[Effects of lecithin-like oxidized low-density lipoprotein receptor-1 on p38 mitogen-activated protein kinase induced by oxidized low-density lipoprotein in endothelial cells].

OBJECTIVE: To investigate the effects of lecithin-like oxidized low-density lipoprotein receptor-1 (LOX-1) on the p38 mitogen-activated protein kinase (p38MAPK) induced by oxidized low-density lipoprotein (ox-LDL) in endothelial cells.

METHODS: Human umbilical vein endothelial cells of the line ECV304 were cultured and treated with LDL 25 microg/ml and ox-LDL of 3 different concentrations (25 microg/ml, 50 microg/ml, and 100 microg/ml) for 24 hours. ECV304 cells without treatment of ox-LDL were used as control group. MTT method was used to detect the optical density (OD) of different groups. RT-PCR was used to detect the mRNA expression of LOX-1. Western blotting was used to detect the protein expression of LOX-1. Another ECV304 cells were randomly divided into 7 groups to be treated with LDL (25 microg/ml), ox-LDL of the concentrations of 25 microg/ml, 50 microg/ml, and 100 microg/ml, ox-LDL 100 microg/ml + JTX92 (LOX-1 blocking antibody) 10 microg/ml, or JTX92 10 microg/ml, or not to be treated with LOX-1 and/or JTX92 (as control group). The p38MAPK protein expression and phosphorylated p38MAPK (p-p38MAPK) protein expression were detected by Western blotting.

RESULTS: The A values of the ECV304 cells treated with ox-LDL were significantly lower than that of the control group dose-dependently (all P < 0.05), however, the A value of the LDL group was not significantly different from that of the control group (P > 0.05). The LOX-1 mRNA expression and protein expression were significantly increased in the ox-LDL groups dose-dependently (both P < 0.01). However, the LOX-1 mRNA expression and protein expression of the LDL group were not significantly different from those of the control group (both P > 0.05). The p38MAPK protein expression level was not significantly different among different groups (all P > 0.05). The p-p38MAPK protein expression was up-regulated by ox-LDL dose-dependently (P < 0.05). The p-p38MAPK protein level of the ox-LDL + JTX92 group was significantly lower than that of the ox-LDL group (P < 0.05), However, the p-p38MAPK protein expression of the JTX92 group was not significantly different from that of the control group.

CONCLUSION: ox-LDL activates the p38MAPK signal pathway through its receptor LOX-1. Upregulation of LOX-1 is an important ring causing atherosclerosis.