1
|
Hall SB, Zuo YY. The biophysical function of pulmonary surfactant. Biophys J 2024; 123:1519-1530. [PMID: 38664968 DOI: 10.1016/j.bpj.2024.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 04/08/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024] Open
Abstract
The type II pneumocytes of the lungs secrete a mixture of lipids and proteins that together acts as a surfactant. The material forms a thin film on the surface of the liquid layer that lines the alveolar air sacks. When compressed by the decreasing alveolar surface area during exhalation, the films reduce surface tension to exceptionally low levels. Pulmonary surfactant is essential for preserving the integrity of the barrier between alveolar air and capillary blood during normal breathing. This review focuses on the major biophysical processes by which endogenous pulmonary surfactant achieves its function and the mechanisms involved in those processes. Vesicles of pulmonary surfactant adsorb rapidly from the alveolar liquid to form the interfacial film. Interfacial insertion, which requires the hydrophobic surfactant protein SP-B, proceeds by a process analogous to the fusion of two vesicles. When compressed, the adsorbed film desorbs slowly. Constituents remain at the surface at high interfacial concentrations that reduce surface tensions well below equilibrium levels. We review the models proposed to explain how pulmonary surfactant achieves both the rapid adsorption and slow desorption characteristic of a functional film.
Collapse
Affiliation(s)
- Stephen B Hall
- Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon.
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii
| |
Collapse
|
2
|
Kumar K, Chavarha M, Loney RW, Weiss TM, Rananavare SB, Hall SB. The L γ Phase of Pulmonary Surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6601-6611. [PMID: 29715426 PMCID: PMC6526724 DOI: 10.1021/acs.langmuir.8b00460] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
To determine how different components affect the structure of pulmonary surfactant, we measured X-ray scattering by samples derived from calf surfactant. The surfactant phospholipids demonstrated the essential characteristics of the Lγ phase: a unit cell with a lattice constant appropriate for two bilayers, and crystalline chains detected by wide-angle X-ray scattering (WAXS). The electron density profile, obtained from scattering by oriented films at different relative humidities (70-97%), showed that the two bilayers, arranged as mirror images, each contain two distinct leaflets with different thicknesses and profiles. The detailed structures suggest one ordered leaflet that would contain crystalline chains and one disordered monolayer likely to contain the anionic compounds, which constitute ∼10% of the surfactant phospholipids. The spacing and temperature dependence detected by WAXS fit with an ordered leaflet composed of dipalmitoyl phosphatidylcholine. Physiological levels of cholesterol had no effect on this structure. Removing the anionic phospholipids prevented formation of the Lγ phase. The cationic surfactant proteins inhibited Lγ structures, but at levels unlikely related to charge. Because the Lγ phase, if arranged properly, could produce a self-assembled ordered interfacial monolayer, the structure could have important functional consequences. Physiological levels of the proteins, however, inhibit formation of the Lγ structures at high relative humidities, making their physiological significance uncertain.
Collapse
Affiliation(s)
- Kamlesh Kumar
- Departments of Biochemistry & Molecular Biology, Medicine, and Physiology & Pharmacology, Oregon Heath & Science University, Portland, OR 97239-3098
| | - Mariya Chavarha
- Departments of Biochemistry & Molecular Biology, Medicine, and Physiology & Pharmacology, Oregon Heath & Science University, Portland, OR 97239-3098
| | - Ryan W. Loney
- Departments of Biochemistry & Molecular Biology, Medicine, and Physiology & Pharmacology, Oregon Heath & Science University, Portland, OR 97239-3098
| | - Thomas M. Weiss
- Stanford University, SLAC/SSRL Building 137, 2575 Sand Hill Road MS69, Menlo Park, CA 94025
| | | | - Stephen B. Hall
- Departments of Biochemistry & Molecular Biology, Medicine, and Physiology & Pharmacology, Oregon Heath & Science University, Portland, OR 97239-3098
- To whom correspondence should be addressed: Stephen B. Hall, Pulmonary & Critical Care Medicine, Mail Code UHN-67, Oregon Health & Science University, Portland, Oregon 97239-3098, , Telephone: (503) 494-6667
| |
Collapse
|
3
|
Dagan MP, Hall SB. The Equilibrium Spreading Tension of Pulmonary Surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:13063-7. [PMID: 26583569 PMCID: PMC4896737 DOI: 10.1021/acs.langmuir.5b03094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Monomolecular films at an air/water interface coexist at the equilibrium spreading tension (γ(e)) with the bulk phase from which they form. For individual phospholipids, γ(e) is single-valued, and separates conditions at which hydrated vesicles adsorb from tensions at which overcompressed monolayers collapse. With pulmonary surfactant, isotherms show that monolayers compressed on the surface of bubbles coexist with the three-dimensional collapsed phase over a range of surface tensions. γ(e) therefore represents a range rather than a single value of surface tension. Between the upper and lower ends of this range, rates of collapse for spread and adsorbed films decrease substantially. Changes during adsorption across this narrow region of coexistence between the two- and three-dimensional structures at least partially explain how alveolar films of pulmonary surfactant become resistant to collapse.
