Macrophage-Lipoprotein Interactions

巨噬细胞-脂蛋白相互作用

• 批准号: 10584618
• 负责人: Frederick R. Maxfield
• 金额: $ 42.38万
• 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 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10584618
• 关键词: 3-Dimensional; AGFG1 gene; Acid Lipase; Actins; Animal Model; Arterial Fatty Streak; Atherosclerosis; Biochemistry; Biological Assay; Biological Process; Blood Vessels; Bone Marrow; Cell Culture Techniques; Cells; Cellular biology; Cholesterol; Cholesterol Esters; Confocal Microscopy; Data; Deposition; Development; Electron Microscopy; Enzymes; Event; Exocytosis; Extracellular Matrix; Fluorescence Microscopy; Foam Cells; Functional disorder; Generations; Goals; Human; Hydrolase; Hydrolysis; Immune system; Inflammasome; Inflammatory; Inflammatory Response; Ions; Knockout Mice; Lipids; Lipoproteins; Low-Density Lipoproteins; Lysosomes; Macrophage; Macrophage Activation; Methods; Microscopy; Modeling; Molecular; Morphology; Mus; Optics; PIK3CG gene; Phagocytes; Polymers; Process; Production; Protein Kinase C; Proteins; Publishing; RNA Interference; Reporting; Resolution; Risk Assessment; Role; SNAP receptor; Scanning Electron Microscopy; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Small Interfering RNA; Structure; Synapses; TREM2 gene; Therapeutic Intervention; Transplantation; Work; crosslink; extracellular; improved; in vivo; knock-down; microscopic imaging; mouse model; novel; novel therapeutic intervention; novel therapeutics; optical imaging; phospholipase C gamma; response; seal; therapy development; three dimensional structure

Aggregates of lipoproteins that are tightly crosslinked to the extracellular matrix are the major type of lipoprotein in atherosclerotic lesions. The majority of the cholesterol in these aggregates is unesterified, but it has been unclear how the cholesteryl esters in the core of retained and aggregated extracellular LDL are hydrolyzed – especially because a lysosomal hydrolase has been reported to be involved. Our recent studies demonstrate a novel mechanism for the hydrolysis of cholesteryl esters in the core of retained and aggregated LDL in which macrophages (M) create tightly sealed compartments that surround portions of the aggregated LDL. They then acidify these compartments and secrete lysosomal enzymes into them, creating a lysosomal synapse. It has been shown that the extracellular hydrolysis of cholesteryl esters by lysosomal acid lipase, in a process called digestive exophagy, leads to production of unesterified cholesterol outside the cell, and transport of this cholesterol into the cell leads to foam cell formation. The high concentrations of cholesterol in the aggregated LDL were observed in a preliminary study to lead to the formation of extracellular cholesterol crystals, which can cause inflammatory responses in M . The overarching hypothesis of this proposal is that this mechanism for degrading lipoproteins has significant differences as compared to conventional phagocytic or endocytic mechanisms and that these differences have important consequences in the pathophysiology of atherosclerosis. Furthermore, understanding this process may lead to improved therapeutic interventions. Work in the first aim will characterize the molecular mechanisms of digestive exophagy. This will include a study of the Rab and SNARE proteins that are required for lysosomal exocytosis. Signaling by Tlr4, Myd88, PI3-kinase, Akt, Syk, Vav, Cdc42, and other molecules has been shown to be important for digestive exophagy, and the roles of additional signaling molecules will be explored. High concentrations of cholesterol are generated in aggregated LDL, and in Aim 2 formation of cholesterol crystals and resulting inflammatory activation of M will be examined. Work in the third aim will use optical imaging and 3-D electron microscopy (FIB-SEM) to examine the 3D structures of lysosomal synapses in a mouse atherosclerosis model. Formation of lysosomal synapses, association of cholesterol crystals with retained and aggregated LDL, and inflammatory activation will be studied in various mouse models of atherosclerosis by optical microscopy. Better understanding of the cellular and molecular events occurring in atherosclerotic lesions can lead to better risk assessments and potentially new therapies.

紧密交联至细胞外基质的脂蛋白的聚集体是主要类型 动脉粥样硬化病变中的脂蛋白。这些聚集体中的大多数胆固醇是未酯化的，但是 尚不清楚保留和聚合细胞外LDL的核心酯是如何 水解 - 尤其是因为据报道涉及溶酶体水解酶。我们最近的研究 展示了一种新型机制，用于在保留和聚集的核心中水解胆固醇酯的水解 LDL巨噬细胞（M）产生紧密密封的隔室，围绕聚合的部分 LDL。然后，他们将这些隔室和秘密溶酶体酶酸酸，形成溶酶体 突触。已经表明，溶酶体酸脂肪酶对胆固醇酯的细胞外水解 工艺称为消化性散发物，导致细胞外未酯化胆固醇的产生，并且 该胆固醇进入细胞会导致泡沫细胞形成。高浓度的胆固醇 在初步研究中观察到聚集的LDL，以导致细胞外胆固醇的形成 晶体，可能导致M炎症反应。该提议的总体假设是 与常规吞噬相比，这种降解脂蛋白的机制具有显着差异 或内吞机制，这些差异在病理生理中具有重要的后果 动脉粥样硬化。此外，了解这一过程可能会导致改进的治疗干预措施。 第一个目的的工作将表征消化散射的分子机制。这会 包括对溶酶体胞吐作用所需的RAB和SNARE蛋白的研究。 TLR4的信号， MyD88，PI3-激酶，AKT，SYK，VAV，CDC42和其他分子已被证明对消化很重要 将探索散射和其他信号分子的作用。 高浓度的胆固醇是在聚集的LDL中产生的，AIM 2形成 将检查胆固醇晶体和由M的炎症激活。 第三个目标的工作将使用光学成像和3-D电子显微镜（FIB-SEM）来检查 小鼠动脉粥样硬化模型中溶酶体突触的3D结构。溶酶体突触的形成， 胆固醇晶体与保留和聚集的LDL的关联，炎症激活将为 通过光学显微镜研究各种小鼠模型的动脉粥样硬化模型。 更好地了解在动脉粥样硬化病变中发生的细胞和分子事件 更好的风险评估和潜在的新疗法。