The Relationship Between LOX-1 And The Stability Of Coronary Atherosclerotic Plaque And The Intervention Of Amlodipine

Acute coronary syndrome (ACS) is the leading cause of death for the patients with atherosclerotic cardiovascular disease. Currently, the diagnosis of ACS mainly baised on clinical manifestation.While there was short of index which is sensitive and specific for predicting the occurrence of ACS. Atherosclerotic plaque rupture followed by thrombus formation is a key mechanism in the onset of acute coronary syndrome. So it has become a focus to identify vulnerable plaques and take measures to prevent it rupture.Matrix Metalloproteinases (MMPs) are a family of Zn2+-dependent enzymes. MMP-9 is a member of the MMPs family and can degrade type IV, V, VII and X collagens. MMP-9 Play an important role in the process of atherosclerotic plaque rupture by degradating fibrous cap of the atherosclerotic plaque. Tissue inhibitor of metalloproteinase-1(TIMP-1) is a specific inhibitor of MMP-9. It can bind to MMP-9, thereby attenuate the ability of MMP-9 degrading collagens. So the balance of MMP-9 and TIMP-1 is an important factor for the stability of atherosclerotic plaque.The studys on TIMP-1 are seldom and its conclusions are imcompatible.Oxidative LDL (oxLDL) plays a pivotal role in the generation and development of atherosclerosis.It can up-regulate the expression of LOX-1.While LOX-1, as the cell member receptor of oxLDL, mediated lots of biological action of oxLDL. For example, it can induce apoptosis of cells and up-regulate the expression of MMPs. The MMPs, once activated, can completely degrade all extracellular matrix components including fibrous cap of the plaque. Apoptosis of cells also attenuate the fibrous cap of plaque. Thus the plaque became instable and vulnerable. But the role of LOX-1 in ACS needed advanced investigation.Several clinical studys have demonstrated that calcium channel blockers reduced the incidence of vascular events and retared the progression of arteriosclerosis. For instance, the PREVENT study demenstrated that amlodipine, a long-acting calcium channel blocker, retared progression of atherosclerosis in carotid arteries and reduced the occurrence of hospitalized unstable angina and coronary revascularizations. But the mechanisms underlying the antiarteriosclerotic actions of amlodipine remain unclear.In the present study, firstly we investigated the changes of serum levels of MMP-9,TIMP-1,hs-CRP to study the relationship between these inflammatory factors and the stability of atherosclerotic plaque.Secondly we investigated the changes of serum levels of sLOX-1 and ox-LDL and studied the relationships between sLOX-1 and ox-LDL or other lipid profile, and MMP-9,TIMP-1,Hs-CRP levrls, and the extent of atherosclerotic lesions in order to evaluate the relationship between LOX-1 and the stability of atherosclerotic plaque. In the third part, we seperated monocytes from patients with CHD and incubated these monocytes with ox-LDL for 24hours. In parallel experiments, these cells were pretreated with different inhibitors to clarify the modulation of LOX-1 on MMP-9 and TIMP-1 and the machanism underlying that modulation. In the end, we investigated the effection of amlodipine on LOX-1, MMP-9 and TIMP-1 expression in order to evaluate the potential beneficial effects and the mechanism of amlodipine in stabilizing the atherosclerotic plaque.1 The relationship between MMP-9 , TIMP-1 and the stability of atherosclerotic plaqueObjective: to investigate the changes of serum levels MMP-9,TIMP-1,hs-CRP and study the relationship among them, the relationship between these inflammatory factors and the extent of atherosclerotic lesions in order to evaluate the relationship between MMP-9 and the stability of atherosclerotic plaque.Method: The subjects included 20patients with ACS (11AMI, 9UAP), 20patients with SAP and 20 controls without CHD.The diagnosis of these subjects was based on the quantitative coronary angiographic (QCA) analysis. Blood samples were obtained from patients with ACS on admission to the hospital and from patients with SAP and controls on the second day to the hospital under fasting conditions. Plasma samples were collected by centrifugation of collection and stored at -700C. The levels of serum MMP-9, TIMP-1 were measured by ELISA and the levels of serum Hs-CRP were measured by immunoturbidimetry assay.Result:1 The clinicl basis including gender of patients, the blood pressure, fast blood glucose, the number of coronary with atherosclerotic lesions and the coronary stenosis score et al were not significantly different between ACS and SAP groups. The years of patients with SAP were higher than patients with ACS and there were more people smoking in group ACS than other group. The medicines which were taken in recent one month were not significantly different between ACS and SAP groups except for statins. But there were different significantly in group CHD and group control.2 The serum level hs-CRP, MMP-9, TIMP-1and MMP-9/TIMP-1 were significantly higher in ACS than in SAP and control. The serum level of MMP-9 was significantly higher in SAP than in control.3 The serum level of hs-CRP,MMP-9,MMP-9/TIMP-1 were significantly decreased after therapy in ACS. 4 The serum level of MMP-9 correlated with serum TIMP-1 (r=0.491, p<0.01) and hs-CRP (r=0.507, p<0.01). But there were no relaionship between serum TIMP-1 and hs-CRP and there were no relaionship between these inflammatory factors with the extent of atherosclerotic lesions. 