Abstract 327: Mitochondrial Functional Variation Contributes to Endothelial Cell Activation

Abstract

Vascular oxidant stress contributes to endothelial dysfunction and plays a critical role in early stage cardiovascular disease (CVD) development. Changes in endothelial function due to oxidant stress may contribute to CVD initiation and progression through the development of a pro-inflammatory environment. Differences in mitochondrial function may contribute to this process and provide insight into why age of onset and clinical outcomes differ amongst individuals form distinct ethnic groups; but no reports demonstrate distinct mitochondrial functional parameters between normal cells. Consequently, we hypothesized that significant variations in normal mitochondrial function and oxidant production exist between endothelial cells from donors representing different ethnic groups. Aspects of mitochondrial oxygen utilization and oxidant production were assessed under basal and inflammatory conditions in human aortic endothelial cells (HAECs) isolated from African Americans (AA) and Caucasians (CA). Bioenergetic analysis indicates that compared to CA, AA HAEC utilized significantly less oxygen for ATP production, possess a lower maximal respiratory capacity, and have reduced electron leak. Significant differences in mitochondrial membrane potential, decreased expression of endothelial nitric oxide synthase, and increased levels of superoxide were also observed and AA HAEC supporting a pro-inflammatory phenotype. As a marker of endothelial cell activation, AA HAEC expressed increased levels of intercellular cell adhesion molecule-1 under both basal and inflammatory conditions that could be partially mitigated but treatment with the mitochondrially targeted antioxidant MitoTEMPO. These data demonstrate that fundamental differences exist in mitochondrial oxygen utilization and oxidant production between CA and AA HAEC and that these changes may affect endothelial cell activation. These findings are consistent with the hypothesis that differences in “normal” mitochondrial function amongst ethnic groups could influence individual susceptibility by contributing to vascular inflammation, providing important insights into the mechanisms that contribute human CVD development.