Collapse
Affiliation(s)
| | - Stephen B. Hall
- Corresponding Author Address: Pulmonary and Critical Care Medicine, Mail Code UHN-67, OHSU, Portland, OR 97239-3098. Telephone: 503-494-6667;
| |
Collapse
|
4
|
Zhou CY, Wu H, Devaraj NK. Rapid access to phospholipid analogs using thiol-yne chemistry. Chem Sci 2015; 6:4365-4372. [PMID: 29218208 PMCID: PMC5707512 DOI: 10.1039/c5sc00653h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/15/2015] [Indexed: 12/22/2022] Open
Abstract
Phospholipids and glycolipids constitute an essential part of biological membranes, and are of tremendous fundamental and practical interest. Unfortunately, the preparation of functional phospholipids, or synthetic analogs, is often synthetically challenging. Here we utilize thiol-yne click chemistry methodology to gain access to phospho- and glycolipid analogs. Alkynyl hydrophilic head groups readily photoreact with numerous thiol modified lipid tails to yield the appropriate dithioether phospho- or glycolipids. The resulting structures closely resemble the structure and function of native diacylglycerolipids. Dithioether phosphatidylcholines (PCs) are suitable for forming giant unilamellar vesicles (GUV), which can be used as vessels for cell-free expression systems. The unnatural thioether linkages render the lipids resistant to phospholipase A2 hydrolysis. We utilize the improved stability of these lipids to control the shrinkage of GUVs composed of a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and dioleyl-dithioether PC, concentrating encapsulated nanoparticles. We imagine that these readily accessible lipids could find a number of applications as natural lipid substitutes.
Collapse
Affiliation(s)
- Cun Yu Zhou
- Department of Chemistry and Biochemistry , University of California , San Diego , La Jolla , California 92093 , USA .
| | - Haoxing Wu
- Department of Chemistry and Biochemistry , University of California , San Diego , La Jolla , California 92093 , USA .
| | - Neal Krishna Devaraj
- Department of Chemistry and Biochemistry , University of California , San Diego , La Jolla , California 92093 , USA .
| |
Collapse
|
5
|
Rugonyi S, Biswas SC, Hall SB. The biophysical function of pulmonary surfactant. Respir Physiol Neurobiol 2008; 163:244-55. [PMID: 18632313 DOI: 10.1016/j.resp.2008.05.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2008] [Revised: 05/23/2008] [Accepted: 05/24/2008] [Indexed: 01/12/2023]
Abstract
Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a 3D bulk phase. Available evidence suggests that adsorption occurs by way of a rate-limiting structure that bridges the gap between the vesicle and the interface, and that the adsorbed film avoids collapse by undergoing a process of solidification. Current models, although incomplete, suggest mechanisms that would partially explain both rapid adsorption and resistance to collapse as well as how different constituents of pulmonary surfactant might affect its behavior.
Collapse
Affiliation(s)
- Sandra Rugonyi
- Division of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239-3098, USA.
| | | | | |
Collapse
|
6
|
Rieger-Fackeldey E, Sindelar R, Sedin G, Jonzon A. Bronchopulmonary C-fibers modulate the breathing pattern in surfactant-depleted juvenile cats. Respir Physiol Neurobiol 2007; 160:341-9. [PMID: 18088566 DOI: 10.1016/j.resp.2007.10.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2007] [Revised: 10/28/2007] [Accepted: 10/31/2007] [Indexed: 10/22/2022]
Abstract
The aim of this study was to investigate the influence of nonmyelinated C-fibers on the breathing pattern by cooling the vagal nerves to temperatures at which myelinated nerve transmission from pulmonary stretch receptors is blocked (+7 degrees C) and further at which nonmyelinated fiber input is blocked (0 degrees C), in anaesthetized spontaneously breathing juvenile cats with normal (L(N)), surfactant-depleted (L(D)) and surfactant-treated (L(T)) lungs. In L(N), vagal cooling from +7 to 0 degrees C decreased respiratory frequency (f(R); -8%; p < 0.01), and increased tidal volume (V(T); +40%; p < 0.01). In the presence of shallow fast breathing in L(D), f(R) decreased (+38 to +7 degrees C: -26%; p < 0.015 and +7 to 0 degrees C: -24%; p < 0.001) and V(T) increased (+37%; p < 0.049 and +88%; p < 0.016). In L(T), f(R) decreased (+7 to 0 degrees C: -21%; p < 0.001), whereas V(T) remained the same at 0 degrees C (+12%; NS). These findings show for the first time that the activity of bronchopulmonary C-fibers have a prominent role in modulating the breathing pattern in juvenile cats with surfactant-depleted lungs.
