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Abstract
Pulmonary surfactant is a critical component of lung function in healthy individuals. It functions in part by lowering surface tension in the alveoli, thereby allowing for breathing with minimal effort. The prevailing thinking is that low surface tension is attained by a compression-driven squeeze-out of unsaturated phospholipids during exhalation, forming a film enriched in saturated phospholipids that achieves surface tensions close to zero. A thorough review of past and recent literature suggests that the compression-driven squeeze-out mechanism may be erroneous. Here, we posit that a surfactant film enriched in saturated lipids is formed shortly after birth by an adsorption-driven sorting process and that its composition does not change during normal breathing. We provide biophysical evidence for the rapid formation of an enriched film at high surfactant concentrations, facilitated by adsorption structures containing hydrophobic surfactant proteins. We examine biophysical evidence for and against the compression-driven squeeze-out mechanism and propose a new model for surfactant function. The proposed model is tested against existing physiological and pathophysiological evidence in neonatal and adult lungs, leading to ideas for biophysical research, that should be addressed to establish the physiological relevance of this new perspective on the function of the mighty thin film that surfactant provides.
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Affiliation(s)
- Fred Possmayer
- Department of Biochemistry, Western University, London, Ontario N6A 3K7, Canada
- Department of Obstetrics/Gynaecology, Western University, London, Ontario N6A 3K7, Canada
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manon, Honolulu, Hawaii 96822, United States
- Department of Pediatrics, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96826, United States
| | - Ruud A W Veldhuizen
- Department of Physiology & Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Department of Medicine, Western University, London, Ontario N6A 3K7, Canada
- Lawson Health Research Institute, London, Ontario N6A 4V2, Canada
| | - Nils O Petersen
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
- Department of Chemistry, Western University, London, Ontario N6A 5B7, Canada
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2
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Timm S, Lettau M, Hegermann J, Rocha ML, Weidenfeld S, Fatykhova D, Gutbier B, Nouailles G, Lopez-Rodriguez E, Hocke A, Hippenstiel S, Witzenrath M, Kuebler WM, Ochs M. The unremarkable alveolar epithelial glycocalyx: a thorium dioxide-based electron microscopic comparison after heparinase or pneumolysin treatment. Histochem Cell Biol 2023:10.1007/s00418-023-02211-7. [PMID: 37386200 PMCID: PMC10387119 DOI: 10.1007/s00418-023-02211-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2023] [Indexed: 07/01/2023]
Abstract
Recent investigations analyzed in depth the biochemical and biophysical properties of the endothelial glycocalyx. In comparison, this complex cell-covering structure is largely understudied in alveolar epithelial cells. To better characterize the alveolar glycocalyx ultrastructure, unaffected versus injured human lung tissue explants and mouse lungs were analyzed by transmission electron microscopy. Lung tissue was treated with either heparinase (HEP), known to shed glycocalyx components, or pneumolysin (PLY), the exotoxin of Streptococcus pneumoniae not investigated for structural glycocalyx effects so far. Cationic colloidal thorium dioxide (cThO2) particles were used for glycocalyx glycosaminoglycan visualization. The level of cThO2 particles orthogonal to apical cell membranes (≙ stained glycosaminoglycan height) of alveolar epithelial type I (AEI) and type II (AEII) cells was stereologically measured. In addition, cThO2 particle density was studied by dual-axis electron tomography (≙ stained glycosaminoglycan density in three dimensions). For untreated samples, the average cThO2 particle level was ≈ 18 nm for human AEI, ≈ 17 nm for mouse AEI, ≈ 44 nm for human AEII and ≈ 35 nm for mouse AEII. Both treatments, HEP and PLY, resulted in a significant reduction of cThO2 particle levels on human and mouse AEI and AEII. Moreover, a HEP- and PLY-associated reduction in cThO2 particle density was observed. The present study provides quantitative data on the differential glycocalyx distribution on AEI and AEII based on cThO2 and demonstrates alveolar glycocalyx shedding in response to HEP or PLY resulting in a structural reduction in both glycosaminoglycan height and density. Future studies should elucidate the underlying alveolar epithelial cell type-specific distribution of glycocalyx subcomponents for better functional understanding.
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Affiliation(s)
- Sara Timm
- Core Facility Electron Microscopy, Charité-Universitätsmedizin Berlin, 13353, Berlin, Germany
| | - Marie Lettau
- Institute of Functional Anatomy, Charité-Universitätsmedizin Berlin, 10115, Berlin, Germany.
