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.

摘要 新生儿呼吸窘迫综合征（NRDS）和急性呼吸窘迫综合征（ARDS）的发病率均高于 每年有25万美国人。NRDS影响早产儿，因为他们的肺发育不全， 以产生足够的功能性肺表面活性剂。NRDS存在动物替代表面活性剂治疗选择， 尽管对猪的生物变异性、种间疾病传播和宗教问题的关注， 与牛衍生的表面活性剂相比，仍然存在。在所有入院的COVID-19 ICU患者中，约75%的患者出现了ARDS， 目前无法治疗，导致死亡率约为40%。ARDS是由肺创伤或疾病引起的， 导致炎症，引起肺内表面张力的异常增加， 肺不张对肺表面活性物质基本结构和极限行为的深入认识 单层可能是建议新的合成替代表面活性剂处理的途径， NRDS中的生物学问题以及为ARDS患者制定治疗方案。我的团队 先前确定的是，单层的“塌陷”决定了在表面张力期间的表面张力下限。 伴随呼气的肺泡区压缩。控制坍塌的物理和化学因素 可能在ARDS期间发生功能障碍、高表面张力肺表面活性物质的患者中发生改变。 健康肺表面活性剂相的单层分离成半结晶有序相和半结晶有序相的结构域。 各种成分的无序液相。我们假设这种相分离决定了许多 影响坍塌的单分子层的动力学和流变学性质。然而， 多组分肺表面活性剂中不同结构域组成的直接信息。我将向 单分子层坍塌和相分离的两个目的。在目标1中，我将可视化单层塌陷 使用共聚焦荧光显微镜的3-D连续切片功能， 单层域改变塌陷行为和最小表面张力。我最近还发现， 在朗缪尔曲线中，与平坦表面相比，弯曲的蜂窝大小界面上的塌陷行为发生了变化。 槽，我将使用共聚焦成像来确定崩溃形态和界面之间的关系， 曲率目的2是开创红外耦合原子力显微镜（AFM-IR）方法来绘制横向 多组分肺表面活性物质单层中化学物质的分布及其局部有序性。我会 使用AFM-IR检查胆固醇集中在域边界以降低线的假设 张力，而棕榈酸和十六醇促进二棕榈酰磷脂酰胆碱结晶， 单层中固相的分数。该项目的成功完成将提供详细的 横向相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坍塌时的最小表面张力。