The Effect Of The Interleukin-8 On The Proliferation Of VSMCs And Its Role In The Restenosis After Balloon Inflation In Rabbit

Percutaneous transluminal coronary angioplasty (PTCA) was a safe and effective method to treat coronary artery disease, but the restenosis rate after 3 to 6 months of the operation could reach to 30% to 50%, that seriously affected their long-term effects. The mechanism of restenosis had not yet been fully clarified. At present, most scholars believed that the migration to the subintimal and excessive proliferation of the vascular smooth muscle cells was essential, therefore the regulation of the proliferation of vascular smooth muscle cells became the focus of the study. Some research data showed that the restenosis after balloon injury was associated with vascular recoil, thrombus formation, excessive proliferation of VSMCs and accumulation of extracellular matrix. The excessive proliferation of VSMCs might be the main reason for the formation of restenosis. After the balloon dilation of blood vessels, vascular endothelial and medial smooth muscle cells were stretched and damaged. the VSMCs could excessive proliferated and moved to the inner membrance under the stimulation of series growth factors during the repair process. Therefore to inhibit the excessive proliferation of VSMCs to prevent and cure the restenosis was a subject concerned and researched by medical workers.Interleukin -8 (IL-8) was a member of the CXC chemokine subfamily, and mainly produced by mononuclear cells. The chief physiological activity of IL-8 was to chemokine and activate the neutrophils and secrete a large number of adhesion molecules to increase the receptors of CD11b/CD18 on the surface of neutrophil cells. IL-8 was a pro-angiogenic factor which could induce the proliferation and migration of smooth muscle cells and played an important role in the process of inflammatory response. IL-8 could promote monocyte rolling on endothelial cells into a strong adhesion. The study found that elevated levels of IL-8 was related to the pathogenesis of coronary artery disease, and could be used as the predictors of cardiac events.Objective: In this study, animal models of restenosis were made by balloon inflation in abdominal aorta of rabbits. The extent of luminal stenosis was examined by angiography. The structural change of intima andmedium were observed by means of pathology. The expression of IL-8 protein and PCNA-positive cells were surveyed using immunohistochemistry technology. The influence of IL-8 levels on proliferation of vascular smooth muscle cells was studied systemly. Our study would provide a reliable theoretical basis for the prevention and treatment of restenosis after PCI.Methods: Twenty-four male New Zealand white rabbits were selected. They were purchased from the Test Animal Center of Hebei Medical University, weighted from 2.5kg to 3.25 kg. They were randomly assigned to experiment group (n=8),treatment group (n=8) and sham group (n=8). 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 sham group were punctured only in femoral artery.1.The peripheral blood was collected at the time of before the experiment and four hours,one day,three days,one week,two weeks,four weeks after the operation. The levels of IL-8 were measured by enzyme linked immunosorbent assay (ELISA) respectively.2. Put the rabbits to death 4 weeks after the surgery and take an histopathologic examination, contented such as luminal area, intima and tunica media area, angiostenosis of blood vessel were assayed by light microscope and computer image analysis system.3.The expression of IL-8 protein was examined by means of immunohistochemistry staining 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: 1. There was no statistical difference among the three groups of experimental animals in general data (P>0.05).2. The preoperative levels of IL-8 was no significant difference among the three groups. The levels of IL-8 in the rabbits of experiment group began to raise in four hours and achieved to peak in one day after balloon inflation. The higher levels of this inflammatory factor would last four weeks. There was no variation above in treatment and sham group.3. It was observed that the 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 sham group. There was no statistical difference between treatment and sham group. Correlation analysis indicated that there were positive relations between IL-8 and luminal area, area of intima and tunica medias respectively(r=0.905,0.897,0.852,0.846,P<0.01).4. It showed that the 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 sham group. Compared with treatment group and sham group, the number and ratio of PCNA in experiment group increased significantly (P<0.05). Treatment group was higher than sham group (P<0.05). Correlation analysis showed that expression of IL-8-positive cells and PCNA-positive cells was positively correlated, the correlation coefficient r = 0.857 (P<0.01).Conclusions:1 The restenosis model in abdominal aorta of rabbits could be established successfully by means of intervention which injuried aorta with balloon inflation;2 The high levels of IL-8 was caused by balloon injury in abdominal aorta. 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.3 The higher expression of IL-8 protein was caused by balloon injury in abdominal aorta. It led to proliferation of vascular smooth muscle cells. The level of IL-8 protein decreased after intervention by monoclonal antibody of IL-8.Therefore, proliferation of vascular smooth muscle cells was inhibited.