2 The correlateion between serum sLOX-1 and MMP-9 and relationship between sLOX-1 and the stability of atherosclerotic plaque in patients with ACSObjective: To investigate the changes of serum levels of sLOX-1 and ox-LDL and study the correlation between sLOX-1 and ox-LDL or other lipid profile,and MMP-9,TIMP-1,Hs-CRP levrls, and the extent of atherosclerotic lesions in order to evaluate the relationship between LOX-1 and the stability of atherosclerot ic plaque.Method: The subjects were the subjects in part one. The blood samples also were blood samples in part one. The levels of serum sLOX-1 and ox-LDL were measured by ELISA.Result:1 The serum levels of ox-LDL,LOX-1 were significantly higher in ACS than in SAP and control and in SAP than in control.2 The serum levels of ox-LDL,LOX-1 were significantly decreased after therapy in ACS.3 The serum level of LOX-1 correlated with serum ox-LDL (r=0.557, p<0.01), MMP-9(r=0.568, p<0.01), MMP-9/TIMP-1(r=0.513, p<0.01). But there were no relationships between serum LOX-1 and TIMP-1,hs-CRP, the number of coronary with atherosclerotic lesions and the coronary stenosis score.3 The modulation of LOX-1 on MMP-9 and TIMP-1 and the machanism underlying that modulationObjective: To investigate the changes of LOX-1, MMP-9 and TIMP-1 mRNA in monocytes which were treated with different stimulators or inhibitors. Then to clarify the modulation of LOX-1 on MMP-9 and TIMP-1 and the machanism underlying those modulations.Method: By the same method, circulating monocytes of patients with coronary heart disease were separated, identified and collected.Then these cells were incubated in RPMI-1640 without serum or with ox-LDL(40ug/ml) for 24hours. In parallel experiments, these cells were pretreated with PIA(250ug/ml) or PDTC (10-5mol/l) for 60 min respectively before incubation with ox-LDL. The supernatant liquid of cultured cells was collected and used to determin the levels of LOX-1, MMP-9 and TIMP-1 by ELISA. Then isolated the total RNAs by the same method as before and examined the expression of LOX-1, MMP-9 and TIMP-1 mRNA by RT-PCR.Result:1 Incubation of monocytes with ox-LDL for 24hours markedly increased the expression of LOX-1 and MMP-9 mRNA (RT-PCR) and protein (ELISA). Pretreatment of monocytes with a blocking antibody to LOX-1 (PIA250ug/ml) prevented the expression of LOX-1 and MMP-9 in response to ox-LDL (P<0.01). Furthermore the NF-kB inhibitor PDTC reduced the expression of LOX-1 and MMP-9 induced by ox-LDL, thereby restoring control levels of MMP-9.2 Ox-LDL decreased the expression of TIMP-1 slightly but not significantly. After pretreatment of monocytes with PIA and PDTC the expression of TIMP-1 did not change.4 The effection of amlodipine on LOX-1, MMP-9 and TIMP-1 expression and the machanism underlying that effectionObjective: To investigate the effection of amlodipine on LOX-1, MMP-9 and TIMP-1 expression in order to evaluate the potential beneficial effects and the mechanism of amlodipine in stabilizing the atherosclerotic plaque. Method: Separated, identified and collected circulating monocytes ofpatients with coronary heart disease. Then incubated these cells in RPMI-1640 without serum or with ox-LDL(40ug/ml) for 24hours. In parallel experiments, pretreated with amlodipine (10?6 mol/l) for 60 min before incubation with ox-LDL. The supernatant liquid of cultured cells were collected and used to determin the levels of LOX-1, MMP-9 and TIMP-1 by ELISA.Cells were isolated the total RNAs by the same method as before. The total RNAs were used for examining the expression of LOX-1, MMP-9 and TIMP-1 mRNA by RT-PCR.Result:1 Pretreatment of monocytes with Amlodipine(10-6mol/l)prevented the expression of LOX-1 and MMP-9 induced by ox-LDL, thereby restoring control levels of MMP-9. But it had no effect on the expression of TIMP-1.2 Amlodipine(10-6mol/l)decreased the levels of LOX-1 and MMP-9 protein induced by ox-LDL in supernate, thereby restoring control levels of MMP-9. But it had no effect on the level of TIMP-1 protein. Conclusion:1 Serum levels of MMP-9 and MMP-9/TIMP-1 were increased and correlated with the instability of atherosclerotic plaque in patients with ACS.2 Serum level of sLOX-1 was correlated with MMP-9 and MMP-9/TIMP-1 in patients with ACS. This imply LOX-1 participate in the forming of unstable plaque by increasing MMP-9 and MMP-9/TIMP-1.3 Serum levels of sLOX-1, ox-LDL, hs-CRP, MMP-9 and MMP-9/TIMP-1 were significantly higher in patients with ACS than in SAP and control subjects, they all can reflect the instability of atherosclerotic plaque.4 LOX-1 can modulate MMP-9mRNA expression in monocytes came from patients with ACS. This suggests that LOX-1 can impact the stability of atherosclerotic lesions by modulating the expression of MMP-9mRNA.5 Amlodipine possess potential plaque stabilization properties by inhibiting the expression of LOX-1 and MMP-9 in monocytes.