Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that stimulates the migration of monocytes into the intima of arterial walls. Although many factors that induce MCP-1 expression have been identi

Objective To understand the role of oxidized low density lipoprotein (OX-LDL) in the pathogenesis of thrombotic complications in atherogenesis. Methods Low density lipoprotein was isolated from normal heparinized bleed by density gradient ultracentrifugation and oxidized by CuCl2. Total RNA was extracted from human umbilical vein endothelial cells (HUVECs) exposed to LDL or OX-LDL, using the guanidinium isothiocyanate method. The quantification of tissue factor pathway inhibitor (TFPI) mRNA in HUVECs was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR). Results HUVECs were able to express TFPI mRNA constitutively. The expression was not affected by LDL but was effectively inhibited by OX-LDL in a time-and dose-dependent manner. Conclusions The results suggest that oxidized LDL may play an important role in inducing coagulation in atherosclerotic lesions by the inhibition of expression of TFPI in vascular endothelial cells.

The migration of monocytes into arterial subendothelial space is one of the earliest events in atherogenesis. Monocyte chemoattractant protein 1 (MCP-1) is a potent monocyte chemoattractant. The purpose of this work was to examine whether oxidized low density lipoprotein (OX-LDL) and very low density lipoprotein (OX-VLDL) have any effect on the expression of MCP-1 mRNA and protein in rabbit peritoneal exudate macrophages. The total RNA was extracted from the macrophages after 24 h exposure to LDL, VLDL, OX-LDL, and OX-VLDL, respectively, and the media (LDL-CM, VLDL-CM, OX-LDL-CM and OX-VLDL-CM) conditioned by the macrophages exposed to the above-mentioned lipoproteins were collected. The MCP-1 mRNA expression in macrophages was examined by Northern blot analysis. Meanwhile, MCP-1 protein in the conditioned media was determined by sandwich ELISA. The chemotactic activity of the conditioned media for monocytes was determined by micropore filter assay. The results revealed that the macrophages can express MCP-1, and 24h exposure to OX-LDL and OX-VLDL induced a 3.2-fold and a 3.4-fold increase in MCP-1 mRNA expression in macrophages and a 2.2-fold and a 2.5-fold increase in the level of MCP-1 protein in the conditioned media, respectively. However, 24h exposure to LDL and VLDL only induced a slight increase in the expression of MCP-1 mRNA and protein in macrophages. Furthermore, the migration distance of monocyte induced by OX-LDL-CM and OX-VLDL-CM was longer than that induced by LDL-CM and VLDL-CM, as well as by CM. We conclude that the macrophages can express MCP-1, and OX-LDL and OX- VLDL induce stronger MCP-1 expression. It suggests that macrophages may amplify the recruitment of monocytes into subendothelial space, and OX-LDL and OX-VLDL may play an important role in the pathogenesis of atherosclerosis through enhancing the MCP-1 expression in macrophages.

Wang, Guoping, Yaw L. Siow, and Karmin O.Homocysteine induces monocyte chemoattractant protein-1 expression by activating NF-kB in THP-1 macrophages. Am J Physiol Heart Circ Physiol 280: H2840-H2847, 2001.-Homocysteinemia is an independent risk factor for cardiovascular disorders. The recruitment of monocytes is an important event in atherogenesis. Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that stimulates monocyte migration into the intima of arterial walls. The objective of the present study was to investigate the effect of homocysteine on MCP-1 expression in macrophages and the underlying mechanism of such effect. Human monocytic cell (THP-1)-derived macrophages were incubated with homocysteine. By nuclease protection assay and ELISA, homocysteine (0.05-0.2mM) was shown to significantly enhance the expression of MCP-1 mRNA (up to 2.6-fold) and protein (up to 4.8-fold) in these cells. Homocysteine-induced MCP-1 expression resulted in increased monocyte chemotaxis. The increase in MCP-1 expression was associated with activation of nuclear factor (NF)-kB due to increased phosphorylation of the inhibitory protein (IkB-a) as well as reduced expression of IkB-a mRNA in homocysteine-treated cells. In conclusion, our results demonstrate that homocysteine, at pathological concentration, stimulates MCP-1 expression in THP-1 macrophages via NF-kB activation.

Homocysteinaemia is an independent risk factor for atherosclerosis. The development of atherosclerosis involves monocyte chemoattractant protein 1 (MCP-1)-mediated monocyte recruitment to the lesion site. The action of MCP-1 is mostly via its interaction with MCP-1 receptor (CCR2), which is the major receptor for MCP-1 on the surface of monocytes. The objective of the present study was to investigate the e

Objective-The stimulatory effect of homocysteine (Hcy) on monocyte chemoattractant protein (MCP)-1 expression in vitro has been suggested to play an important role in Hcy-mediated atherosclerosis. We investigated whether such a stimulatory effect occurs in vivo, leading to monocyte adhesion to the endothelium. Methods and Results-Sprague-Dawley rats were divided into 4 groups. Hyperhomocysteinemia was induced in 1 group of rats after 4 weeks of a high-methionine diet (serum Hcy levels were 4-to 5-fold higher than levels in control rats). The number of ED-1–positive cells present on the surface of aortic endothelium was significantly elevated in hyperhomocysteinemic rats. There was a significant increase in the expression of MCP-1, vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in the endothelium. Antibodies recognizing MCP-1, VCAM-1, or E-selectin could abolish the enhanced monocyte binding to the aortic endothelium of hyperhomocysteinemic rats. Endotheliumdependent aortic relaxation was impaired in hyperhomocysteinemic rats. Conclusions-These results suggest that in the absence of other known risk factors, hyperhomocysteinemia stimulates the expression of MCP-1, VCAM-1, and E-selectin in vivo, leading to increased monocyte adhesion to the aortic endothelium. Such an effect may contribute significantly to the development of atherosclerosis by facilitating monocyte/macrophage infiltration into the arterial wall. (Arterioscler Thromb Vasc Biol. 2002; 22: 1777-1783.)