The Effects of Several Phytoestrogens on Atherosclerosis related Factors

[[abstract]]Atherosclerosis is now considered to be an inflammatory disease of the blood vessel wall, characterized in early stages by endothelial dysfunction, recruitment and activation of monocyte/macrophages, and dedifferentiation and migration of vascular smooth muscle cells (VSMCs) to later form the bulk of the atherosclerotic plaque. Many clinical studies indicate that dietary soy isoflavones exhibit the atheroprotective effects through their estrogen activity. The aim of this study was to investigate the effects of botanical extracts (ethyl ester extracts of yam and alfalfa & methanolic extracts of jasmine and chrysanthemum) and chemicals (enterolactone, sesamin and genistein), which possess potential estrogen activity, on (1) cellular cholesterol accumulation and gene expression of CD36 and ABCA1, (2) the concentration and gene expression of proinflammatory mediators (IL-1β, TNF-α, and MCP-1) and MMP-9 in oxidized LDL (oxLDL)-stimulated THP-1 macrophages; (3) the adhesion of monocytic THP-1 cells to oxLDL-treated human aorta endothelial cells (HAECs). THP-1 derived macrophages activated by PMA were treated with oxLDL for 2 days to induce lipid uptake by macrophages and establish a foam cell-like phenotype. The cells were co-incubated with the botanical extracts and chemicals for 24~48 hr. The concentrations of IL-1β, TNF-α, MCP-1 and MMP-9 in cultural supernatants were determined by ELISA method. To evaluate the monocyte adhesion to endothelial cells, HAECs were pretreated with the test compounds and oxLDL for 24 hours and then co-cultured with fluorescence-labeled monocytic THP-1 cells. The monocyte adhesion was determined by measuring the fluorescent intensity. These results showed that enterolactone, sesamin, jasmine and chrysanthemum extracts significantly decreased the cellular cholesterol content. Enterolactone, genistein, jasmine and chrysanthemum extracts significantly inhibited the expression of CD36 after THP-1 macrophages incubated with oxLDL for 16hrs. All of the chemicals significantly inhibited the expression of CD36 after THP-1 macrophages incubated with oxLDL for 48hrs. All of the test compounds significantly inhibited the secretion of IL-1β. Sesamin, genistein and the extracts of yam, alfalfa, jasmine and chrysanthemum significantly decreased the concentration of TNF-α. All of the chemicals and alfalfa extract inhibited the secretion of MCP-1. Yam and alfalfa extracts, enterolactone and genistein decreased the production and the activity of MMP-9. All of the test compounds significantly inhibited the adhesion of THP-1 monocytes to HAECs. These results suggest that enterolactone, sesamin, jasmine and chrysanthemum extracts may reduce cellular cholesterol via the inhibition of CD36 expression. All of the chemicals and extracts may prevent atherogenesis, probably via its anti-inflammatory function by reducing the production of pro-inflammatory cytokines and the adhesiveness between monocytes and endothelial cells.