Castillo-Sánchez Juan Carlos, Collada Ainhoa, Batllori-Badia Emma, Galindo Alberto, Cruz Antonio, Pérez-Gil Jesús
Biochemistry and Molecular Biology Department, Faculty of Biology, Complutense University, Madrid, Spain.
Research Institute Hospital 12 de Octubre (Imas12), Madrid, Spain.
Physiol Rep. 2025 Jun;13(12):e70403. doi: 10.14814/phy2.70403.
Pulmonary surfactant is a lipid/protein complex that coats the alveolar air-liquid interface to minimize surface tension facilitating breathing mechanics. Native surfactant (NS) is typically obtained from lavages of animal lungs, where it has gone through structural alterations as a result of exposure to respiratory dynamics and highly oxidative environments. We have studied here the structure of interfacial films formed by human amniotic fluid surfactant (AFS), thought to maintain the structural and functional features of a fully operative still non-used surfactant, as it has not been subjected to breathing dynamics yet. The results show that AFS adsorbs better at the interface, to form films supporting higher compression rates, than NS upon spreading at comparable concentrations and amounts. Films formed by AFS exhibit condensed regions excluding fluorescently labeled lipids from the mere adsorption, while films formed by NS only showed segregation of ordered-like domains once subjected to compression-expansion dynamics. Finally, AFS films were consistent with the presence of solid-like highly ordered phases, while NS consisted under comparable conditions of a coexistence of liquid-disordered/liquid-ordered fluid phases. This indicates that operative surfactant films formed by freshly secreted surfactant could be much more condensed than previously supposed, likely providing maximal stability under breathing mechanics.
肺表面活性物质是一种脂质/蛋白质复合物，它覆盖在肺泡气液界面，以最小化表面张力，促进呼吸力学。天然表面活性物质（NS）通常从动物肺灌洗中获得，由于暴露于呼吸动力学和高氧化环境，它经历了结构改变。我们在此研究了人羊水表面活性物质（AFS）形成的界面膜结构，AFS被认为保持了完全可操作但尚未使用的表面活性物质的结构和功能特征，因为它尚未经历呼吸动力学。结果表明，在可比浓度和量下铺展时，AFS在界面处吸附更好，形成支持更高压缩率的膜，比NS更好。AFS形成的膜表现出凝聚区域，仅通过吸附就排除了荧光标记的脂质，而NS形成的膜仅在经历压缩-膨胀动力学后才显示出有序样结构域的分离。最后，AFS膜与类固体高度有序相的存在一致，而NS在可比条件下由液体无序/液体有序流体相共存组成。这表明，由新分泌的表面活性物质形成的可操作表面活性物质膜可能比以前认为的更凝聚，可能在呼吸力学下提供最大稳定性。
