Regulation of MD-2 function and expression

MD-2 功能和表达的调节

基本信息

批准号：
8101047
负责人：
JERROLD P WEISS
金额：
$ 35.36万
依托单位：
UNIVERSITY OF IOWA
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-06-01 至 2014-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8101047
关键词：
Abbreviations Acids Acylation Affect Agonist Albumins Antigens Bacteria Binding Binding Proteins Binding Sites Biochemical Biological Buffers CCL4 gene CD14 gene Cells Complex Development Diet Disease Divalent Cations E protein Embryo Endotoxins Environment Epithelial Cells Epitopes Fatty Acids Glycolipids Gram-Negative Bacteria Gram-Negative Bacterial Infections Health Host Defense Human Hydrolase IL8 gene Immune Immune response Immunomodulators Infection Inflammation Inflammatory Response Interleukin-8 Invaded Irrigation Label Lead Ligands Lipid A Lipids Lipopolysaccharides Membrane Microbe Modeling Monoclonal Antibodies Mus Myelogenous Neisseria meningitidis Nonesterified Fatty Acids Nose Pathology Phosphate Buffer Phospholipids Phosphorylation Physiological Physiology Play Pneumonic Plague Proliferating Property Receptor Activation Recombinants Regulation Risk Role Saline Serum Albumin Signal Transduction Site Sodium Sodium Chloride Solutions Specific qualifier value Structure Surface Properties System TLR4 gene Toll-like receptors Translating Variant Virulence bactericidal permeability increasing protein in vivo insight kidney cell lipooligosaccharide lipopolysaccharide-binding protein mutant neutrophil novel novel strategies pathogen polyacrylamide gels polyhistidine protein E protein protein interaction public health relevance receptor response toll-like receptor 4

项目摘要

DESCRIPTION (provided by applicant): Host defense against many invading Gram-negative bacteria (GNB) depends upon innate immune recognition of endotoxin (E), unique, abundant and generally conserved glycolipids of GNB. Optimal TLR4- dependent responses are exquisitely sensitive and robust, but also self-limited. How this is normally achieved and why regulation of TLR4 activation may go awry under various patho-physiological conditions is incompletely known. The most potent inflammatory responses to E require certain canonical structural features of E and ordered protein-E and protein-protein interactions involving the LPS-binding protein (LBP), CD14, MD-2, and Toll-like receptor (TLR) 4. MD-2 plays an essential role in regulation of TLR4 activation by E, by bridging recognition of E, normally initiated by LBP and CD14, to receptor activation or antagonism. Our identification and characterization of monomeric E.MD-2 complexes as potent TLR4 agonists or antagonists, depending on E and/or MD-2 structure, have clearly demonstrated that it is the properties of the E.MD-2 complex, not E alone, that specifies TLR4 activation or receptor occupancy without activation. The unique structural and functional properties of these complexes suggest novel approaches to investigate how endotoxin induces TLR4 activation, how differences in E structure can dictate differences in TLR4 responsiveness, and how these new mechanistic insights may be translated to the development of novel TLR4-directed immunomodulators. Growing evidence of a broader array of molecules that can act as TLR4 agonists or antagonists, including host and/or diet-derived lipids, suggest many other circumstances in which the regulation or dysregulation of MD-2/TLR4 function could be pivotal in host physiology and patho-physiology. We will make use of novel synthetic, biochemical, structural biological, and functional approaches (e.g., metabolically labeled native and synthetic E and lipid A variants, recombinant wild-type and mutant human E-binding proteins and TLR4 ectodomain, monoclonal antibodies, models of airway infection and inflammation) to: 1) Further define the structural properties of ligands that promote binding to MD-2 and the action of ligand.MD-2 complexes as TLR4 agonists or antagonists; 2) Define more specifically the structural properties of E.MD-2 complexes that activate TLR4; and 3) Better define in vivo actions in the murine airway of wt and variant E(lipdA).Md-2. PUBLIC HEALTH RELEVANCE: TLR4-dependent cell activation by endotoxin plays a critical role in host response and defense against many Gram-negative bacteria. The ubiquity of endotoxin in the surrounding environment and the apparent existence of other microbe- and host-derived agonists/antagonists of TLR4 suggest an even broader role of TLR4 in health and disease. Better understanding of how endotoxin induces TLR4 activation and how differences in endotoxin structure dictate differences in TLR4 responsiveness is likely to lead to a better understanding of how mammalian hosts, including humans, normally respond effectively against invading Gram-negative bacteria and how certain Gram-negative bacterial pathogens can evade/resist these normally efficient host responses. The new mechanistic insights may also be translated to the development of novel TLR4-directed immuno-modulators whose application would likely include, but not be limited, to Gram-negative bacterial infections.

