Role Of Lectin-like Oxidized Low Density Lipoprotein Receptor-1 In Rabbit's Carotid Atherosclerosis

There is a great relationship between cerebrovascular disease and carotid atherosclerosis(AS). Detection of carotid artery stenosis is more frequent as living conditions improved and development of imageology. To find the pathogenesis and intervention method of carotid atherosclerotic stenosis is one of an important question for discussion in the field of neurology.Lectin-like oxidized low density lipoprotein receptor-1(LOX-1)is an important receptor for oxidized low density lipoprotein(ox-LDL) expressed on endothelial cells. LOX-1 participates in ox-LDL recognization, combination and transportation into endothelium. A large number biological effect of ox-LDL is believed to be critical in the pathogenesis of atherosclerosis. LOX-1 mediate most biology toxicity of ox-LDL such as induce cell adhesion molecule and monocyte chemotactic factor, transformation of macrophage into foam cells and induce smooth muscle cell apoptosis. LOX-1 is an important receptor in the development of AS which derived from endothelium disfunction, abnormity of blood fat level, as while as induce endothelium disfunction and apoptosis. Nevertheless, location of atherosclerotic plaques in vivo is usually on furcation and bending section of arterys. This phenomenon may be well explained by hemodynamics. Wall shear stress ( WSS) is friction of blood flow on artery. WSS play an important role in endothelium injury, growth or rupture of plaques and artery remodeling which is a important pathogenesis of atherosclerosis. LOX-1 expression can be regulated by hemodynamics and blood fat level, which had been improved in some empirical study in vitro. But in vivo the relationship between LOX-1 expression and AS, as while as its main regulators is still unclear. It is important to study in the relationship between LOX-1 and AS. It will help us understand the pathogenesis of AS and may provide a new target for treatment.Carotid artery atherosclerosis model in rabbit was successfully established by surgical partial ligation (SPL) combined with highcholesterol diet. We got the image of the angiostenosis by digital subtraction angiography (DSA) and doppler ultrasound. Computational fluid dynamics simulation(CFDS)was performed in the carotid artery stenosed model in a whole cardiac cycle with the application of softwares and came to WSS distribution. Immunohistochemistry and RT-PCR to detect expression of protein and mRNA of LOX-1. We analyzed relationship among location of LOX-1, WSS and atherosclerosis plaques in order to understand role of OX-1 in rabbit's carotid atherosclerosis.Part 1 Establishment and evaluation of carotid artery atherosclerosis model in rabbitsObjectives To establish and evaluate new carotid artery atherosclerosis model in rabbits.Methods Carotid artery atherosclerosis model in rabbits were made by surgical partial ligation (SPL) combine with highcholesterol diet. The ratio of stenosis was about 50% as expected. We measured angiostenosis models by digital subtraction angiography (DSA) and doppler ultrasound. TC, LDLC, TG level in peripheral blood were measured at the beganing and on the 6th and 12th week after operation respectively. We came to the ratio of stenosis from DSA image.and doppler ultrasound. Rabbits were sacrificed in batch at 6th and 12th week with gas embolism. Carotid histological section and HE/MASSON stained. We analyzed the image by Image-Pro Plus system measured thickness of intima(I), thickness of tunica media(M), areas of intima(SI) and areas of tunica media(SM), calculated I/M,SI/SM.Results Rabbit models of carotid artery atherosclerosis in rabbits were successfully performed by SPL and high fat diet. HE/MASSON staining showed extensive intima hyperplasy and plaques were successfully induced in SPL combined with highcholesterol diet group amd in SPL, high fat diet group. Intima thickening was mainly at the external part of the stenosis as well as lipochondria deposition in SPL combined with high fat diet group. I/M and SI/SM increased in all stenosed group at 12th week compared with high fat diet group and the control group. The most often position of intima hyperplasy was the stenosis and the post-stenotic part of the stenosis respectively.Conclusions Carotid artery atherosclerosis model