Abstract P3013: MicroRNA-122 Targeting With Gamma Peptide Nucleic Acid Inhibitor Improves Vascular Endothelial Dysfunction In Pre-diabetic Mice.

Background: In patients with diabetes, the endothelial function precedes and predicts the risk of cardiovascular disorders. Current treatment approaches fail to decrease unwanted cardiovascular outcomes in these patients. The blood levels of microRNA-122 (miR-122) elevated in patients with diabetes and correlated with risk and severity of cardiovascular disorders. Therefore, targeting miR-122 with efficient and safer inhibitors could be a promising approach. The objective of this study was to investigate the effectiveness of gamma peptide nucleic acid (γPNA)-based miR-122 inhibitor in preventing the development of endothelial dysfunction in pre-diabetic mice. Methods: To test the effectiveness of γPNA technology in inhibiting miR-122, we synthesized γPNA-miR-122 inhibitor (γP-122-I) and γPNA-scrambled control (γP-SC). The purity and molecular weight of γP-122-I and γP-SC were assessed by HPLC and MALDI spectrometry, respectively. The binding and affinity of γP-122-I were determined by gel-shift assay and thermal denaturation. The insulin-resistance (induced by high-fat-diet, HFD) mice were injected with γP-122-I (5 mg/kg/day, i.p., 6 weeks). miR-122 expression was measured by real-time PCR. The safety of γP-122-I was evaluated by biochemical and histological analysis of vital organs (liver & kidney). The vascular endothelial function was assessed by determining endothelium-dependent and independent relaxation of phenylephrine-induced precontracted aortic rings. Results were expressed as mean ± s.e.m. Results: The HPLC of γPNA oligomers show that both γP-122-I and γP-SC were >95% pure. The molecular weight of γP-122-I (m/z: 9227.4) and γP-SC (m/z: 9232.7) were confirmed by MALDI spectrometry. γP-122-I strongly binds with miR-122 and forms a stable complex compared to commercially available miR-122 inhibitor. A comprehensive safety analysis of γP-122-I in mice shows that neither it affected liver and kidney function nor their morphology during acute and chronic exposure, respectively. Next, HFD-fed mice show higher serum and aortic miR-122 levels, endothelial dysfunction, and inflammation, which were reversed by γP-122-I treatment. Conclusions: γP-122-I inhibits the development of impaired endothelial function in pre-diabetic mice without any evidence of toxicity