| | - Jan Hegermann
- Research Core Unit Electron Microscopy and Institute of Functional and Applied Anatomy, Hannover Medical School, 30625, Hannover, Germany
| | - Maria Linda Rocha
- Institute of Functional Anatomy, Charité-Universitätsmedizin Berlin, 10115, Berlin, Germany
- Institute of Pathology, Vivantes Klinikum im Friedrichshain, 10249, Berlin, Germany
| | - Sarah Weidenfeld
- Institute of Physiology, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Diana Fatykhova
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Birgitt Gutbier
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Geraldine Nouailles
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional Anatomy, Charité-Universitätsmedizin Berlin, 10115, Berlin, Germany
| | - Andreas Hocke
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
- German Center for Lung Research (DZL), Berlin, Germany
| | - Stefan Hippenstiel
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
- German Center for Lung Research (DZL), Berlin, Germany
| | - Martin Witzenrath
- Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
- German Center for Lung Research (DZL), Berlin, Germany
| | - Wolfgang M Kuebler
- Institute of Physiology, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
- German Center for Lung Research (DZL), Berlin, Germany
| | - Matthias Ochs
- Core Facility Electron Microscopy, Charité-Universitätsmedizin Berlin, 13353, Berlin, Germany
- Institute of Functional Anatomy, Charité-Universitätsmedizin Berlin, 10115, Berlin, Germany
- German Center for Lung Research (DZL), Berlin, Germany
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3
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Szabová J, Mravec F, Mokhtari M, Le Borgne R, Kalina M, Berret JF. N,N,N-Trimethyl chitosan as a permeation enhancer for inhalation drug delivery: Interaction with a model pulmonary surfactant. Int J Biol Macromol 2023; 239:124235. [PMID: 37001781 DOI: 10.1016/j.ijbiomac.2023.124235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/13/2023] [Accepted: 03/26/2023] [Indexed: 04/08/2023]
Abstract
N,N,N-Trimethyl chitosan (TMC), a biocompatible and biodegradable derivative of chitosan, is currently used as a permeation enhancer to increase the translocation of drugs to the bloodstream in the lungs. This article discusses the effect of TMC on a mimetic pulmonary surfactant, Curosurf®, a low-viscosity lipid formulation administered to preterm infants with acute respiratory distress syndrome. Curosurf® exhibits a strong interaction with TMC, resulting in the formation of aggregates at electrostatic charge stoichiometry. At nanoscale, Curosurf® undergoes a profound reorganization of its lipid vesicles in terms of size and lamellarity. The initial micron-sized vesicles (average size 4.8 μm) give way to a froth-like network of unilamellar vesicles about 300 nm in size. Under such conditions, neutralization of the cationic charges by pulmonary surfactant may inhibit TMC permeation enhancer capacity, especially as electrostatic charge complexation is found at low TMC content. The permeation properties of pulmonary surfactant-neutralized TMC should then be evaluated for its applicability as a permeation enhancer for inhalation in the alveolar region.
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Affiliation(s)
- Jana Szabová
- Université Paris Cité, CNRS, Matière et Systèmes Complexes, 75013 Paris, France; Materials Research Centre, Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic.
| | - Filip Mravec
- Materials Research Centre, Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic
| | - Mostafa Mokhtari
- Neonatal Intensive Care Unit, Hôpitaux Universitaires Paris - Saclay, Hôpital Universitaire de Bicêtre, Espace Ethique/Île-deFrance, Hôpital Universitaire Saint-Louis - APHP, Paris, France
| | - Rémi Le Borgne
- Université de Paris, CNRS, Institute Jacques Monod, 75013 Paris, France
| | - Michal Kalina
- Materials Research Centre, Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic
| | - Jean-François Berret
- Université Paris Cité, CNRS, Matière et Systèmes Complexes, 75013 Paris, France.
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4
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Wang Z, Li S, Huang B. Alveolar macrophages: Achilles' heel of SARS-CoV-2 infection. Signal Transduct Target Ther 2022; 7:242. [PMID: 35853858 PMCID: PMC9295089 DOI: 10.1038/s41392-022-01106-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/11/2022] [Accepted: 07/04/2022] [Indexed: 11/23/2022] Open
Abstract
The coronavirus disease 2019 (COVID-19) pandemic has caused more than 6.3 million deaths to date. Despite great efforts to curb the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccines and neutralizing antibodies are in the gloom due to persistent viral mutations and antiviral compounds face challenges of specificity and safety. In addition, vaccines are unable to treat already-infected individuals, and antiviral drugs cannot be used prophylactically. Therefore, exploration of unconventional strategies to curb the current pandemic is highly urgent. Alveolar macrophages (AMs) residing on the surface of alveoli are the first immune cells that dispose of alveoli-invading viruses. Our findings demonstrate that M1 AMs have an acidic endosomal pH, thus favoring SARS-CoV-2 to leave endosomes and release into the cytosol where the virus initiates replication; in contrast, M2 AMs have an increased endosomal pH, which dampens the viral escape and facilitates delivery of the virus for lysosomal degradation. In this review, we propose that AMs are the Achilles’ heel of SARS-CoV-2 infection and that modulation of the endosomal pH of AMs has the potential to eliminate invaded SARS-CoV-2; the same strategy might also be suitable for other lethal respiratory viruses.
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Affiliation(s)
- Zhenfeng Wang
- Department of Immunology & National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College, 100005, Beijing, China
| | - Shunshun Li
- Department of Immunology, Basic Medicine College, China Medical University, 110122, Shenyang, Liaoning, China
| | - Bo Huang
- Department of Immunology & National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College, 100005, Beijing, China. .,Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science & Technology, 430030, Wuhan, China.