Collapse
Affiliation(s)
- Esther Rieger-Fackeldey
- Department of Women's and Children's Health, Section for Pediatrics, Uppsala University, Uppsala, Sweden.
| | | | | | | |
Collapse
|
7
|
Wang Z, Chang Y, Schwan AL, Notter RH. Activity and inhibition resistance of a phospholipase-resistant synthetic surfactant in rat lungs. Am J Respir Cell Mol Biol 2007; 37:387-94. [PMID: 17556674 PMCID: PMC2176125 DOI: 10.1165/rcmb.2006-0434oc] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This study investigates the activity and inhibition resistance in excised rat lungs of a novel synthetic surfactant containing the phospholipase-resistant diether phosphonolipid DEPN-8 plus 1.5% bovine surfactant protein (SP)-B/C compared to calf lung surfactant extract (CLSE). DEPN-8 + 1.5% SP-B/C surpassed CLSE in normalizing surfactant-deficient pressure-volume (P-V) deflation mechanics in lavaged excised lungs in the presence of phospholipase A(2) (PLA(2)) or C18:1 lyso-phosphatidylcholine (LPC). DEPN-8 + 1.5% SP-B/C had activity equal to CLSE in normalizing P-V mechanics in the absence of inhibitors or in the presence of serum albumin. These physiologic activity findings were directly consistent with surface activity measurements on the pulsating bubble surfactometer. In the absence of inhibitors, DEPN-8 + 1.5% SP-B/C and CLSE rapidly reached minimum surface tensions < 1 mN/m (0.5 and 2.5 mg surfactant phospholipid/ml). DEPN-8 + 1.5% SP-B/C maintained its high surface activity in the presence of PLA(2), while the surface activity of CLSE was significantly inhibited by exposure to this enzyme. DEPN-8 + 1.5% SP-B/C also had greater surface activity than CLSE in the presence of LPC, and the two surfactants had equivalent surface activity in the presence of albumin. DEPN-8 + 1.5% SP-B/C also had slightly greater surface activity than CLSE when exposed to peroxynitrite in pulsating bubble studies. These results support the potential of developing highly active and inhibition-resistant synthetic exogenous surfactants containing DEPN-8 + apoprotein/peptide constituents for use in treating direct pulmonary forms of clinical acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS).
Collapse
Affiliation(s)
- Zhengdong Wang
- Department of Pediatrics, Box 850 (MRBX), University of Rochester School of Medicine, Rochester, NY 14642, USA
| | | | | | | |
Collapse
|
8
|
Sindelar R, Jonzon A, Schulze A, Sedin G. Surfactant replacement partially restores the activity of pulmonary stretch receptors in surfactant-depleted cats. J Appl Physiol (1985) 2006; 100:594-601. [PMID: 16210438 DOI: 10.1152/japplphysiol.00389.2005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Single units of slowly adapting pulmonary stretch receptors (PSRs) were investigated in anesthetized cats during spontaneous breathing on continuous positive airway pressure (2–5 cmH2O), before and after lung lavage and then after instillation of surfactant to determine the PSR response to surfactant replacement. PSRs were classified as high threshold (HT) and low threshold (LT), and their instantaneous impulse frequency ( fimp) was related to transpulmonary pressure (Ptp) and tidal volume (Vt). Both the total number of impulses and maximal fimp of HT and LT PSRs decreased after lung lavage (55 and 45%, respectively) in the presence of increased Ptp and decreased Vt. While Ptp decreased markedly and Vt remained unchanged after surfactant instillation, all except one PSR responded with increased total number of impulses and maximal fimp (42 and 26%, respectively). Some HT PSRs ceased to discharge after lung lavage but recovered after surfactant instillation. The end-expiratory activity of LT PSRs increased or was regained after surfactant instillation. After instillation of surfactant, respiratory rate increased further with a shorter inspiratory time, resulting in a lower inspiratory-to-expiratory time ratio. Arterial pH decreased (7.31 ± 0.04 vs. 7.22 ± 0.06) and Pco2 increased (5.5 ± 0.7 vs. 7.2 ± 1.3 kPa) after lung lavage, but they were the same after as before instillation of surfactant (pH = 7.21 ± 0.08 and Pco2 = 7.6 ± 1.4 kPa) during spontaneous breathing. In conclusion, surfactant instillation increased lung compliance, which, in turn, increased the activity of both HT and LT PSRs. A further increase in respiratory rate due to a shorter inspiratory time after surfactant instillation suggests that the partially restored PSR activity after surfactant instillation affected the breathing pattern.
Collapse
Affiliation(s)
- Richard Sindelar
- Dept. of Women's and Children's Health, Uppsala Univ., Univ. Children's Hospital, 751 85 Uppsala, Sweden.
