Lipid and Protein Effects on Mono-Layer Stability

脂质和蛋白质对单层稳定性的影响

• 批准号: 7924688
• 负责人: Joseph Anthony Zasadzinski
• 金额: $ 36.11万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA BARBARA
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-07-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7924688
• 关键词: Acute Lung Injury; Address; Adsorption; Affect; Albumins; Alveolar; Animal Model; Animals; Atomic Force Microscopy; Breathing; Calcium; Cations; Chemicals; Cholesterol; Clinical; Confocal Microscopy; Drug Formulations; Dyes; Elasticity; Film; Fluorescence; Fluorescent Dyes; Goals; In Vitro; Incidence; Infectious Agent; Ions; Label; Laboratories; Letters; Lipids; Liquid substance; Maps; Measures; Mechanics; Meconium Aspiration; Membrane Fluidity; Methods; Microscope; Modeling; Molecular; Mono-S; Newborn Infant; Newborn Respiratory Distress Syndrome; Optics; Peptides; Performance; Phosphatidyl glycerol; Phosphatidylglycerols; Polymers; Premature Birth; Property; Proteins; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactants; Recording of previous events; Research; Research Personnel; Respiratory physiology; Rheology; Role; Serum Proteins; Structure; Surface; Surface Tension; Survanta; Synchrotrons; Time; Treatment Efficacy; Unsaturated Fats; Vesicle; Viscosity; Weight; Work; X ray diffraction analysis; X-Ray Diffraction; cholesterol control; cohesion; cost; improved; in vivo; inhibitor/antagonist; instrument; interfacial; lung injury; monolayer; pressure; public health relevance; respiratory; respiratory distress syndrome; saturated fat; surfactant

DESCRIPTION (provided by applicant): We hypothesize that small fractions (1-5 wt%) of cholesterol reduce the crystalline ordering of saturated lipids in lung surfactant monolayers, leading to a reduction in the shear viscosity, which enhances the surfactant's ability to flow and cover the alveolar interface. At higher concentrations, cholesterol reduces the monolayer elasticity, which in turn, leads to a decrease in the ability of the monolayer to resist collapse, leading to higher minimum surface tensions and a decrease in lung function. These hypotheses suggest an ptimal cholesterol content for a replacement lung surfactant. We will determine this optimal cholesterol content by measuring the shear viscosity and elasticity of clinical and model lung surfactants as a function of cholesterol composition using macro- and micro- rheology instruments unique to our laboratory. These mechanical properties will be correlated with isotherms, fluorescence and atomic force microscopy, and grazing incidence synchrotron X-ray diffraction to determine how cholesterol alters the molecular packing of lung surfactant lipids, which determines the mechanical properties of monolayers necessary for low surface tensions and rapid respreading and adsorption. Our goal is to determine the physiologically optimal viscosity and elasticity for rapid spreading and low surface tension and how best to achieve this optimum by controlling the cholesterol, lipid and protein fractions of a synthetic replacement lung surfactant for respiratory distress syndrome. In addition to an optimal composition, sufficient surfactant must be adsorbed to the interface from the alveolar fluid during the respiratory cycle. The lung surfactant specific proteins SP-A, B and C, along with lipids such as phosphatidylglycerol and cholesterol, are hypothesized to enhance exchange between surfactant in the subphase and the interface. However, little quantitative evidence for specific lipid and/or protein exchange exists. Also unknown is the surface pressures at what adsorption occurs, or if adsorption occurs during compression or expansion of the interface. To address this hypothesis, we will map out the three-dimensional distribution of lung surfactant components from the interface to the subphase using optical sectioning with a confocal microscope and multiple fluorescent dyes. We expect that SP-A, B and C promote adsorption; however, we do not know if specific lipids or proteins are adsorbed preferentially to the interface to optimize the monolayer composition that collapses at high surface pressures. Native SP- A, B and C will be compared to peptide mimics to evaluate the efficacy of the peptides. PUBLIC HEALTH RELEVANCE: A lack of lung surfactant, often due to premature delivery, is responsible for neonatal respiratory distress syndrome (NRDS). In 2002, NRDS affected an estimated 24,000 newborns in the US, current treatments utilize replacement surfactants derived from animals. The goal of this research is to develop an entirely synthetic replacement surfactant that should reduce costs of NRDS treatment, improve uniformity, decrease the likelihood of contamination with infectious agents, and improve the efficacy of treatment of RDS associated with meconium aspiration or acute lung injury.

描述（由申请人提供）：我们假设胆固醇的小部分（1-5 wt％）降低了肺表面活性剂单层中饱和脂质的结晶顺序，从而降低了剪切粘度，从而增强了表面活性剂的流动能力并覆盖肺泡界面。在较高的浓度下，胆固醇会降低单层弹性，从而导致单层抵抗塌陷的能力降低，从而导致最小的表面紧张局势和肺功能降低。这些假设表明替代肺表面活性剂具有ptimal胆固醇含量。我们将通过测量临床和模型肺表面活性剂的剪切粘度和弹性来确定这种最佳胆固醇含量，这是我们实验室独有的宏观和微风湿工具的胆固醇组成的函数。这些机械性能将与等温线，荧光和原子力显微镜以及放牧的发病率X射线衍射相关，以确定胆固醇如何改变肺表面活性剂脂质的分子堆积，从而确定低表面紧张局部和快速验证和快速验证的单层机械性能。我们的目标是确定生理上最佳的粘度和弹性，以快速扩散和低表面张力，以及如何通过控制合成替换肺部表面活性剂的胆固醇，脂质和蛋白质分数来最佳实现这一最佳水平。除最佳组成外，还必须在呼吸周期中将足够的表面活性剂吸附到肺泡液的界面上。假设肺表面活性剂特异性蛋白SP-A，B和C以及磷脂酰甘油和胆固醇等脂质，以增强亚相和界面中表面活性剂之间的交换。但是，存在特定脂质和/或蛋白质交换的定量证据。同样未知的是在吸附发生的表面压力，或者是否在界面的压缩或扩展过程中发生吸附。为了解决这一假设，我们将使用带有共聚焦显微镜和多个荧光染料的光学分段来绘制肺表面活性剂成分从界面到亚相的三维分布。我们期望SP-A，B和C促进吸附。但是，我们不知道特定的脂质或蛋白质是否优先吸附到界面上，以优化在高表面压力下崩溃的单层组成。将天然SP-A，B和C与肽模拟物进行比较，以评估肽的功效。公共卫生相关性：缺乏肺表面活性剂（通常是由于过早分娩）是新生儿呼吸窘迫综合征（NRDS）的原因。 2002年，NRDS影响了美国估计有24,000名新生儿，目前的治疗方法利用了源自动物的替代表面活性剂。这项研究的目的是开发一种完全合成的替代表面活性剂，该表面活性剂应降低NRDS治疗的成本，改善均匀性，减少传染剂污染的可能性，并提高与Meconium saffimation或急性肺损伤相关的RDS治疗的疗效。