TLR4 Mutations: Molecular Mechanisms of Impaired LPS Sensitivity

TLR4 突变：LPS 敏感性受损的分子机制

基本信息

批准号：
7870345
负责人：
ANDREI E MEDVEDEV
金额：
$ 18.56万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-06-15 至 2012-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7870345
关键词：
Affect Alleles Alveolar Macrophages Apoptosis Boutonneuse Fever Breathing CD14 Antigen CD14 gene Candida Cell Line Cessation of life Communicable Diseases Data Dendritic Cells Development Disseminated Intravascular Coagulation Dissociation Endothelial Cells Epithelial Cells Escherichia coli Failure Gene Expression Genetic Polymorphism Gram-Negative Bacteria Gram-Negative Bacterial Infections Health Host Defense Human IL8 gene IRF3 gene Immune Immune response Immune system Incidence Individual Inflammation Mediators Inflammatory Inflammatory Response Knock-in Mouse Life Link Lipopolysaccharides Literature Malaria Mediating Microbe Molecular Multiple Organ Failure Mus Mutation Patients Pattern Phagocytosis Pharmaceutical Preparations Pharmacologic Substance Phosphotransferases Point Mutation Predisposition Prevention Production Publishing Reaction Receptor Signaling Reporting Research Respiratory Syncytial Virus Infections Sepsis Septic Shock Signal Pathway Signal Transduction Signaling Molecule Single Nucleotide Polymorphism Survival Rate TLR4 gene Testing Toll-Like Receptor Pathway Toll-like receptors Tuberculosis Tyrosine Phosphorylation Variant base cytokine design enzyme activity human subject macrophage monocyte mutant neutrophil new therapeutic target novel therapeutic intervention pathogen public health relevance receptor receptor function receptor-mediated signaling response transcription factor

项目摘要

DESCRIPTION (provided by applicant):TLR4, the predominant signaling receptor for LPS, is critical for host defense against Gram negative bacterial infections. Two point mutations, D299G and T399I, in the ectodomain of TLR4 have been associated with a blunted response to inhaled LPS, increased incidence of Gram negative bacterial infection and sepsis. These results suggest that these mutations alter the capacity of TLR4 to signal, leading to impaired host immune response against bacterial pathogens. The molecular mechanisms by which TLR4 polymorphisms affect receptor-mediated signaling are currently unknown. The central hypothesis to be tested is that the single nucleotide polymorphisms alter TLR4 recognition of Gram negative bacteria and LPS, its interactions with co-receptors and recruitment and activation of adapters and kinases, resulting in impaired TLR4 signaling and deficient host immune response against pathogens. This hypothesis will be examined by pursuit of the following Specific Aims: (1) Define whether the TLR4 SNPs alter recognition of Gram negative bacteria and LPS, receptor signalosome assembly, and activation of kinases and transcription factors; (2) Determine the effect of the TLR4 SNPs on expression of inflammatory mediators and phagocytosis of Gram negative bacteria. Complementary approaches will be used to conduct our studies, including transfected cell lines, primary TLR4-/- mouse macrophages with "knocked-in" human wild-type or mutant TLR4s introduced by nucleofection, and human monocytes obtained from human subjects who carry wild-type or mutant TLR4 alleles. At the completion of these studies, we expect to identify molecular mechanisms by which TLR4 mutations affect sensing of Gram negative bacteria and LPS. This research will advance our general understanding of TLR4 signaling, and provide a rationale for the development of new therapeutic approaches to correct functions of components of the TLR signaling pathway compromised in individuals expressing mutant TLR4 variants. PUBLIC HEALTH RELEVANCE: Bacterial sepsis is a major threat to human health worldwide, with the annual incidence in the U.S.A. is ~750,000 patients, with more than ~210,000 (> 28%) deaths. Mutations in TLR4, the main receptor for Gram negative bacteria and lipopolysaccharide, have been associated with many infectious diseases and sepsis. However, molecular mechanisms by which these mutations affect receptor signaling and macrophage reactions to microbes are unknown. Our proposed studies will determine how these TLR4 mutations change receptor functions at the molecular level. Our research will identify earliest disturbances in functions of receptor and signaling molecules that are caused by TLR4 mutations, and may aid to development of new pharmaceutical drugs to correct such deficiencies.

描述（由申请人提供）：LPS的主要信号受体TLR4对于宿主防御革兰氏阴性细菌感染至关重要。在TLR4的外生域中，两个点突变，D299G和T399i与对吸入LP的反应钝化有关，革兰氏阴性细菌感染和败血症的发生率增加。这些结果表明，这些突变改变了TLR4信号的能力，从而导致对细菌病原体的宿主免疫反应受损。目前尚不清楚TLR4多态性影响受体介导的信号传导的分子机制。要测试的中心假设是，单核苷酸多态性改变了TLR4对革兰氏阴性细菌和LPS的识别，其与共受体的相互作用以及适配器和激酶的募集以及激活TLR4信号传导受损以及对病原体的宿主免疫反应受损。该假设将通过追求以下特定目的来研究：（1）定义TLR4 SNP是否改变了对革兰氏阴性细菌和LP的识别，受体信号组装以及激酶和转录因子的激活；（2）确定TLR4 SNP对炎症介质表达的影响和革兰氏阴性细菌的吞噬作用。互补方法将用于进行我们的研究，包括转染的细胞系，原代TLR4 - / - 小鼠巨噬细胞，其中具有核反理引入的“敲入”人类野生型或突变体TLR4，以及从携带野生型或突变体TLR4 Elleles的人类受试者获得的人类单核细胞。这些研究完成时，我们希望确定TLR4突变影响革兰氏阴性细菌和LPS的传感的分子机制。这项研究将促进我们对TLR4信号传导的一般理解，并为开发新的治疗方法的开发提供了理由，以纠正在表达突变体TLR4变体的个体中受损的TLR信号通路的功能。公共卫生相关性：细菌败血症是全世界人类健康的主要威胁，在美国的年发病率约为75万名患者，大约210,000（> 28％）死亡。 TLR4中的突变是革兰氏阴性细菌和脂多糖的主要受体，与许多传染病和败血症有关。然而，这些突变影响受体信号传导和巨噬细胞反应的分子机制尚不清楚。我们提出的研究将确定这些TLR4突变如何在分子水平上改变受体功能。我们的研究将确定由TLR4突变引起的受体和信号分子功能的最早干扰，并可能有助于开发新的药物以纠正此类缺陷。