The Dynamic Alteration Of Hemodynamics Parameters And Chemokines Expression In The Rabbit Atherosclerotic Plaque

Atherosclerosis is caused by multiple factors such as gene , environment and metabolism.Many studies indicate that inflammation plays a crucial role in the initiation and development of atherosclerosis.In clinic inflammation runs through all the process of atherosclerosis.Therefore, the pathogenesis studies of atherosclerosis can help to discover new therapy to reduce the development of atherosclerosis. PURPOSES:(1)To investigate the alteration of hemodynamics parameters in the AS model and the distribution of wall shear stress in the atherosclerotic lesions .(2)To investigate the expression of chemokines (IL-8 ,MCP-1,Fractalkine) in the atherosclerotic lesions of the rabbit AS model.(3) To identify the correlation between the chemokines concentration and the lipid level and atherosclerosis process . METHODS: (1) The combination of high-cholesterol-containing diet and immunologic injury is adopted to establish the rabbit AS model. Animals were divided into 6 groups: 4 week control group,4 week AS model group,8 week control group,8 week AS model group, 12 week control group,12 week AS model group.(2) We determine the external diameter of the common carotid artery with vernier caliper , the blood flow of the common carotid artery with electromagnetic flow , blood pressure with electrophysiolograph and the blood viscosity with viscometer at different shear rate(0.512 S^-1,5.96 S^-1,51.2 S^-1,128.5 S^-1).(3) The method of computer fluid dynamics(CFD)is adopted to simulate the wall shear stress distribution of the carotid bifurcation.(4)By the immunohistochemistry,we determine the expression of IL-8 , MCP-1 , Fractalkine and CX3CR1 protein in atherosclerotic lesions of the aortic arch in the AS model. (5)Quantitative sandwich enzyme-linked immunosorbent assay (ELISA) is employed to assay the production of IL-8 and MCP-1 protein in the aortic arch homogenate.(6)In situ hybridization is employed to locate the expression of IL-8 and MCP-1 mRNA in atherosclerotic lesions of the aortic arch in the AS model.(7) By the correlation analysis ,we analyze the correlation between the IL-8 and MCP-1 protein concentration and the blood lipid(TC,TG,LDL-C,HDL-C) ,intima-media thickness(IMT). RESULTS: (1) The method of the combination of high-cholesterol-containing diet and immunologic injury to establish the rabbit AS model was successful .(2) Blood viscosity of the AS model group increased obviously under the 0.512 S-1 and 5.96 S-1 at 12 week. Blood flow increased obviously at 8 and 12 week.SBP increased obviously at 8 and 12 week. Alteration of the plasma viscosity and vascular diameter were not obvious.(3)As the blood viscosity with blood apparent viscosity at shear rate (5.96 S-1,51.2 S-1,128.5 S-1),the wall shear stress of the atherosclerotic lesions of AS model was lower than that of the carotid sinus of the control group.The lowest wall shear stress distributed in perimeter of the atherosclerotic lesions of AS model.(4) By location of immunohistochemistry:1) expression of IL-8 protein increased obviously in intima of hyperlipemia rabbits at 8 and 12 week. Quantitative analysis of the expression of IL-8 immunohistochemistry indicated that positive area of AS model was 4.48 times and 8.76 times than that of control group at 8 and 12 week.The value of integrated optical density (IOD) of AS model was 4.16 times and 4.36 times than that of control group at 8 and 12 week.2) expression of MCP-1 protein increased obviously in intima of hyperlipemia rabbits at 8 and 12 week.Quantitative analysis of the expression of MCP-1 immunohistochemistry indicated that positive area of AS model was 2.04 times and 3.32 times than that of control group at 8 and 12 week.The value of IOD ofAS model was 2.33 times and 3.43 times than that of control group at 8 and 12 week. 3)Fractalkine had no expression at vessel of the control group; Fractalkine had positive staining at the endothelial cell of 4 week AS model group; Fractalkine had weak positive expression at the incrassate intima of 8 week AS model group; Fractalkine had strong positive staining at the atherosclerotic lesion of 12 week AS model group. 4)CX3CR1 had no expression at vessel of the control group and 4 week AS model group; CX3CR1 had weak positive expression at the incrassate intima of 8 week AS model group; CX3CR1 had strong positive staining at the atherosclerotic lesion of 12 week AS model group. (5) By specific ELISA :1)the ratio of the IL-8 protein to total protein of AS model was 1.84 times and 2.06 times than that of control group at 8 and 12 week.2)the ratio of the MCP-1 protein to total protein of AS model was 2.90 times and 3.58 times than that of control group at 8 and 12 week.(6) By location of in situ hybridization:1)IL-8 positive location was strong in intima of hyperlipemia rabbits at 8 week. 2)MCP-1 positive location was strong in intima of hyperlipemia rabbits at 8 week.(7) By the correlation analysis , 1) IL-8 protein concentration had strong correlation with LDL-C. The correlation coefficients was r=0.495,p=0.026<0.05.The correlation coefficients of IMT and Interleukin-8 was r=0.582,p=0.007<0.01. 2) MCP-1 protein concentration had strong correlation with TC, LDL-C and HDL-C.The correlation coefficients were r=0.721,r=0. 816,r=0.562, p <0.01.The correlation coefficients of IMT and MCP-1 was r=0.867,p =0.000<0.01. CONCLUSIONS: (1)The wall shear stress is low in the rabbit carotid atherosclerotic lesions.The low wall shear stress is a risk dynamics factor in the development of atherosclerosis.(2) The expression IL-8 ,MCP-1and Fractalkine protein are up-regulated in the atherosclerotic lesions of the aortic arch in AS model group.These chemokines participate in the development of atherosclerosis.(3) IL-8 and MCP-1 play important role in the early atherosclerosis.(4)The expression of IL-8 and MCP-1 protein are effected by LDL-C and associated with the atherosclerosis process.