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5
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A recipe for a good clinical pulmonary surfactant. Biomed J 2022; 45:615-628. [PMID: 35272060 PMCID: PMC9486245 DOI: 10.1016/j.bj.2022.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 12/11/2022] Open
Abstract
The lives of thousands premature babies have been saved along the last thirty years thanks to the establishment and consolidation of pulmonary surfactant replacement therapies (SRT). It took some time to close the gap between the identification of the biophysical and molecular causes of the high mortality associated with respiratory distress syndrome in very premature babies and the development of a proper therapy. Closing the gap required the elucidation of some key questions defining the structure–function relationships in surfactant as well as the particular role of the different molecular components assembled into the surfactant system. On the other hand, the application of SRT as part of treatments targeting other devastating respiratory pathologies, in babies and adults, is depending on further extensive research still required before enough amounts of good humanized clinical surfactants will be available. This review summarizes our current concepts on the compositional and structural determinants defining pulmonary surfactant activity, the principles behind the development of efficient natural animal-derived or recombinant or synthetic therapeutic surfactants, as well as a the most promising lines of research that are already opening new perspectives in the application of tailored surfactant therapies to treat important yet unresolved respiratory pathologies.
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6
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Castillo-Sánchez JC, Roldán N, García-Álvarez B, Batllori E, Galindo A, Cruz A, Perez-Gil J. The highly packed and dehydrated structure of pre-formed unexposed human pulmonary surfactant isolated from amniotic fluid. Am J Physiol Lung Cell Mol Physiol 2021; 322:L191-L203. [PMID: 34851730 DOI: 10.1152/ajplung.00230.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
By coating the alveolar air-liquid interface, lung surfactant overwhelms surface tension forces that, otherwise, would hinder the lifetime effort of breathing. Years of research have provided a picture of how highly hydrophobic and specialized proteins in surfactant promote rapid and efficient formation of phospholipid-based complex three-dimensional films at the respiratory surface, highly stable under the demanding breathing mechanics. However, recent evidence suggest that the structure and performance of surfactant typically isolated from bronchoalveolar lung lavages may be far from that of nascent, still unused, surfactant as freshly secreted by type II pneumocytes into the alveolar airspaces. In the present work, we report the isolation of lung surfactant from human amniotic fluid (amniotic fluid surfactant, AFS) and a detailed description of its composition, structure and surface activity in comparison to a natural surfactant (NS) purified from porcine bronchoalveolar lavages. We observe that the lipid/protein complexes in AFS exhibit a substantially higher lipid packing and dehydration than in NS. AFS shows melting transitions at higher temperatures than NS and a conspicuous presence of non-lamellar phases. The surface activity of AFS is not only comparable to that of NS under physiologically-meaningful conditions, but displays significantly higher resistance to inhibition by serum or meconium, agents that inactivate surfactant in the context of severe respiratory pathologies. We propose that AFS may be the optimal model to study the molecular mechanisms sustaining pulmonary surfactant performance in health and disease, and the reference material to develop improved therapeutic surfactant preparations to treat yet unresolved respiratory pathologies.
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Affiliation(s)
- José Carlos Castillo-Sánchez
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institute "Hospital 12 Octubre (imas12)", Complutense University, Madrid, Spain
| | - Nuria Roldán
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institute "Hospital 12 Octubre (imas12)", Complutense University, Madrid, Spain
| | - Begoña García-Álvarez
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, Madrid, Spain
| | - Emma Batllori
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institute "Hospital 12 Octubre (imas12)", Complutense University, Madrid, Spain
| | - Alberto Galindo
- Department of Obstetrics and Gynecology, Hospital Universitario 12 de Octubre. Red de Salud Materno Infantil y del Desarrollo (SAMID). Instituto de Investigación Hospital 12 de Octubre (imas12). Universidad Complutense de Madrid, Spain
| | - Antonio Cruz
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institute "Hospital 12 Octubre (imas12)", Complutense University, Madrid, Spain
| | - Jesus Perez-Gil
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institute "Hospital 12 Octubre (imas12)", Complutense University, Madrid, Spain
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7
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Da Silva E, Vogel U, Hougaard KS, Pérez-Gil J, Zuo YY, Sørli JB. An adverse outcome pathway for lung surfactant function inhibition leading to decreased lung function. Curr Res Toxicol 2021; 2:225-236. [PMID: 34345865 PMCID: PMC8320609 DOI: 10.1016/j.crtox.2021.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/19/2021] [Accepted: 05/25/2021] [Indexed: 12/27/2022] Open
Abstract
Inhaled substances, such as consumer products, chemicals at the workplace, and nanoparticles, can affect the lung function in several ways. In this paper, we explore the adverse outcome pathway (AOP) that starts when inhaled substances that reach the alveoli inhibit the function of the lung surfactant, and leads to decreased lung function. Lung surfactant covers the inner surface of the alveoli, and regulates the surface tension at the air-liquid interface during breathing. The inhibition of the lung surfactant function leads to alveolar collapse because of the resulting high surface tension at the end of expiration. The collapsed alveoli can be re-opened by inspiration, but this re-opening causes shear stress on cells covering the alveoli. This can damage the alveolar-capillary membrane integrity, allowing blood components to enter the alveolar airspace. Blood components, such as albumin, can interact with the lung surfactant and further inhibit its function. The collapse of the alveoli is responsible for a decrease in the surface area available for blood oxygenation, and it reduces the volume of air that can be inhaled and exhaled. These different key events lead to decreased lung function, characterized by clinical signs of respiratory toxicity and reduced blood oxygenation. Here we present the weight of evidence that supports the AOP, and we give an overview of the methods available in vitro and in vivo to measure each key event of the pathway, and how this AOP can potentially be used in screening for inhalation toxicity.
