Abstract 11678: Mitochondrial Reactive Oxygen Species Mediate Lysophosphatidylcholine-Induced Endothelial Cell Activation

Background: Lysophosphatidylcholines (LPCs) are a class of pro-inflammatory lipids that play important roles in atherogenesis. LPC activates endothelial cells (ECs) to upregulate adhesion molecules and chemokines, which is the initiation step of atherogenesis. However, the mechanisms underlying LPC-triggered EC activation are not fully understood. Previously considered as the toxic by-products of cellular metabolism, mitochondrial ROS (mtROS) are recently found to directly contribute to both the innate and adaptive immune responses. Here we tested a novel hypothesis that mtROS serve as signaling mediators for LPC-induced EC activation. Methods and Results: Using electron spin resonance and flow cytometry with fluorescence probe MitoSOX, we found that several LPC species including LPC 16:0, 18:0, and 18:1 induced mtROS in human primary aortic ECs (HAECs). Mechanistically, our analysis using mitochondrial calcium inhibitor and Seahorse XF96 mitochondrial function analyzer showed that LPC induced mtROS via increasing mitochondrial calcium entry which resulted in mitochondrial proton leakage. In addition, we found that mtROS scavenger MitoTEMPO abolished LPC-induced EC activation by downregulating Intercellular adhesion molecule 1 (ICAM-1) and Vascular cell adhesion protein 1 (VCAM-1) in HAECs. Moreover, our analysis with transcription factor profiling screening showed that MitoTEMPO acts by blocking LPC-induced nuclear translocation of pro-inflammatory transcription factor activator protein-1 (AP-1). Conclusions: Our results indicate that mtROS are responsible for LPC-induced EC activation and that mtROS may serve as a novel therapeutic target for vascular inflammation.