【作者】 刘珊；

【导师】 陈正望；

【作者基本信息】 华中科技大学 ， 生物化学分子生物学， 2011， 硕士

【摘要】 动脉粥样硬化及其引起的中风、心肌梗塞等继发性病症是严重危害人类健康的常见疾病，其发病机制是一个复杂的过程，涉及到多种因子的相互作用。近年来，除高血压、高胆固醇、高LDL等传统危险因素外，高同型半胱氨酸血症以及凝血-纤溶系统失衡在动脉粥样硬化的发病中所起的作用受到越来越多的关注。Daintain是Chen等在研究胃肠道多肽激素时从猪小肠中分离出的一个活性多肽，因与Utans等1995年从发生慢性排斥反应的大鼠心脏移植物中克隆出的同种异体移植炎症因子（Allograft Inflammatory Factor-1，AIF-1）高度同源，故并成为Daintain/AIF-1。大量研究证明，Daintain/AIF-1在动脉粥样硬化的发生发展中起着重要作用。本课题组的前期研究发现，Daintain在体外能够与同型半胱氨酸（Homocysteine，Hcy）的代谢关键酶——胱硫醚-β-合成酶（Cystathinoine β-synthase, CBS）结合，故推测Daintain/AIF-1可能影响血液中的Hcy含量。此外，小鼠注射Daintain/AIF-1后血液变得粘稠、更易凝固，提示Daintain/AIF-1可能影响机体的凝血-纤溶系统。纤溶酶原激活物抑制因子-1（plasminogen activator inhibitor-1，PAI-1）是纤溶系统的重要调控元件，炎症因子如白细胞介素-1（IL-1）、肿瘤坏死因子α（TNFα）等均能诱导其产生。本研究探讨了Daintain/AIF-1与Hcy和PAI-1之间的关系，完成的工作主要有以下几个方面：1）尾静脉注射Daintain/AIF-1上调雌性昆明小鼠血清中的Hcy含量，但在本实验条件下未发现Daintain/AIF-1对CBS活性有显著影响；2）尾静脉注射Daintain/AIF-1使雌性昆明小鼠血浆中PAI-1的浓度增加；3）培养基中添加Daintain/AIF-1促进人脐静脉内皮细胞HUVEC和人肝癌细胞系HepG2中PAI-1mRNA的表达；4）高浓度的Hcy上调HUVEC中PAI-1的mRNA水平，但Hcy与Daintain/AIF-1之间无协同作用；5） Hcy对体外培养的HUVEC中Daintain/AIF-1的表达水平没有显著影响。以上结果提示，上调血液中的Hcy和PAI-1水平并提高血管壁中PAI-1的局部表达可能是Daintain/AIF-1促进动脉粥样硬化发生发展的又一机制，值得深入研究。更多还原

【Abstract】 Atherosclerosis (AS) is a disease of large and medium-sized muscular arteries and ischaracterized by endothelial dysfunction, vascular inflammation, and the buidup if lipids,cholesterol, calcium, and cellular debris within the intima of the vessel wall. Thepathogenesis of AS is a complex process, involving the interaction of multiple factor.Recently, in addition of traditional risk factors, effects of hyperhomocysteinemia and theimbalance of Coagulation and Fibrinolysis System on atherosclerosis cause more andmore attentions.Daintain was isolated and characterized from porcine intestines, which is highlyhomologous with Allograft Inflammatory Factor-1(AIF-1) cloned from activatedmacrophages of rat atherosclerotic allogenic heart grafts, therefore, we call itDaintain/AIF-1. Our and others’ studies have shown that, Daintain/AIP-1plays animportant role in the occurrence and development of atherosclerosis.We have previously observed that Daintain/AIF-1could bind to Cystathinoineβ-synthase (CBS) in vitro, which is essential for metabolism of homocysteine (Hcy),suggesting that Daintain/AIF-1may affect Hcy concentration in blood. In addition, bloodof mice injected with Daintain/AIF-1via the tail vein coagulates more quickly thancontrol, indicating that Daintain/AIF-1may play a role in the balance of Coagulation andFibrinolysis System. Plasminogen activator inhibitor-1(PAI-1), an important regulatoryelement in fibrinolysis, is classified as an acute phase reactant. A number of inflammatorycytokines have been found to up-regulate the PAI-1expression.Effects of Daintain/AIF-1on Hcy and PAI-1were investigated in this study, here arethe results:1） Injecting Daintain/AIF-1into female Kunming mice via the tail vein increasedthe concentration of Hcy in serum, however, the activity of CBS had no signficant changewhen stimulated with Daiintain/AIF-1in our study. 2） PAI-1in plasma was significantly elevated in mice administrated Daintain/AIF-1by tail intravenous injection.3） Daintain/AIF-1stimulated PAI-1mRNA expression in human umbilical veinendothelial cells (HUVECs) and HepG2cells.4） Stimulation with high concentration of Hcy caused a significant increase of PAI-1mRNA expression in HUVECs, however, compared with Daintain/AIF-1or Hcystimulated respectively, there was no obvious change in HUVECs co-incubated withDaintain/AIF-1and Hcy.5） The expression level of Daintain/AIF-1in HUVECs had no significant changewhen stimulated with Hcy.Our results suggested that Daintain/AIF-1may promote the occurrence anddevelopment of atherosclerosis through increasing serum Hcy concentration andup-regulating PAI-1expression.更多还原