Chemokines and Immune Cells in Hind Limb Ischemia

描述(由申请人提供)： 需要新的治疗方法来减少动脉粥样硬化的并发症，包括死亡、残疾、心脏病发作和截肢。值得注意的是，侧支动脉的形成“自然”地绕过了动脉阻塞，但程度各不相同。了解侧支动脉形成和缺血组织坏死的机制可能会导致动脉粥样硬化的新的初级和辅助治疗。我的长期研究目标是了解侧支动脉形成和组织坏死的基本机制，特别是在这一应用中！将决定免疫系统在侧支动脉形成和继发于缺血的组织坏死中的影响。我的假设的核心是，炎症细胞的招募和激活以及伴随的免疫反应影响侧支动脉的形成和对组织坏死的易感性。我推测，1)免疫差异是两个近交系小鼠对组织坏死的不同易感性的原因，2)T细胞的募集和激活是组织坏死易感性的重要决定因素，3)MCP-1/CCR2轴是组织坏死易感性的重要决定因素。单核细胞趋化蛋白-1(MCP-1)及其受体CCR2是免疫细胞募集和分化的重要调节因子。为了验证这些假设，我在初步研究中：a)建立了小鼠后肢缺血模型，并证明了近交系小鼠对组织坏死有不同的易感性；b)证明缺乏T细胞的裸鼠和缺乏MCP-1或CCR2的小鼠与野生型对照鼠相比，组织坏死的发生率和严重程度均有所增加；c)显示炎症细胞向缺血后肢的募集增加。为了验证我的假设，我提出了三个具体目标。在目标1中，我将确定两个近交系小鼠对组织坏死的不同易感性背后的机制。在目标2中，我将确定T细胞和Th1/Th2免疫反应在组织坏死中的作用，在目标3中，我将通过使用CCR2及其配体MCP-1基因失活的小鼠来确定MCP-1tCCR2轴在组织坏死中的作用。这项提案中概述的实验具有创新性，因为它们利用了基因敲除小鼠在后肢缺血模型中的力量。我已经召集了一支经验丰富的研究团队，他们来自血管生物学、免疫学和生理学的不同领域，以检验这些假设。这项研究的意义在于，更好地了解侧支动脉形成的机制和对组织坏死的易感性，可以指导设计新的动脉粥样硬化性闭塞症的初级或辅助治疗方法，从而降低心肌梗死和截肢的死亡率和致残率。

DESCRIPTION (provided by applicant): New treatments are needed to decrease the complications of atherosclerosis, which include death, disability, heart attack, and amputation. Notably, collateral artery formation that "naturally" bypasses arterial obstructions occurs in all patients, but to a variable degree. Understanding the mechanisms of collateral artery formation and ischemic tissue necrosis could lead to new primary and adjuvant therapies for atherosclerosis. My long term research goal is to understand the basic mechanisms underlying collateral artery formation and tissue necrosis and specifically, in this application, ! will determine the influence of the immune system in collateral artery formation and tissue necrosis secondary to ischemia. Central to my hypothesis is that the recruitment and activation of inflammatory cells and the concomitant immune response influences collateral artery formation and susceptibility to tissue necrosis. I hypothesize that 1) immune differences account for their differential susceptibility to tissue necrosis in two inbred mouse strains, 2) T-cell recruitment and activation is an important determinant of susceptibility to tissue necrosis and 3) the MCP-1/CCR2 axis is an important determinant of susceptibility to tissue necrosis. Monocyte Chemoattractant Protein-1 (MCP-1) and its receptor CCR2 are important regulators of immune cell recruitment and differentiation. To test these hypotheses, I have in preliminary studies a) developed a mouse hind limb model of ischemia and have demonstrated that inbred strains of mice have differential susceptibilities to tissue necrosis; b) demonstrated that nude mice lacking T-cells and mice lacking MCP-1 or CCR2 have an increased incidence and severity of tissue necrosis as compared to wild type controls and c) shown that there is an increased recruitment of inflammatory cells to the ischemic hind limb. To test my hypothesis, I have proposed three specific aims. In aim #1, I will identify the mechanisms underlying the differential susceptibility to tissue necrosis in two inbred strains of mice. In aim #2, I will determine the role of T-cells and the Thl/Th2 immune response in tissue necrosis and in aim #3 I will determine the role of the MCP-1tCCR2 axis in tissue necrosis by using mice that are genetically inactivated for CCR2 and its ligand, MCP-1. The experiments outlined in this proposal are innovative because they utilize the power of genetic knockout mice in a hind limb ischemia model. I have assembled an experienced team of researchers in the diverse areas of vascular biology, immunology and physiology to test these hypotheses. The significance of this research is that a better understanding of the mechanisms of collateral artery formation and susceptibility to tissue necrosis could lead to the design of novel primary or adjuvant treatments for atherosclerotic occlusive disease and thereby decrease death and disability rates from myocardial infarction and amputations.