| Background:Lectin-like oxidized low density lipoprotein recaptor-1(LOX-1),a receptor for oxidized low-density lipoprotein(ox-LDL),resides in the vascular endothelial cells(ECs).Their special binding produces the damaging effect fo EC,triggers a serial of signal path,thus contributes to hypertension,thrombisis,artherosclerosis,and so on.Plasminogen activator inhibitor-1(PAI-1) is a main inhibtor with plasma fibrinolysis activity in vivo,which regulating and maintaining the dynamic balance between the system of fibrinolysis and thrombosis.High plasma level of PAI-1 is closely associated with many thromboembolic diseases such as artherosclerosis,coronary heart disease,myocardial infarction and cerebral infarction and so on. Peroxisome proliferators-activated receptor alapha(PPARα) is a family of nuclear transcriptional factors that activated by ligand.They have various biological effects and play a key role in many process of physiology and pathology.PPARαregulates expression of key proteins involved in atherogenesis,vascular inflammation,plaque instability,and thrombosis.Thus,PPAR-αmay exert direct antiatherogenic actions in the vascular wall.Bezafibrate is artificial specific exogenous activator of PPARα,but the mechanism how they regulate LOX-1,PAI-1 mduced by ox-LDL are less know.So we use molecular biology techniques to investigate the effects and mechanism and the study include two parts.Frist part:Effects of LOX-1 on expression of plasminogen activator inhibit-tot-1 induced by ox-LDL in HUVECsMethods:Firstly,HUVECs were isolated form freshly obtained human umbilical cords by parenzyme treatment.The cells were cultured in DMEM culture medium supplemented with 10%bovine colf serum and passages 4 to 5 were used by in this study.Secondly:Three groups were selected for the study:①control group:HUVECs were incubated by the normal culture medium;②different concentration ox-LDL group:different concentration(10mg/L,25mg/L,50mg/L,100mg/L) ox-LDL for 24h;③LOX-1 inhibitor group: HUVECs were pretreated with with 250μg/mL Poly(I) for 2h,then was incubated with 50mg/L ox-LDL group.LOX-1 mRNA,PAI-1 mRNA were detected by RT-PCR;LOX-1 protein were detected by Western-blot;PAI-1 protein were detected by ELISA.Results:1.Different concentration ox-LDL upregulated the expressions of LOX-1,PA1-1mRNA, compared with control group(P＜0.01),in a concentration-dependent manner(P＜0.01).2.Different concentration ox-LDL upregulated the expressions of LOX-1,PAI-1 protein compared with control group(P＜0.01),in a concentration-dependent manner(P＜0.01).3.The expression of LOX-1,PAI-1 mRNA and protein were reduced in HUVECs pretreated with 250μg/mL poly(I) for 2h and then incubated with 50mg/L ox-LDL for 24h,This showed that poly(I) markly decreased the expression of LOX-1,PAI-1 induced by ox-LDL.Conclusions:ox-LDL may upregulate the expression of LOX-1 and PAl-1,and LOX-1 medical inhibitor may partly inhibit this up regulation.The results suggest that the expression of PAI-1 induced by ox-LDL in HUVECs is mediated by LOX-1.Second part:Effect and Mechanism of Bezafibrate on Expression of PAI-1 Induced by ox-LDL in HUVECsMethods:Firstly,HUVECs were isolated form freshly obtained human umbilical cords by parenzyme treatment.The cells were cultured in DMEM cμlture medium supplemented with 10%bovine colf serum and passages 4 to 5 were used by in this study.Secondly:Three groups were selected for the study:①50mg/L ox-LDL group:HUVECs were incubated with 50mg/L ox-LDL for 24h;②different concentration bezafibrate group: HUVECs were pretreated with different concentration bezafibrate(50,100,200mmol/mL) for 2h,then incubated with;50mg/L ox-LDL for 24h;③100 mmol/mL benzafibrate and LOX-I inhibitor group:HUVECs were pretreated with 250μg/mL Poly(I) for 2h,then was incubated with 100 mmol/mL benzafibrate 50mg/L for 2h,incubated with 50mg/L ox-LDL for 24h; LOX-1 mRNA,PAI-1 mRNA were detected by RT-PCR;LOX-1 protein were detected by Western-blot;PAI-1 protein were detected by ELISA.Results:Incubation of HUVECs with different concentration of bezafibrate decreased the expressions of PAI-1,compared with 50μg/ml ox-LDL group(P＜0.001),The expression of LOX-1 and PAI-1 were reduced(P＜0.001) in HUVECs pretreated with 250μg/ml poly(I) for 2 h and then incubated with 100mmol/mL benzafibrate for 2 h,This showed that poly(I) obviously decreased the expression of PAI-1.This inhibitor may be mediated by the LOX-1.Conclusions:Bezafibrate,as the antilipemic agent,may be inhibit the expression of LOX-1 and PAI-1 in endothelial cell.This show that the clinic beneft of bezafibrate result not only from their lipidlowering properties but also from their multiple effects on the components of the atherosclerotic lesions,which may be responsible for bezafibrate to prevent and treat atherosclerosis,however, the relation between this roles and LOX-1 will be wait for study further. |
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