1
|
Herman L, De Smedt SC, Raemdonck K. Pulmonary surfactant as a versatile biomaterial to fight COVID-19. J Control Release 2021; 342:170-188. [PMID: 34813878 PMCID: PMC8605818 DOI: 10.1016/j.jconrel.2021.11.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/13/2021] [Accepted: 11/15/2021] [Indexed: 02/06/2023]
Abstract
The COVID-19 pandemic has wielded an enormous pressure on global health care systems, economics and politics. Ongoing vaccination campaigns effectively attenuate viral spreading, leading to a reduction of infected individuals, hospitalizations and mortality. Nevertheless, the development of safe and effective vaccines as well as their global deployment is time-consuming and challenging. In addition, such preventive measures have no effect on already infected individuals and can show reduced efficacy against SARS-CoV-2 variants that escape vaccine-induced host immune responses. Therefore, it is crucial to continue the development of specific COVID-19 targeting therapeutics, including small molecular drugs, antibodies and nucleic acids. However, despite clear advantages of local drug delivery to the lung, inhalation therapy of such antivirals remains difficult. This review aims to highlight the potential of pulmonary surfactant (PS) in the treatment of COVID-19. Since SARS-CoV-2 infection can progress to COVID-19-related acute respiratory distress syndrome (CARDS), which is associated with PS deficiency and inflammation, replacement therapy with exogenous surfactant can be considered to counter lung dysfunction. In addition, due to its surface-active properties and membrane-interaction potential, PS can be repurposed to enhance drug spreading along the respiratory epithelium and to promote intracellular drug delivery. By merging these beneficial features, PS can be regarded as a versatile biomaterial to combat respiratory infections, in particular COVID-19.
Collapse
Affiliation(s)
- Lore Herman
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| | - Stefaan C De Smedt
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| | - Koen Raemdonck
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| |
Collapse
|
2
|
Sever N, Miličić G, Bodnar NO, Wu X, Rapoport TA. Mechanism of Lamellar Body Formation by Lung Surfactant Protein B. Mol Cell 2020; 81:49-66.e8. [PMID: 33242393 DOI: 10.1016/j.molcel.2020.10.042] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 09/14/2020] [Accepted: 10/28/2020] [Indexed: 11/30/2022]
Abstract
Breathing depends on pulmonary surfactant, a mixture of phospholipids and proteins, secreted by alveolar type II cells. Surfactant requires lamellar bodies (LBs), organelles containing densely packed concentric membrane layers, for storage and secretion. LB biogenesis remains mysterious but requires surfactant protein B (SP-B), which is synthesized as a precursor (pre-proSP-B) that is cleaved during trafficking into three related proteins. Here, we elucidate the functions and cooperation of these proteins in LB formation. We show that the N-terminal domain of proSP-B is a phospholipid-binding and -transfer protein whose activities are required for proSP-B export from the endoplasmic reticulum (ER) and sorting to LBs, the conversion of proSP-B into lipoprotein particles, and neonatal viability in mice. The C-terminal domain facilitates ER export of proSP-B. The mature middle domain, generated after proteolytic cleavage of proSP-B, generates the striking membrane layers characteristic of LBs. Together, our results lead to a mechanistic model of LB biogenesis.
Collapse
Affiliation(s)
- Navdar Sever
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Goran Miličić
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Nicholas O Bodnar
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Xudong Wu
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
| |
Collapse
|
3
|
Loney RW, Panzuela S, Chen J, Yang Z, Fritz JR, Dell Z, Corradi V, Kumar K, Tieleman DP, Hall SB, Tristram-Nagle SA. Location of the Hydrophobic Surfactant Proteins, SP-B and SP-C, in Fluid-Phase Bilayers. J Phys Chem B 2020; 124:6763-6774. [PMID: 32600036 DOI: 10.1021/acs.jpcb.0c03665] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The hydrophobic surfactant proteins, SP-B and SP-C, promote rapid adsorption by the surfactant lipids to the surface of the liquid that lines the alveolar air sacks of the lungs. To gain insights into the mechanisms of their function, we used X-ray diffuse scattering (XDS) and molecular dynamics (MD) simulations to determine the location of SP-B and SP-C within phospholipid bilayers. Initial samples contained the surfactant lipids from extracted calf surfactant with increasing doses of the proteins. XDS located protein density near the phospholipid headgroup and in the hydrocarbon core, presumed to be SP-B and SP-C, respectively. Measurements on dioleoylphosphatidylcholine (DOPC) with the proteins produced similar results. MD simulations of the proteins with DOPC provided molecular detail and allowed direct comparison of the experimental and simulated results. Simulations used conformations of SP-B based on other members of the saposin-like family, which form either open or closed V-shaped structures. For SP-C, the amino acid sequence suggests a partial α-helix. Simulations fit best with measurements of XDS for closed SP-B, which occurred at the membrane surface, and SP-C oriented along the hydrophobic interior. Our results provide the most definitive evidence yet concerning the location and orientation of the hydrophobic surfactant proteins.
Collapse
Affiliation(s)
- Ryan W Loney
- Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Sergio Panzuela
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada.,Department of Theoretical Physics and Condensed Matter, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Jespar Chen
- Biological Physics Group, Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Zimo Yang
- Biological Physics Group, Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jonathan R Fritz
- Biological Physics Group, Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Zachary Dell
- Biological Physics Group, Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Kamlesh Kumar
- Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Stephen B Hall
- Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Stephanie A Tristram-Nagle
- Biological Physics Group, Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| |
Collapse
|
4
|
Martinez-Calle M, Prieto M, Olmeda B, Fedorov A, Loura LM, Pérez-Gil J. Pulmonary surfactant protein SP-B nanorings induce the multilamellar organization of surfactant complexes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183216. [DOI: 10.1016/j.bbamem.2020.183216] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/17/2020] [Accepted: 02/02/2020] [Indexed: 11/25/2022]
|
5
|
Liekkinen J, Enkavi G, Javanainen M, Olmeda B, Pérez-Gil J, Vattulainen I. Pulmonary Surfactant Lipid Reorganization Induced by the Adsorption of the Oligomeric Surfactant Protein B Complex. J Mol Biol 2020; 432:3251-3268. [DOI: 10.1016/j.jmb.2020.02.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/22/2020] [Accepted: 02/24/2020] [Indexed: 12/11/2022]
|
6
|
Robichaud NAS, Khatami MH, Saika-Voivod I, Booth V. All-Atom Molecular Dynamics Simulations of Dimeric Lung Surfactant Protein B in Lipid Multilayers. Int J Mol Sci 2019; 20:ijms20163863. [PMID: 31398818 PMCID: PMC6719169 DOI: 10.3390/ijms20163863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/29/2019] [Accepted: 08/06/2019] [Indexed: 02/07/2023] Open
Abstract
Although lung surfactant protein B (SP-B) is an essential protein that plays a crucial role in breathing, the details of its structure and mechanism are not well understood. SP-B forms covalent homodimers, and in this work we use all-atom molecular dynamics simulations to study dimeric SP-B’s structure and its behavior in promoting lipid structural transitions. Four initial system configurations were constructed based on current knowledge of SP-B’s structure and mechanism, and the protein maintained a helicity consistent with experiment in all systems. Several SP-B-induced lipid reorganization behaviors were observed, and regions of the protein particularly important for these activities included SP-B’s “central loop” and “hinge” regions. SP-B dimers with one subunit initially positioned in each of two adjacent bilayers appeared to promote close contact between two bilayers. When both subunits were initially positioned in the same bilayer, SP-B induced the formation of a defect in the bilayer, with water penetrating into the centre of the bilayer. Similarly, dimeric SP-B showed a propensity to interact with preformed interpores in the bilayer. SP-B dimers also promoted bilayer thinning and creasing. This work fleshes out the atomistic details of the dimeric SP-B structures and SP-B/lipid interactions that underlie SP-B’s essential functions.