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Key Words
- AO, adverse outcome
- AOP, adverse outcome pathway
- ARDS, acute respiratory distress syndrome
- Adverse outcome pathway
- Alternative method
- EAGMST, Extended Advisory Group on Molecular Screening and Toxicogenomics
- GHS, Globally Harmonized System of Classification and Labelling of Chemicals
- Inhalation
- KE, key event
- Lung surfactant
- MIE, molecular initiating event
- Nanomaterials
- New approach methodology
- OECD, Organisation for Economic Cooperation and Development
- OI, oxygenation index
- PaO2, dissolved oxygen in the plasma
- SaO2, percentage of hemoglobin saturated with oxygen
- Spray products
- TEER, trans epithelial electrical resistance
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Affiliation(s)
- Emilie Da Silva
- National Research Centre for the Working Environment, Copenhagen, Denmark
- DTU Environment, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Ulla Vogel
- National Research Centre for the Working Environment, Copenhagen, Denmark
- DTU Health Tech, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Karin S. Hougaard
- National Research Centre for the Working Environment, Copenhagen, Denmark
- Department of Public Health, University of Copenhagen, Denmark
| | - Jesus Pérez-Gil
- Faculty of Biology and Research Institute “12 de Octubre (imas12)”, Complutense University, Madrid, Spain
| | - Yi Y. Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Jorid B. Sørli
- National Research Centre for the Working Environment, Copenhagen, Denmark
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8
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Structural hallmarks of lung surfactant: Lipid-protein interactions, membrane structure and future challenges. Arch Biochem Biophys 2021; 703:108850. [PMID: 33753033 DOI: 10.1016/j.abb.2021.108850] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/20/2021] [Accepted: 03/16/2021] [Indexed: 11/23/2022]
Abstract
Lung surfactant (LS) is an outstanding example of how a highly regulated and dynamic membrane-based system has evolved to sustain a wealth of structural reorganizations in order to accomplish its biophysical function, as it coats and stabilizes the respiratory air-liquid interface in the mammalian lung. The present review dissects the complexity of the structure-function relationships in LS through an updated description of the lipid-protein interactions and the membrane structures that sustain its synthesis, secretion, interfacial performance and recycling. We also revise the current models and the biophysical techniques employed to study the membranous architecture of LS. It is important to consider that the structure and functional properties of LS are often studied in bulk or under static conditions, in spite that surfactant function is strongly connected with a highly dynamic behaviour, sustained by very polymorphic structures and lipid-lipid, lipid-protein and protein-protein interactions that reorganize in precise spatio-temporal coordinates. We have tried to underline the evidences available of the existence of such structural dynamism in LS. A last important aspect is that the synthesis and assembly of LS is a strongly regulated intracellular process to ensure the establishment of the proper interactions driving LS surface activity, while protecting the integrity of other cell membranes. The use of simplified lipid models or partial natural materials purified from animal tissues could be too simplistic to understand the true molecular mechanisms defining surfactant function in vivo. In this line, we will bring into the attention of the reader the methodological challenges and the questions still open to understand the structure-function relationships of LS at its full biological relevance.
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9
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Brandt R, Timm S, Gorenflos López JL, Kwame Abledu J, Kuebler WM, Hackenberger CPR, Ochs M, Lopez-Rodriguez E. Metabolic Glycoengineering Enables the Ultrastructural Visualization of Sialic Acids in the Glycocalyx of the Alveolar Epithelial Cell Line hAELVi. Front Bioeng Biotechnol 2021; 8:614357. [PMID: 33520965 PMCID: PMC7841390 DOI: 10.3389/fbioe.2020.614357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/23/2020] [Indexed: 12/13/2022] Open
Abstract
The glycocalyx—a plethora of sugars forming a dense layer that covers the cell membrane—is commonly found on the epithelial surface of lumen forming tissue. New glycocalyx specific properties have been defined for various organs in the last decade. However, in the lung alveolar epithelium, its structure and functions remain almost completely unexplored. This is partly due to the lack of physiologically relevant, cost effective in vitro models. As the glycocalyx is an essential but neglected part of the alveolar epithelial barrier, understanding its properties holds the promise to enhance the pulmonary administration of drugs and delivery of nanoparticles. Here, using air-liquid-interface (ALI) cell culture, we focus on combining metabolic glycoengineering with glycan specific electron and confocal microscopy to visualize the glycocalyx of a recently immortalized human alveolar epithelial cell line (hAELVi). For this purpose, we applied different bioorthogonal labeling approaches to visualize sialic acid—an amino sugar that provides negative charge to the lung epithelial glycocalyx—using both fluorescence and gold-nanoparticle labeling. Further, we compared mild chemical fixing/freeze substitution and standard cytochemical electron microscopy embedding protocols for their capacity of contrasting the glycocalyx. In our study, we established hAELVi cells as a convenient model for investigating human alveolar epithelial glycocalyx. Transmission electron microscopy revealed hAELVi cells to develop ultrastructural features reminiscent of alveolar epithelial type II cells (ATII). Further, we visualized extracellular uni- and multilamellar membranous structures in direct proximity to the glycocalyx at ultrastructural level, indicating putative interactions. The lamellar membranes were able to form structures of higher organization, and we report sialic acid to be present within those. In conclusion, combining metabolite specific glycoengineering with ultrastructural localization presents an innovative method with high potential to depict the molecular distribution of individual components of the alveolar epithelial glycocalyx and its interaction partners.
