Soy diet inhibits expression of inflammation‐induced vascular cell adhesion molecules in endothelial cells

Abstract

Recently we reported that dietary soy attenuated atherogenesis in apolipoprotein E knockout (apoE‐/‐) mice. However, the molecular mechanisms contributing to the atheroprotective effect of soy diet is not clear. Since interactions between endothelial cells and monocytes play a pivotal role in the initiation of atherosclerosis, we hypothesize that components in soy diet prevent monocyte adhesion to endothelial cells by inhibiting vascular cell adhesion molecule expression on endothelial cells. Genistein, a major soy isoflavone, inhibited expression of TNF‐α‐induced vascular adhesion molecules CD62E (E‐selectin) and CD106 (VCAM‐1) in HUVEC cells in a concentration‐dependent (1‐100 µM) manner, with no effect on CD54 (ICAM‐1) expression. Interestingly, equol, a metabolite of the soy isoflavone daidzein produced by gut microflora, also showed significant inhibition of inducible CD62E and CD106 expression. The effect of soy feeding on expression of CD106 was further addressed in apoE‐/‐ mice. Quantitative RT‐PCR analyses of proximal aorta showed reduced expression of CD106 in soy‐fed compared to casein‐fed mice. These findings suggest that the atheroprotective effect of soy diet is mediated, in part, by inhibition of vascular cell adhesion molecule expression that could lead to reduced monocyte adhesion and migration, an early event in atherogenesis. USDA‐CRIS‐6251‐5100002‐06S.