Collapse
Affiliation(s)
- Nicholas A S Robichaud
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
| | - Mohammad Hassan Khatami
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
| | - Ivan Saika-Voivod
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
| | - Valerie Booth
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
| |
Collapse
|
7
|
Miranda C, Booth VK, Morrow MR. Effects of Amphipathic Polypeptides on Membrane Organization Inferred from Studies Using Bicellar Lipid Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11759-11771. [PMID: 30196696 DOI: 10.1021/acs.langmuir.8b02257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
SP-B63-78, a lung surfactant protein fragment, and magainin 2, an antimicrobial peptide, are amphipathic peptides with the same overall charge but different biological functions. Deuterium nuclear magnetic resonance has been used to compare the interactions of these peptides with dispersions of 1,2-dimyristoyl- sn-glycero-3-phophocholine (DMPC)/1,2-dihexanoyl- sn-glycero-3-phophocholine (DHPC) (4:1) and DMPC/1,2-dimyristoyl- sn-glycero-3-phopho-(1'-rac-glycerol) (DMPG)/DHPC (3:1:1), two mixtures of long-chain and short-chain lipids that display bicellar behavior. This study exploited the sensitivity of a bicellar system structural organization to factors that modify partitioning of their lipid components between different environments. In small bicelle particles formed at low temperatures, short-chain components preferentially occupy curved rim environments around bilayer disks of the long-chain components. Changes in chain order and lipid mixing, on heating, can drive transitions to more extended assemblies including a magnetically orientable phase at intermediate temperature. In this work, neither peptide had a substantial effect on the behavior of the zwitterionic DMPC/DHPC mixture. For bicellar mixtures containing the anionic lipid DMPG, the peptide SP-B63-78 lowered the temperature at which magnetically orientable particles coalesced into more extended lamellar structures. SP-B63-78 did not promote partitioning of the zwitterionic and anionic long-chain lipid components into different environments. Magainin 2, on the other hand, was found to promote separation of the anionic lipid, DMPG, and the zwitterionic lipid, DMPC, into different environments for temperatures above 34 °C. The contrast between the effects of these two peptides on the lipid mixtures studied appears to be consistent with their functional roles in biological systems.
Collapse
Affiliation(s)
- Chris Miranda
- Department of Physics and Physical Oceanography , Memorial University of Newfoundland , St. John's , Newfoundland and Labrador , Canada A1B 3X7
| | - Valerie K Booth
- Department of Biochemistry , Memorial University of Newfoundland , St. John's , Newfoundland and Labrador , Canada A1B 3X9
| | - Michael R Morrow
- Department of Physics and Physical Oceanography , Memorial University of Newfoundland , St. John's , Newfoundland and Labrador , Canada A1B 3X7
| |
Collapse
|
8
|
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: 64] [Impact Index Per Article: 9.1] [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.
Collapse
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.
| |
Collapse
|
9
|
All-atom molecular dynamics simulations of lung surfactant protein B: Structural features of SP-B promote lipid reorganization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:3082-3092. [DOI: 10.1016/j.bbamem.2016.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/30/2016] [Accepted: 09/20/2016] [Indexed: 01/07/2023]
|
10
|
Banfi C, Agostoni P. Surfactant protein B: From biochemistry to its potential role as diagnostic and prognostic marker in heart failure. Int J Cardiol 2016; 221:456-62. [PMID: 27414721 DOI: 10.1016/j.ijcard.2016.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/29/2016] [Accepted: 07/02/2016] [Indexed: 01/21/2023]
Abstract
Growing interest raised on circulating biomarkers of structural alveolar-capillary unit damage and very recent data support surfactant protein type B (SP-B) as the most promising candidate in this setting. With respect to other proteins proposed as possible markers of lung damage, SP-B has some unique qualities: it is critical for the assembly of pulmonary surfactant, making its lack incompatible with life; it has no other known site of synthesis except alveolar epithelial cells different from other surfactant proteins; and, it undergoes a proteolytic processing in a pulmonary-cell-specific manner. In the recent years circulating SP-B isoforms, mature or immature, have been demonstrated to be detectable in the circulation depending on the magnitude of the damage of alveolar capillary membrane. In the present review, we summarize the recent knowledge on SP-B regulation, function and we discuss its potential role as reliable biological marker of alveolar capillary membrane (dys)function in the context of heart failure.
Collapse
Affiliation(s)
- Cristina Banfi
- Centro Cardiologico Monzino, IRCCS, Via Parea 4, 20138 Milano, Italy
| | - Piergiuseppe Agostoni
- Centro Cardiologico Monzino, IRCCS, Via Parea 4, 20138 Milano, Italy; Department of Clinical Sciences and Community Health, University of Milan, Milano, Italy.
| |
Collapse
|
11
|
Olmeda B, García‐Álvarez B, Gómez MJ, Martínez‐Calle M, Cruz A, Pérez‐Gil J. A model for the structure and mechanism of action of pulmonary surfactant protein B. FASEB J 2015; 29:4236-47. [DOI: 10.1096/fj.15-273458] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/15/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Bárbara Olmeda
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| | | | - Manuel J. Gómez
- Centro de Astrobiología (INTA‐CSIC), Torrejón de ArdozMadridSpain
| | - Marta Martínez‐Calle
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| | - Antonio Cruz
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| | - Jesús Pérez‐Gil
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| |
Collapse
|
12
|
Sylvester A, MacEachern L, Booth V, Morrow MR. Interaction of the C-terminal peptide of pulmonary surfactant protein B (SP-B) with a bicellar lipid mixture containing anionic lipid. PLoS One 2013; 8:e72248. [PMID: 23991073 PMCID: PMC3753361 DOI: 10.1371/journal.pone.0072248] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 07/08/2013] [Indexed: 01/12/2023] Open
Abstract
The hydrophobic lung surfactant SP-B is essential for respiration. SP-B promotes spreading and adsorption of surfactant at the alveolar air-water interface and may facilitate connections between the surface layer and underlying lamellar reservoirs of surfactant material. SP-B63–78 is a cationic and amphipathic helical peptide containing the C-terminal helix of SP-B. 2H NMR has been used to examine the effect of SP-B63–78 on the phase behavior and dynamics of bicellar lipid dispersions containing the longer chain phospholipids DMPC-d54 and DMPG and the shorter chain lipid DHPC mixed with a 3∶1∶1 molar ratio. Below the gel-to-liquid crystal phase transition temperature of the longer chain components, bicellar mixtures form small, rapidly reorienting disk-like particles with shorter chain lipid components predominantly found around the highly curved particle edges. With increasing temperature, the particles coalesce into larger magnetically-oriented structures and then into more extended lamellar phases. The susceptibility of bicellar particles to coalescence and large scale reorganization makes them an interesting platform in which to study peptide-induced interactions between lipid assemblies. SP-B63–78 is found to lower the temperature at which the orientable phase transforms to the more extended lamellar phase. The peptide also changes the spectrum of motions contributing to quadrupole echo decay in the lamellar phase. The way in which the peptide alters interactions between bilayered micelle structures may provide some insight into some aspects of the role of full-length SP-B in maintaining a functional surfactant layer in lungs.
Collapse
Affiliation(s)
- Alexander Sylvester
- Department of Physics & Physical Oceanography, Memorial University of Newfoundland St. John’s, Newfoundland and Labrador, Canada
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Lauren MacEachern
- Department of Physics & Physical Oceanography, Memorial University of Newfoundland St. John’s, Newfoundland and Labrador, Canada
| | - Valerie Booth
- Department of Physics & Physical Oceanography, Memorial University of Newfoundland St. John’s, Newfoundland and Labrador, Canada
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Michael R. Morrow
- Department of Physics & Physical Oceanography, Memorial University of Newfoundland St. John’s, Newfoundland and Labrador, Canada
- * E-mail:
| |
Collapse
|
13
|
Bräuer L, Schicht M, Worlitzsch D, Bensel T, Sawers RG, Paulsen F. Staphylococcus aureus and Pseudomonas aeruginosa express and secrete human surfactant proteins. PLoS One 2013; 8:e53705. [PMID: 23349731 PMCID: PMC3551896 DOI: 10.1371/journal.pone.0053705] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 12/03/2012] [Indexed: 01/21/2023] Open
Abstract
Surfactant proteins (SP), originally known from human lung surfactant, are essential to proper respiratory function in that they lower the surface tension of the alveoli. They are also important components of the innate immune system. The functional significance of these proteins is currently reflected by a very large and growing number of publications. The objective goal of this study was to elucidate whether Staphylococcus aureus and Pseudomonas aeruginosa is able to express surfactant proteins. 10 different strains of S. aureus and P. aeruginosa were analyzed by means of RT-PCR, Western blot analysis, ELISA, immunofluorescence microscopy and immunoelectron microscopy. The unexpected and surprising finding revealed in this study is that different strains of S. aureus and P. aeruginosa express and secrete proteins that react with currently commercially available antibodies to known human surfactant proteins. Our results strongly suggest that the bacteria are either able to express ‘human-like’ surfactant proteins on their own or that commercially available primers and antibodies to human surfactant proteins detect identical bacterial proteins and genes. The results may reflect the existence of a new group of bacterial surfactant proteins and DNA currently lacking in the relevant sequence and structure databases. At any rate, our knowledge of human surfactant proteins obtained from immunological and molecular biological studies may have been falsified by the presence of bacterial proteins and DNA and therefore requires critical reassessment.