performed by SPL and high fat diet group successfully induced artery atherosclerosis featuers such as intima hyperplasy, lipochondria deposition as well as plaques mainly at the external part of the stenosis. The model was an ideal animal model for atherosclerosis study and hemodynamic analysis. The model is convenient and fast outcome. DSA image proved SPL effectually made carotid artery stenosis. Intima hyperplasy and plaques were mainly located at the stenosis or post-stenotic part of the stenosis, which revealed hemodynamic factors may play an important role in AS. The method SPL combined with highcholesterol diet keep integrity of endothelial cells as it is possible. Furthermore, the wall of angiostenosis models is keeping its elastic and pulsant features. The model can be applied in study of endothelial cells'function and hemodynamic evaluation in AS and stenosed artery.Part 2 Computational hemodynamic simulation in rabbit carotid artery atherosclerosis model and examine of wall shear stress distribution.Objectives To establish carotid artery stenosis model in rabbits and assess wall shear stress (WSS) distribution in this animal model in a cardiac cycle.Methods Carotid artery stenosis model was established in rabbits by partial microsurgicalligation. Image of the angiostenosis was got by digital subtraction angiography (DSA). Computational fluid dynamics simulation (CFDS)was performed in the carotid artery stenosis model in one whole cardiac cycle with the application of softwares as Photoshop, Matlab, Ansys and Fluent.Results Elastic carotid artery stenosis model in rabbits were successfully performed. Hemodynamics features including wall shear stress distribution in 2-dimensional pulsating carotid artery stenosed model were well discribed in a whole cardiac cycle. We found WSS changed with blood flow rate and peak at mid contraction of a cardiac cycle. High WSS and low WSS were found in the position of stenosis and the post-stenotic part respectively. The maximum range of WSS was at the position of stenosis while the minimum at the extremal part of the stenosis. During late phase of relaxation WSS at the position of external part of the stenosis decreased and closed to 0.Conclusions CFDS is a novel method to discribe WSS distribution in carotid artery stenosed model which provides theoretical evidence for clinical; WSS changed with blood flow rate and peak at mid contraction of a cardiac cycle; High WSS and low WSS were found in the position of stenosis and the post-stenotic part respectively, where is the most often position of intima hyperplasy. WSS may play a role in inducing AS.Part 3 LOX-1 expression in rabbit's carotid atherosclerosisObjectives To study LOX-1 expression in rabbit's carotid atherosclerosis model and evaluate its role in AS development.Methods Carotid artery atherosclerosis model in rabbits were established by surgical partial ligation (SPL) combined with high fat diet. Immunohistochemical staining and RT-PCR detection were used to detect the protein and mRNA expression of LOX-1. Image-ProPlus image analysis system was used to analyze the positive area ratio of LOX-1. Expression of LOX-1 mRNA was semi-quantitated by relative optical density band compared with LOX-1/GAPDH. The dependablity between LOX-1 expression and intimia/media thickness (I/M), plasma LDLC level was examined was analyzed with Spearman correlation analytical system, SPSS13.0.Results LOX-1protein and mRNA expression was elevated in AS models. LOX-1 protein was mainly expressed in the surface of new intima. LOX-1 expression increased obviously in SPL combined with high fat diet group compared with SPL group and high fat diet group. There was no or only a very low expression could be detected in the control group. LOX-1 expression was positive correlation to I/M and LDLC.Conclusions LOX-1 protein and mRNA expression was elevated in AS modes. LOX-1 expression was positive correlation to I/M. LOX-1 may play an important role in the pathogenesis of AS and reflect degree of AS. LOX-1 protein was mainly expressed in the surface of new intima and could be coordinately upregulated by high cholesterol level and change of WSS. Hemodynamics factors including WSS were precipitating factors in AS by upregalate LOX-1. LOX-1 was regulated by multiple factors and play an important role in the pathogenesis of AS.