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Affiliation(s)
- Raphael Brandt
- Institute of Functional Anatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Sara Timm
- Core Facility Electron Microscopy, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jacob L Gorenflos López
- Department Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Department of Chemistry, Humboldt Universität zu Berlin, Berlin, Germany
| | | | - Wolfgang M Kuebler
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.,German Center for Lung Research (DZL), Berlin, Germany
| | - Christian P R Hackenberger
- Department Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Department of Chemistry, Humboldt Universität zu Berlin, Berlin, Germany
| | - Matthias Ochs
- Institute of Functional Anatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Core Facility Electron Microscopy, Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Center for Lung Research (DZL), Berlin, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional Anatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany
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10
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Hu S, Zhao T, Li H, Cheng D, Sun Z. Effect of tetracaine on dynamic reorganization of lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183351. [PMID: 32416192 DOI: 10.1016/j.bbamem.2020.183351] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 04/18/2020] [Accepted: 05/07/2020] [Indexed: 12/16/2022]
Abstract
To understand the intrinsic influence of a drug on lipid membranes is of critical importance in pharmacological science. Herein, we report fluorescence microscopy analysis of the interaction between the local anesthetic tetracaine (TTC) and planar supported lipid bilayers (SLBs), as model membranes. Our results show that TTC increases lipid chain mobility, destabilizes the SLBs and remarkably induces membrane disruption and solubilization. Upon TTC binding, a local curvature change in the bilayer was observed, which led to the subsequent formation of up to 20-μm-long flexible lipid tubules as well as the formation of micron-size holes. Quantitative analysis revealed that membrane solubilization process can be divided into two distinct different stages as a function of TTC concentration. In the first stage (<800 μM), the bilayer disruption profiles fit well to a Langmuir isotherm, while in the second stage (800 μM-25 mM), TTC solubilizes the membrane in a detergent-like manner. Notably, the onset of membrane solubilization occurred below the critical micelle concentration (cmc) of TTC, indicating a local accumulation of the drug in the membrane. Additionally, cholesterol increases the insertion of TTC into the membrane and thus promotes the solubilization effect of TTC on lipid bilayers. These findings may help to elucidate the possible mechanisms of TTC interaction with lipid membranes, the dose dependent toxicity attributed to local anesthetics, as well as provide valuable information for drug development and modification.
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Affiliation(s)
- Shipeng Hu
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Tao Zhao
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
| | - Hewen Li
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Danling Cheng
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Zhihua Sun
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
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11
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Ochs M, Hegermann J, Lopez-Rodriguez E, Timm S, Nouailles G, Matuszak J, Simmons S, Witzenrath M, Kuebler WM. On Top of the Alveolar Epithelium: Surfactant and the Glycocalyx. Int J Mol Sci 2020; 21:ijms21093075. [PMID: 32349261 PMCID: PMC7246550 DOI: 10.3390/ijms21093075] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/16/2020] [Accepted: 04/18/2020] [Indexed: 12/14/2022] Open
Abstract
Gas exchange in the lung takes place via the air-blood barrier in the septal walls of alveoli. The tissue elements that oxygen molecules have to cross are the alveolar epithelium, the interstitium and the capillary endothelium. The epithelium that lines the alveolar surface is covered by a thin and continuous liquid lining layer. Pulmonary surfactant acts at this air-liquid interface. By virtue of its biophysical and immunomodulatory functions, surfactant keeps alveoli open, dry and clean. What needs to be added to this picture is the glycocalyx of the alveolar epithelium. Here, we briefly review what is known about this glycocalyx and how it can be visualized using electron microscopy. The application of colloidal thorium dioxide as a staining agent reveals differences in the staining pattern between type I and type II alveolar epithelial cells and shows close associations of the glycocalyx with intraalveolar surfactant subtypes such as tubular myelin. These morphological findings indicate that specific spatial interactions between components of the surfactant system and those of the alveolar epithelial glycocalyx exist which may contribute to the maintenance of alveolar homeostasis, in particular to alveolar micromechanics, to the functional integrity of the air-blood barrier, to the regulation of the thickness and viscosity of the alveolar lining layer, and to the defence against inhaled pathogens. Exploring the alveolar epithelial glycocalyx in conjunction with the surfactant system opens novel physiological perspectives of potential clinical relevance for future research.