Collapse
Affiliation(s)
- Lars Bräuer
- Department of Anatomy II, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.
| | | | | | | | | | | |
Collapse
|
14
|
Rausch F, Schicht M, Paulsen F, Ngueya I, Bräuer L, Brandt W. "SP-G", a putative new surfactant protein--tissue localization and 3D structure. PLoS One 2012; 7:e47789. [PMID: 23094088 PMCID: PMC3475697 DOI: 10.1371/journal.pone.0047789] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 09/17/2012] [Indexed: 12/30/2022] Open
Abstract
Surfactant proteins (SP) are well known from human lung. These proteins assist the formation of a monolayer of surface-active phospholipids at the liquid-air interface of the alveolar lining, play a major role in lowering the surface tension of interfaces, and have functions in innate and adaptive immune defense. During recent years it became obvious that SPs are also part of other tissues and fluids such as tear fluid, gingiva, saliva, the nasolacrimal system, and kidney. Recently, a putative new surfactant protein (SFTA2 or SP-G) was identified, which has no sequence or structural identity to the already know surfactant proteins. In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G. With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level. The localization of this protein in different human tissues, sequence based prediction tools for posttranslational modifications and molecular dynamic simulations reveal that SP-G has physicochemical properties similar to the already known surfactant proteins B and C. This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G. In conclusion, the results indicate SP-G as a new surfactant protein which represents an until now unknown surfactant protein class.
Collapse
Affiliation(s)
- Felix Rausch
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Martin Schicht
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Friedrich Paulsen
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Ivan Ngueya
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Lars Bräuer
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Wolfgang Brandt
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany
- * E-mail:
| |
Collapse
|
15
|
Olmeda B, García-Álvarez B, Pérez-Gil J. Structure–function correlations of pulmonary surfactant protein SP-B and the saposin-like family of proteins. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 42:209-22. [DOI: 10.1007/s00249-012-0858-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 08/18/2012] [Accepted: 09/03/2012] [Indexed: 02/06/2023]
|
16
|
Duncan SL, Larson RG. Folding of lipid monolayers containing lung surfactant proteins SP-B1–25 and SP-C studied via coarse-grained molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1632-50. [DOI: 10.1016/j.bbamem.2010.04.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 04/05/2010] [Accepted: 04/08/2010] [Indexed: 12/31/2022]
|
17
|
Dohm MT, Mowery BP, Czyzewski AM, Stahl SS, Gellman SH, Barron AE. Biophysical mimicry of lung surfactant protein B by random nylon-3 copolymers. J Am Chem Soc 2010; 132:7957-67. [PMID: 20481635 PMCID: PMC2981085 DOI: 10.1021/ja909734n] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Non-natural oligomers have recently shown promise as functional analogues of lung surfactant proteins B and C (SP-B and SP-C), two helical and amphiphilic proteins that are critical for normal respiration. The generation of non-natural mimics of SP-B and SP-C has previously been restricted to step-by-step, sequence-specific synthesis, which results in discrete oligomers that are intended to manifest specific structural attributes. Here we present an alternative approach to SP-B mimicry that is based on sequence-random copolymers containing cationic and lipophilic subunits. These materials, members of the nylon-3 family, are prepared by ring-opening polymerization of beta-lactams. The best of the nylon-3 polymers display promising in vitro surfactant activities in a mixed lipid film. Pulsating bubble surfactometry data indicate that films containing the most surface-active polymers attain adsorptive and dynamic-cycling properties that surpass those of discrete peptides intended to mimic SP-B. Attachment of an N-terminal octadecanoyl unit to the nylon-3 copolymers, inspired by the post-translational modifications found in SP-C, affords further improvements by reducing the percent surface area compression to reach low minimum surface tension. Cytotoxic effects of the copolymers are diminished relative to that of an SP-B-derived peptide and a peptoid-based mimic. The current study provides evidence that sequence-random copolymers can mimic the in vitro surface-active behavior of lung surfactant proteins in a mixed lipid film. These findings raise the possibility that random copolymers might be useful for developing a lung surfactant replacement, which is an attractive prospect given that such polymers are easier to prepare than are sequence-specific oligomers.
Collapse
Affiliation(s)
- Michelle T. Dohm
- Department of Chemistry, Northwestern University, 2145 N. Sheridan Rd., Evanston, Illinois 60208-3100
| | - Brendan P. Mowery
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706
| | - Ann M. Czyzewski
- Department of Chemical and Biological Engineering, Northwestern University, 2145 N. Sheridan Rd., Evanston, Illinois 60208-3100
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706
| | - Samuel H. Gellman
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706
| | - Annelise E. Barron
- Department of Chemical and Biological Engineering, Northwestern University, 2145 N. Sheridan Rd., Evanston, Illinois 60208-3100
- Department of Bioengineering, Stanford University, W300B James H. Clark Center, 318 Campus Drive, Stanford, California 94305-5440
| |
Collapse
|
18
|
Dohm MT, Seurynck-Servoss SL, Seo J, Zuckermann RN, Barron AE. Close mimicry of lung surfactant protein B by "clicked" dimers of helical, cationic peptoids. Biopolymers 2010; 92:538-53. [PMID: 19777571 DOI: 10.1002/bip.21309] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A family of peptoid dimers developed to mimic SP-B is presented, where two amphipathic, cationic helices are linked by an achiral octameric chain. SP-B is a vital therapeutic protein in lung surfactant replacement therapy, but its large-scale isolation or chemical synthesis is impractical. Enhanced biomimicry of SP-B's disulfide-bonded structure has been previously attempted via disulfide-mediated dimerization of SP-B(1-25) and other peptide mimics, which improved surface activity relative to the monomers. Herein, the effects of disulfide- or "click"-mediated (1,3-dipolar cycloaddition) dimerization, as well as linker chemistry, on the lipid-associated surfactant activity of a peptoid monomer are described. Results revealed that the 'clicked' peptoid dimer enhanced in vitro surface activity in a DPPC:POPG:PA lipid film relative to its disulfide-bonded and monomeric counterparts in both surface balance and pulsating bubble surfactometry studies. On the pulsating bubble surfactometer, the film containing the "clicked" peptoid dimer outperformed all presented peptoid monomers and dimers, and two SP-B derived peptides, attaining an adsorbed surface tension of 22 mN m(-1), and maximum and minimum cycling values of 42 mN m(-1) and near-zero, respectively.
