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 患者和患有“允许性高碳酸血症”的机械通气患者的 pCO2 可能显着升高。我们假设高碳酸血症通过特异性下调肺泡上皮 Na,K-ATP 酶并降低肺泡液清除率而导致肺泡上皮功能障碍。该应用的重点是确定短期（30-60 分钟）高碳酸血症是否会通过抑制 Na,K-ATP 酶并通过涉及 JNK 和 ERK 激酶的特定途径促进其从质膜内吞到细胞内区室来损害可逆性肺泡液重吸收和蛋白激酶 C (PKC) 信号分子。我们还建议确定长期（5 和 7 天）高碳酸血症是否会使肺泡上皮对通气引起的肺损伤敏感，并且不仅导致内吞作用，还会通过泛素/蛋白酶体途径导致 Na,K-ATP 酶降解。感知高碳酸血症的细胞信号在很大程度上是未知的，因此我们将利用线虫基因组已完全绘制的优势，并在线虫中进行实验，以研究可能参与高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标来研究高碳酸血症对肺泡上皮和秀丽隐杆线虫的影响：在具体目标 1 中，我们建议确定高碳酸血症是否会降低正常和受损肺部的肺泡液重吸收，以及这些影响是否是由于高碳酸血症造成的。 pCO2 或相关酸中毒，在具体目标 2 中，我们将确定高碳酸血症促进肺泡上皮 Na,K-ATP 酶内吞作用的信号通路肺泡上皮细胞，在特定目标 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，导致 Na,K-ATP 酶蛋白的内吞作用和降解，在特定目标 4 中，我们将确定水平升高的影响研究了 CO2 对线虫发育、运动性和繁殖力的影响，并建立了一系列基因突变的品系，这些基因突变可调节对 CO2 水平升高的感知和细胞反应。针对每个具体目标都进行了实验，初步结果支持了该提案的可行性。拟议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，这对于高碳酸血症患者的治疗可能很重要。