COX-2-Derived PGE2 Promotes Injury-Induced Vascular Neointimal Hyperplasia Through the EP3 Receptor

Rationale: Vascular smooth muscle cell (VSMC) migration and proliferation are the hallmarks of restenosis pathogenesis after angioplasty. Cyclooxygenase (COX)-derived prostaglandin (PG)E2is implicated in the vascular remodeling response to injury. However, its precise molecular role remains unknown. Objective: This study investigates the impact of COX-2-derived PGE2 on neointima formation after injury. Methods and Results: Vascular remodeling was induced by wire-injury in femoral arteries of mice. Both neointima formation and the restenosis ratio were diminished in COX-2 KO mice as compared to controls, whereas these parameters were enhanced in COX-1>COX-2 mice where COX-1 is governed by COX-2 regulatory elements. PG profile analysis revealed that the reduced PGE2 by COX-2 deficiency, but not PGI2, could be rescued by COX-1 replacement, indicating COX-2-derived PGE2 enhanced neointima formation. Through multiple approaches, the EP3 receptor was identified to mediate the VSMC migration response to various stimuli. Disruption of EP3 impaired VSMC polarity for directional migration by depressing small GTPase activity and retarded vascular neointimal hyperplasia while overexpression of EP3α and EP3β aggravated neointima formation. Inhibition or deletion of EP3α/β, a Gαi protein-coupled receptor, activated thecAMP/PKA pathway and depressed activation of RhoA in VSMCs. PGE2 could stimulate PI3K/Akt/GSK3β signaling in VSMCs through Gβγ subunits upon EP3α/β activation. Ablation of EP3 suppressed PI3K signaling and reduced GTPase activity in VSMCs, and altered cell polarity and directional migration. Conclusions: COX-2-derived PGE2 facilitated the neointimal hyperplasia response to injury through EP3α/β-mediated cAMP/PKA and PI3K pathways, indicating EP3 inhibition maybe a promising therapeutic strategy for percutaneous transluminal coronary angioplasty.