Collapse
Affiliation(s)
- Michelle T Dohm
- Department of Chemistry, Northwestern University, 2145 N. Sheridan Road, Evanston, IL 60208-3100, USA
| | | | | | | | | |
Collapse
|
19
|
Walther FJ, Waring AJ, Hernandez-Juviel JM, Gordon LM, Wang Z, Jung CL, Ruchala P, Clark AP, Smith WM, Sharma S, Notter RH. Critical structural and functional roles for the N-terminal insertion sequence in surfactant protein B analogs. PLoS One 2010; 5:e8672. [PMID: 20084172 PMCID: PMC2805716 DOI: 10.1371/journal.pone.0008672] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 12/18/2009] [Indexed: 01/14/2023] Open
Abstract
Background Surfactant protein B (SP-B; 79 residues) belongs to the saposin protein superfamily, and plays functional roles in lung surfactant. The disulfide cross-linked, N- and C-terminal domains of SP-B have been theoretically predicted to fold as charged, amphipathic helices, suggesting their participation in surfactant activities. Earlier structural studies with Mini-B, a disulfide-linked construct based on the N- and C-terminal regions of SP-B (i.e., ∼residues 8–25 and 63–78), confirmed that these neighboring domains are helical; moreover, Mini-B retains critical in vitro and in vivo surfactant functions of the native protein. Here, we perform similar analyses on a Super Mini-B construct that has native SP-B residues (1–7) attached to the N-terminus of Mini-B, to test whether the N-terminal sequence is also involved in surfactant activity. Methodology/Results FTIR spectra of Mini-B and Super Mini-B in either lipids or lipid-mimics indicated that these peptides share similar conformations, with primary α-helix and secondary β-sheet and loop-turns. Gel electrophoresis demonstrated that Super Mini-B was dimeric in SDS detergent-polyacrylamide, while Mini-B was monomeric. Surface plasmon resonance (SPR), predictive aggregation algorithms, and molecular dynamics (MD) and docking simulations further suggested a preliminary model for dimeric Super Mini-B, in which monomers self-associate to form a dimer peptide with a “saposin-like” fold. Similar to native SP-B, both Mini-B and Super Mini-B exhibit in vitro activity with spread films showing near-zero minimum surface tension during cycling using captive bubble surfactometry. In vivo, Super Mini-B demonstrates oxygenation and dynamic compliance that are greater than Mini-B and compare favorably to full-length SP-B. Conclusion Super Mini-B shows enhanced surfactant activity, probably due to the self-assembly of monomer peptide into dimer Super Mini-B that mimics the functions and putative structure of native SP-B.
Collapse
Affiliation(s)
- Frans J Walther
- Los Angeles Biomedical Research Institute at Harbor, University of California Los Angeles Medical Center, Torrance, California, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Yang TC, McDonald M, Morrow MR, Booth V. The effect of a C-terminal peptide of surfactant protein B (SP-B) on oriented lipid bilayers, characterized by solid-state 2H- and 31P-NMR. Biophys J 2009; 96:3762-71. [PMID: 19413982 DOI: 10.1016/j.bpj.2009.02.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 01/29/2009] [Accepted: 02/03/2009] [Indexed: 02/02/2023] Open
Abstract
SP-B(CTERM), a cationic, helical peptide based on the essential lung surfactant protein B (SP-B), retains a significant fraction of the function of the full-length protein. Solid-state (2)H- and (31)P-NMR were used to examine the effects of SP-B(CTERM) on mechanically oriented lipid bilayer samples. SP-B(CTERM) modified the multilayer structure of bilayers composed of POPC, POPG, POPC/POPG, or bovine lipid extract surfactant (BLES), even at relatively low peptide concentrations. The (31)P spectra of BLES, which contains approximately 1% SP-B, and POPC/POPG with 1% SP-B(CTERM), look very similar, supporting a similarity in lipid interactions of SP-B(CTERM) and its parent protein, full-length SP-B. In the model systems, although the peptide interacted with both the oriented and unoriented fractions of the lipids, it interacted differently with the two fractions, as demonstrated by differences in lipid headgroup structure induced by the peptide. On the other hand, although SP-B(CTERM) induced similar disruptions in overall bilayer orientation in BLES, there was no evidence of lipid headgroup conformational changes in either the oriented or the unoriented fractions of the BLES samples. Notably, in the model lipid systems the peptide did not induce the formation of small, rapidly tumbling lipid structures, such as micelles, or of hexagonal phases, the observation of which would have provided support for functional mechanisms involving peptide-induced lipid flip-flop or stabilization of curved lipid structures, respectively.
Collapse
Affiliation(s)
- Tran-Chin Yang
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada
| | | | | | | |
Collapse
|
21
|
Bastonero S, Le Priol Y, Armand M, Bernard CS, Reynaud-Gaubert M, Olive D, Parzy D, de Bentzmann S, Capo C, Mege JL. New microbicidal functions of tracheal glands: defective anti-infectious response to Pseudomonas aeruginosa in cystic fibrosis. PLoS One 2009; 4:e5357. [PMID: 19399182 PMCID: PMC2670521 DOI: 10.1371/journal.pone.0005357] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 01/14/2009] [Indexed: 12/19/2022] Open
Abstract
Tracheal glands (TG) may play a specific role in the pathogenesis of cystic fibrosis (CF), a disease due to mutations in the cftr gene and characterized by airway inflammation and Pseudomonas aeruginosa infection. We compared the gene expression of wild-type TG cells and TG cells with the cftr DeltaF508 mutation (CF-TG cells) using microarrays covering the whole human genome. In the absence of infection, CF-TG cells constitutively exhibited an inflammatory signature, including genes that encode molecules such as IL-1alpha, IL-beta, IL-32, TNFSF14, LIF, CXCL1 and PLAU. In response to P. aeruginosa, genes associated with IFN-gamma response to infection (CXCL10, IL-24, IFNgammaR2) and other mediators of anti-infectious responses (CSF2, MMP1, MMP3, TLR2, S100 calcium-binding proteins A) were markedly up-regulated in wild-type TG cells. This microbicidal signature was silent in CF-TG cells. The deficiency of genes associated with IFN-gamma response was accompanied by the defective membrane expression of IFNgammaR2 and altered response of CF-TG cells to exogenous IFN-gamma. In addition, CF-TG cells were unable to secrete CXCL10, IL-24 and S100A8/S100A9 in response to P. aeruginosa. The differences between wild-type TG and CF-TG cells were due to the cftr mutation since gene expression was similar in wild-type TG cells and CF-TG cells transfected with a plasmid containing a functional cftr gene. Finally, we reported an altered sphingolipid metabolism in CF-TG cells, which may account for their inflammatory signature. This first comprehensive analysis of gene expression in TG cells proposes a protective role of wild-type TG against airborne pathogens and reveals an original program in which anti-infectious response was deficient in TG cells with a cftr mutation. This defective response may explain why host response does not contribute to protection against P. aeruginosa in CF.
Collapse
Affiliation(s)
- Sonia Bastonero
- Unité de Recherche sur les Maladies Infectieuses Tropicales et Emergentes, CNRS UMR 6236, Faculté de Médecine, Marseille, France
| | - Yannick Le Priol
- Transcriptomic platform, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Martine Armand
- UMR Nutriments Lipidiques et Prévention des Maladies Métaboliques, INSERM U476 INRA UMR1260, Faculté de Médecine, Marseille, France
| | - Christophe S. Bernard
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, CNRS-IMM-UPR 9027, Marseille, France
| | | | - Daniel Olive
- Institut Paoli Calmettes, INSERM Unité 891, Centre de Recherche en Cancérologie, Marseille, France
| | - Daniel Parzy
- Transcriptomic platform, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Sophie de Bentzmann
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, CNRS-IMM-UPR 9027, Marseille, France
| | - Christian Capo
- Unité de Recherche sur les Maladies Infectieuses Tropicales et Emergentes, CNRS UMR 6236, Faculté de Médecine, Marseille, France
| | - Jean-Louis Mege
- Unité de Recherche sur les Maladies Infectieuses Tropicales et Emergentes, CNRS UMR 6236, Faculté de Médecine, Marseille, France
| |
Collapse
|
22
|
Russell-Schulz B, Booth V, Morrow MR. Perturbation of DPPC/POPG bilayers by the N-terminal helix of lung surfactant protein SP-B: a (2)H NMR study. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 38:613-24. [PMID: 19224204 DOI: 10.1007/s00249-009-0415-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 01/30/2009] [Accepted: 02/02/2009] [Indexed: 12/21/2022]
Abstract
SP-B(8-25) is a synthetic peptide comprising the N-terminal helix of the essential lung surfactant protein SP-B. Rat lung oxygenation studies have shown that SP-B(8-25) retains some of the function of full-length SP-B. We have used deuterium nuclear magnetic resonance ((2)H-NMR) to examine the influence of SP-B(8-25) on the mixing properties of saturated PC and unsaturated PG lipids in model mixed lipid bilayers containing dipalmitoylphosphatidylcholine (DPPC) and palmitoyl-oleoyl-phosphatidylglycerol (POPG), in a molar ratio of 7:3. In the absence of the peptide, (2)H-NMR spectra of DPPC/POPG mixtures, with one or the other lipid component deuterated, indicate coexistence of large liquid crystal and gel domains over a range of about 10 degrees C through the liquid crystal to gel transition of the bilayer. Addition of SP-B(8-25) has little effect on the width of the transition but the spectra through the transition range cannot be resolved into distinct liquid crystal and gel spectral components suggesting that the peptide interferes with the tendency of the DPPC and POPG lipid components in this mixture to phase separate near the bilayer transition temperature. Quadrupole echo decay observations suggest that the peptide may also reduce differences in the correlation times for local reorientation of the two lipids. These observations suggest that SP-B(8-25) promotes a more thorough mixing of saturated PC and unsaturated PG components and may be relevant to understanding the behaviour of lung surfactant material under conditions of lateral compression which might be expected to enhance the propensity for saturated and unsaturated surfactant lipid components to segregate.
