Dietary Citrate Restores Age-Related Endothelial Cell Mitochondrial Dysfunction and Alleviates Atherosclerosis

Vascular aging increases the susceptibility to cardio-cerebrovascular conditions, such as atherosclerotic diseases and hypertension, the leading causes of global disability and mortality. Dietary citrate extends the lifespan of Drosophila melanogaster and Caenorhabditis elegans as well as improves the memory of mice injured by a high-fat diet (HFD); whether it alleviates vascular aging and age-related vascular diseases; however, remains unknown. Here, we showed that dietary supplementation of citrate delayed vascular aging, as evidenced by maintaining the integrity of elastic fibers and decreasing the level of the aging-related marker, CDKN1A (p21). Functionally, citrate improved the sensitivity to endothelial-dependent vasodilators and lowered blood pressure, and in HFD-fed ApoE^-/- mice, it reduced the size of atherosclerotic plaques, decreased the necrotic core area and vulnerability index in aortic root plaques. Additionally, citrate decreased the frailty index, increased bone density, and improved maximal grip strength and balance speed in both aged and HFD-fed ApoE^-/- mice. Mechanistically, we showed that citrate exposure delayed human umbilical vein endothelial cell senescence with a decreased percentage of cells stained with senescence-associated β-galactosidase and p21 levels. Moreover, citrate activated AMPK-related pathways and reversed senescence-related mitochondrial dysfunction in basal respiration, maximal respiration, and ATP production and reduced the production of reactive oxygen species (ROS). The citrate-promoted beneficial effects were abolished due to inactivated AMPK and the increased mitochondrial ROS. Thus, we demonstrate that dietary citrate delays vascular aging and alleviates age-related vascular diseases by improving mitochondrial function via activation of AMPK-related pathways. Citrate may have potential clinical implications for interventions against vascular aging and age-related vascular diseases.