Regulation of alveolar epithelial barrier function by claudins

密蛋白对肺泡上皮屏障功能的调节

• 批准号: 7664294
• 负责人: JAMES A FRANK
• 金额: $ 39.4万
• 依托单位: NORTHERN CALIFORNIA INSTITUTE/RES/EDU
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7664294
• 关键词: Acute Lung Injury; Adult Respiratory Distress Syndrome; Alveolar; Binding; Biological; Chloride Ion; Chlorides; Clostridium perfringens enterotoxin; Data; Development; Edema; Environmental air flow; Epidermal Growth Factor Receptor; Epithelial; Epithelial Cells; Family; Fluid Balance; Functional disorder; Gene Proteins; Human; In Vitro; Ion Transport; Ions; Laboratories; Light; Liquid substance; Lung; Measurement; Measures; Mediator of activation protein; Modeling; Movement; Mus; Pathway interactions; Patients; Peptides; Permeability; Play; Property; Protein Family; Proteins; Pulmonary Edema; RNA Interference; Rattus; Receptor Activation; Regulation; Research; Respiratory Failure; Role; Severities; Small Interfering RNA; Sodium; Stimulus; Tidal Volume; Tight Junctions; Time; Transplantation; Type II Epithelial Receptor Cell; Ventilator; Ventilator-induced lung injury; Work; alveolar type II cell; claudin 4; in vivo; inhibitor/antagonist; insight; lung injury; mortality; mouse model; novel therapeutics; physical property; protein expression; research study; response

DESCRIPTION (provided by applicant): Acute Respiratory Distress Syndrome (ARDS), the most severe form of acute lung injury, is a common cause of respiratory failure with an overall mortality rate of nearly 40%; however, there are currently no specific pharmacological therapies. A hallmark of ARDS is increased alveolar barrier permeability and decreased clearance of fluid from the airspaces resulting in pulmonary edema. Although work by our group and others has begun to shed light on the regulation of transcellular epithelial ion transport, much less is known about how paracellular permeability and ion transport are regulated in acute lung injury. New research into the regulation of paracellular permeability and selective transport through tight junctions is of fundamental importance to understanding epithelial function in ARDS. In preliminary studies, we have found that tight junction claudins are differentially expressed in acute lung injury. Differential regulation of the claudin family of proteins may represent a central mechanism by which epithelial cells alter the physical properties of the paracellular pathway to control permeability and ion movement. Our hypothesis is that alveolar epithelial cells control the particular tight junction claudins expressed in response to environmental stimuli. We found a significant increase in claudin 4 expression during acute lung injury. This may represent an adaptive response to limit airspace edema formation and allow higher rates of edema clearance because claudin 4 decreases paracellular permeability to large molecules and favors a paracellular pathway that excludes sodium but allows chloride transport. These properties would promote airspace fluid clearance. In Aim 1, we will determine the functional contribution of claudin 4 to tight junctions using a peptide inhibitor and RNAi in primary rat and human alveolar epithelial type II cells. We will also determine the mechanisms by which claudin 4 and other tight junction protein expression is regulated. In Aim 2, we will study the function and regulation of claudin 4 in our mouse model of ventilator-induced lung injury. In Aim 3, we will for the first time examine expression of several claudins in human lungs rejected for transplantation and, using our perfused human lung model, correlate expression levels with measures of epithelial function ex vivo. These studies will provide a more complete understanding of the mechanisms of alveolar epithelial barrier regulation during lung injury and facilitate the development of new therapeutic strategies for ARDS patients.

描述（由申请方提供）：急性呼吸窘迫综合征（ARDS）是急性肺损伤的最严重形式，是呼吸衰竭的常见原因，总体死亡率接近40%;然而，目前尚无特异性药物治疗。ARDS的一个标志是肺泡屏障通透性增加和液体从气隙的清除减少，导致肺水肿。虽然我们小组和其他人的工作已经开始阐明跨细胞上皮离子转运的调节，但对急性肺损伤中细胞旁通透性和离子转运的调节知之甚少。通过紧密连接调节细胞旁通透性和选择性转运的新研究对于理解ARDS中的上皮功能至关重要。在初步的研究中，我们发现紧密连接蛋白在急性肺损伤中表达差异。claudin蛋白家族的差异调节可能代表了上皮细胞改变细胞旁途径的物理性质以控制渗透性和离子运动的中心机制。我们的假设是，肺泡上皮细胞控制特定的紧密连接claudins表达的环境刺激。我们发现在急性肺损伤过程中claudin 4的表达显著增加。这可能代表了限制气腔水肿形成并允许更高的水肿清除率的适应性反应，因为密蛋白4降低了对大分子的细胞旁渗透性并有利于排除钠但允许氯离子转运的细胞旁途径。这些特性将促进空气空间流体清除。在目的1中，我们将使用肽抑制剂和RNAi在原代大鼠和人肺泡上皮II型细胞中确定紧密连接蛋白4对紧密连接的功能贡献。我们还将确定claudin 4和其他紧密连接蛋白表达的调节机制。目的2：研究claudin 4在呼吸机诱导的肺损伤小鼠模型中的作用和调节。在目标3中，我们将首次检查几种claudin在移植排斥的人肺中的表达，并使用我们的灌注人肺模型，将表达水平与离体上皮功能的测量相关联。这些研究将提供一个更完整的了解肺泡上皮细胞屏障的调节机制在肺损伤和促进发展的新的治疗策略，为ARDS患者。