Collapse
Affiliation(s)
- Bretta Russell-Schulz
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St John's, NF, Canada
| | | | | |
Collapse
|
23
|
Abstract
Although a minor constituent by weight, surfactant protein B (SP-B) plays a major role in surfactant function. It is the unique structure of SP-B that promotes permeabilization, cross-linking, mixing, and fusion of phospholipids, facilitating the proper structure and function of pulmonary surfactant as well as contributing to the formation of lamellar bodies. SP-B production is a complex process within alveolar type 2 cells and is under hormonal and developmental control. Understanding the posttranslational events in the maturation of SP-B may provide new insight into the process of lamellar body formation and into the pathophysiology of pulmonary disorders associated with surfactant abnormalities.
Collapse
|
24
|
Surfactant replacement and open lung concept--comparison of two treatment strategies in an experimental model of neonatal ARDS. BMC Pulm Med 2008; 8:10. [PMID: 18625067 PMCID: PMC2483254 DOI: 10.1186/1471-2466-8-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 07/14/2008] [Indexed: 12/29/2022] Open
Abstract
Background Several concepts of treatment in neonatal ARDS have been proposed in the last years. The present study compared the effects of open lung concept positive pressure ventilation (PPVOLC) with a conventional ventilation strategy combined with administration of two different surfactant preparations on lung function and surfactant homoeostasis. Methods After repeated whole-lung saline lavage, 16 newborn piglets were assigned to either PPVOLC (n = 5) or surfactant treatment under conventional PPV using a natural bovine (n = 5) or a monomeric protein B based surfactant (n = 6). Results Comprehensive monitoring showed each treatment strategy to improve gas exchange and lung function, although the effect on PaO2 and pulmonary compliance declined over the study period in the surfactant groups. The overall improvement of the ventilation efficiency index (VEI) was significantly greater in the PPVOLC group. Phospholipid and protein analyses of the bronchoalveolar lavage fluid showed significant alterations to surfactant homoeostasis in the PPVOLC group, whereas IL-10 and SP-C mRNA expression was tendentially increased in the surfactant groups. Conclusion The different treatment strategies applied could be shown to improve gas exchange and lung function in neonatal ARDS. To which extent differences in maintenance of lung function and surfactant homeostasis may lead to long-term consequences needs to be studied further.
Collapse
|
25
|
Walther FJ, Waring AJ, Sherman MA, Zasadzinski JA, Gordon LM. Hydrophobic surfactant proteins and their analogues. Neonatology 2007; 91:303-10. [PMID: 17575474 DOI: 10.1159/000101346] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Lung surfactant is a complex mixture of phospholipids and four surfactant-associated proteins (SP-A, SP-B, SP-C and SP-D). Its major function in the lung alveolus is to reduce surface tension at the air-water interface in the terminal airways by the formation of a surface-active film enriched in surfactant lipids, hence preventing cellular collapse during respiration. Surfactant therapy using bovine or porcine lung surfactant extracts, which contain only polar lipids and native SP-B and SP-C, has dramatically improved the therapeutic outcomes of preterm infants with respiratory distress syndrome (RDS). One important goal of surfactant researchers is to replace animal-derived therapies with fully synthetic preparations based on SP-B and SP-C, produced by recombinant technology or peptide synthesis, and reconstituted with selected synthetic lipids. Here, we review recent research developments with peptide analogues of SP-B and SP-C, designed using either the known primary sequence and three-dimensional (3D) structure of the native proteins or, alternatively, the known 3D structures of closely homologous proteins. Such SP-B and SP-C mimics offer the possibility of studying the mechanisms of action of the respective native proteins, and may allow the design of optimized surfactant formulations for specific pulmonary diseases (e.g., acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)). These synthetic surfactant preparations may also be a cost-saving therapeutic approach, with better quality control than may be obtained with animal-based treatments.
Collapse
Affiliation(s)
- Frans J Walther
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
| | | | | | | | | |
Collapse
|
26
|
Abstract
Advances in genetic engineering have allowed the creation of animals with additional or deleted genes. New genes may be inserted in mice, specific genes inactivated or "knocked out," and more complex animals created in which genes can be turned on or off at different times in development or in different tissues. These animal models allow for more detailed studies of the proteins encoded by the manipulated gene, an improved understanding of the pathophysiology of diseases resulting from the genetic alterations, and model organisms in which to study potential new therapies. Multiple mouse models involving genes important in surfactant production and regulation relevant to lung disease observed in human newborns have been created. This review will discuss the creation of such animals and illustrate their utility in understanding human disease.
Collapse
Affiliation(s)
- Stephan W Glasser
- Division of Pulmonary Biology, Children's Hospital Medical Center and University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.
| | | |
Collapse
|
27
|
Miller NJ, Postle AD, Orgeig S, Koster G, Daniels CB. The composition of pulmonary surfactant from diving mammals. Respir Physiol Neurobiol 2005; 152:152-68. [PMID: 16140043 DOI: 10.1016/j.resp.2005.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 08/03/2005] [Accepted: 08/03/2005] [Indexed: 10/25/2022]
Abstract
Maintaining a functional pulmonary surfactant system at depth is critical for diving mammals to ensure that inspiration is possible upon re-emergence. The lipid and protein composition of lavage extracts from three pinniped species (California sea lion, Northern elephant seal and Ringed seal) were compared to several terrestrial species. Lavage samples were purified using a NaBr discontinuous gradient. Concentrations of phospholipid classes and molecular species were measured using electrospray ionisation mass spectrometry, cholesterol was measured using high-performance liquid chromatography, surfactant protein A (SP-A) and SP-B were measured using enzyme-linked immunosorbent assays. There were small differences in phospholipid classes, with a lower level of anionic surfactant phospholipids, PG and PI, between diving and terrestrial mammals. There were no differences in PL saturation or SP-A levels between species. PC16:0/14:0, PC16:0/16:1, PC16:0/16:0, long chain PI species and the total concentrations of alkyl-acyl species of PC and PG as a ratio of diacyl species were increased in diving mammals, whereas concentrations of PC16:0/18:1, PG16:0/16:0 and PG16:0/18:1 were decreased. Cholesterol levels were very variable between species and SP-B was very low in diving mammals. These differences may explain the very poor surface activity of pinniped surfactant that we have previously described [Miller, N.J., Daniels, C.B., Schürch, S., Schoel, W.M., Orgeig, S., 2005. The surface activity of pulmonary surfactant from diving mammals. Respir. Physiol. Neurobiol. 150 (2006) 220-232], supporting the hypothesis that pinniped surfactant has primarily an anti-adhesive function to meet the challenges of regularly collapsing lungs.
