Reprogramming epigenetic changes blunts p66Shc-induced vascular dysfunction in experimental and human obesity: insights for mechanisms-based therapeutic strategies

Introduction: Epigenetic signatures may represent key modulators of oxidative stress in patients with obesity. The mitochondrial adaptor p66Shc is a major source of reactive oxygen species (ROS) in the vasculature. Hypothesis: The present study was designed to investigate whether epigenetic regulation of p66Shc mediates vascular dysfunction in human and experimental obesity. Methods: Visceral fat arteries (VFA) were isolated from 10 obese and 10 age-matched healthy subjects. To characterize the role of p66Shc, genetically obese mice (leptin deficient, LepOb/Obp66WT) were crossed with p66KO to generate double-mutant mice (LepOb/Obp66KO). Organ chamber experiments were performed to assess endothelium-dependent relaxations to acetylcholine (Ach, 10-9-10-4 mol/L). Mitochondrial superoxide anion (O2-) was assessed by ESR spectroscopy. mRNA and protein expression were assessed by real-time PCR and immunoblotting. Chromatin immunoprecipitation (ChIP) was performed to investigate epigenetic modifications on p66Shc promoter. Results: Maximal endothelium-dependent relaxation was impaired in VFA from obese as compared with controls (64.9%±4.8 vs 93±2.9, p<0.01). p66Shc expression was increased in obese vessels (AU, 1.5±0.3 vs 0.7±0.2, p<0.01) and correlated with mitochondrial oxidative stress (r= 0.76, p<0.01) and endothelial dysfunction (r= -0.47, p