Mechanisms of innate immune response modulation by mechanical ventilation

机械通气调节先天免疫反应的机制

• 批准号: 7370145
• 负责人: William A Altemeier
• 金额: $ 39万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7370145
• 关键词: Acute; Acute Lung Injury; Adult Respiratory Distress Syndrome; Affect; Agonist; Alveolar; Alveolar Macrophages; Attenuated; Bacteremia; Binding; Biological Assay; Caring; Cell Wall; Cells; Cessation of life; Chimera organism; Chronic; Condition; Critical Illness; DNA Binding; Data; Defect; Development; Disruption; Distal; Dominant-Negative Mutation; Dose; Double-Stranded RNA; Economics; Endothelial Cells; Environmental air flow; Epithelial; Epithelial Cells; Exposure to; Family; Figs - dietary; Future; Gene Expression; Gene Targeting; Generations; Genes; Genetic Transcription; Goals; Gram-Negative Bacteria; Gram-Positive Bacteria; Hospitalization; Human; Immune response; In Vitro; Incidence; Individual; Inflammation; Inflammatory; Inflammatory Response; Influenza; Interferons; Interleukin-1 Receptors; Intervention; JUN gene; Knowledge; Lead; Length; Ligands; Link; Lipopolysaccharides; Lung; Lung Inflammation; Measures; Mechanical ventilation; Mediating; Messenger RNA; Methods; Mitogen-Activated Protein Kinases; Modeling; Molecular; Mus; Mutant Strains Mice; Myelogenous; Myeloid Cells; Nuclear Translocation; Oxidation-Reduction; Pathogenesis; Pathway interactions; Patients; Pattern; Pattern Recognition; Phosphorylation; Phosphotransferases; Pneumonia; Promoter Regions; Protein Subunits; Proteins; Public Health; RNA Interference; Rate; Receptor Activation; Receptor Signaling; Recruitment Activity; Reporting; Research; Role; Safety; Secondary to; Severities; Signal Pathway; Signal Transduction; Source; Specificity; Standards of Weights and Measures; Stretching; Time; Tissue-Specific Gene Expression; Toll-Like Receptor 2; Toll-like receptors; Transcription Factor AP-1; Transgenic Mice; Ventilator; Ventilator-induced lung injury; activating transcription factor; adapter protein; attenuation; base; cell type; chemokine; chromatin immunoprecipitation; concept; design; disability; human IRF3 protein; human TLR3 protein; immunoregulation; improved; in vivo; injured; interferon regulatory factor-3; lung injury; macrophage; microbial; mortality; mutant; novel; partial response; pathogen; promoter; research study; respiratory virus; response; stress-activated protein kinase 1; toll-like receptor 4; transcription factor

DESCRIPTION (provided by applicant): Mechanical ventilation is frequently used to support critically ill patients even in the absence of overt lung injury. A recent study, however, has linked exposure to mechanical ventilation with subsequent development of the acute respiratory distress syndrome (ARDS). The mechanism linking mechanical ventilation with initiation of lung injury is unknown. We have shown that mechanical ventilation can alter the transcriptional response to low-dose bacterial product exposure leading to excessive inflammation and early development of lung injury. Our long-term goal is to identify how mechanical ventilation modulates the transcriptional response to microbial pathogens as a first step toward developing specific interventions to improve survival in mechanically ventilated patients. The specific hypothesis for this proposal is that mechanical ventilation activates the activator protein-1 (AP-1) transcription factor, which augments gene transcription in response to pathogen-associated molecular pattern (PAMP) recognition by toll-like receptors (TLRs). We base this hypothesis on the observations that: A) mechanical ventilation preferentially induces transcription of genes with a promoter region containing the AP-1 binding sequence, B) mechanical ventilation causes nuclear translocation of AP-1, C) mechanical ventilation synergistically augments mRNA levels of genes transcribed in response to lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria, and D) inhibition of c-Jun amino-terminal kinase (JNK - a kinase activator of AP-1) is protective against other types of lung injury. The specific aims of this proposal are to: 1) Determine whether ventilator augmentation of PAMP-induced inflammation is (a) specific for individual TLR- signaling pathways and/or (b) dependent on generation of endogenous TLR ligands. This aim is accomplished through the combination of highly specific toll-like receptor agonists and genetically modified mice, which lack either the MyD88 or TRIF adapter protein necessary for specific TLR signaling. 2) Determine the lung cell type primarily responsive to ventilator-induced immunomodulation by (a) measuring response to TLR ligands and ventilation in chimeric mice, which lack MyD88 in either myeloid or non- myeloid cells and (b) measuring response to TLR ligands and ventilation in transgenic mice in which distal lung epithelial cells have an isolated defect in downstream TLR signaling pathways. 3) Determine the role of AP-1 activation in ventilator-augmentation of LPS-induced inflammation by (a) using chromatin immunoprecipitation assay to identify which protein subunits of AP-1 are recruited to target gene promoters by mechanical ventilation, (b) inhibiting AP-1 activation during mechanical ventilation and LPS exposure, and (c) using RNA interference to determine the function of specific AP-1 subunits identified in (a). Relevance for public health - The incidence of acute lung injury (ALI) is 78.9 per 100,000 patient-years with a mortality rate of 38.5%. Based on these values, there are an estimated 190,600 cases of ALI in the U.S. each year with 74,500 associated deaths. Additionally, the economic impact of ALI is high secondary to prolonged ICU care and overall length of hospitalization and to chronic post-hospitalization disability. These data highlight the importance of further research to help understand the factors, which promote the development of ALI. This project will help identify mechanisms by which mechanical ventilation support causes lung injury; thereby, providing guidance for the development of future interventions to decrease the incidence and severity of acute lung injury.