描述（由申请人提供）：宿主对许多入侵的革兰氏阴性菌（GNB）的防御依赖于内毒素（E）的先天免疫识别，内毒素（E）是GNB独特、丰富且普遍保守的糖脂。最佳的 TLR4 依赖性反应非常敏感且稳健，但也是自限性的。通常如何实现这一点以及为什么 TLR4 激活的调节在各种病理生理条件下可能会出错尚不完全清楚。对 E 最有效的炎症反应需要 E 的某些典型结构特征以及涉及 LPS 结合蛋白 (LBP)、CD14、MD-2 和 Toll 样受体 (TLR) 4 的有序蛋白质-E 和蛋白质-蛋白质相互作用。 MD-2 通过桥接通常由 LBP 和 CD14 启动的 E 识别与受体激活或拮抗，在 E 调节 TLR4 激活中发挥重要作用。我们根据 E 和/或 MD-2 结构对单体 E.MD-2 复合物作为有效 TLR4 激动剂或拮抗剂的鉴定和表征，清楚地证明了这是 E.MD-2 复合物的特性，而不是 E 单独的特性，指定 TLR4 激活或受体占用而不激活。这些复合物独特的结构和功能特性提出了新的方法来研究内毒素如何诱导 TLR4 激活、E 结构的差异如何决定 TLR4 反应性的差异，以及这些新的机制见解如何转化为新型 TLR4 导向的免疫调节剂的开发。越来越多的证据表明，更广泛的分子可以充当 TLR4 激动剂或拮抗剂，包括宿主和/或饮食来源的脂质，这表明在许多其他情况下，MD-2/TLR4 功能的调节或失调可能在宿主生理学中发挥关键作用和病理生理学。我们将利用新的合成、生化、结构生物学和功能方法（例如，代谢标记的天然和合成的 E 和脂质 A 变体、重组野生型和突变型人 E 结合蛋白和 TLR4 胞外域、单克隆抗体、气道感染和炎症）以：1）进一步定义促进与MD-2结合的配体的结构特性以及配体的作用。MD-2复合物作为TLR4激动剂或拮抗剂； 2) 更具体地定义激活TLR4的E.MD-2复合物的结构特性； 3)更好地定义wt和变体E(lipdA).Md-2在小鼠气道中的体内作用。公共卫生相关性：内毒素引起的 TLR4 依赖性细胞激活在宿主反应和防御许多革兰氏阴性细菌中发挥着关键作用。周围环境中普遍存在的内毒素以及其他微生物和宿主来源的 TLR4 激动剂/拮抗剂的明显存在表明 TLR4 在健康和疾病中具有更广泛的作用。更好地了解内毒素如何诱导 TLR4 激活，以及内毒素结构的差异如何决定 TLR4 反应性的差异，可能有助于更好地了解包括人类在内的哺乳动物宿主通常如何有效地应对入侵的革兰氏阴性菌，以及某些革兰氏阴性菌如何做出反应。细菌病原体可以逃避/抵抗这些通常有效的宿主反应。新的机制见解也可能转化为新型 TLR4 定向免疫调节剂的开发，其应用可能包括但不限于革兰氏阴性细菌感染。