Collapse
Affiliation(s)
- Natalie J Miller
- Environmental Biology, School of Earth and Environmental Sciences, Darling Building, University of Adelaide, North Tce, Australia
| | | | | | | | | |
Collapse
|
28
|
Hornef MW, Pütsep K, Karlsson J, Refai E, Andersson M. Increased diversity of intestinal antimicrobial peptides by covalent dimer formation. Nat Immunol 2004; 5:836-43. [PMID: 15235601 DOI: 10.1038/ni1094] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 05/21/2004] [Indexed: 12/21/2022]
Abstract
Antimicrobial peptides are essential effector molecules of the innate immune system. Here we describe the structure, function and diversity of cryptdin-related sequence (CRS) peptides, a large family of antimicrobial molecules. We identified the peptides as covalent dimers in mouse intestinal tissue in amounts comparable to those of Paneth cell-derived enteric alpha-defensins. CRS peptides caused rapid and potent killing of commensal and pathogenic bacteria. The CRS peptides formed homo- and heterodimers in vivo, thereby expanding the repertoire of antimicrobial peptides and increasing the peptide diversity of Paneth cell secretions. CRS peptides might therefore be important in the maintenance of the microbial homeostasis within the intestinal tract.
Collapse
Affiliation(s)
- Mathias W Hornef
- Institute of Medical Microbiology and Hygiene, University of Freiburg, D-79104 Freiburg, Germany
| | | | | | | | | |
Collapse
|
29
|
Le Cras TD, Spitzmiller RE, Albertine KH, Greenberg JM, Whitsett JA, Akeson AL. VEGF causes pulmonary hemorrhage, hemosiderosis, and air space enlargement in neonatal mice. Am J Physiol Lung Cell Mol Physiol 2004; 287:L134-42. [PMID: 15033636 DOI: 10.1152/ajplung.00050.2004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether increased levels of VEGF disrupt postnatal lung formation or function, conditional transgenic mice in which VEGF 164 expression was enhanced in respiratory epithelial cells were produced. VEGF expression was induced in the lungs of VEGF transgenic pups with doxycycline from postnatal day 1 through 2 and 6 wk of age. VEGF levels were higher in bronchoalveolar lavage fluid (BALF) and lung homogenates of VEGF transgenic mice compared with endogenous VEGF levels in controls. Neonatal mortality was increased by 50% in VEGF transgenic mice. Total protein content in BALF was elevated in VEGF transgenic mice. Surfactant protein B protein expression was unaltered in VEGF transgenic mice. Although postnatal alveolar and vascular development were not disrupted by VEGF expression, VEGF transgenic mice developed pulmonary hemorrhage, alveolar remodeling, and macrophage accumulation as early as 2 wk of age. Electron microscopy demonstrated abnormal alveolar capillary endothelium in the VEGF transgenic mice. In many locations, the endothelium was discontinuous with segments of attenuated endothelial cells. Large numbers of hemosiderin-laden macrophages and varying degrees of emphysema were observed in adult VEGF transgenic mice. Overexpression of VEGF in the neonatal lung increased infant mortality and caused pulmonary hemorrhage, hemosiderosis, alveolar remodeling, and inflammation.
Collapse
Affiliation(s)
- T D Le Cras
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, OH 45229-3039, USA.
| | | | | | | | | | | |
Collapse
|
30
|
Abstract
The hydrophobic surfactant proteins, SP-B and SP-C, have important roles in surfactant function. The importance of these proteins in normal lung function is highlighted by the lung diseases associated with abnormalities in their expression. Mutations in the gene encoding SP-B result in severe, fatal neonatal lung disease, and mutations in the gene encoding SP-C are associated with chronic interstitial lung diseases in newborns, older children, and adults. This work reviews the current state of knowledge concerning the lung diseases associated with mutations in the SP-B and SP-C genes, and the potential roles of abnormal SP-B and SP-C expression and genetic variation in these genes in other lung diseases.
Collapse
Affiliation(s)
- Lawrence M Nogee
- Division of Neonatology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-3200, USA.
| |
Collapse
|
31
|
Walther FJ, Hernández-Juviel JM, Mercado PE, Gordon LM, Waring AJ. Surfactant with SP-B and SP-C analogues improves lung function in surfactant-deficient rats. Neonatology 2003; 82:181-7. [PMID: 12373069 DOI: 10.1159/000063607] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The use of mammalian lung surfactant extracts has sharply reduced mortality and morbidity from respiratory distress syndrome in premature infants. Synthesis of surfactant protein B and C (SP-B and SP-C) analogues may lead the way to a synthetic surfactant preparation. Dimeric SP-B(1-25) (dSP-B(1-25)) is based on the N-terminal domain of human SP-B and SP-Cfc is a modified human SP-C in which a single phenylalanine is substituted for a palmitoylated cysteine residue in the N-terminal segment (Phe-4 > Cys-4 variant). We tested the effects of synthetic surfactants with 1 or 2% dSP-B(1-25) and 1% SP-Cfc on lung function in surfactant-deficient rats. Four experimental surfactant preparations were prepared by mixing 1% dSP-B(1-25), 2% dSP-B(1-25), 1% dSP-B(1-25) +1% SP-Cfc, and 2% dSP-B(1-25) +1% SP-Cfc with phospholipids (PL). PL and Survanta, a bovine lung extract, were controls. Groups of 8 rats were ventilated, lavaged until surfactant deficiency, and treated with 100 mg/kg surfactant. Arterial blood gas values and dynamic compliance were measured every 15 min and after 2 h of ventilation, the rats were killed and pressure-volume curves performed. Oxygenation improved quickly after instillation of surfactant with synthetic peptides and Survanta. Oxygenation and lung volumes were consistently higher in the 2% than in the 1% dSP-B(1-25) groups. Addition of 1% SP-Cfc to the synthetic surfactants further improved oxygenation and lung volume, but to a lesser extent than increasing the dSP-B(1-25) content from 1 to 2%. These data indicate that improvements in oxygenation and lung volume in lavaged rats are dependent on the concentration of dSP-B(1-25) in the surfactant preparation and that the presence of SP-Cfc has a relative minor effect on these parameters.
Collapse
Affiliation(s)
- Frans J Walther
- Harbor-University of California Los Angeles Research & Education Institute, Torrance, Calif 90502, USA.
| | | | | | | | | |
Collapse
|
32
|
Wüstneck N, Wüstneck R, Perez-Gil J, Pison U. Effects of oligomerization and secondary structure on the surface behavior of pulmonary surfactant proteins SP-B and SP-C. Biophys J 2003; 84:1940-9. [PMID: 12609896 PMCID: PMC1302763 DOI: 10.1016/s0006-3495(03)75002-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The relationship among protein oligomerization, secondary structure at the interface, and the interfacial behavior was investigated for spread layers of native pulmonary surfactant associated proteins B and C. SP-B and SP-C were isolated either from butanol or chloroform/methanol lipid extracts that were obtained from sheep lung washings. The proteins were separated from other components by gel exclusion chromatography or by high performance liquid chromatography. SDS gel electrophoresis data indicate that the SP-B samples obtained using different solvents showed different oligomerization states of the protein. The CD and FTIR spectra of SP-B isolated from all extracts were consistent with a secondary structure dominated by alpha-helix. The CD and FTIR spectra of the first SP-C corresponded to an alpha-helical secondary structure and the spectra of the second SP-C corresponded to a mixture of alpha-helical and beta-sheet conformation. In contrast, the spectra of the third SP-C corresponded to antiparallel beta-sheets. The interfacial behavior was characterized by surface pressure/area (pi-A) isotherms. Differences in the oligomerization state of SP-B as well as in the secondary structure of SP-C all produce significant differences in the surface pressure/area isotherms. The molecular cross sections determined from the pi-A isotherms and from dynamic cycling experiments were 6 nm(2)/dimer molecule for SP-B and 1.15 nm(2)/molecule for SP-C in alpha-helical conformation and 1.05 nm(2)/molecule for SP-C in beta-sheet conformation. Both the oligomer ratio of SP-B and the secondary structure of SP-C strongly influence organization and behavior of these proteins in monolayer assemblies. In addition, alpha-helix --> beta-sheet conversion of SP-C occurs simply by an increase of the summary protein/lipid concentration in solution.
