The gradual decline of endothelial function and the intensification of inflammatory responses form the basis for the occurrence and development of age-related diseases such as atherosclerosis (AS). Mitochondrial dysfunction-manifested by excessive reactive oxygen species (ROS) production, reduced mitochondrial membrane potential, and impaired mitophagic flux-and sterile inflammation are hallmarks of aged vasculature. We investigated whether bolstering mitochondrial quality control via the novel cell-penetrating antioxidant PEP-1-Catalase (CAT) could mitigate these key features of vascular aging. To model age-associated vascular pathology, ApoE⁻/⁻ mice were fed a high-fat diet (HFD) and treated with PEP-1-CAT. Endothelial cell function, plaque burden, and inflammation were analyzed. In vitro, human endothelial cells (HUVECs) were subjected to inflammatory stress and treated with PEP-1-CAT, with or without modulators of mitophagy. We assessed mitochondrial ROS, membrane potential, NOD-like receptor protein 3 (NLRP3) inflammasome activation, and the PINK1-Parkin pathway. PEP-1-CAT treatment significantly ameliorated atherogenesis and improved features of plaque stability in mice. It suppressed vascular oxidative stress, restored mitochondrial membrane potential, enhanced mitophagic flux, and inhibited NLRP3-driven inflammation. In endothelial cells, PEP-1-CAT attenuated mitochondrial oxidative stress and dysfunction. Crucially, it activated the PINK1-Parkin pathway to promote mitophagy, which was essential for its anti-inflammatory effects, as mitophagy inhibition abrogated the suppression of the NLRP3 inflammasome. Our findings demonstrate that targeting mitochondrial health with PEP-1-CAT alleviates hallmarks of atherosclerotic vascular pathology, including endothelial dysfunction and inflammation, by enhancing mitophagy. This strategy of restoring mitochondrial quality control presents a promising therapeutic approach to delay atherosclerotic vascular pathology.
