Panax quinquefolium saponin combined with dual antiplatelet drugs inhibits platelet adhesion to injured HUVECs via PI3K/AKT and COX pathways

Abstract

Ethnopharmacological relevance: Panax quinquefolium saponin (PQS) is the active component extracted from traditional Chinese medicine Panax quinquefolius L. and has been widely used as a supplement to dual antiplatelet drugs (DA) for treatment of coronary artery disease (CAD) for two decades; however, the efficacy of PQS combined with DA against platelet adhesion to endothelial cells (ECs), an essential step in thrombosis, remains unclear.

Aim of the study: To compare PQS combined with DA and DA alone in inhibiting platelet adhesion to injured human umbilical vein endothelial cells (HUVECs) and to explore the possible mechanisms focusing on PI3K/AKT, COX-2/6-keto-PGF_1α, and COX-1/TXB₂ pathways.

Methods: HUVECs injured by oxidized low-density lipoprotein (ox-LDL) were randomly allocated into control, model, DA, PQS+DA (P+DA), LY294002 (a PI3K inhibitor)+DA (L+DA), and LY294002+PQS+DA (LP+DA) groups. HUVEC apoptosis, platelet adhesion to injured HUVECs, and platelet CD62p expression were assayed by fluorescence activated cell sorting (FACS). The concentrations of 6-keto-PGF_1α and TXB₂ in the supernatant were measured by radioimmunoassay. Protein expression of phosphorylated-PI3K, PI3K, phosphorylated-AKT, AKT, COX-1, and COX-2 in both platelets and HUVECs was evaluated by western blot.

Results: Compared to DA alone, PQS combined with DA reduced platelet adhesion to HUVECs and HUVEC apoptosis more potently, increased the concentration of supernatant 6-keto-PGF_1α and up-regulated phospho-AKT protein in HUVECs. LY294002 mitigated the effects of PQS on HUVEC apoptosis and platelet adhesion.

Conclusions: These findings show that PQS as a powerful supplement to DA, attenuated HUVEC apoptosis and improved the DA-mediated reduction of platelet adhesion to injured HUVECs and the underlying mechanisms may be associated with PI3K/AKT and COX pathways in HUVECs and platelets. PQS might provide a new complementary approach to improve the prognosis of thrombotic diseases in future.

Keywords: Cyclooxygenase; Dual antiplatelet; Endothelial cell; Panax quinquefolium saponin; Platelet adhesion; Thrombogenesis.