Hypercholesterolemia-induced Nrf2 pathway disbalance in early stages of atherosclerosis development is reversed by inosine.

Introduction: Atherosclerosis is characterized as a chronic process closely related to inflammatory response in the endothelium after injury. Oxidative stress is directly associated with atherosclerosis development, contributing to endothelial dysfunction. Inosine, an endogenous purine nucleoside, has important antioxidant effects in different models of inflammatory diseases. The present study aims to evaluate the antioxidant properties of inosine in the early stages of atherosclerosis development.

Methodology: The animal protocols were approved by the Ethics Committee for Experimental Research of the Federal Fluminense University (CEUA/UFF 1479140219). Wistar rats (250-300g) were randomly divided in control group (C) and control group + inosine (C+I) fed standard chow diet, hypercholesterolemic group (HC) and hypercholesterolemic group + inosine (HC+I). Subacute treatment with inosine (10mg/kg/orally) was performed at day 31, once daily, for 15 days. The animals were euthanized by cervical dislocation under anesthesia. Blood samples and thoracic aorta were collected for functional, biochemical and molecular analysis.

Results: The HC diet decreased the maximum relaxation induced by acetylcholine which seems to be associated to an increase in NOX4 and CD36 protein expression. We also observed that HC diet led to dysregulation of antioxidant defense system by enhancement of Nrf2/Keap-1 and iNOS protein expression, while it reduced Bcl-2, BAX, and Caspase-3 protein expression. These effects were reversed by subacute inosine treatment (p<0.05).

Conclusion: Hypercholesterolemia-induced vascular dysfunction was associated with lipid peroxidation and NOX4 overexpression, Nrf2/CD36 and Bcl-2/BAX/Caspase-3 pathways disbalance, suggesting early atherosclerotic development. Subacute inosine treatment was able to revert those effects. Our results indicate inosine as a potential drug for the treatment of cardiovascular disorders such as atherosclerosis.