvious plaques with massive macrophage infiltration were found in the aortic roots of the mice fed a HFD, and smooth muscle cells were found at the margin of the plaques. In the HFD + miR-4291 mimic group, the number of plaques and macrophages was significantly declined, but there were no significant changes in the smooth muscle cells compared to those in the HFD + miR-4291 NC group. The Western blot results showed that miR-4291 reduced the protein expression of p-ERK1-2, t-ERK1-2, TNF-alpha, MCP-1, MMP-1, MMP-3, and MMP-9 in the AS plaques and the ox-LDL-induced RAW264.7 macrophages of the mice fed a HFD.Conclusions: MiR-4291 reduced the expression of MMP-2/9 by inhibiting the activity of ERK2, which in turn increased the fibrous cap thickness and stabilized the vulnerable plaques in AS.