Collapse
Affiliation(s)
- N Wüstneck
- Humboldt-Universität Berlin, Charité Campus Virchow-Klinikum, Anaesthesiologie, Germany.
| | | | | | | |
Collapse
|
33
|
Abstract
Pulmonary surfactant is a lipid-protein complex which has the essential physiological role of stabilizing the respiratory surface of lungs against collapse. To achieve this function, surfactant forms films at the air-liquid interface that reduce dramatically the surface tension of the thin aqueous layer lining the alveoli. Natural surfactant has optimised two important properties. Once secreted to the alveolar spaces, surfactant adsorbs rapidly to the interface. There, surfactant films reduce surface tension close to 0 mN/m when compressed during expiration. The design and production of efficient artificial surfactants for respiratory therapeutics is critically dependent on the knowledge of the molecular mechanisms governing efficient interfacial adsorption and optimal surface activity, in the context of respiratory cycling. The present review summarizes the data available today on the behaviour of the different molecular components of pulmonary surfactant at air-liquid interfaces. A working model is proposed of how surfactant films could modulate the respiratory dynamics.
Collapse
Affiliation(s)
- Jesús Pérez-Gil
- Departamento de Bioquímica y Biología Molecular I, Facultad Biología, Universidad Complutense, Madrid, Spain.
| |
Collapse
|
34
|
Ikegami M, Takabatake N, Weaver TE. Intersubunit disulfide bridge is not required for the protective role of SP-B against lung inflammation. J Appl Physiol (1985) 2002; 93:505-11. [PMID: 12133857 DOI: 10.1152/japplphysiol.01137.2001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Surfactant protein B (SP-B) is known to promote surfactant phospholipid film formation and reduce surface tension. Native SP-B is a homodimer in which subunit association is stabilized via covalent linkage through cysteine 48. We hypothesized that loss of the intersubunit bridge would alter SP-B function and lead to increased inflammation in response to challenge by hyperoxia or endotoxin. Transgenic mice in which SP-B cysteine 48 was mutated to serine were generated and crossed into the SP-B(-/-) background. Wild-type mice and transgenic mice carrying a single copy (SP-Bmon(+)) or two copies (SP-Bmon(++)) of the transgene were exposed to 95% O2 for 3 days or intratracheally injected with 10 microg of endotoxin. Interleukin-1beta, major intrinsic protein 2, and interleukin-6 in lung homogenates after 3 days of hyperoxia were significantly higher (P < 0.001) in SP-Bmon(+) mice than SP-Bmon(++) or wild-type mice. At 16 h after endotoxin injection, cytokines in lung tissues were higher in SP-Bmon(+) mice compared with wild-type mice (P < 0.05). Consistent with prolonged recovery in SP-Bmon(+) mice, the percentage of apoptotic cells in alveolar lavage was significantly lower in SP-Bmon(+) mice than in SP-Bmon(++) and wild-type mice. Overall, increased inflammation in SP-Bmon(+) mice was corrected to a large extent by increased gene dosage, indicating that formation of the intersubunit disulfide bridge is not critical for SP-B function.
Collapse
Affiliation(s)
- Machiko Ikegami
- Division of Pulmonary Biology, Cincinnati Children's Hospital, Cincinnati, Ohio 45229-3039, USA.
| | | | | |
Collapse
|
35
|
Baatz JE, Zou Y, Cox JT, Wang Z, Notter RH. High-yield purification of lung surfactant proteins sp-b and sp-c and the effects on surface activity. Protein Expr Purif 2001; 23:180-90. [PMID: 11570861 DOI: 10.1006/prep.2001.1492] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several protocols for purification of milligram quantities of lung surfactant proteins (SP)-B and SP-C were studied for separation efficiency and surface activity of the isolated proteins recombined with synthetic phospholipids (SPL). SP-B and SP-C were obtained from calf lung surfactant extract by C8 chromatography with isocratic elution by either of three solvent systems: 7:1:0.4 MeOH/CHCl(3)/5% 0.1 M HCl (solvent A), 7:1 MeOH/CHCl(3)+ 0.1% TFA (solvent B), and 7:1:0.4 MeOH/CHCl(3)/H(2)O + 0.1% TFA (solvent C). Solvents A and C yielded pure apoprotein in a single pass, with estimated total protein recoveries of >85 and >90%, respectively. Solvent B was less effective in purifying SP-B and SP-C, had a lower recovery efficiency, and gave isolates with less surface activity. Mixtures of SPL plus SP-B eluted with solvents A and C adsorbed to equilibrium surface tensions of 21-22 mN/m and reached minimum surface tensions <1 mN/m during dynamic cycling. Mixtures of SPL with SP-C obtained with solvents A and C had equilibrium surface tensions of 26-27 mN/m and minimum dynamic values of 2-7 mN/m. The ability to obtain milligrams of virtually lipid-free SP-B and SP-C in a single column pass will facilitate research on their biological, structural, and biophysical properties.
Collapse
Affiliation(s)
- J E Baatz
- Department of Pediatrics, Medical University of South Carolina, 171 Ashley Avenue, Charleston, South Carolina 29425-3313, USA.
| | | | | | | | | |
Collapse
|
36
|
Haagsman HP, Diemel RV. Surfactant-associated proteins: functions and structural variation. Comp Biochem Physiol A Mol Integr Physiol 2001; 129:91-108. [PMID: 11369536 DOI: 10.1016/s1095-6433(01)00308-7] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Pulmonary surfactant is a barrier material of the lungs and has a dual role: firstly, as a true surfactant, lowering the surface tension; and secondly, participating in innate immune defence of the lung and possibly other mucosal surfaces. Surfactant is composed of approximately 90% lipids and 10% proteins. There are four surfactant-specific proteins, designated surfactant protein A (SP-A), SP-B, SP-C and SP-D. Although the sequences and post-translational modifications of SP-B and SP-C are quite conserved between mammalian species, variations exist. The hydrophilic surfactant proteins SP-A and SP-D are members of a family of collagenous carbohydrate binding proteins, known as collectins, consisting of oligomers of trimeric subunits. In view of the different roles of surfactant proteins, studies determining the structure-function relationships of surfactant proteins across the animal kingdom will be very interesting. Such studies may reveal structural elements of the proteins required for surface film dynamics as well as those required for innate immune defence. Since SP-A and SP-D are also present in extrapulmonary tissues, the hydrophobic surfactant proteins SP-B and SP-C may be the most appropriate indicators for the evolutionary origin of surfactant. SP-B is essential for air-breathing in mammals and is therefore largely conserved. Yet, because of its unique structure and its localization in the lung but not in extrapulmonary tissues, SP-C may be the most important indicator for the evolutionary origin of surfactant.
Collapse
Affiliation(s)
- H P Haagsman
- Department of Biochemistry, Cell Biology and Histology and Graduate School of Animal Health, Utrecht University, P.O. Box 80175, 3508 TD, Utrecht, The Netherlands.
| | | |
Collapse
|
37
|
Abstract
SP-B is the only surfactant-associated protein absolutely required for postnatal lung function and survival. Complete deficiency of SP-B in mice and humans results in lethal, neonatal respiratory distress syndrome and is characterized by a virtual absence of lung compliance, highly disorganized lamellar bodies, and greatly diminished levels of SP-C mature peptide; in contrast, lung structure and function in SP-C null mice is normal. This review attempts to integrate recent findings in humans and transgenic mice with the results of in vitro studies to provide a better understanding of the functions of SP-B and SP-C and the structural basis for their actions.
