The Levels Variation Of Interleukin-8 And Its Role In Atherosclerosis After Balloon Inflation In Rabbits

Background: With the improvement of people living standard, the morbidity of vascular disease (including cardiovascular disease, cerebrovascular disease, peripheralvasvular disease) increased gradually, which influenced health of mankind seriously, and become public health problems on the earth. On the meantime, vascular disease was the first death cause of adults in china. Atherosclerosis was the patho-foundation of vascular disease above. On the basis of AS, vessel stenosis and plaque formation emerged, leading to a series of clinical event.The study on vascular disease in clinical and basis was focused in medical domain at present. The mechanic research would help us to look for the new effective targets in therapy of atherosclerosis. By this way, the prognosis of patients would be improved subsequently.It had been confirmed that atherosclerosis(AS) was a kind of chronic inflammation disease. On each stage of its occuring and development, inflammation reaction happened to some extent accordingly. It proved that cytokines and its specific receptor, such as interleukin-8(IL-8),might play an important role in progress of atherosclerosis. These cytokines could injury vessel endothelium, and cause dysfunction of endothelials cells. Thus, the effects on anti-sticky and anti-congregation were lost. Monocyte collected and migrated to intima on the background. Expression of IL-8,MCP-1,TNF-α,IL-βand GM-CSF were enhanced by this way. Monocaryon-macrophage would be activated, smooth muscle cell migrated to plaque and changed into foam cells. It also showed that accrementition of endothelials cell and proliferation and migration of smooth muscle cell were the main cause of restenosis after PCI. Inflammatory reaction made larger contribution in the process of restenosis. To observe the regulation of inflammation factors and proliferation of smooth muscle cells would contribute the understanding of AS, demonstrate mechanics of main complications after PCI, such as restenosis, and improve therapeutic results of angioplasty.Objective: In this study, animal models of AS were made by balloon inflation in abdominal aorta of rabbits. The levels of IL-8,CRP,IL-6,TNF-αwere measured in different points after injury of vessels. The extent of luminal stenosis was examined by angiography. The structural change of intima and medium were observed by means of pathology. The expression of IL-8 mRNA and proliferation of smooth muscle cells were surveyed using immunohistochemistry and RT-PCR technology. The relationship between IL-8 and CRP,IL-6,TNF-αwere analyzed. The effects of IL-8 changes on angiostenosis, structure of intima and medium of vessels were demonstrated .The influence of IL-8 levels on proliferation of vascular smooth muscle cells was studied systemly. Our study would offer theory basis for intervention of AS progress and prevention of restenosis after PCI.This study was divided into four parts as follows:1. Establishment of AS model in abdominal aorta of rabbitsMethods Twenty-four New Zealand white rabbits aging from eight months to twelve were selected. All of animals were fed adaptably before experiment. Each rabbit was in single cage, no limiting waters and foods. These rabbits were continued to feed after experiment, till models were made successfully. They were randomly assigned to experiment group (n=12) and control group (n=12).The rabbits were anesthetized by 10g/L sodium pentobarbital (3.0-3.5 ml/kg) through intravenous injection. The femoral artery was punctured and sheathing canal was preserved. Two hundreds units heprin were injected to anticoagulate through sheathing canal. Rabbits in experiment group were injuried in abdominal aorta by balloon inflation after punctured in femoral artery. The balloon was inserted along the guide wire and put in two centra above arteria iliaca. The balloon was inflated in pressure of 405.30~607.95 To observe the regulation of inflammation factors and proliferation of smooth muscle cells would contribute the understanding of AS, demonstrate mechanics of main complications after PCI, such as restenosis, and improve therapeutic results of angioplasty.Objective: In this study, animal models of AS were made by balloon inflation in abdominal aorta of rabbits. The levels of IL-8,CRP,IL-6,TNF-αwere measured in different points after injury of vessels. The extent of luminal stenosis was examined by angiography. The structural change of intima and medium were observed by means of pathology. The expression of IL-8 mRNA and proliferation of smooth muscle cells were surveyed using immunohistochemistry and RT-PCR technology. The relationship between IL-8 and CRP,IL-6,TNF-αwere analyzed. The effects of IL-8 changes on angiostenosis, structure of intima and medium of vessels were demonstrated .The influence of IL-8 levels on proliferation of vascular smooth muscle cells was studied systemly. Our study would offer theory basis for intervention of AS progress and prevention of restenosis after PCI. This study was divided into four parts as follows:1. Establishment of AS model in abdominal aorta of rabbitsMethods Twenty-four New Zealand white rabbits aging from eight months to twelve were selected. All of animals were fed adaptably before experiment. Each rabbit was in single cage, no limiting waters and foods. These rabbits were continued to feed after experiment, till models were made successfully. They were randomly assigned to experiment group (n=12) and control