EXPLORING CD14-DEPENDENT ENDOTOXIN RECOGNITION MECHANISM

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 内毒素是革兰氏阴性和革兰氏阳性细菌外细胞壁的组成部分，是人类单核细胞和巨噬细胞的强大免疫刺激因子，与败血症和感染性休克的发病机制有关，这种临床进展仅在美国就导致25万人死亡。作为先天免疫的一部分，炎症反应是通过这些内毒素与关键的宿主细胞受体CD14的高亲和力结合来启动的，通过涉及Toll样受体的信号转导途径触发包括细胞因子在内的各种促炎介质的释放。然而，这种细胞反应的过度激活可能会导致促炎介质的过度释放，导致感染性休克和死亡。已知CD14通过调节炎症反应和增强内毒素诱导的激活敏感性，在先天系统中发挥核心作用。然而，它实现这一目标的分子机制尚不清楚。建议的研究集中在用全原子分子动力学模拟来理解CD14-内毒素相互作用的分子细节。根据我们的高分辨率核磁共振谱结果，我们将使用特定的模拟来确定与不同内毒素相互作用的关键CD14残基，这表明了人CD14与各种内毒素和配体之间的潜在结合界面。模拟结果将通过诱变和生物物理研究进一步验证。这些研究的完成将为研究内毒素、前列环素的有害作用和合理设计潜在的新型内毒素、前列环素拮抗剂治疗脓毒症提供结构基础。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Endotoxins such as LPS and PGN, components of outer cell walls from Gram-negative and Gram-positive bacteria are potent immunostimulators of monocytes and macrophages in humans and have been implicated in the pathogenesis of sepsis and septic shock, a clinical progression that results in 250,000 deaths annually in the United States alone. Inflammatory responses as part of innate immunity are initiated via high-affinity binding of these endotoxins to a key host cell receptor CD 14, triggering release of a variety of pro inflammatory mediators, including cytokines, through a signal transduction pathway involving Toll-like receptors. An overactivation of this cellular response may, however, result in excessive release of the proinflammatory mediators, inducing septic shock and death. CD 14 is known to play a central role in the innate system, by modulating the inflammatory response and enhancing the sensitivity of endotoxininduced activation. However, the molecular mechanisms by which it accomplishes this are not clear. The proposed studies are focused on understanding the molecular details of CD 14-endotoxin interactions with all atom molecular dynamics simulations. Specific simulations will be applied to identify key CD14 residues involved in interaction with different endotoxins according to our high resolution NMR spectroscopy results which indicated the potential binding interfaces between human CD14 and various endotoxins and ligands. Simulation results will be further tested by mutagenesis and biophysical studies. Completion of these studies will provide the structural basis for the deleterious effects of LPS, PGN and rational design of potentially novel LPS, PGN antagonists for treatment of sepsis.