| BackgroundAtherosclerosis, a progressive pathological disorder leading to cardiovascular and cerebrovascular diseases, is still the leading cause of mortality and morbidity in human society. For the major part of the 20th century, the lipid theory dominated the field of atherogenesis. R. Ross reopened the discussion on the inflammatory nature of atherosclerosis in 1999, with his significant review on atherosclerotic.leukocyte adhesion molecules, cytokines, growth factors and metalloproteinases participate in all stages of atherogenesis. Almost all of the traditional risk factors for atherosclerosis are associated with and participate in the inflammatory process. Vascular adhesion protein-1 is one of the endothelial cell adhesion molecules that present on both normal and inflammatory conditions. Transcription factor nuclear factor– kappaB has been regarded as a proatherogenic factor, mainly because of its regulation of many of the proinflammatory genes linked to atherosclerosis. Nuclear factor– kappaB may play an important role in guarding the delicate balance of the atherosclerotic process as a direct regulator of proinflammatory and anti- inflammatory genes and as a regulator of cell survival and proliferation. Smooth muscle cell migration occurs during atherosclerosis. Vascular smooth muscle cells migrate to populate the intima during atherosclerosis, the proliferation and migration of VSMC play a significant role in the development of atherosclerotic plaque.Recent work has provided a broad experimental base supporting a critical role for oxidative stress in the normal functioning of cardiac and vascular cells, as well as in the pathogenesis of vascular disease. Exogenous application of ROS stimulates many of these same cascades. Ligand-induced receptor activation rapidly increases intracellular O2·- and H2O2, and accumulating evidence suggests that these endogenously derived ROS play critical roles as intracellular signaling molecules. 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, inhibit the synthesis of cholesterol and have been demonstrated to reduce cardiovascular morbidity and mortality. Recently, statins have been shown to modulate several of the mechanisms of inflammation in atherosclerosis in vitro and in vivo, including reduction of inflammatory markers in clinical trials. There is a growing body of evidence, that statins exert effects by much exceeding the effect of cholesterol level decrease. Statins have antiatherosclerotic, antiinflammatory, antioxidant, immunomodulatory and antithrombotic effects.Objective:1. To detect expression of vascular adhesion protein-1,nuclear factor-kappaB as well as their correlations in atherosclerosis lesions.2. To observe the proliferation of rabbit vascular smooth muscle cells stimulated by hydrogen peroxide.3. To investigate the effect of simvastatinon proliferation and migration of rabbit vascular smooth muscle cells stimulated by hydrogen peroxideMethods and Materials:1. Immunohistochemistry was used to detect the vascular adhesion protein-1,nuclear factor-kappaB in 15 specimens of atherosclerosis lesions of human artery and 5 specimen of normal human artery. The corresponding data were analyzed retrospectively.2. Cultured rabbit arterial vascular smooth muscle cells were divided into six groups, CCK-8 was used to detect the effect of simvastatin on proliferation of vascular smooth muscle cells, TBA method was used to detect the MDA levels of the culture medium.3. Cultured rabbit arterial vascular smooth muscle cells were divided into four groups CCK-8 was used to detect the effect of simvastatin on proliferation of rabbit vascular smooth muscle cells stimulated by hydrogen peroxide; TBA method was used to detect the MDA levels of the culture medium; Immunohistochemistry was used to detect the expression of nuclear factor-kappaB and vascular adhesion protein-1.Results:1. The positive rates of vascular adhesion protein-1and nuclear factor-kappaB expression in atherosclerosis lesions were (17.54±9.86)/HP and (28.31±8.62)/HP, respectively, which were significantly correlated with the development of atherosclerosis. The expression of in normal artery is(6.20±2.59)/HP, and the expression of vascular adhesion protein-1 in normal artery is just in the adventitia of artery. There existed positive correlation between the expression of vascular adhesion protein-1 and nuclear factor-kappaB (r=0.558,P= 0.004) .2. 10~100μmol/L hydrogen peroxide promoted proliferation of rabbit arterial VSMCs in a time- dependant manner. 200μmol/L hydrogen peroxide was lethal to rabbit arterial vascular smooth muscle cells. The MDA level was reached to peak at 72h after continuing stimulation of 50~200μmol/L hydrogen peroxide;3. Compared with group control, group hydrogen peroxide A value and the MDA level increased; the expression of nuclear factor-kappaB in group hydrogen peroxide was higher(P<0.01). Pretreatment of rabbit arterial vascular smooth muscle cells with 50μmol/L simvastatin for 30 minutes prior to hydrogen peroxide stimulation exhibited significant inhibition of vascular smooth muscle cells proliferation and the MDA level after 48h(P<0.01); the proliferation was significantly inhibited in vascular smooth muscle cells treated by simvastatin of 10μmol/L,50μmol/L, and the MDA level was significantly decreased after 72h than 48h. The inhibitory effects of simvastatin of 50μmol/L was stronger than that of 10μmol/L. And at the same time, the expression of nuclear factor-kappaB reduced remarkably compared with group hydrogen peroxide (P<0.01).Conclusions:1. The expression of vascular adhesion protein-1 and nuclear factor-kappaB are closely correlated with the development of atherosclerosis.2. Hydrogen peroxide at suitable concentrations stimulated proliferation of cultured rabbit arterial vascular smooth muscle cells, and increased the MDA level of the culture medium.3. Simvastatin with certain concentrations could inhibited proliferation and migration of cultured rabbit arterial vascular smooth muscle cells, which stimulated by hydrogen peroxide, reduced MDA level of culture medium, and this effect related with dose and time. At the same time, the expression of nuclear factor-kappaB was inhibited, which may be one of the key mechanisms of simvastatin on the inhibition of vascular smooth muscle cells proliferation and migration induced by hydrogen peroxide.
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