| | | | | | | |
Collapse
|
9
|
Wang Z, Baatz JE, Holm BA, Notter RH. Content-dependent activity of lung surfactant protein B in mixtures with lipids. Am J Physiol Lung Cell Mol Physiol 2002; 283:L897-906. [PMID: 12376341 DOI: 10.1152/ajplung.00431.2001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The content-dependent activity of surfactant protein (SP)-B was studied in mixtures with dipalmitoyl phosphatidylcholine (DPPC), synthetic lipids (SL), and purified phospholipids (PPL) from calf lung surfactant extract (CLSE). At fixed SP-B content, adsorption and dynamic surface tension lowering were ordered as PPL/SP-B approximately SL/SP-B > DPPC/SP-B. All mixtures were similar in having increased surface activity as SP-B content was incrementally raised from 0.05 to 0.75% by weight. SP-B had small but measurable effects on interfacial properties even at very low levels < or =0.1% by weight. PPL/SP-B (0.75%) had the highest adsorption and dynamic surface activity, approaching the behavior of CLSE. All mixtures containing 0.75% SP-B reached minimum surface tensions <1 mN/m in pulsating bubble studies at low phospholipid concentration (1 mg/ml). Mixtures of PPL or SL with SP-B (0.5%) also had minimum surface tensions <1 mN/m at 1 mg/ml, whereas DPPC/SP-B (0.5%) reached <1 mN/m at 2.5 mg/ml. Physiological activity also was strongly dependent on SP-B content. The ability of instilled SL/SP-B mixtures to improve surfactant-deficient pressure-volume mechanics in excised lavaged rat lungs increased as SP-B content was raised from 0.1 to 0.75% by weight. This study emphasizes the crucial functional activity of SP-B in lung surfactants. Significant differences in SP-B content between exogenous surfactants used to treat respiratory disease could be associated with substantial activity variations.
Collapse
Affiliation(s)
- Z Wang
- Department of Pediatrics, University of Rochester, Rochester, NY 14642, USA
| | | | | | | |
Collapse
|
10
|
Notter RH, Wang Z, Egan EA, Holm BA. Component-specific surface and physiological activity in bovine-derived lung surfactants. Chem Phys Lipids 2002; 114:21-34. [PMID: 11841823 DOI: 10.1016/s0009-3084(01)00197-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Composition, surface activity and effects on pressure-volume (P-V) mechanics are examined for lavaged calf lung surfactant (LS) and the clinical exogenous surfactants Infasurf and Survanta. Lavaged LS and Infasurf had closely-matching compositions of phospholipids and neutral lipids. Survanta had higher levels of free fatty acids and triglycerides consistent with its content of added synthetic palmitic acid and tripalmitin. Infasurf and Survanta both contained less total protein than LS because of extraction with hydrophobic solvents, but the total protein content relative to phospholipid in Survanta was about 45% lower than in Infasurf. This difference was primarily due to surfactant protein (SP)-B, which was present by ELISA at a mean weight percent relative to phospholipid of 1.04% in LS, 0.90% in Infasurf, and 0.044% in Survanta. Studies on component fractions separated by gel permeation chromatography showed that SP-B was a major contributor to the adsorption, dynamic surface activity, and P-V mechanical effects of Infasurf, which approached whole LS in magnitude. Survanta had lower adsorption, higher minimum surface tension, and a smaller effect on surfactant-deficient P-V mechanics consistent with minimal contributions from SP-B. Addition of 0.05% by weight of purified bovine SP-B to Survanta did not improve surface or physiological activity, but added 0.7% SP-B improved adsorption, dynamic surface tension lowering, and P-V activity to levels similar to Infasurf. The SP-B content of lung surfactants appears to be a crucial factor in their surface activity and efficacy in improving surfactant-deficient pulmonary P-V mechanics.
Collapse
Affiliation(s)
- Robert H Notter
- Department of Pediatrics (Neonatology, Box 777), University of Rochester School of Medicine, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | | | | | | |
Collapse
|
11
|
Abstract
Films of pulmonary surfactant in the lung are metastable at surface pressures well above the equilibrium spreading pressure of 45 mN/m but commonly collapse at that pressure when compressed in vitro. The studies reported here determined the effect of compression rate on the ability of monolayers containing extracted calf surfactant at 37 degrees C to maintain very high surface pressures on the continuous interface of a captive bubble. Increasing the rate from 2 A(2)/phospholipid/min (i.e., 3% of (initial area at 40 mN/m)/min) to 23%/s produced only transient increases to 48 mN/m. Above a threshold rate of 32%/s, however, surface pressures reached > 68 mN/m. After the rapid compression, static films maintained surface pressures within +/- 1 mN/m both at these maximum values and at lower pressures following expansion at < 5%/min to > or = 45 mN/m. Experiments with dimyristoyl phosphatidylcholine at 37 degrees C produced similar results. These findings indicate that compression at rates comparable to values in the lungs can transform at least some phospholipid monolayers from a form that collapses readily at the equilibrium spreading pressure to one that is metastable for prolonged periods at higher pressures. Our results also suggest that transformation of surfactant films can occur without refinement of their composition.
Collapse
Affiliation(s)
- J M Crane
- Departments of Biochemistry and Molecular Biology, Medicine, and Physiology and Pharmacology, Oregon Health Sciences University, Portland, Oregon 97201-3098, USA
| | | |
Collapse
|
12
|
Bruni R, Hernández-Juviel JM, Tanoviceanu R, Walther FJ. Synthetic mimics of surfactant proteins B and C: in vitro surface activity and effects on lung compliance in two animal models of surfactant deficiency. Mol Genet Metab 1998; 63:116-25. [PMID: 9562965 DOI: 10.1006/mgme.1997.2657] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Synthetic surfactant peptides SP-B1-78 and SP-C1-31 in a standard phospholipid mixture have been employed to examine the correlation between in vitro surface activity and in vivo function of synthetic surfactant preparations in the isolated rat lung and premature rabbit models of respiratory distress syndrome. Monolayer techniques showed that SP-B peptides have a high propensity for association with a phospholipid structure. By dynamic respreading, synthetic SP-B and SP-C showed rapid spreading and attained low surface tensions. Used as replacement surfactants in two animal models, these synthetic surfactant preparations partially restored lung compliance in lavaged rats and premature rabbits better than a pure phospholipid preparation and to a degree comparable to clinical surfactant, measured by pressure/volume curves. Our data confirm that in vitro functional determinations of synthetic surfactant peptides are instrumental in the preparation of replacement surfactants, and that dispersions thus selected represent viable therapeutic alternatives to current treatments for respiratory distress syndrome.
