MiR-140-5p inhibits oxidized low-density lipoprotein-induced oxidative stress and cell apoptosis via targeting toll-like receptor 4

Critical roles of several microRNAs have been implicated in atherosclerosis (AS). In this study, we studied the functional role of miR-140-5p in AS. An AS model was constructed in THP-1 macrophages challenged with oxidized low-density lipoprotein (ox-LDL). The expression of miR-140-5p was up- or downregulated with corresponding mimic or inhibitor regents. Our experiments showed that the levels of cell apoptosis and fatty acid accumulation were decreased in THP-1 macrophages treated with miR-140-5p mimic, whereas increased in those treated with miR-140-5p inhibitor. The levels of ROS (reactive oxygen species), MDA (malondialdehyde), TC (Triglyceride), and TG (total cholesterol) were reduced and the level of SOD (superoxide dismutase) was improved in miR-140-5p overexpressed THP-1 macrophages, which can be reversed with miR-140-5p depletion. Moreover, through bioinformatics analysis, we found toll-like receptor 4 (TLR4) was a potential target of miR-140-5p. Luciferase reporter assay demonstrated that miR-140-5p regulated TLR4 expression via binding 3'UTR of TLR4 in THP-1 macrophages. In ox-LDL challenged THP-1 macrophages, the expression of TLR4 was decreased after miR-140-5p mimic transfection, whereas improved after treatment with miR-140-5p inhibitors. As a conclusion, miR-140-5p can participate in inhibiting ox-LDL-induced oxidative stress and cell apoptosis via targeting TLR4 in macrophage-mediated ox-LDL induced AS.