EXPLORING CD14-DEPENDENT ENDOTOXIN RECOGNITION MECHANISM

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 内毒素如LPS和PGN，来自革兰氏阴性和革兰氏阳性细菌的外细胞壁的组分是人类单核细胞和巨噬细胞的有效免疫刺激剂，并且已经涉及脓毒症和脓毒性休克的发病机制，仅在美国每年导致250，000例死亡的临床进展。作为先天免疫的一部分的炎症反应通过这些内毒素与关键宿主细胞受体CD 14的高亲和力结合而引发，从而通过涉及Toll样受体的信号转导途径触发多种促炎介质（包括细胞因子）的释放。然而，这种细胞反应的过度激活可能导致促炎介质的过度释放，诱导败血性休克和死亡。已知CD 14通过调节炎症反应和增强内毒素诱导的活化的敏感性在先天系统中发挥中心作用。然而，它实现这一点的分子机制尚不清楚。拟议的研究集中在理解CD 14-内毒素相互作用的分子细节与所有原子分子动力学模拟。根据我们的高分辨率NMR光谱结果（表明人CD 14与各种内毒素和配体之间的潜在结合界面），将应用特定模拟来鉴定参与与不同内毒素相互作用的关键CD 14残基。模拟结果将通过诱变和生物物理研究进一步检验。这些研究的完成将为LPS、PGN的毒性作用和合理设计治疗脓毒症的潜在新型LPS、PGN拮抗剂提供结构基础。

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.