The role of the G2A receptor in Atherosclerosis

G2A受体在动脉粥样硬化中的作用

• 批准号: 7879341
• 负责人: JANUSZ H KABAROWSKI
• 金额: $ 36.25万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-30 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7879341
• 关键词: Ablation; Address; Antiatherogenic; Aorta; Apolipoproteins; Apoptosis; Arterial Fatty Streak; Arterial Intimas; Arteries; Atherosclerosis; Attenuated; Biological; Biological Assay; Bone Marrow; Bone Marrow Cells; Bone Marrow Stem Cell; Cell Adhesion Molecules; Cells; Chemosensitization; Chemotaxis; Cholesterol; Chronic; Clinical; Dependence; Development; Disease; Electrospray Ionization; Endothelial Cells; Endothelium; Enzymes; Event; Exhibits; G-Protein-Coupled Receptors; G2A receptor; Genetic; Goals; Hepatocyte; High Density Lipoprotein Cholesterol; High Density Lipoproteins; Hydrolysis; Immunofluorescence Immunologic; In Vitro; Individual; Infiltration; Inflammation; Inflammatory; Knock-out; LDL Cholesterol Lipoproteins; Laboratories; Lecithin; Lesion; Link; Lipoproteins; Liquid Chromatography; Liver; Low Density Lipoprotein Receptor; Low Density Lipoprotein oxidation; Low-Density Lipoproteins; Lymphocyte; Lysophosphatidylcholines; Lysophospholipids; Manuscripts; Measures; Mediating; Mediator of activation protein; Metabolism; Methods; Modification; Molecular; Mus; Penetrance; Performance; Phospholipase A2; Phospholipids; Plasma; Platelet Activating Factor; Process; Production; Regulation; Research Personnel; Retroviridae; Risk Factors; Role; Signal Transduction; Site; Source; Specificity; Staining method; Stains; Stimulus; Testing; Transplantation; Western Blotting; atherogenesis; cell type; chemokine; group X secretory phospholipase A(2); hematopoietic tissue; hypercholesterolemia; in vivo; macrophage; monocyte; overexpression; particle; programs; receptor; research study; response; scavenger receptor; therapeutic development; uptake; vascular inflammation

DESCRIPTION (provided by applicant): Atherosclerosis is a chronic inflammatory disease characterized by the accumulation and subsequent modification of low-density lipoprotein (LDL)-cholesterol particles within the arterial wall. Establishing which of the many biological effects of modified LDL demonstrable in vitro are relevant to atherogenesis in vivo, and identifying the mechanisms of action and production of the principal molecular components responsible, remain important goals in the search for new targets for therapy in atherosclerosis. Lysophosphatidylcholine (LPC) is a major product of LDL oxidation and phospholipid hydrolysis by pro-inflammatory phospholipase A2 (PLA2) enzymes. It has been proposed that a principal effect of LPC is to promote sub-endothelial macrophage recruitment into the arterial wall at atherosclerotic foci by directly attracting monocytes and activating endothelial cells. The recently identified role of the G protein-coupled receptor, G2A, as a mediator of chemotaxis to LPC has led to the proposal that this key event is promoted by G2A. Loss of G2A function in atherosclerosis-susceptible low-density lipoprotein receptor knockout (LDLR-/-) mice led to robust suppression of aortic atherosclerosis. Intimal monocyte infiltration at lesion-prone sites of the aorta was significantly suppressed in G2A-deficient LDLR-/- (G2A-/-LDLR-/-) mice. However, elevated HDL-cholesterol levels in G2A-/-LDLR-/- mice revealed possible G2A-mediated effects on lipoprotein metabolism. Thus, G2A provides a pro-atherogenic stimulus in vivo consistent with penetrance of its chemotactic action but to which alterations in lipoprotein metabolism may also contribute. We hypothesize that stimulation of sub-endothelial monocyte infiltration in response to locally generated LPC is the principal mechanism by which G2A promotes atherosclerosis in LDLR-/- mice and that this is mediated independently of G2A-expressing endothelium. We propose that modulation of HDL-cholesterol levels by G2A is due to direct effects of this receptor on macrophage cholesterol efflux and this partially contributes to its pro-atherogenic action. To address these hypotheses, we will generate chimeric LDLR-/- mice in which G2A deficiency or G2A expression is restricted to bone marrow derived cells. HDL composition and macrophage cholesterol efflux will be examined in G2A??/- and G2A-/-LDLR-/- mice to determine the cellular mechanism by which G2A modulates HDL-cholesterol levels in hypercholesterolemic LDLR-/- mice. Finally, the LPC-dependence of G2A-mediated pro-atherogenic action will be investigated by macrophage-restricted overexpression of secretory PLA2 group X in LDLR-/- mice using a macrophage-specific retrovirus. By determining the cell specificity and LPC-dependence of G2A action, these studies will provide a molecular framework for the development of therapeutic approaches to target G2A and thereby attenuate atherosclerosis.