group (n=12).The rabbits were anesthetized by 10g/L sodium pentobarbital (3.0-3.5 ml/kg) through intravenous injection. The femoral artery was punctured and sheathing canal was preserved. Two hundreds units heprin were injected to anticoagulate through sheathing canal. Rabbits in experiment group were injuried in abdominal aorta by balloon inflation after punctured in femoral artery. The balloon was inserted along the guide wire and put in two centra above arteria iliaca. The balloon was inflated in pressure of 405.30~607.95 showed that IL-8 positively correlated to IL-6,TNF,CRP, r=0.769,0.673,0.897(p < 0.05). Abdominal aorta became stenosis after four weeks in experiment group.3 The effects of Interleukin-8 on artherosclerosis of abdominal aorta in rabbitsMethods Thirty-six New Zealand white rabbits purchased from the Test Animal Center of Hebei Medical University, weighting from 2.5kg to 3.25 kg, were selected. They were randomly assigned to experiment group (n=12), treatment group (n=12) and control group (n=12). Rabbits in experiment group and treatment group were injuried in abdominal aorta by balloon inflation after punctured in femoral artery. Monoclonal antibody of IL-8 was injected by venous in rabbits of treatment group. Rabbits in control group were punctured only in femoral artery. Peripheral blood was collected before experiment and four hours,one day,three days,one week,two weeks,four weeks later. The levels of IL-8 were measured by enzyme linked immunosorbent assay (ELISA) respectively. The luminals of abdomial aorta in three groups were observed four weeks later. Histopathologic examination was performed after death. Such contents as follows were assayed using light microscope and computer image analysis system: luminal area, intima and tunica media area, angiostenosis of blood vessel.Results: The levels of interleukin-8 begun to raise in four hours and achieved to peak in one day after balloon inflation in rabbits of experiment group. The higher levels of this inflammatory factor lasted four weeks. There was no variation above in treatment and control group. It was observed that abdominal aorta become stenosis obviously in experiment group. The area of intima and tunica media as well as extent of stenosis in experiment group were bigger than those in treatment group and control group. There was no statistical difference between treatment and control group. Correlation analysis indicated that there were positive relations between IL-8 and luminal area, area of intima and tunica medias respectively(r=0.815,0.894,0.783,0.801,0.912,p<0.01). Multiple regression analysis of Logistic indicated that IL-8 was an independent risk for the AS(p <0.01).4 The relationship between expression of IL-8 mRNA and protein proliferation of vascular smooth muscle cells in rabbits with artherosclerosisMethods Thirty-six New Zealand white rabbits purchased from the Test Animal Center of Hebei Medical University, weighting from 2.5kg to 3.25 kg, were selected. They were randomly assigned to experiment group (n=12), treatment group (n=12) and control group (n=12). Rabbits in experiment group and treatment group were injuried in abdominal aorta by balloon inflation after punctured in femoral artery. Monoclonal antibody of IL-8 was injected by venous in rabbits of treatment group. Rabbits in control group were punctured only in femoral artery. The expression of IL-8 mRNA and protein in abdomial aorta was examined by means of immunohistochemistry staining and RT-PCR technology. After proliferating cell nuclear antigen (PCNA) stained, the ratio of masculine cells was calculated per 40 times field of vision using light microscope and computer image analysis system. Index of masculine cells was determined.Results There was no statistical difference among three groups in general data (p>0.05). The expression of IL-8 mRNA in experiment group was significantly higher than those in treatment group and control group (p<0.05). Compared to control group, there was no significant difference in treatment group. It showed that expression of IL-8 protein in experiment group was significantly higher than others (p<0.05). There was no statistical difference between treatment group and control group. Compared with treatment group and control group, the number and ratio of PCNA in experiment group increased significantly (p<0.05). Treatment group was higher than control group (p>0.05).Conclusions:1 Atherosclerosis model in abdominal aorta of rabbits could be established successfully by means of intervention which injuried aorta with balloon inflation; 2 The levels of IL-8,IL-6,TNF-αand CRP increased significantly after abdominal aorta injuried by balloon inflation in rabbits. The level of IL-8 increased at first among these inflammation factors. The period to peak required was less than others.IL-8 might play key role in activation of inflammatory reaction;3 The high levels of IL-8 leaded to atherosclerosis in abdominal aorta of rabbits. The severity of stenosis became lessen after intervention by monoclonal antibody of IL-8.Positive corelation was found between level of IL-8 and severity of arterial stenosis. IL-8 was one of independent risks factor leading occurrence and development of atherosclerosis.4 The higher expression of IL-8 mRNA and protein was caused by balloon injury in abdominal aorta. It led to proliferation of vascular smooth muscle cells. The level of IL-8 mRNA and protein decreased after intervention by monoclonal antibody of IL-8.Therefore, proliferation of vascular smooth muscle cells was inhibited.