Collapse
Affiliation(s)
- R Bruni
- Department of Pediatrics, Charles R. Drew University of Medicine and Science, Los Angeles, California, USA
| | | | | | | |
Collapse
|
13
|
Wang Z, Gurel O, Weinbach S, Notter RH. Primary importance of zwitterionic over anionic phospholipids in the surface-active function of calf lung surfactant extract. Am J Respir Crit Care Med 1997; 156:1049-57. [PMID: 9351602 DOI: 10.1164/ajrccm.156.4.96-10077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The relative contributions of zwitterionic and anionic phospholipids to the surface-active function of calf lung surfactant extract (CLSE) were assessed by measurements of surface properties in vitro and pressure-volume (P-V) mechanics in excised rat lungs in situ. Surface activity and mechanical effects were compared for chromatographically purified CLSE subfractions containing the complete mix of phospholipids (PPL) or modified phospholipids depleted in anionic components (mPPL), alone or combined with 1.3% (by weight) of hydrophobic surfactant proteins (SP-B and SP-C). Surface pressure-time (pi-t) adsorption isotherms at 37 degrees C were very similar for dispersions of PPL and mPPL in a Teflon dish with a stirred subphase to minimize diffusion resistance. Combination of either PPL or mPPL with hydrophobic SP substantially improved adsorption, but mixtures of PPL:SP and mPPL:SP had only small differences in pi-t isotherms and reached the same final equilibrium pi of approximately 47 mN/m achieved by CLSE. Surface pressure-area (pi-A) isotherms and maximum surface pressures were also very similar for spread films of PPL versus mPPL and PPL:SP versus mPPL:SP on the Wilhelmy balance (23 degrees C and 37 degrees C). Respreading based on pi-A isotherm area calculations was slightly better in surface-excess films of PPL versus mPPL and PPL:SP versus mPPL:SP, but differences were minor and were smaller at 37 degrees C than at 23 degrees C. Overall dynamic surface activity in oscillating bubble studies was not significantly different for PPL versus mPPL or for PPL:SP versus mPPL:SP, and the latter two mixtures both reached minimum surface tensions < 1 mN/m (37 degrees C, 20 cycles/min, 0.5 mM phospholipid). Dispersions of PPL:SP, mPPL:SP, and CLSE were also not significantly different in improving P-V mechanics almost to normal when instilled in lavaged, excised rat lungs at 37 degrees C (30 mg/2.5 ml saline). These data suggest that zwitterionic phospholipids have a major role over anionic phospholipids in interacting with hydrophobic SP in the adsorption, dynamic surface tension lowering, film respreading, and pulmonary mechanical activity of the hydrophobic components of calf lung surfactant in CLSE.
Collapse
Affiliation(s)
- Z Wang
- Department of Pediatrics, University of Rochester, New York 14642, USA
| | | | | | | |
Collapse
|
14
|
|
15
|
Affiliation(s)
- M J Kresch
- University of Connecticut Health Center, Division of Neonatology, Farmington 06030-2203, USA
| | | | | |
Collapse
|
16
|
Krill SL, Harn J, Hahn KR, Gupta SL. Activity loss on room temperature storage of Survanta®, a bovine lung extract based surfactant. Int J Pharm 1996. [DOI: 10.1016/0378-5173(95)04335-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
17
|
Abstract
Considerable progress has been made in the development of defined mixtures of proteins or peptides with phospholipids which mimic the activity of natural pulmonary surfactants. Several of these biomimetic surfactants are active in animal models and clinical syndromes of surfactant deficiency. This review summarizes the structure and composition of natural surfactants and the development of defined mixtures of peptides and lipids that may be useful in the treatment of respiratory distress.
