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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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Abstract
Drug delivery using a surfactant vehicle has the potential to prevent systemic side effects by delivering therapeutic agents directly to the respiratory system. The inherent chemical properties of surfactant allows it to readily distribute throughout the respiratory system. Therapeutic agents delivered by surfactant can primarily confer additional benefits but have potential to improve surfactant function. It is critically important that additional agents do not interefere with the innate surface tension lowering function of surfactant. Systemic evaluation through benchtop, translational and human trials are required to translate this potential technique into clinical practice.
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Affiliation(s)
- Arun Sett
- Newborn Research, The Royal Women's Hospital, Melbourne, Australia; Department of Obstetrics, Gynaecology and Newborn Health, The University of Melbourne, Melbourne, Australia; Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia; Newborn Services, Joan Kirner Women's and Children's, Sunshine Hospital, Victoria, Australia.
| | - Charles C Roehr
- Newborn Services, Southmead Hospital, North Bristol NHS Trust Bristol, Bristol, UK; Faculty of Health Sciences, University of Bristol, Bristol, UK; Oxford Population Health, National Perinatal Epidemiology Unit, Medical Sciences Division, University of Oxford, Oxford, UK
| | - Brett J Manley
- Newborn Research, The Royal Women's Hospital, Melbourne, Australia; Department of Obstetrics, Gynaecology and Newborn Health, The University of Melbourne, Melbourne, Australia; Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia
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3
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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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4
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Dynamic tensiometry studies on interactions of novel therapeutic inhalable powders with model pulmonary surfactant at the air–water interface. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.02.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Seehase M, Collins JJP, Kuypers E, Jellema RK, Ophelders DRMG, Ospina OL, Perez-Gil J, Bianco F, Garzia R, Razzetti R, Kramer BW. New surfactant with SP-B and C analogs gives survival benefit after inactivation in preterm lambs. PLoS One 2012; 7:e47631. [PMID: 23091635 PMCID: PMC3473048 DOI: 10.1371/journal.pone.0047631] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 09/13/2012] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Respiratory distress syndrome in preterm babies is caused by a pulmonary surfactant deficiency, but also by its inactivation due to various conditions, including plasma protein leakage. Surfactant replacement therapy is well established, but clinical observations and in vitro experiments suggested that its efficacy may be impaired by inactivation. A new synthetic surfactant (CHF 5633), containing synthetic surfactant protein B and C analogs, has shown comparable effects on oxygenation in ventilated preterm rabbits versus Poractant alfa, but superior resistance against inactivation in vitro. We hypothesized that CHF 5633 is also resistant to inactivation by serum albumin in vivo. METHODOLOGY/PRINCIPAL FINDINGS Nineteen preterm lambs of 127 days gestational age (term = 150 days) received CHF 5633 or Poractant alfa and were ventilated for 48 hours. Ninety minutes after birth, the animals received albumin with CHF 5633 or Poractant alfa. Animals received additional surfactant if P(a)O(2) dropped below 100 mmHg. A pressure volume curve was done post mortem and markers of pulmonary inflammation, surfactant content and biophysiology, and lung histology were assessed. CHF 5633 treatment resulted in improved arterial pH, oxygenation and ventilation efficiency index. The survival rate was significantly higher after CHF 5633 treatment (5/7) than after Poractant alfa (1/8) after 48 hours of ventilation. Biophysical examination of the surfactant recovered from bronchoalveolar lavages revealed that films formed by CHF 5633-treated animals reached low surface tensions in a wider range of compression rates than films from Poractant alfa-treated animals. CONCLUSIONS For the first time a synthetic surfactant containing both surfactant protein B and C analogs showed significant benefit over animal derived surfactant in an in vivo model of surfactant inactivation in premature lambs.
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Affiliation(s)
- Matthias Seehase
- Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jennifer J. P. Collins
- Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Elke Kuypers
- Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Reint K. Jellema
- Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Olga L. Ospina
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain
- Department of Physics, Pontificia Universidad Javeriana, Bogota, Colombia
| | - J. Perez-Gil
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain
| | - Federico Bianco
- Research and Development Department, Chiesi Farmaceutici SpA, Parma, Italy
| | - Raffaella Garzia
- Research and Development Department, Chiesi Farmaceutici SpA, Parma, Italy
| | - Roberta Razzetti
- Research and Development Department, Chiesi Farmaceutici SpA, Parma, Italy
| | - Boris W. Kramer
- Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands
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Surfactant and its Role in the Upper Respiratory System and Eustachian Tube. ACTA MEDICA MARTINIANA 2012. [DOI: 10.2478/v10201-011-0028-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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7
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Zuo YY, Veldhuizen RAW, Neumann AW, Petersen NO, Possmayer F. Current perspectives in pulmonary surfactant--inhibition, enhancement and evaluation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1947-77. [PMID: 18433715 DOI: 10.1016/j.bbamem.2008.03.021] [Citation(s) in RCA: 361] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 03/26/2008] [Accepted: 03/26/2008] [Indexed: 02/06/2023]
Abstract
Pulmonary surfactant (PS) is a complicated mixture of approximately 90% lipids and 10% proteins. It plays an important role in maintaining normal respiratory mechanics by reducing alveolar surface tension to near-zero values. Supplementing exogenous surfactant to newborns suffering from respiratory distress syndrome (RDS), a leading cause of perinatal mortality, has completely altered neonatal care in industrialized countries. Surfactant therapy has also been applied to the acute respiratory distress syndrome (ARDS) but with only limited success. Biophysical studies suggest that surfactant inhibition is partially responsible for this unsatisfactory performance. This paper reviews the biophysical properties of functional and dysfunctional PS. The biophysical properties of PS are further limited to surface activity, i.e., properties related to highly dynamic and very low surface tensions. Three main perspectives are reviewed. (1) How does PS permit both rapid adsorption and the ability to reach very low surface tensions? (2) How is PS inactivated by different inhibitory substances and how can this inhibition be counteracted? A recent research focus of using water-soluble polymers as additives to enhance the surface activity of clinical PS and to overcome inhibition is extensively discussed. (3) Which in vivo, in situ, and in vitro methods are available for evaluating the surface activity of PS and what are their relative merits? A better understanding of the biophysical properties of functional and dysfunctional PS is important for the further development of surfactant therapy, especially for its potential application in ARDS.
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Affiliation(s)
- Yi Y Zuo
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
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