IRAK Family Function in Bacterial Infection

IRAK 家族在细菌感染中的功能

• 批准号: 6885330
• 负责人: JAMES Alanson THOMAS
• 金额: $ 31.2万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6885330
• 关键词: Klebsiella pneumoniae; RNase protection assay; Staphylococcus aureus; Streptococcus pneumoniae; antigen antibody reaction; attenuated microorganism; bacteria infection mechanism; biological signal transduction; cellular immunity; cytokine receptors; disease /disorder model; enzyme activity; enzyme linked immunosorbent assay; gene deletion mutation; genetically modified animals; gram negative bacteria; gram positive bacteria; host organism interaction; inflammation; laboratory mouse; lipopolysaccharides; macrophage; protein kinase; protein structure function; tissue /cell culture; toll like receptor

Infection represents one of the most fundamental threats to host integrity. When bacterial pathogens breach an epithelial barrier, the host innate immune system detects the attack and triggers a response to contain and eliminate the invader. Cellular sensors, such as macrophages and dendritic cells, detect pathogen through receptors that recognize bacterial macromolecules. These cells then mount a proinflammatory reaction that leads to cellular responses that contain and eliminate the infection. Thus, the innate immune response contains both afferent (pathogen-sensing) and efferent (proinflammatory) limbs. The Toll/IL-1 signal transduction pathway mediates both arms of this innate response to infection. This conserved signaling cascade consists of the proteins MyD88, the interleukin-1 receptor-associated kinase (IRAK) family of molecules (IRAK, IRAK2, and IRAK-M) and the tumor necrosis factor associated factor 6. It processes signals from at least 10 Toll-like receptors (TLRs) and three IL-1 receptor family members (IL-1, IL-18, and Ti/ST2), distributing them to multiple downstream targets, including NF-kB and several mitogen activated protein kinase cascades. We have genetically deleted IRAK, the primary proximal kinase in this pathway, in mice. IRAK-deficient animals and macrophages exhibit impaired responses to lipopolysachharide (LPS), peptidoglycan (PGN), lipotechoic acid (LTA), and CpG DNA, bacterial molecules that activate the afferent arm of innate immunity through TLR4 and TLR2. These mice also exhibit attenuated proinflammatory (efferent) responses due to disrupted IL-1 and IL-18 signaling. The overall objective of this proposal is to determine IRAK function in the host response to Gram-negative and Gram-positive infections. Aim 1 is to determine the role of IRAK in the acute inflammatory response to Gram-negative and Gram-positive infections. We will subject IRAK- deficient macrophages and mice to increasingly complex models of these infections, using toxin challenges, stimulation with nonreplicating bacteria, and Klesiella pneumoniae and Staphylococcus aureus pneumonia. Aim 2 is to isolate IRAK function genetically to either the TLR4 or IL-1receptor pathway by generating IRAK/IL-121 and IRAK/TLR4 double knockout animals and comparing the responses of double and single KO macrophages and mice to LPS stimulation, nonreplicating K. pneumoniae, and K. pneumoniae pneumonia. Aim 3 is to determine the contributions of IRAK2 and IRAK-M to residual TLR signaling in IRAK-deficient cells, as deletion of IRAK impairs, but does not completely abrogate signaling. These studies should provide fundamental new information about the role of IRAK in the innate immune response to acute bacterial infection and may eventually lead to the development of strategies to modulate deleterious aspects of this response.

感染代表了托管诚信最根本的威胁之一。 当细菌病原体违反上皮屏障时，宿主先天免疫系统检测到攻击并触发对遏制和消除入侵者的反应。 细胞传感器（例如巨噬细胞和树突状细胞）通过识别细菌大分子的受体检测病原体。 然后，这些细胞安装了促炎反应，导致细胞反应包含并消除感染。 因此，先天免疫反应既包含传入（病原体感应）和传出（促炎）四肢。 Toll/IL-1信号转导途径介导了这种对感染的先天反应的两个臂。 这种保守的信号级联反应由蛋白质MYD88，介菌1受体相关的激酶（IRAK）家族（IRAK，IRAK，IRAK2和IRAK2和IRAK-M）以及肿瘤坏死因子6。 Ti/ST2），将它们分配到多个下游靶标，包括NF-KB和几种有丝分裂原激活的蛋白激酶级联反应。 我们在小鼠中具有遗传上删除的IRAK，这是该途径中的主要近端激酶。 缺乏IRAK的动物和巨噬细胞表现出对脂多年术（LPS），肽聚糖（PGN），脂肪酸（LTA）和CPG DNA的反应受损，可激活通过TLR4和TLR2的固有免疫力激活智力免疫的细菌分子。 这些小鼠还表现出由于IL-1和IL-18信号的破坏而导致的促炎（传出）反应。该提案的总体目的是确定宿主对革兰氏阴性和革兰氏阳性感染的反应中的IRAK功能。 目的1是确定IRAK在对革兰氏阴性和革兰氏阳性感染的急性炎症反应中的作用。 我们将使用毒素挑战，非复制细菌刺激以及肺炎克莱西氏菌和金黄色葡萄球菌肺炎，使这些感染的不足巨噬细胞和小鼠对这些感染的越来越复杂的模型。 Aim 2 is to isolate IRAK function genetically to either the TLR4 or IL-1receptor pathway by generating IRAK/IL-121 and IRAK/TLR4 double knockout animals and comparing the responses of double and single KO macrophages and mice to LPS stimulation, nonreplicating K. pneumoniae, and K. pneumoniae pneumonia. AIM 3是确定Irak2和Irak-M对Irak缺陷细胞中残留TLR信号的贡献，因为IRAK的缺失会损害，但并未完全消除信号传导。这些研究应提供有关IRAK在对急性细菌感染的先天免疫反应中的作用的基本新信息，并最终可能导致制定这种反应的有害方面的策略。