Collapse
Affiliation(s)
- T E Weaver
- Division of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
| | | |
Collapse
|
38
|
Zaltash S, Griffiths WJ, Beck D, Duan CX, Weaver TE, Johansson J. Membrane activity of (Cys48Ser) lung surfactant protein B increases with dimerisation. Biol Chem 2001; 382:933-9. [PMID: 11501758 DOI: 10.1515/bc.2001.116] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
One of the possible functions of lung surfactant protein B (SP-B), an hydrophobic membrane-associated saposin-like protein, is to reduce the alveolar surface tension by promoting insertion of phospholipids into the air/liquid interface of the lung. SP-B is a covalent homodimer; Cys48 of two polypeptides form an intermolecular disulphide bond. In order to test whether dimerisation of SP-B is important for surfactant function, transgenic mice which express (Cys48Ser) human SP-B in a mouse SP-B null background were generated. In previous studies (Cys48Ser)SP-B showed a concentration-dependent in vitro activity, suggesting that it may form non-covalent dimers. Here (Cys48Ser)SP-B isolated from bronchoalveolar lavage of transgenic mice was studied at different concentrations by circular dichroism (CD) spectroscopy, pulsating bubble surfactometry, mass spectrometry and reversed-phase HPLC. The results indicate that (Cys48Ser)SP-B, both in a phospholipid environment and in organic solvents, is largely monomeric and exhibits low activity at concentrations lower than 1 -2 microM, while at higher concentrations it forms non-covalent dimers, which are nearly functionally equivalent to native SP-B in vitro. Furthermore, electrospray mass spectrometry showed that more dimers were found relative to the monomer when the polarity of the solvent was decreased, and when the concentration of SP-B increased. (Cys48Ser)SP-B also eluted earlier than native SP-B in reversed-phase HPLC. Taken together, these results indicate that a polar surface is buried upon dimerisation, thereby promoting formation of interchain ion pairs between Glu51-Arg52' and Glu51'-Arg52.
Collapse
Affiliation(s)
- S Zaltash
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
39
|
Paananen R, Glumoff V, Sormunen R, Voorhout W, Hallman M. Expression and localization of lung surfactant protein B in Eustachian tube epithelium. Am J Physiol Lung Cell Mol Physiol 2001; 280:L214-20. [PMID: 11158999 DOI: 10.1152/ajplung.2001.280.2.l214] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Surfactant protein (SP) B is an essential component of the pulmonary surfactant complex, which participates in reducing the surface tension across the alveolar air-liquid interface. The Eustachian tube (ET) connects the upper respiratory tract to the middle ear, serving as an intermittent airway between the pharynx and the middle ear. Recently, we described the expression of SP-A and SP-D in the ET, suggesting their role in middle ear host defense. Our present aim was to detect whether the expression of SP-B is evident in the porcine ET. With Northern blot analysis, RT-PCR, and in situ hybridizations, SP-B mRNA was identified and localized in the ET epithelium. The cellular localization of SP-B was revealed with immunohistochemistry, electron microscopy, and immunoelectron microscopy. The protein was found in the secretory granules of epithelial cells and also attached to the microvilli at the luminal side of these cells. The SP-B immunoreactivity of aggregates isolated from ET lavage fluid was similar to that isolated from bronchoalveolar lavage fluid. We conclude that there are specialized cells in the ET epithelium expressing and secreting SP-B and propose that SP-B may facilitate normal opening of the tube and mucociliary transport.
Collapse
Affiliation(s)
- R Paananen
- Biocenter Oulu, University of Oulu, 90014 Oulu, Finland.
| | | | | | | | | |
Collapse
|
40
|
Spragg RG, Lewis JF. Pathology of the surfactant system of the mature lung: second San Diego conference. Am J Respir Crit Care Med 2001; 163:280-2. [PMID: 11208658 DOI: 10.1164/ajrccm.163.1.2004028] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Knowledge of the surfactant system has grown immensely in the past decade. A variety of investigative strategies, including manipulation of surfactant protein gene expression in mice, has contributed dramatically to our understanding of the role of surfactant components in lung function. These approaches have fostered investigations that will further our knowledge of the role of lung surfactant in host defense and will provide information that should lead to improved strategies for the treatment of lung disease.
Collapse
Affiliation(s)
- R G Spragg
- Department of Medicine, University of California, San Diego, USA.
| | | |
Collapse
|
41
|
Diemel RV, Bader D, Walch M, Hotter B, van Golde LM, Amann A, Haagsman HP, Putz G. Functional Tests for the Characterization of Surfactant Protein B (SP-B) and a Fluorescent SP-B Analog. Arch Biochem Biophys 2001; 385:338-47. [PMID: 11368015 DOI: 10.1006/abbi.2000.2157] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Surfactant protein B (SP-B) enhances lipid insertion into the alveolar air/liquid interface upon inhalation. The aim of this study was (i) to apply a palette of tests for a detailed biochemical and biophysical characterization of SP-B and (ii) to use these tests to compare native SP-B with a fluorescent (Bodipy) SP-B analog. The method of labeling was fast and resulted in a covalent fluorophore-protein bond. The ability of both proteins to spread a surfactant film on top of a buffer surface was determined in a spreading tray using the Wilhelmy plate technique to allow detection of alterations in surface tension and calculation of spreading velocities. In a captive bubble surfactometer surface tensions of spread films were measured. Similar biophysical properties were found for both native and Bodipy-labeled SP-B. It is concluded that the combination of tests used allows detection of small differences in structure and activity between the two proteins.
Collapse
Affiliation(s)
- R V Diemel
- Department of Anaesthesiology and Critical Care Medicine, The Leopold-Franzens-University of Innsbruck, Austria.
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Egas C, Lavoura N, Resende R, Brito RM, Pires E, de Lima MC, Faro C. The saposin-like domain of the plant aspartic proteinase precursor is a potent inducer of vesicle leakage. J Biol Chem 2000; 275:38190-6. [PMID: 10982803 DOI: 10.1074/jbc.m006093200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A unique feature of plant aspartic proteinase precursors is the presence of an internal domain, known as plant-specific insert, whose function is not completely understood. The three-dimensional structure of the plant-specific insert resembles that of saposin-like proteins, a group of lipid-binding proteins involved in a variety of physiological processes. Here we show that recombinant plant-specific insert is able to interact with phospholipid vesicles and to induce leakage of their contents in a pH- and lipid-dependent manner. The leakage activity is higher at pH 4.5 and requires the presence of acidic phospholipids such as phosphatidylserine. To determine whether the same effect could be observed when the plant-specific insert is part of the precursor form, procardosin A and a mutant form lacking this specific domain were produced and characterized. Procardosin A displays a similar activity profile, whereas the mutant without the plant-specific insert shows only residual activity. These findings indicate that the plant-specific insert domain of plant aspartic proteinases mediates an interaction of their precursors with phospholipid membranes and induces membrane permeabilization. It is therefore possible that the plant-specific insert, alone or in conjunction with the proteolytic activity of plant aspartic proteinases, may function either as a defensive weapon against pathogens or in late autolysis of plant cells.
Collapse
Affiliation(s)
- C Egas
- Centro de Neurociências de Coimbra, Universidade de Coimbra, 3004-517 Coimbra, Portugal.
| | | | | | | | | | | | | |
Collapse
|
43
|
Veldhuizen EJ, Waring AJ, Walther FJ, Batenburg JJ, van Golde LM, Haagsman HP. Dimeric N-terminal segment of human surfactant protein B (dSP-B(1-25)) has enhanced surface properties compared to monomeric SP-B(1-25). Biophys J 2000; 79:377-84. [PMID: 10866963 PMCID: PMC1300941 DOI: 10.1016/s0006-3495(00)76299-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Surfactant protein B (SP-B) is a 17-kDa dimeric protein produced by alveolar type II cells. Its main function is to lower the surface tension by inserting lipids into the air/liquid interface of the lung. SP-B's function can be mimicked by a 25-amino acid peptide, SP-B(1-25), which is based on the N-terminal sequence of SP-B. We synthesized a dimeric version of this peptide, dSP-B(1-25), and the two peptides were tested for their surface activity. Both SP-B(1-25) and dSP-B(1-25) showed good lipid mixing and adsorption activities. The dimeric peptide showed activity comparable to that of native SP-B in the pressure-driven captive bubble surfactometer. Spread surface films led to stable near-zero minimum surface tensions during cycling while protein free, and films containing SP-B(1-25) lost material from the interface during compression. We propose that dimerization of the peptide is required to create a lipid reservoir attached to the monolayer from which new material can enter the surface film upon expansion of the air/liquid interface. The dimeric state of SP-B can fulfill the same function in vivo.
Collapse
Affiliation(s)
- E J Veldhuizen
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, the Netherlands
| | | | | | | | | | | |
Collapse
|