Transforming growth factor-β1 modulates oxidatively modified LDL-induced expression of adhesion molecules: Role of LOX-1

Abstract

Oxidatively modified LDL (ox-LDL) activates a lectin-like receptor, LOX-1, which results in the expression of adhesion molecules on endothelial surface. We investigated the regulation of the expression of transforming growth factor-β1 (TGF-β1) and its receptors by ox-LDL and the functional significance of this interaction with regard to adhesion molecule expression in human coronary artery endothelial cells (HCAECs). Ox-LDL, in a time- and concentration-dependent manner, upregulated the expression of all 3 subtypes (1, 2, and 3 [including endoglin]) of TGF-β1 receptors and decreased active TGF-β1 synthesis (all P<0.05 versus control and native-LDL-treated cells). Treatment of HCAECs with a monoclonal antibody to LOX-1 attenuated ox-LDL-mediated upregulation of TGF-β1, receptors and decrease in TGF-β1 synthesis (P<0.05 versus ox-LDL alone). Ox-LDL also enhanced the expression of P-selectin and ICAM-1 as well as monocyte adhesion to HCAECs (P<0.05 versus control untreated cells). Pretreatment with recombinant TGF-β1 attenuated the enhanced expression of adhesion molecules and monocyte adhesion to HCAECs (P<0.05 versus ox-LDL alone). Effects of recombinant TGF-β1 were blocked by antibody to TGF-β1 receptor type 2, but not by antibody to endoglin. Thus ox-LDL, via activation of LOX-1, increases the expression of TGF-β1 receptors and decreases TGF-β1 synthesis in HCAECs. Recombinant TGF-β1, by binding to TGF-β1 type 2 receptors, modulates ox-LDL-mediated expression of adhesion molecules and monocyte adhesion to HCAECs.