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）：动脉粥样硬化的部分原因是脂蛋白在动脉壁中的积累，单核细胞/巨噬细胞募集到该地区，以及形成含脂质的巨噬细胞的形成，称为泡沫细胞。泡沫细胞的形成取决于特定细胞内室之间与脂蛋白的相互作用以及随后的细胞胆固醇转运。该项目将研究脂蛋白和巨噬细胞的特征如何导致泡沫细胞的形成以及动脉粥样硬化的发病机理。将检查此过程的几个关键方面。首先，血管壁中的许多脂蛋白聚集并紧密地结合到细胞外基质成分，这通过简单的内吞过程来阻止它们的内在化。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，接触时间很长。初步数据表明，在此接触期间，巨噬细胞形成了一个异常的细胞外，酸性，消化室。使用定量荧光显微镜将进一步表征该细胞外室的酸化，并将检查酸化机制。细胞外室的结构将使用中间电压电子显微镜和断层扫描成像检查。还将检查将酸水解酶输送到室内的机制，包括钙信号传导和特定的圈套分子在与质膜中介导溶酶体融合中的作用。该室中溶酶体酸脂肪酶的存在将导致胆固醇酯的水解并释放游离固醇，可以将其局部插入到质膜中。富有特征的荧光固醇及其酯衍生物将掺入脂蛋白中，以直接监测该过程。将研究该室中其他分解代谢过程（例如，蛋白质降解）。胆固醇向质膜的递送导致信号转导机制的激活，包括小GTPase，RAC，导致肌动蛋白聚合增加。将检查从聚集的脂蛋白到RAC，RHO和PI3-激酶活性以及肌动蛋白组装的巨噬细胞递送到巨噬细胞的后果。肌动蛋白增加增加细胞外，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。不同类别的巨噬细胞对聚集的脂蛋白的反应不同。在组织培养中，将比较源自经典和非经典单核细胞与聚集的脂蛋白的巨噬细胞与聚集的脂蛋白的相互作用。还将研究在动脉粥样硬化小鼠模型中的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：该项目研究了由于免疫系统细胞（巨噬细胞）与血管壁上脂蛋白之间的相互作用而导致动脉粥样硬化病变的早期步骤。这些动脉粥样硬化病变会导致心脏病和中风，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，以防止或扭转动脉粥样硬化病变的形成。