The injurious effects of hypercapnia on the alveolar epithelium

高碳酸血症对肺泡上皮的损伤作用

• 批准号: 7256236
• 负责人: Jacob I Sznajder
• 金额: $ 44.03万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7256236
• 关键词: Acidosis; Adult Respiratory Distress Syndrome; Affect; Alveolar; Animal Model; Apical; C. elegans genome; Caenorhabditis elegans; Carbon Dioxide; Cell membrane; Chronic; Chronic Obstructive Airway Disease; Collection; Data; Development; Disease; Down-Regulation; Edema; Elevation; Endocytosis; Environmental air flow; Epithelial; Epithelial Cells; Epithelium; Exposure to; Fertility; Functional disorder; Gases; Gene Targeting; Genes; Genetic; Genetic Screening; Hypercapnia; Impairment; Liquid substance; Locomotion; Lung; Lung diseases; MAPK8 gene; Maps; Measures; Mediating; Modeling; Mutate; Na(+)-K(+)-Exchanging ATPase; Numbers; Outcome; Pathway interactions; Patients; Phosphorylation; Protein Kinase C; Proteins; Pulmonary Edema; Pulmonary Gas Exchange; Regulation; Reporting; Research Personnel; Respiratory Failure; Rodent; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Ubiquitin; Ubiquitination; Universities; Ventilator-induced lung injury; Visit; Water; alveolar epithelium; base; cell motility; clinically relevant; day; injured; insight; lung injury; multicatalytic endopeptidase complex; novel; professor; programs; protein kinase C kinase; research study; response; sensor

DESCRIPTION (provided by applicant): Patients with COPD and mechanically ventilated patients with "permissive hypercapnia" can have significant elevation of pCO2. We hypothesize that hypercapnia causes dysfunction of the alveolar epithelium by specifically downregulating the alveolar epithelial Na,K-ATPase and decreasing alveolar fluid clearance. The focus of this application is to determine whether short term (30-60 min) hypercapnia impairs reversibly alveolar fluid reabsorption by inhibiting the Na,K-ATPase and promoting its endocytosis from the plasma membrane into intracellular compartments via specific pathways involving JNK and ERK kinases and protein kinase C (PKC) signaling molecules. We also propose to determine whether long term (5 and 7 days) hypercapnia sensitizes the alveolar epithelium to ventilation induced lung injury and causes not only endocytosis but degradation of the Na,K-ATPase via the ubiquitin/proteosome pathway. The cellular signals that sense hypercapnia are largely unknown, therefore we will take advantage that the genome of C. Elegans has been completely mapped and conduct experiments in C. elegans to study potential genes that may participate in the sensing and response to high pCO2. As such, we will study the effects of hypercapnia on the alveolar epithelium and C. elegans via four interrelated aims: in Specific Aim 1 we propose to determine whether hypercapnia decreases alveolar fluid reabsorption in normal and injured lungs and whether these effects are due to high pCO2 or the associated acidosis, in Specific Aim 2 we will determine the signaling pathways by which hypercapnia promotes alveolar epithelial Na,K-ATPase endocytosis in alveolar epithelial cells , in Specific Aim 3 we will determine whether hypercapnia inhibits Na,K-ATPase activity via phosphorylation and ubiquitination leading to the endocytosis and degradation of Na,K-ATPase proteins and in Specific Aim 4 we will determine the effect of elevated levels of CO2 on C. elegans development, motility and fertility and establish a collection of lines mutated in genes that regulate the sensing and cellular response to elevated levels of CO2. Experiments have been conducted for each of the specific aims and the preliminary results support the feasibility of this proposal. Completion of the proposed studies will provide novel information on the effects of hypercapnia on the alveolar epithelium, specifically as it pertains to mechanisms of alveolar epithelial barrier dysfunction which may be of importance for the treatment of hypercapnic patients.

描述（由申请人提供）：COPD患者和机械通气的“允许性高碳酸血症”患者可出现明显的pCO2升高。我们假设高碳酸血症通过特异性下调肺泡上皮Na、k - atp酶和肺泡液清除率而导致肺泡上皮功能障碍。本应用程序的重点是确定短期（30-60分钟）高碳酸血症是否通过抑制Na， k - atp酶并通过涉及JNK和ERK激酶以及蛋白激酶C （PKC）信号分子的特定途径促进其从质膜内吞入细胞内室，从而可逆地损害肺泡液重吸收。我们还建议确定长期（5天和7天）高碳酸血症是否使肺泡上皮对通气诱导的肺损伤敏感，并不仅引起内吞作用，而且通过泛素/蛋白体途径降解Na， k - atp酶。感知高碳酸血症的细胞信号在很大程度上是未知的，因此我们将利用秀丽隐杆线虫基因组已经完全定位的优势，在秀丽隐杆线虫中进行实验，研究可能参与高pCO2感知和响应的潜在基因。因此，我们将通过四个相互关联的目的来研究高碳酸血症对肺泡上皮和秀丽隐杆线虫的影响：在特异性目标1中，我们建议确定高碳酸血症是否会减少正常和受伤肺部的肺泡液重吸收，以及这些影响是由于高二氧化碳分压还是相关的酸中毒，在特异性目标2中，我们将确定高碳酸血症促进肺泡上皮细胞Na， k - atp酶内吞的信号通路。在Specific Aim 3中，我们将确定高碳酸血症是否通过磷酸化和泛素化抑制Na， k - atp酶活性，从而导致Na， k - atp酶蛋白的内吞和降解。在Specific Aim 4中，我们将确定二氧化碳水平升高对秀丽隐杆线虫发育，运动和繁殖的影响，并建立一系列突变基因，这些基因调节对二氧化碳水平升高的感知和细胞反应。针对每个具体目标进行了实验，初步结果支持该建议的可行性。这些研究的完成将为高碳酸血症对肺泡上皮的影响提供新的信息，特别是因为它涉及肺泡上皮屏障功能障碍的机制，这可能对高碳酸血症患者的治疗具有重要意义。