Abstract: Objective To investigate the effect of miR-218-5p on high glucose (HG)-induced injury in a mouse podocyte cell line MPC5 and its potential mechanism involving targeting tissue inhibitor of metalloproteinase 2 (TIMP2). Methods MPC5 cells were divided into the following groups: control group, HG group, NC-mimics group, miR-218-5p-mimics group, miR-218-5p-mimics+pcDNA-NC group, and miR-218-5p-mimics+pcDNA-TIMP2 group. All groups except the control group were treated with 30 mmol/L glucose for 24 hours to induce injury.The expression levels of miR-218-5p and TIMP2 mRNA were detected by RT-qPCR. Cell proliferation and apoptosis were assessed using the CCK-8 assay and flow cytometry, respectively. The activities of reactive oxygen species (ROS) and superoxide dismutase (SOD), as well as the content of malondialdehyde (MDA), were measured using ELISA kits. Protein expression levels were detected by Western blot. The targeting relationship between miR-218-5p and TIMP2 was verified by a dual-luciferase reporter assay. Results Compared with the control group, the HG group showed decreased A₄₅₀ value, miR-218-5p expression, and SOD activity, but increased apoptosis rate, TIMP2 mRNA and protein expression, ROS activity, MDA content, and cleaved caspase-3 expression (P＜0.05). Compared with the HG and NC-mimics groups, the miR-218-5p-mimics group exhibited an increased A₄₅₀ value, elevated miR-218-5p expression, and higher SOD activity, whereas the apoptosis rate, TIMP2 mRNA and protein expression, ROS activity, MDA content, and cleaved caspase-3 expression were decreased (P＜0.05). Furthermore, compared with the miR-218-5p-mimics group and the miR-218-5p-mimics+pcDNA-NC group, the miR-218-5p-mimics+pcDNA-TIMP2 group displayed a reduced A₄₅₀ value and SOD activity, alongside an increased apoptosis rate, elevated TIMP2 mRNA and protein expression, higher ROS activity, increased MDA content, and enhanced cleaved caspase-3 expression (P＜0.05).The dual-luciferase reporter assay confirmed that miR-218-5p could directly target and negatively regulate TIMP2. Conclusions Overexpression of miR-218-5p protects against HG-induced podocyte injury, and this protective effect may be mediated through the negative regulation of TIMP2.

Key words: miR-218-5p, matrix metalloproteinase inhibitor 2, high glucose, diabetic kidney disease, podocyte injury