Macrophage-lipoprotein interactions

巨噬细胞-脂蛋白相互作用

• 批准号: 7650897
• 负责人: Frederick R. Maxfield
• 金额: $ 42.25万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7650897
• 关键词: 1-Phosphatidylinositol 3-Kinase; Acid Lipase; Acids; Actins; Affect; American; Arterial Fatty Streak; Atherosclerosis; Binding; Biology; Blood; Blood Vessels; Calcium Signaling; Catabolic Process; Cell membrane; Cell physiology; Cells; Cellular biology; Cessation of life; Characteristics; Cholesterol; Cholesterol Esters; Cholesterol Homeostasis; Cyclodextrins; Data; Electron Microscopy; Esters; Extracellular Matrix; Extracellular Structure; F-Actin; Fluorescence Microscopy; Foam Cells; Gene Expression; Heart Diseases; Heterogeneity; Human; Hydrolase; Hydrolysis; Image; Immune system; Lead; Lesion; Life; Lipid-Laden Macrophage; Lipoproteins; Low-Density Lipoproteins; M cell; Measures; Mediating; Membrane; Microscopy; Monitor; Monomeric GTP-Binding Proteins; Pathogenesis; Phosphatidylinositols; Play; Process; Receptor Signaling; Recruitment Activity; Regulation; Research; Role; SNAP receptor; Signal Pathway; Signal Transduction; Signaling Protein; Sterols; Stroke; Testing; Work; atherogenesis; base; cholesterol analog; disability; extracellular; inhibitor/antagonist; macrophage; monocyte; mouse model; novel; polymerization; prevent; protein degradation; public health relevance; ratiometric; receptor; response; rho; tissue culture; uptake; vacuolar H+-ATPase; voltage

DESCRIPTION (provided by applicant): Atherosclerosis results in part from the accumulation of lipoproteins in the arterial wall, recruitment of monocytes/macrophages to the region, and formation of lipid-laden macrophages, known as foam cells. Foam cell formation is dependent on interactions with lipoproteins and subsequent cellular cholesterol transport among specific intracellular compartments. This project will examine how characteristics of both the lipoprotein and the macrophage lead to foam cell formation and the pathogenesis of atherosclerosis. Several key aspects of this process will be examined. First, many of the lipoproteins in the wall of blood vessels become aggregated and tightly bound to extracellular matrix components, and this prevents their internalization by simple endocytic processes. When macrophages encounter these aggregated lipoproteins, there is a prolonged period of contact before the lipoprotein is internalized. Preliminary data indicate that macrophages form an unusual extracellular, acidic, digestive compartment during this contact period. The acidification of this extracellular compartment will be characterized further using quantitative fluorescence microscopy, and the mechanism for acidification will be examined. The structure of the extracellular compartment will be examined using intermediate voltage electron microscopy and tomographic imaging. The mechanism for delivering acid hydrolases into the compartment will also be examined, including the role of calcium signaling and specific SNARE molecules in mediating lysosomal fusion with the plasma membrane. The presence of lysosomal acid lipase in this compartment would lead to hydrolysis of cholesterol esters and release of free sterol, which can be inserted locally in to the plasma membrane. Well- characterized fluorescent sterols and their ester derivatives will be incorporated into lipoproteins to monitor this process directly. Other catabolic processes (e.g., protein degradation) in this compartment will be investigated. Delivery of cholesterol to the plasma membrane leads to activation of signal transduction mechanisms, including the small GTPase, Rac, leading to increased actin polymerization. The consequences of sterol delivery from aggregated lipoproteins to macrophages on Rac, Rho and PI3-kinase activity and actin assembly will be examined. The possibility that increased actin assembly enlarges the extracellular, acidic, digestive compartment will be examined using inhibitors of these signaling proteins. Different classes of macrophages may respond differently to aggregated lipoproteins. The interactions of macrophages derived from classical and nonclassical monocytes with aggregated lipoproteins will be compared in tissue culture. The abundance of macrophages and foam cells derived from classical and nonclassical Mo subsets in atherosclerotic lesions in mouse models of atherosclerosis will also be examined. PUBLIC HEALTH RELEVANCE: This project examines the early steps leading to an atherosclerotic lesion as a consequence of the interaction between an immune system cell, the macrophage, with lipoproteins in the wall of blood vessels. These atherosclerotic lesions can lead to heart disease and stroke, which are major causes of disability and death of Americans. Research findings based on these studies may lead to new treatments to prevent or reverse the formation of atherosclerotic lesions.

描述（由申请人提供）：动脉粥样硬化部分是由于脂蛋白在动脉壁中的积累、单核细胞/巨噬细胞向该区域的募集以及富含脂质的巨噬细胞（称为泡沫细胞）的形成所致。泡沫细胞的形成依赖于与脂蛋白的相互作用以及随后的细胞胆固醇在特定细胞内区室之间的转运。本研究将探讨脂蛋白和巨噬细胞的特性如何导致泡沫细胞的形成和动脉粥样硬化的发病机制。将审查这一进程的几个关键方面。首先，血管壁中的许多脂蛋白聚集并与细胞外基质成分紧密结合，这阻止了它们通过简单的内吞过程内化。当巨噬细胞遇到这些聚集的脂蛋白时，在脂蛋白被内化之前有一段长时间的接触。初步数据表明，巨噬细胞形成一个不寻常的细胞外，酸性，消化室在此接触期间。将使用定量荧光显微镜进一步表征该细胞外室的酸化，并将检查酸化的机制。将使用中压电子显微镜和断层成像检查细胞外室的结构。还将检查用于将酸性水解酶递送到隔室中的机制，包括钙信号传导和特定SNARE分子在介导溶酶体与质膜融合中的作用。在该隔室中溶酶体酸性脂肪酶的存在将导致胆固醇酯的水解和游离固醇的释放，其可以局部插入质膜中。特征明确的荧光甾醇及其酯衍生物将被掺入脂蛋白中以直接监测这一过程。其他分解代谢过程（例如，蛋白质降解）。将胆固醇递送至质膜导致信号转导机制的激活，包括小的GTdR，Rac，导致增加的肌动蛋白聚合。将检查固醇从聚集的脂蛋白递送到巨噬细胞对Rac、Rho和PI 3-激酶活性和肌动蛋白组装的影响。增加肌动蛋白组装扩大细胞外，酸性，消化室的可能性将使用这些信号蛋白的抑制剂进行检查。不同种类的巨噬细胞可能对聚集的脂蛋白有不同的反应。将在组织培养中比较来自经典和非经典单核细胞的巨噬细胞与聚集的脂蛋白的相互作用。还将检查动脉粥样硬化小鼠模型中动脉粥样硬化病变中源自经典和非经典Mo亚群的巨噬细胞和泡沫细胞的丰度。公共卫生相关性：本项目研究导致动脉粥样硬化病变的早期步骤，作为免疫系统细胞，巨噬细胞与血管壁中的脂蛋白之间相互作用的结果。这些动脉粥样硬化病变可导致心脏病和中风，这是美国人残疾和死亡的主要原因。基于这些研究的研究结果可能会导致新的治疗方法，以防止或逆转动脉粥样硬化病变的形成。