描述（由申请人提供）：动脉粥样硬化是一种慢性炎症性疾病，其特征是动脉壁内低密度脂蛋白（LDL）胆固醇颗粒的积累和随后的改变。确定体外可证实的修饰 LDL 的众多生物学效应中的哪些与体内动脉粥样硬化相关，并确定主要分子成分的作用机制和产生机制，仍然是寻找动脉粥样硬化治疗新靶点的重要目标。溶血磷脂酰胆碱 (LPC) 是促炎磷脂酶 A2 (PLA2) 酶氧化 LDL 和磷脂水解的主要产物。有人提出，LPC 的主要作用是通过直接吸引单核细胞并激活内皮细胞，促进内皮下巨噬细胞募集到动脉粥样硬化病灶处的动脉壁中。最近确定的 G 蛋白偶联受体 G2A 作为 LPC 趋化介质的作用导致有人提出这一关键事件是由 G2A 促进的。动脉粥样硬化易感性低密度脂蛋白受体敲除 (LDLR-/-) 小鼠中 G2A 功能的丧失导致主动脉粥样硬化的强烈抑制。在 G2A 缺陷 LDLR-/- (G2A-/-LDLR-/-) 小鼠中，主动脉易病变部位的内膜单核细胞浸润明显受到抑制。然而，G2A-/-LDLR-/- 小鼠中高密度脂蛋白胆固醇水平升高揭示了 G2A 可能介导的对脂蛋白代谢的影响。因此，G2A 在体内提供促动脉粥样硬化刺激，与其趋化作用的外显率一致，但脂蛋白代谢的改变也可能对此有所贡献。我们推测，局部产生的 LPC 刺激内皮下单核细胞浸润是 G2A 促进 LDLR-/- 小鼠动脉粥样硬化的主要机制，并且这是独立于表达 G2A 的内皮介导的。我们认为，G2A 对 HDL 胆固醇水平的调节是由于该受体对巨噬细胞胆固醇流出的直接影响，这部分促成了其促动脉粥样硬化作用。为了解决这些假设，我们将产生嵌合 LDLR-/- 小鼠，其中 G2A 缺陷或 G2A 表达仅限于骨髓来源的细胞。将在G2Aβ/-和G2A-/-LDLR-/-小鼠中检查HDL组成和巨噬细胞胆固醇流出，以确定G2A调节高胆固醇血症LDLR-/-小鼠中HDL胆固醇水平的细胞机制。最后，将使用巨噬细胞特异性逆转录病毒在 LDLR-/- 小鼠中通过巨噬细胞限制性过表达分泌型 PLA2 X 组来研究 G2A 介导的促动脉粥样硬化作用的 LPC 依赖性。通过确定 G2A 作用的细胞特异性和 LPC 依赖性，这些研究将为开发针对 G2A 的治疗方法提供分子框架，从而减轻动脉粥样硬化。