Early Forms of Oxidized LDL, TLRs and Atherosclerosis

描述（由申请人提供）：低密度脂蛋白的氧化修饰是一个重要的，如果不是强制性的，介导低密度脂蛋白动脉粥样硬化的步骤。许多病理条件和环境因素促进LDL氧化，特别是形成早期形式的氧化LDL，称为最小修饰LDL （mmLDL）。除了在动脉粥样硬化病变中存在氧化LDL外，最近的报告发现，即使在表面健康的个体血液中也存在早期氧化形式的LDL，并且在心血管疾病患者中水平升高。本提案将检验我的假设，即mmLDL通过调节toll样受体（TLR）信号传导促进动脉粥样硬化病变中的炎症。我们最近发表的研究结果支持了这一假设，即mmLDL（而非广泛氧化的LDL）与CD14结合，该复合物激活TLR4，导致细胞骨架重排、促炎信号和细胞因子表达。此外，我们的初步数据表明，mmLDL增加了体外巨噬细胞分泌lps诱导的细胞因子。CD14和TLR4是感知细菌LPS的重要先天免疫受体。mmLDL信号通过CD14/TLR4的存在提示免疫应答对氧化特异性自身抗原和微生物病原体的趋同。我提出本项目的具体目的如下：1)验证mmLDL诱导TLR4与巨噬细胞表面其他受体特异性聚集，从而启动独特的细胞内信号级联的假设。2)验证一组独特的促炎基因在响应mmLDL时的表达和分泌是tlr4依赖性和独立信号通路之间串扰的结果。3)在炎症动物模型中验证mmLDL增强LPS及其他TLR配体诱导的促炎基因表达的假设。4)验证mmLDL促进动脉粥样硬化病变中tlr依赖性炎症的假说。我的假设的进一步发展将有助于阐明慢性炎症在动脉粥样硬化发展中的机制，并更好地理解特定微生物病原体如何增加动脉粥样硬化并发症的风险。由于mmLDL中的氧化部分通常可能是氧化膜的共同组成部分，因此这些研究可能具有普遍的重要性。

DESCRIPTION (provided by applicant): Oxidative modification of LDL is an important, if not obligatory, step that mediates the atherogenicity of LDL. Many pathological conditions and environmental factors promote LDL oxidation, especially formation of early forms of oxidized LDL, termed minimally modified LDL (mmLDL). In addition to established presence of oxidized LDL in atherosclerotic lesions, recent reports find early oxidized forms of LDL even in the blood of apparently healthy individuals, and elevated levels in people with cardiovascular disease. This proposal will examine my hypothesis that mmLDL promotes inflammation in atherosclerotic lesions via modulation of Toll-like receptor (TLR) signaling. This hypothesis has been supported by our recently published findings that mmLDL, but not extensively oxidized LDL, binds to CD14 and that this complex activates TLR4, resulting in cytoskeletal rearrangements and pro-inflammatory signaling and cytokine expression. In addition, our preliminary data demonstrate that mmLDL augments LPS-induced cytokine secretion by macrophages in vitro. CD14 and TLR4 are crucial innate immune receptors that sense bacterial LPS. The existence of mmLDL signaling through CD14/TLR4 suggests convergence of immune responses to oxidation-specific self-antigens and to microbial pathogens. I propose the following Specific Aims for this project: 1) To test the hypothesis that mmLDL induces specific clustering of TLR4 with other receptors on the surface of macrophages, thereby initiating a unique intracellular signaling cascade. 2) To test the hypothesis that a unique set of pro-inflammatory genes expressed and secreted in response to mmLDL is a result of a crosstalk between TLR4-dependent and independent signaling pathways. 3) To test the hypothesis that mmLDL augments pro-inflammatory gene expression induced by LPS and other TLR ligands in animal models of inflammation. 4) To test the hypothesis that mmLDL promotes TLR-dependent inflammation in atherosclerotic lesions. Further development of my hypothesis will help elucidate mechanisms of chronic inflammation in development of atherosclerosis and better understand how particular microbial pathogens increase the risk of atherosclerotic complications. Because the oxidized moieties in mmLDL are likely to be common components of oxidized membranes in general, these studies are likely to have generalized importance.