Collapse
Affiliation(s)
- L R McLean
- Marion Merrell Dow Research Institute, Cincinnati, Ohio
| | | |
Collapse
|
18
|
Wilcox DT, Glick PL, Karamanoukian H, Rossman J, Morin FC, Holm BA. Pathophysiology of congenital diaphragmatic hernia. V. Effect of exogenous surfactant therapy on gas exchange and lung mechanics in the lamb congenital diaphragmatic hernia model. J Pediatr 1994; 124:289-93. [PMID: 8301441 DOI: 10.1016/s0022-3476(94)70322-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The aim of this study was to assess the impact of surfactant deficiency on the pathophysiology of congenital diaphragmatic hernia (CDH). Pregnant ewes were operated on at 80 days of gestation for creation of a diaphragmatic hernia in the lambs. Twenty-one lambs survived to be delivered by cesarean section and were studied. Compliance was improved when surface tension effects were removed by saline solution in lungs of both control animals and lambs with CDH; however, the lungs of the lambs with CDH still had significantly impaired compliance. In a second series of experiments, two groups were studied: a surfactant-treated and a control, nontreated group. Surfactant was given prophylactically into the liquid-filled lungs before the first breath. All lambs were paralyzed and sedated and their lungs mechanically ventilated with 100% oxygen for 30 minutes; gas exchange was then assessed, pressure-volume data were obtained, and compliance was calculated. Surfactant significantly improved gas exchange; arterial oxygen pressure increased from 39 +/- 11.4 to 316 +/- 53.6 mm Hg, arterial carbon dioxide pressure decreased from 148 to 63 mm Hg, and pH increased from 6.87 to 7.16 (p < 0.001). Lung volume at 25 cm H2O, functional residual capacity, and compliance were all increased (p < 0.02). Thus, in the CDH lamb model, pulmonary mechanics are impaired by both parenchymal and surfactant abnormalities. Both lung mechanics and gas exchange are markedly improved by exogenous surfactant therapy.
Collapse
Affiliation(s)
- D T Wilcox
- Buffalo Institute of Fetal Therapy, Children's Hospital of Buffalo, State University of New York at Buffalo, NY 14222
| | | | | | | | | | | |
Collapse
|
19
|
Glick PL, Stannard VA, Leach CL, Rossman J, Hosada Y, Morin FC, Cooney DR, Allen JE, Holm B. Pathophysiology of congenital diaphragmatic hernia II: the fetal lamb CDH model is surfactant deficient. J Pediatr Surg 1992; 27:382-7; discussion 387-8. [PMID: 1501015 DOI: 10.1016/0022-3468(92)90865-5] [Citation(s) in RCA: 125] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The high mortality for congenital diaphragmatic hernia (CDH) has been attributed to a combination of pulmonary hypoplasia and pulmonary hypertension. We hypothesize that a surfactant deficiency may in part be contributing to the pathophysiology of CDH. This study documents the functional, quantitative, and qualitative aspects of the surfactant status of the alveolar air-liquid interface and the type II pneumocyte in the fetal lamb CDH model. Ten lamb fetuses (gestational age, 80 days) had a CDH created via a left thoracotomy and then were allowed to continue in utero development until term. Three litter mates and three nonoperated time-dated fetuses served as controls. At term, pressure-volume curves were performed to measure pulmonary compliance and total lung capacity. Alveolar lavage was then performed to measure the quantitative and the qualitative aspects of pulmonary surfactant. Finally, isolation of type II pneumocytes allowed quantification of phospholipid synthesis. When compared with controls (N = 6), the CDH lambs (N = 5) had significantly smaller lungs (P = .009), decreased total lung capacity (P less than .001) and compliance (P less than .001), reduced total lavaged phospholipids (P = .006), and decreased percent phosphatidylcholine (P = .02). CDH lambs also had increased total lavaged proteins (P = .05) and higher minimum dynamic surface tension (P less than .001). A surfactant deficiency may be contributing to the pathophysiology of CDH. Surfactant replacement therapy in premature infants has been shown to improve lung compliance, decrease morbidity, and improve survival. Exogenous surfactant may also benefit infants with CDH.
Collapse
Affiliation(s)
- P L Glick
- Buffalo Institute of Fetal Therapy, Children's Hospital, NY 14222
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Hall SB, Venkitaraman AR, Whitsett JA, Holm BA, Notter RH. Importance of hydrophobic apoproteins as constituents of clinical exogenous surfactants. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1992; 145:24-30. [PMID: 1731593 DOI: 10.1164/ajrccm/145.1.24] [Citation(s) in RCA: 137] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The biophysical properties and physiologic effects of a series of clinical exogenous pulmonary surfactants was compared to determine the importance of the hydrophobic apoproteins (SP-B and C) as constituents of these preparations. The three exogenous surfactants studied, calf lung surfactant extract (CLSE), Survanta (Surfactant-TA), and Exosurf, all contain dipalmitoyl phosphatidylcholine (DPPC) as their major constituent. CLSE and Survanta also contain 1 to 2% of SP-B,C but Exosurf has the additives hexadecanol and tyloxapol instead to enhance the activity of DPPC. In adsorption experiments, CLSE reached a final surface tension of 22 mN/m, and Survanta and Exosurf reached 28 and 38 mN/m, respectively. Addition of 1% by weight of an apoprotein isolate containing both SP-B and C to Exosurf slightly improved its adsorption. In oscillating bubble studies, CLSE and Survanta decreased surface tension to low values of less than 1 and 2 mN/m, respectively, but Exosurf achieved a minimum value of only 29 mN/m. Addition of SP-B,C to Exosurf improved this minimum to 1 mN/m and approached the behavior of mixtures of synthetic DPPC with SP-B,C. In both adsorption and pulsating bubble experiments, the minimum surface tensions found for Exosurf were almost identical to those generated by tyloxapol alone. In studies of physiologic activity, 20 mg of CLSE or Survanta restored the pressure-volume mechanics of lavaged, surfactant-deficient excised rat lungs to 95 and 50%, respectively, of normal prelavage levels. Instillation of Exosurf (37.5 mg) produced a minimal improvement of only 10% compared to 70% for mixtures containing 1% SP-B,C with either Exosurf or DPPC.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- S B Hall