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Affiliation(s)
- Matthias Ochs
- Institute of Functional Anatomy, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany;
- German Center for Lung Research (DZL), 10117 Berlin, Germany; (M.W.); (W.M.K.)
- Correspondence:
| | - Jan Hegermann
- Research Core Unit Electron Microscopy and Institute of Functional and Applied Anatomy, Hannover Medical School, 30625 Hannover, Germany;
| | - Elena Lopez-Rodriguez
- Institute of Functional Anatomy, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany;
| | - Sara Timm
- Core Facility Electron Microscopy, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany;
| | - Geraldine Nouailles
- Department of Infectious Diseases and Respiratory Medicine, and Division of Pulmonary Inflammation, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany;
| | - Jasmin Matuszak
- Institute of Physiology, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (J.M.); (S.S.)
| | - Szandor Simmons
- Institute of Physiology, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (J.M.); (S.S.)
| | - Martin Witzenrath
- German Center for Lung Research (DZL), 10117 Berlin, Germany; (M.W.); (W.M.K.)
- Department of Infectious Diseases and Respiratory Medicine, and Division of Pulmonary Inflammation, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany;
| | - Wolfgang M. Kuebler
- German Center for Lung Research (DZL), 10117 Berlin, Germany; (M.W.); (W.M.K.)
- Institute of Physiology, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (J.M.); (S.S.)
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12
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Lugones Y, Blanco O, López-Rodríguez E, Echaide M, Cruz A, Pérez-Gil J. Inhibition and counterinhibition of Surfacen, a clinical lung surfactant of natural origin. PLoS One 2018; 13:e0204050. [PMID: 30235278 PMCID: PMC6147439 DOI: 10.1371/journal.pone.0204050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/31/2018] [Indexed: 12/23/2022] Open
Abstract
Inactivation of pulmonary surfactant by different components such as serum, cholesterol or meconium contributes to severe respiratory pathologies through destabilization and collapse of airspaces. Recent studies have analyzed in detail how the interfacial properties of natural surfactant purified from animal lungs are altered as a consequence of its exposure to serum proteins or meconium-mobilized cholesterol. It has been also demonstrated that pre-exposure of surfactant to polymers such as hyaluronic acid provides resistance to inactivation by multiple inhibitory agents. In the current work, we have extended these studies to the analysis of Surfacen, a clinical surfactant currently in use to rescue premature babies suffering or at risk of respiratory distress due to congenital lack of surfactant. This surfactant is also strongly inhibited by both meconium and serum when tested in the captive bubble surfactometer (CBS) under conditions mimicking respiratory dynamics. As it occurs with native surfactant, Surfacen is markedly protected from inhibition by pre-exposure to hyaluronic acid, confirming that clinical surfactants can be improved to treat pathologies associated with strongly deactivating contexts, such as those associated with lung injury and inflammation. Remarkably, we found that, under physiologically-mimicking conditions, a cholesterol-free clinical surfactant such as Surfacen is less susceptible to inhibition by cholesterol-mobilizing environments than cholesterol-containing natural surfactant, as a consequence of a markedly reduced susceptibility to incorporation of exogenous cholesterol.
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Affiliation(s)
- Yuliannis Lugones
- Dept. Biochemistry, Fac. of Biology, Complutense University, Madrid, Spain
- Centro Nacional de Sanidad Agropecuaria, Mayabeque, Cuba
| | - Odalys Blanco
- Dept. Biochemistry, Fac. of Biology, Complutense University, Madrid, Spain
- Centro Nacional de Sanidad Agropecuaria, Mayabeque, Cuba
| | | | - Mercedes Echaide
- Dept. Biochemistry, Fac. of Biology, Complutense University, Madrid, Spain
- Research Institut “Hospital 12 de Octubre (imas12)”, Madrid, Spain
| | - Antonio Cruz
- Dept. Biochemistry, Fac. of Biology, Complutense University, Madrid, Spain
- Research Institut “Hospital 12 de Octubre (imas12)”, Madrid, Spain
| | - Jesús Pérez-Gil
- Dept. Biochemistry, Fac. of Biology, Complutense University, Madrid, Spain
- Research Institut “Hospital 12 de Octubre (imas12)”, Madrid, Spain
- * E-mail:
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13
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Zhang J, Li Q, Shao Q, Song J, Zhou B, Shu P. Effects of panax notoginseng saponin on the pathological ultrastructure and serum IL‐6 and IL‐8 in pulmonary fibrosis in rabbits. J Cell Biochem 2018; 119:8410-8418. [DOI: 10.1002/jcb.27045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/23/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Jizhou Zhang
- Department of OncologyWenzhou Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medicine UniversityWenzhouZhejiangChina
| | - Qing Li
- Department of Integrated TCM & Western MedicineThe Second Affiliated Hospital of Kunming Medical CollegeKunmingYunnanChina
| | - Qiqi Shao
- Department of NursingWenzhou Lucheng District Wuma Community Health Service CenterWenzhouZhejiangChina
| | - Jingling Song
- Teaching and Research Section of PathologyKunming Medical UniversityKunmingYunnanChina
| | - Bin Zhou
- Department of OncologyWenzhou Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medicine UniversityWenzhouZhejiangChina
| | - Peng Shu
- Department of OncologyJiangsu Province Hospital of TCMNanjingJiangsuChina
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14
