Endotoxin Neutralization by HDL-Mimetic Peptide

描述(由申请人提供)： 这项建议的目标是为申请者提供以下方面的强化培训 这项研究的目的是提高申请人的研究技能和专业知识，以促进其成为一名独立的研究人员。候选人将接受资深研究人员和多学科咨询委员会的指导，并将开展一项教育计划(课程作业、会议和研讨会)和一项研究项目，以解决HDL模拟肽减轻脂多糖(LPS)介导的脓毒症的保护机制。败血症是一个主要的健康问题。25%-30%的脓毒症是由革兰氏阴性菌(GNB)感染引起的。脂多糖是GNB外膜的一种成分，它介导了与脓毒症相关的许多毒性效应。结果表明，高密度脂蛋白治疗脓毒症可能是有效的。然而，获得治疗剂量的高密度脂蛋白是不切实际的。高密度脂蛋白中和内毒素的一种机制被认为是通过将内毒素的脂类A结构域插入和掩蔽到覆盖在高密度脂蛋白表面的磷脂小叶中而发生的。这可能是由于载脂蛋白A-L(高密度脂蛋白的主要蛋白质成分)和脂多糖的脂A成分的分子形状互补所致。我们开发了一种基于载脂蛋白A-L结构的新型多肽。该肽4F是一种A类两亲性螺旋分子，具有许多载脂蛋白A-L的抗动脉粥样硬化特性。 4F的有益作用被认为是由于它能够调节高密度脂蛋白的性质，包括形成前β-高密度脂蛋白样颗粒。我们观察到，4F的分子形状与脂类A的分子形状是互补的。在这一应用中，我们证明了在体外和体内，给药4F显著减少了内毒素诱导的炎性细胞因子和黏附分子的激活。我们提出了载脂蛋白A-L模拟肽4F抑制脂多糖诱导的炎症过程的新假说，并将检验这种反应是否源于：1)脂蛋白A与4F之间的直接物理相互作用；2)4F的间接作用，通过促进载脂蛋白A-L丰富的前β-高密度脂蛋白样颗粒的形成，从而增强高密度脂蛋白清除内毒素的能力。本研究对于了解载脂蛋白A-L和高密度脂蛋白在脂多糖介导的脓毒症中的作用具有重要意义。这也将为开发高密度脂蛋白模拟肽作为有效的败血症/炎症治疗剂提供理论基础。 (摘要结束)

DESCRIPTION (provided by applicant): The objectives of this proposal are to provide the applicant with intensive training in the areas of inflammation and lipidology and to advance applicant's research skills and expertise so as to facilitate his development as an independent investigator. The candidate will be mentored by established investigators and a multidisciplinary advisory committee and will pursue a program of education (coursework, conferences, and seminars) and a research project addressing the protective mechanisms by which an HDLmimetic peptide attenuates lipopolysaccharide (LPS)-mediated sepsis. Sepsis is a major health problem. 25- 30% of all cases of sepsis is due to gram negative bacterial (GNB) infection. LPS, a component of the outer membrane of GNB, mediates many of the toxic effects associated with sepsis. Results indicate that HDL administration may be effective in treating sepsis. However obtaining therapeutic quantities of the HDL is impractical. One mechanism by which HDL neutralizes LPS is thought to occur by insertion and masking of the lipid A domain of LPS into the phospholipid leaflet that covers the surface of HDL. This may occur due to complementary molecular shape of apo A-l (a major protein constituent of HDL) and the lipid A component of LPS. We have developed a novel peptide whose design is based on the structure of apo A-l. This peptide 4F is a class A amphipathic helical molecule that has many of the anti-atherosclerotic properties of apo A-l. Beneficial effects of 4F are thought to be due to its ability to modulate HDL properties including formation of pre-beta HDL like particles. We have observed that the molecular shape of 4F is complementary to that of lipid A. In this application, we demonstrate that administration of 4F significantly reduces LPS-induced activation of inflammatory cytokines and adhesion molecules both in-vitro and in-vivo. We propose the novel hypothesis that the apo A-l mimetic peptide 4F inhibits LPS induced inflammatory processes and will test whether this response is due to : i) Direct physical interaction between lipid A and 4F; ii) Indirect effects of 4F, by promoting the formation of apo A-l rich pre-beta HDL-like particles and thus enhancing the LPS scavenging capacity of HDL. This study will have important implications in understanding the role of apo A-l and HDL in LPS mediated sepsis. It will also provide a rationale for developing HDL-mimetic peptides as effective therapeutic agents against sepsis/inflammation. (End of Abstract)