- Department of Medicine, Oregon Health Sciences University, Portland 97201-3098
| | | | | | | | | |
Collapse
|
21
|
Turcotte JG, Lin WH, Pivarnik PE, Sacco AM, Shirali SS, Bermel MM, Lu Z, Notter RH. Chemical synthesis and surface activity of lung surfactant phospholipid analogs. II. Racemic N-substituted diether phosphonolipids. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1084:1-12. [PMID: 2054372 DOI: 10.1016/0005-2760(91)90048-m] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A series of racemic 16:0 disaturated N-substituted diether phosphonolipid analogs of glycerophospholipids have been synthesized and purified. Isosteric methylene substitution at three of the four ester sites (carboxyl, phosphate) of conventional glycerophospholipids enhanced the hydrophobicity of analog compounds compared with dipalmitoyl phosphatidylcholine (DPPC), the major glycerophospholipid component of lung surfactant. Further substitutions at the nitrogen headgroup also contributed to hydrophobicity/hydrophilicity characteristics, as well as allowing graded variations in headgroup size among the members of the diether phosphonolipid analog series. Interfacial property studies showed that these compounds had significant differences in surface activity characteristics compared with DPPC, including increased adsorption and respreading facility, plus an enhanced ability to generate low surface tension (less than 1 to 4 mN/m) on an oscillating bubble apparatus at 37 degrees C. In addition, pressure-volume mechanical studies in surfactant-deficient excised rat lungs showed that the diether phosphonate analog of DPPC could partially restore pressure-volume characteristics toward normal, both as a pure component and in binary mixtures with palmitoyl-oleoyl phosphatidylglycerol. These findings suggest that selected analog compounds, synthesized with relatively small structural modifications from biologic glycerophospholipids, may have eventual applications as components of synthetic exogenous lung surfactants. Of more immediate importance, analog molecules with defined structural variations are convenient molecular probes for developing structure-surface activity correlates for phospholipid-like surfactants and for investigating the specificity of interactions between glycerophospholipids and other compounds such as proteins.
Collapse
Affiliation(s)
- J G Turcotte
- Department of Medicinal Chemistry, College of Pharmacy, University of Rhode Island, Kingston 02861
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Sarin VK, Gupta S, Leung TK, Taylor VE, Ohning BL, Whitsett JA, Fox JL. Biophysical and biological activity of a synthetic 8.7-kDa hydrophobic pulmonary surfactant protein SP-B. Proc Natl Acad Sci U S A 1990; 87:2633-7. [PMID: 2320580 PMCID: PMC53744 DOI: 10.1073/pnas.87.7.2633] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have synthesized pulmonary surfactant apoprotein SP-B peptides by solid-phase chemistry and demonstrated their ability to enhance the surface-active properties of synthetic lipid mixtures. The synthetic peptides were reactive with antiserum generated against the native bovine surfactant peptide. Both peptides conferred surfactant-like properties to synthetic lipid mixtures as assessed by a Wilhelmy balance and pulsating bubble surfactometer. Likewise, mixtures of synthetic SP-B peptides and lipid restored compliance of isolated surfactant-deficient rat lungs. This work demonstrates the utility of SP-B as a functional component of pulmonary surfactant mixtures for treatment of respiratory distress syndrome or other disorders characterized by surfactant deficiency.
Collapse
Affiliation(s)
- V K Sarin
- Corporate Molecular Biology, Abbott Laboratories, Abbott Park, IL 60064
| | | | | | | | | | | | | |
Collapse
|
23
|
Horiuchi T, Mason RJ, Kuroki Y, Cherniack RM. Surface and tissue forces, surfactant protein A, and the phospholipid components of pulmonary surfactant in bleomycin-induced pulmonary fibrosis in the rat. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1990; 141:1006-13. [PMID: 1691603 DOI: 10.1164/ajrccm/141.4_pt_1.1006] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Administration of bleomycin to animals results in an alteration of the pressure-volume relationship of the lungs with an increased elastic recoil at any given volume. We sought to evaluate the relative importance of surface forces to elastic recoil by comparing the differences between the air and saline pressure-volume curves. The difference in elastic recoil between air- and saline-filled lungs was altered in bleomycin-treated rats when elastic recoil was compared at 35% of predicted TLC or at 80% of observed TLC. This pressure difference was present both during the early phase (Days 4 and 7) of the injury and acute inflammation as well as during the later phase (Days 14 to 28) when there was chronic inflammation and an elevation in the lung hydroxyproline content. The total amount of phospholipids recovered in lavage was decreased at Day 4 and increased more than 2.5-fold over saline-instilled control animals at Days 21 and 28. The percentage of phosphatidylglycerol was reduced and that of phosphatidylinositol increased. There was no consistent change in the percentage of phosphatidylcholine that was disaturated. The amount of surfactant protein A (SP-A) did not change during the course of the experiment and was not a useful independent marker of alveolar injury or changes in pulmonary compliance. The ratio of SP-A to total phospholipid decreased 14 to 28 days after instillation of bleomycin. These results support the hypothesis that individual components of surfactant are independently regulated and indicate that SP-A content in lavage is insensitive to lung injury and repair.
