Pathophysiological Activities of Oxidized Phospholipids

描述（由申请人提供）：最近的研究表明，血小板活化在动脉粥样硬化病变形成的所有阶段中起重要作用：斑块破裂引发的起始、进展、稳定和血栓形成。另一个对动脉粥样硬化发展至关重要的事件是通过脂蛋白氧化产生生物活性脂质。大量证据表明，体内产生特异性氧化磷脂，并在动脉粥样硬化中发挥重要作用。我们最近已经确定了脂蛋白氧化的生理相关机制，并发现清道夫受体CD 36是负责识别氧化脂蛋白的主要受体。氧化型脂蛋白中结构保守的氧化胆碱甘油磷脂（oxPCcd 36）家族是CD 36的高亲和力配体。oxPCcd 36在体内产生，并在动脉粥样硬化病变中富集。oxPCcd 36与血小板结合并诱导血小板活化。清除剂受体B型（CD 36和SR-BI）似乎参与其中。我们假设血小板通过这些受体识别oxPCcd 36，这种相互作用导致体内血小板活化。这种激活可以解释动脉粥样硬化发展初始阶段血小板-单核细胞和血小板-内皮细胞的相互作用以及斑块富脂核心的血栓形成。该提案的长期目标是评估血小板与oxPCcd 36相互作用的分子和细胞机制及其在动脉粥样硬化和血栓形成过程中的作用。具体目标是：目标一。为了评估血小板识别oxPCcd 36的机制并确定清道夫受体B型在该过程中的作用，a）我们将表征血小板和相关受体识别oxPCcd 36的特异性，B）我们将鉴定氧化磷脂的结构基序，其对于与CD 36的结合是必需的。c）我们将确定CD 36识别oxPCcd 36- Aim II的分子要求。评估oxPCcd 36与血小板相互作用与血小板粘附、活化、聚集和单核细胞募集相关的生理和病理生理后果。我们将研究oxPCcd 36是否诱导血小板活化和粘附，通过各种测定进行评估。我们将测试SR-BI介导的与HDL的相互作用是否在血小板活化中起作用。我们将测试oxPCcd 36激活血小板是否会诱导血小板-单核细胞聚集体的形成。我们将进一步确定这种聚集体中的血小板是否可以激活单核细胞。Aim III.我们将寻求证据表明oxPCcd 36可以通过体内CD 36诱导血小板活化。我们将评估oxPCcd 36是否能够在体内诱导血小板活化和血小板-单核细胞聚集体的形成。我们将研究清道夫受体B型在体内高胆固醇血症条件下oxPCcd 36的作用。总的来说，从这项研究中获得的数据应该提供关于CD 36在动脉粥样硬化和急性冠状动脉事件发展中的作用的新信息。

DESCRIPTION (provided by applicant): Recent studies indicate that platelet activation plays an important role in all stages of atherosclerotic lesion formation: initiation, progression, stability and thrombosis triggered by plaque rupture. Another event that is critical for the development of atherosclerosis is the generation of biologically active lipids via oxidation of lipoproteins. Considerable evidence has shown that specific oxidized phospholipids are generated in vivo and play a significant role in atherosclerosis. We have recently identified a physiologically relevant mechanism of lipoprotein oxidation and have found that the scavenger receptor CD36 is a major receptor responsible for the recognition of oxidized lipoproteins. A novel structurally conserved family of oxidized choline glycerophospholipids (oxPCcd36) in oxidized lipoproteins serves as high affinity ligands for CD36. oxPCcd36 is generated in vivo, and is enriched in atherosclerotic lesions . oxPCcd36 binds to platelets and induces platelet activation. Scavenger receptors type B (CD36 and SR-BI) appear to be involved. We hypothesized that platelets recognize oxPCcd36 via these receptors and this interaction leads to platelet activation in vivo. This activation could account for the platelet-monocyte and platelet-endothelial cell interaction in the initial stages of atherosclerosis development and for thrombogenicity of the lipid-rich core of plaque. The long-term goal of this proposal is to assess the molecular and cellular mechanisms of platelet interactions with oxPCcd36 and their role in the process of atherogenesis and thrombosis. The Specific Aims are: Aim I. To assess the mechanism by which platelet recognize oxPCcd36 and to determine the role of scavenger receptors type B in this process, a) We will characterize the specificity of oxPCcd36 recognition by platelets and receptors involved, b) We will identify the structural motifs of oxidized phospholipids that are essential for the binding to CD36. c) We will determine the molecular requirements for CD36 to recognize oxPCcd36- Aim II. To assess the physiological and pathophysiological consequences of the interaction of oxPCcd36 and platelets as related to platelet adhesion, activation, aggregation, and monocyte recruitment. We will study whether oxPCcd36 induces platelet activation and adhesion as assessed by a variety of assays. We will test whether SR-BI mediated interaction with HDL plays a role in platelet activation. We will test whether platelet activation by oxPCcd36 will induce the formation of platelet-monocyte aggregates. We will further determine whether platelets in such aggregates can activate monocytes. Aim III. We will seek to obtain evidence that oxPCcd36 can induce platelet activation via CD36 in vivo. We will assess whether oxPCcd36 are able to induce platelet activation and formation of platelet-monocyte aggregates in vivo. We will study the role of scavenger receptors type B in effects of oxPCcd36 in vivo in conditions of hypercholesterolemia. Collectively, the data obtained from this study should provide new information about the role of CD36 in development of atherosclerosis and acute coronary events.