Protease-Activated Receptor 2 (PAR-2) Antagonist AZ3451 Mitigates Oxidized Low-Density Lipoprotein (Ox-LDL)-Induced Damage and Endothelial Inflammation.

Oxidized low-density lipoprotein (ox-LDL)-induced endothelial dysfunction plays an important role in the initiation and development of cardiovascular diseases, especially atherosclerosis (AS). Protease-activated receptor 2 (PAR-2) is a receptor for inflammatory proteases. However, the biological function of PAR-2 in endothelial cells and the pathophysiological process of AS are still unknown. In the current study, we found that treatment with ox-LDL increased the gene and protein expressions of PAR-2 in EA.hy926 endothelial cells. Interestingly, we found that antagonism of PAR-2 with its specific antagonist AZ3451 could ameliorate ox-LDL-induced lactate dehydrogenase (LDH) release. Treatment with AZ3451 considerably improved the mitochondrial function by restoring the mitochondrial membrane potential and increasing the levels of intracellular adenosine triphosphate (ATP). Also, we found that AZ3451 attenuated ox-LDL-induced expression and production of pro-inflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-8 (IL-8). Treatment with AZ3451 also mitigated the expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). Notably, our results demonstrated that the presence of AZ3451 alleviated ox-LDL-induced expression of the endothelial cell adhesion molecules vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1). Mechanistically, we found that AZ3451 attenuated ox-LDL-induced activation of nuclear factor-κB (NF-κB) by reducing the levels of intracellular NF-κB p65 and the luciferase activity of NF-κB promoter. Based on these findings, we conclude that PAR-2 might become a novel therapeutic target for the treatment of AS.