描述（由申请人提供）：即使没有明显的肺损伤，机械通气也经常用于支持危重患者。然而，最近的一项研究将机械通气暴露与随后发生的急性呼吸窘迫综合征 (ARDS) 联系起来。机械通气与肺损伤发生之间的联系机制尚不清楚。我们已经证明，机械通气可以改变对低剂量细菌产品暴露的转录反应，导致过度炎症和肺损伤的早期发展。我们的长期目标是确定机械通气如何调节对微生物病原体的转录反应，这是制定具体干预措施以提高机械通气患者生存率的第一步。该提议的具体假设是机械通气激活激活蛋白 1 (AP-1) 转录因子，该因子响应 Toll 样受体 (TLR) 的病原体相关分子模式 (PAMP) 识别而增强基因转录。我们的这一假设基于以下观察结果：A) 机械通气优先诱导具有包含 AP-1 结合序列的启动子区域的基因转录，B) 机械通气导致 AP-1 的核易位，C) 机械通气协同增强响应脂多糖 (LPS)（革兰氏阴性细菌的细胞壁成分）而转录的基因的 mRNA 水平，以及 D) 抑制 c-Jun 氨基末端激酶（JNK - AP-1 的激酶激活剂）可预防其他类型的肺损伤。该提案的具体目标是：1) 确定呼吸机增强 PAMP 诱导的炎症是否 (a) 对个体 TLR 信号传导途径具有特异性和/或 (b) 依赖于内源性 TLR 配体的生成。这一目标是通过高度特异性的 Toll 样受体激动剂和转基因小鼠的组合来实现的，这些小鼠缺乏特定 TLR 信号传导所需的 MyD88 或 TRIF 接头蛋白。 2) 通过以下方式确定主要响应呼吸机诱导的免疫调节的肺细胞类型：(a) 测量嵌合小鼠对 TLR 配体和通气的反应，嵌合小鼠在骨髓或非骨髓细胞中缺乏 MyD88，以及 (b) 测量转基因小鼠对 TLR 配体和通气的反应，其中远端肺上皮细胞在下游 TLR 中具有孤立的缺陷 信号通路。 3) 通过以下方法确定 AP-1 激活在呼吸机增强 LPS 诱导的炎症中的作用：(a) 使用染色质免疫沉淀测定来鉴定 AP-1 的哪些蛋白亚基通过机械通气被招募到靶基因启动子，(b) 在机械通气和 LPS 暴露期间抑制 AP-1 激活，以及 (c) 使用 RNA 干扰来确定中鉴定的特定 AP-1 亚基的功能 （一）。与公共卫生的相关性 - 急性肺损伤 (ALI) 的发病率为每 100,000 患者年 78.9 例，死亡率为 38.5%。根据这些数据，美国每年估计有 190,600 例 ALI 病例，其中 74,500 例相关死亡。此外，ALI 的经济影响仅次于 ICU 护理时间延长、住院总时间以及慢性住院后残疾。这些数据凸显了进一步研究的重要性，以帮助了解促进 ALI 发展的因素。该项目将有助于确定机械通气支持导致肺损伤的机制；从而为未来干预措施的制定提供指导，以降低急性肺损伤的发生率和严重程度。