Genistein alleviates atherosclerosis in apolipoprotein E-deficient mice by interrupting the OX40/OX40L pathway

More and more evidence shows that the OX40/OX40L interaction plays a critical role in the development of atherosclerosis. However, it is not known whether genistein, a natural phytoestrogen with anti-inflammatory effects found in soybean extract, can prevent experimental atherosclerosis by regulating the OX40/OX40L pathway. This study aims to explore the effect and the underlying mechanisms of genistein on the development of atherosclerosis in apolipoprotein E gene knockout (ApoE^-/-) mice. ApoE^-/- mice, fed an atherogenic diet, were treated with genistein (15 and 45 mg kg^-1 day^-1). In vitro studies were carried out in oxidized LDL (oxLDL)-stimulated SMCs. Our results show that genistein treatment remarkably reduced atherosclerotic plaque formation and reduced the serum levels of pro-inflammatory cytokines in ApoE^-/- mice. Also, genistein promotes plaque stability in ApoE^-/- mice, characterized by smaller necrotic core areas of atherosclerotic plaques and reduced MMP-9 protein expression in primary smooth muscle cells (SMCs). Furthermore, when mRNA expression and the protein expression of OX40 were significantly increased, they were inhibited by genistein in response to an atherogenic diet. Notably, ApoE^-/- mice with an anti-OX40L antibody presented a significant decrease in atherosclerotic lesion formation, which has no further beneficial effects when combined with genistein. These results suggest that genistein potentially has atheroprotective effects that involve the inhibition of the OX40/OX40L pathway, which could be used to prevent and treat atherosclerosis.