Estrogenic and anti-inflammatory effects of pseudoprotodioscin in atherosclerosis-prone mice: Insights into endothelial cells and perivascular adipose tissues

Pseudoprotodioscin (PPD), a phytoestrogen isolated from Dioscorea nipponica Makino, is recognized to possess anti-inflammatory and antiadipogenic capacities. However, little is known about the antiatherosclerotic effects of PPD and the underlying mechanisms. Here, the contribution of estrogen receptors (ERs) and inflammation to PPD-mediated amelioration of endothelial dysfunction has been fully assessed. PPD administration alleviated atherosclerotic lesions by lowering total cholesterol in ovariectomized apoE(-/-) mice fed a high-cholesterol diet. Molecular docking analysis suggested a selective interaction of PPD with ER alpha. Upon PPD treatment, ER alpha and endothelial nitric oxide synthase (eNOS) protein levels were increased, whereas cell adhesion molecule and monocyte chemoattractant protein-1 (MCP-1) mRNA levels were suppressed in human umbilical vein endothelial cells (HUVECs) after injury caused by oxidized low-density lipoprotein (ox-LDL). These effects could be abolished by an ERa antagonist or a NOS inhibitor. Whereas, PPD can ER alpha-independently suppress TNF alpha expression in peritoneal macrophages upon LPS induction. Estrogen deficiency induced inflammatory phenotypes in perivascular adipose tissue (PAT), which could be partially attenuated by PPD. The increased release of adiponectin in PAT after PPD treatment is in accordance with previous reported data showing that adiponectin exerts anti-inflammatory effects in multiple cell types. ER alpha-dependent antiadipogenic effects of PPD were also detected in PAT-derived stromal cells. The present study reveals a novel mechanism through which PPD exerts estrogenic and anti-inflammatory properties in atherosclerosis-prone mice. Thus, PPD is a promising compound which has potential therapeutic effects on atherosclerotic cardiovascular diseases in postmenopausal women.