Three-dimensional Confocal Microscopy Visualization and AFM-IR Chemical Mapping of Lung Surfactant Monolayer Collapse Morphologies

肺表面活性剂单层塌陷形态的三维共焦显微镜可视化和 AFM-IR 化学图谱

• 批准号: 10751972
• 负责人: Zachary D McAllister
• 金额: $ 4.39万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-15 至 2026-09-14
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10751972
• 关键词: 3-Dimensional; Acute Respiratory Distress Syndrome; Admission activity; Affect; Air; Alveolar; Alveolus; American; Animals; Architecture; Area; Atelectasis; Atomic Force Microscopy; Behavior; Biological; Blood capillaries; Breathing; COVID-19; Cattle; Chemical Surfactants; Chemicals; Cholesterol; Complex; Confocal Microscopy; Coupled; Crystallization; Data; Disease; Exhalation; Family suidae; Fluorescence Microscopy; Frequencies; Growth; Image; Immune response; Inflammation; Lateral; Life; Lipase; Lipids; Liquid substance; Lung; Maps; Methods; Minnesota; Minor; Modulus; Morphology; Neonatal Respiratory Distress; Palmitic Acids; Patients; Phase; Positioning Attribute; Premature Infant; Property; Proteins; Pulmonary Surfactants; Radial; Religion; Research; Resolution; Route; Signal Transduction; Solid; Spatial Distribution; Structure; Surface; Surface Tension; Surfactant therapy; System; Trauma; Universities; Unsaturated Fats; Visualization; Water; Work; behavior change; confocal imaging; fluorescence microscope; improved; interfacial; microscopic imaging; monolayer; mortality; nanometer; pressure; prevent; protein distribution; respiratory distress syndrome; segregation; submicron; surfactant; surfactant replacement; surfactant replacement therapy; three dimensional structure; trend; two-dimensional

ABSTRACT Neonatal respiratory distress syndrome (NRDS) and acute respiratory distress syndrome (ARDS) afflict upwards of 250,000 Americans every year. NRDS affects premature infants due to their underdeveloped lung’s inability to produce sufficient functional lung surfactant. Animal replacement surfactant treatment options exist for NRDS, although concerns over bio-variability, interspecies disease transmittance, and religious questions over porcine versus bovine derived surfactants remain. ARDS was seen in ~75% of all admitted COVID-19 ICU patients and is currently untreatable leading to a mortality rate of ~40%. ARDS is initiated by lung trauma or disease that leads to inflammation, causing an uncharacteristic increase of the surface tension within the lungs, leading to atelectasis. A deeper understanding of the fundamental structure and limiting behavior of lung surfactant monolayers may be the avenue to suggest new synthetic replacement surfactant treatments that could mitigate the biological concerns in NRDS as well as develop treatment options for patients with ARDS. My group has previously identified that the “collapse” of a monolayer determines the lower surface tension limit during the alveolar area compression accompanying exhalation. The physical and chemical factors that govern collapse may be altered in patients who develop dysfunctional, high surface tension lung surfactant during ARDS. Monolayers of healthy lung surfactant phase separate into domains of a semi-crystalline ordered phase and a disordered liquid phase of varied composition. We hypothesize that this phase separation dictates many of the dynamic and rheological properties of the monolayer that influence collapse. However, there is little direct information on the composition of the different domains in multicomponent lung surfactants. I will address monolayer collapse and phase separation in the following two aims. In Aim 1, I will visualize monolayer collapse structures using the 3-D serial sectioning capabilities of the confocal fluorescence microscope to determine how monolayer domains alter collapse behavior and the minimum surface tension. I have also recently found that collapse behavior changes on curved, alveolar-size interfaces compared to the flat surfaces in a Langmuir trough, and I will use confocal imaging to determine the relationship between collapse morphology and interfacial curvature. Aim 2 is to pioneer infrared-coupled atomic force microscopy (AFM-IR) methods to map the lateral distribution of the chemical species and their local ordering in multicomponent lung surfactant monolayers. I will use AFM-IR to examine the hypothesis that cholesterol concentrates at domain boundaries to lower the line tension while palmitic acid and hexadecanol promote crystallization of dipalmitoylphosphatidylcholine, increasing the fraction of solid phase in the monolayer. Successful completion of this project will provide a detailed description of the two-dimensional chemical distribution in laterally phase separated lung surfactant monolayers and how this phase separation influences the minimum surface tension at monolayer collapse.

抽象的 新生儿呼吸窘迫综合征（NRDS）和急性呼吸窘迫综合征（ARDS）向上折磨 每年有25万美国人。 NRDS由于肺部欠发达而影响早产婴儿 产生足够的功能性肺表面。 NRDS存在动物替代表面处理选项， 尽管对生物变异性，种间疾病传播以及猪的宗教问题的担忧 仍然存在与牛衍生的表面活性剂。在所有入院的Covid-19 ICU患者中，约有75％在约75％的ARDS和 目前无法治疗导致死亡率约40％。 ARDS是由肺部创伤或疾病引发的 导致炎症，导致肺部表面张力的异常增加，导致 对肺表面活性剂的基本结构和限制行为有更深入的了解 单层可能是建议新的合成替代生存治疗方法的途径 NRDS的生物学问题以及ARDS患者的开发治疗选择。我的小组有 先前确定的单层“崩溃”决定了较低的表面张力极限 肺泡区域压缩发生呼气。控制崩溃的物理和化学因素 在ARDS期间患有功能失调的高表面肺表面活性剂的患者可能会改变。 健康的肺表面活性剂相的单层分离为半晶有序相的结构域和A 各种成分的液相无序。我们假设这个阶段分离决定了许多 影响崩溃的单层的动态和流变特性。但是，几乎没有 有关多组分肺表面活性剂中不同域组成的直接信息。我会解决的 单层崩溃和相位分离在以下两个目标中。在AIM 1中，我将可视化单层崩溃 使用共聚焦荧光显微镜的3-D系列切片能力的结构来确定如何 单层域改变了塌陷行为和最小表面张力。我最近还发现 与Langmuir中的平面相比 槽，我将使用共共聚焦成像来确定塌陷形态与界面之间的关系 曲率。 AIM 2是先锋红外耦合原子力显微镜（AFM-IR）的方法，以绘制以后的 化学物种及其在多组分肺表面活性剂单层中的局部顺序的分布。我会 使用AFM-IR检查胆固醇浓缩在结构域边界的假设以降低线 张力时棕榈酸和六烷醇促进二甲米二酰磷脂酰胆碱的结晶，增加 单层中固相的比例。成功完成该项目将提供详细的 横向分离的肺表面活性剂单层中二维化学分布的描述 以及这种相分离如何影响单层塌陷处的最小表面张力。