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Modulation of hyaluronan polymer size regulates proliferation of perimysial fibroblasts in thyroid eye disease. Biochem Biophys Res Commun 2018; 496:1376-1381. [DOI: 10.1016/j.bbrc.2018.02.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 02/04/2018] [Indexed: 11/22/2022]
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15
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Hidalgo A, Salomone F, Fresno N, Orellana G, Cruz A, Perez-Gil J. Efficient Interfacially Driven Vehiculization of Corticosteroids by Pulmonary Surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7929-7939. [PMID: 28738158 DOI: 10.1021/acs.langmuir.7b01177] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Pulmonary surfactant is a crucial system to stabilize the respiratory air-liquid interface. Furthermore, pulmonary surfactant has been proposed as an effective method for targeting drugs to the lungs. However, few studies have examined in detail the mechanisms of incorporation of drugs into surfactant, the impact of the presence of drugs on pulmonary surfactant performance at the interface under physiologically meaningful conditions, or the ability of pulmonary surfactant to use the air-liquid interface to vehiculise drugs to long distances. This study focuses on the ability of pulmonary surfactant to interfacially vehiculize corticosteroids such as beclomethasone dipropionate (BDP) or Budesonide (BUD) as model drugs. The main objectives have been to (a) characterize the incorporation of corticosteroids into natural and synthetic surfactants, (b) evaluate whether the presence of corticosteroids affects surfactant functionality, and (c) determine whether surfactant preparations enable the efficient spreading and distribution of BDP and BUD along the air-liquid interface. We have compared the performance of a purified surfactant from porcine lungs and two clinical surfactants: Poractant alfa, a natural surfactant of animal origin extensively used to treat premature babies, and CHF5633, a new synthetic surfactant preparation currently under clinical trials. Both, natural and clinical surfactants spontaneously incorporated corticosteroids up to at least 10% by mass with respect to phospholipid content. The presence of the drugs did not interfere with their ability to efficiently adsorb into air-liquid interfaces and form surface active films able to reach and sustain very low surface tensions (<2 mN/m) under compression-expansion cycling mimicking breathing dynamics. Furthermore, the combination of clinical surfactant with corticosteroids efficiently promoted the active diffusion of the drug to long distances along the air-liquid interface. This effect could not be mimicked by vehiculisation of corticosteroids in liposomes or in micellar emulsions similar to the formulations currently in use to deliver anti-inflammatory corticosteroids through inhalation.
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Affiliation(s)
- Alberto Hidalgo
- Department of Biochemistry, Faculty of Biology, and Research Institute Hospital "12 de Octubre", Complutense University , Madrid 28040, Spain
| | | | - Nieves Fresno
- Department of Organic Chemistry, Faculty of Chemistry, Complutense University , Madrid 28040, Spain
| | - Guillermo Orellana
- Department of Organic Chemistry, Faculty of Chemistry, Complutense University , Madrid 28040, Spain
| | - Antonio Cruz
- Department of Biochemistry, Faculty of Biology, and Research Institute Hospital "12 de Octubre", Complutense University , Madrid 28040, Spain
| | - Jesus Perez-Gil
- Department of Biochemistry, Faculty of Biology, and Research Institute Hospital "12 de Octubre", Complutense University , Madrid 28040, Spain
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16
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Beck-Broichsitter M, Ruge CA, Bohr A. Impact of triblock copolymers on the biophysical function of naturally-derived lung surfactant. Colloids Surf B Biointerfaces 2017; 156:262-269. [PMID: 28544958 DOI: 10.1016/j.colsurfb.2017.05.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/08/2017] [Accepted: 05/14/2017] [Indexed: 12/28/2022]
Abstract
The current study aimed at investigating the general applicability of triblock copolymers consisting of poly(ethylene glycol) and poly(propylene glycol) (Pluronic®) as excipients for lung delivery. After thorough physicochemical characterization of the diverse polymers, their cytotoxicity was evaluated using alveolar epithelial cells. Next, a naturally-derived lung surfactant was challenged with the distinct triblock copolymers with respect to changes in microstructure, adsorption to the air/liquid interface and dynamic surface tension behavior under bubble pulsation. Biocompatibility assessment of triblock copolymers in A549 cells demonstrated some cytotoxicity, dependent on the hydrophobicity and dose of the substance applied (effective at ≥0.1mg/ml). Supplementing triblock copolymers onto Alveofact® had an obvious influence on the aggregation state and surface activity (>25 and >5mN/m during adsorption and bubble pulsation, respectively) of the lung surfactant. Interestingly, Pluronic® F127, a rather hydrophilic triblock copolymer, showed the most intense effect on the microstructure and biophysical performance of Alveofact®. This is likely due to the synergistic interplay of its low critical micelle concentration and rather high molecular weight, leading to the penetration of lung surfactant film/vesicles and accompanied by a partial replacement of relevant surfactant components from the air/liquid interface. Overall, suitable compositions and concentrations of triblock copolymers were identified with respect to compatibility with the physiological environment of the deep lungs.
