Lamellar bodies form solid three-dimensional films at the respiratory air-liquid interface.
Pulmonary surfactant is essential for lung function. It is assembled, stored and secreted as particulate entities (lamellar body-like particles; LBPs). LBPs disintegrate when they contact an air-liquid interface, leading to an instantaneous spreading of material and a decline in surface tension. Here, we demonstrate that the film formed by the adsorbed material spontaneously segregate into distinct ordered and disordered lipid phase regions under unprecedented near-physiological conditions and, unlike natural surfactant purified from bronchoalveolar lavages, dynamically reorganized into highly viscous multilayer domains with complex three-dimensional topographies. Multilayer domains, in coexistence with liquid phases, showed a progressive stiffening and finally solidification, probably driven by a self-driven disassembly of LBPs from a sub-surface compartment. We conclude that surface film formation from LBPs is a highly dynamic and complex process, leading to a more elaborated scenario than that observed and predicted by models using reconstituted, lavaged, or fractionated preparations.
Ravasio
Andrea
A
Department of Physiology and Medical Physics, Medical University, 6020 Innsbruck, Austria.
Olmeda
Bárbara
B
Bertocchi
Cristina
C
Haller
Thomas
T
Pérez-Gil
Jesús
J
D000388:Air; D056809:Alveolar Epithelial Cells / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001896:Boron Compounds / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008968:Molecular Conformation; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D012119:Respiration; D013499:Surface Properties; D013997:Time Factors
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D011663:Pulmonary Surfactants