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Affiliation(s)
- Moritz Beck-Broichsitter
- Medical Clinic II, Department of Internal Medicine, Justus-Liebig-Universität, Giessen, Germany; Institut Galien, Faculté de Pharmacie, Université Paris-Sud XI, Châtenay-Malabry, France.
| | - Christian A Ruge
- Institut Galien, Faculté de Pharmacie, Université Paris-Sud XI, Châtenay-Malabry, France
| | - Adam Bohr
- Institut Galien, Faculté de Pharmacie, Université Paris-Sud XI, Châtenay-Malabry, France; Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark
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17
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Echaide M, Autilio C, Arroyo R, Perez-Gil J. Restoring pulmonary surfactant membranes and films at the respiratory surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1725-1739. [PMID: 28341439 DOI: 10.1016/j.bbamem.2017.03.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/14/2017] [Accepted: 03/19/2017] [Indexed: 02/08/2023]
Abstract
Pulmonary surfactant is a complex of lipids and proteins assembled and secreted by the alveolar epithelium into the thin layer of fluid coating the respiratory surface of lungs. There, surfactant forms interfacial films at the air-water interface, reducing dramatically surface tension and thus stabilizing the air-exposed interface to prevent alveolar collapse along respiratory mechanics. The absence or deficiency of surfactant produces severe lung pathologies. This review describes some of the most important surfactant-related pathologies, which are a cause of high morbidity and mortality in neonates and adults. The review also updates current therapeutic approaches pursuing restoration of surfactant operative films in diseased lungs, mainly through supplementation with exogenous clinical surfactant preparations. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- Mercedes Echaide
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain
| | - Chiara Autilio
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain
| | - Raquel Arroyo
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain
| | - Jesus Perez-Gil
- Dept. Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, Madrid, Spain.
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18
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Composition, structure and mechanical properties define performance of pulmonary surfactant membranes and films. Chem Phys Lipids 2014; 185:153-75. [PMID: 25260665 DOI: 10.1016/j.chemphyslip.2014.09.002] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/06/2014] [Accepted: 09/11/2014] [Indexed: 12/30/2022]
Abstract
The respiratory surface in the mammalian lung is stabilized by pulmonary surfactant, a membrane-based system composed of multiple lipids and specific proteins, the primary function of which is to minimize the surface tension at the alveolar air-liquid interface, optimizing the mechanics of breathing and avoiding alveolar collapse, especially at the end of expiration. The goal of the present review is to summarize current knowledge regarding the structure, lipid-protein interactions and mechanical features of surfactant membranes and films and how these properties correlate with surfactant biological function inside the lungs. Surfactant mechanical properties can be severely compromised by different agents, which lead to surfactant inhibition and ultimately contributes to the development of pulmonary disorders and pathologies in newborns, children and adults. A detailed comprehension of the unique mechanical and rheological properties of surfactant layers is crucial for the diagnostics and treatment of lung diseases, either by analyzing the contribution of surfactant impairment to the pathophysiology or by improving the formulations in surfactant replacement therapies. Finally, a short review is also included on the most relevant experimental techniques currently employed to evaluate lung surfactant mechanics, rheology, and inhibition and reactivation processes.
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19
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Lopez-Rodriguez E, Pérez-Gil J. Structure-function relationships in pulmonary surfactant membranes: from biophysics to therapy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1568-85. [PMID: 24525076 DOI: 10.1016/j.bbamem.2014.01.028] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 01/22/2014] [Accepted: 01/27/2014] [Indexed: 01/01/2023]
Abstract
Pulmonary surfactant is an essential lipid-protein complex to maintain an operative respiratory surface at the mammalian lungs. It reduces surface tension at the alveolar air-liquid interface to stabilise the lungs against physical forces operating along the compression-expansion breathing cycles. At the same time, surfactant integrates elements establishing a primary barrier against the entry of pathogens. Lack or deficiencies of the surfactant system are associated with respiratory pathologies, which treatment often includes supplementation with exogenous materials. The present review summarises current models on the molecular mechanisms of surfactant function, with particular emphasis in its biophysical properties to stabilise the lungs and the molecular alterations connecting impaired surfactant with diseased organs. It also provides a perspective on the current surfactant-based strategies to treat respiratory pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.
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Affiliation(s)
- Elena Lopez-Rodriguez
- Departamento de Bioquimica y Biologia Molecular, Facultad de Biologia, Universidad Complutense de Madrid, Madrid, Spain; Institute for Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany; Biomedical Research in End Stage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover, Germany
| | - Jesús Pérez-Gil
- Departamento de Bioquimica y Biologia Molecular, Facultad de Biologia, Universidad Complutense de Madrid, Madrid, Spain
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