Collapse
Affiliation(s)
- T Horiuchi
- Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, University of Colorado Health Sciences Center, Denver 80206
| | | | | | | |
Collapse
|
24
|
Merritt TA, Hallman M, Spragg R, Heldt GP, Gilliard N. Exogenous surfactant treatments for neonatal respiratory distress syndrome and their potential role in the adult respiratory distress syndrome. Drugs 1989; 38:591-611. [PMID: 2684594 DOI: 10.2165/00003495-198938040-00006] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Exogenous surfactant therapy has been recognised as an approach to alleviating the surfactant-deficine state for 3 decades. Natural and lipid-extracted surfactants derived from amniotic fluid, lung lavage, or lung homogenates are being used in worldwide clinical trials in premature infants. These studies are demonstrating a generally favourable influence on lung function by improving oxygenation and reducing the risk for pneumothorax and pulmonary interstitial emphysema. In some studies, reduction in death and the occurrence of bronchopulmonary dysplasia have been found. Numerous questions are unresolved and pharmacokinetic data are limited in preterm infants. Artificial surfactants are similarly under evaluation but current data demonstrate less overall effect. Adult respiratory distress syndrome has also been treated with exogenous surfactants. Although complex in terms of multiple initiating factors and in terms of high permeability of surfactant inhibitors, further studies are under way to determine the ideal methods of administration to enhance distribution and to monitor surfactant function in vivo.
Collapse
Affiliation(s)
- T A Merritt
- Department of Pediatrics, UCSD School of Medicine
| | | | | | | | | |
Collapse
|
25
|
Davis JM, Veness-Meehan K, Notter RH, Bhutani VK, Kendig JW, Shapiro DL. Changes in pulmonary mechanics after the administration of surfactant to infants with respiratory distress syndrome. N Engl J Med 1988; 319:476-9. [PMID: 3405254 DOI: 10.1056/nejm198808253190804] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We assessed pulmonary mechanics in 35 premature infants with respiratory distress syndrome just before and one hour after the administration of 90 mg of surfactant to each infant. Transpulmonary pressure was measured between the airway opening and an esophageal balloon with use of a differential transducer, and flow rates were measured by a pneumotachometer. Values for pulmonary mechanics were then calculated by microcomputer processing. The administration of surfactant produced a large decrease (56 percent) in the mean (+/- SEM) ratio of alveolar to arterial oxygen, from 7.1 +/- 0.5 to 3.1 +/- 0.2 (P less than 0.0001)--a change that indicates improvement in gas exchange. Associated changes in pulmonary mechanics were not demonstrable when 10 of the infants were studied during continuous mechanical ventilation. However, in the 25 infants examined during spontaneous breathing with continuous positive airway pressures (identical airway pressures before and after treatment), large and consistent improvements in pulmonary mechanics were found after the administration of surfactant. Tidal volume increased by 32 percent (P less than 0.03), minute ventilation by 38 percent (P less than 0.02), dynamic compliance by 29 percent (P less than 0.004), and inspiratory flow rates by 54 percent (P less than 0.01). We conclude that significant improvement in pulmonary mechanics results from surfactant-replacement therapy for respiratory distress syndrome, but that these mechanical changes are apparent only during spontaneous respiration and can be masked if measurements are made during mechanical ventilation.
Collapse
Affiliation(s)
- J M Davis
- Department of Pediatrics (Neonatology), University of Rochester School of Medicine and Dentistry, N.Y
| | | | | | | | | | | |
Collapse
|
26
|
Affiliation(s)
- B Robertson
- Department of Pediatrics, St. Göran's Children's Hospital, Stockholm, Sweden
| | | |
Collapse
|
27
|
Jobe A, Ikegami M. Surfactant for the treatment of respiratory distress syndrome. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1987; 136:1256-75. [PMID: 3314618 DOI: 10.1164/ajrccm/136.5.1256] [Citation(s) in RCA: 176] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- A Jobe
- Department of Pediatrics, Harbor-UCLA Medical Center, UCLA School of Medicine, Torrance 90509
| | | |
Collapse
|
28
|
Notter RH, Shapiro DL, Ohning B, Whitsett JA. Biophysical activity of synthetic phospholipids combined with purified lung surfactant 6000 dalton apoprotein. Chem Phys Lipids 1987; 44:1-17. [PMID: 3607971 DOI: 10.1016/0009-3084(87)90002-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This research studies the biophysical surface activity of synthetic phospholipids combined in vitro with purified lung surfactant apoprotein, having an Mr of 6000. Hydrophobic surfactant-associated protein (SAP-6) was delipidated and purified from both bovine and canine lung lavage, and was combined in vitro with a synthetic phospholipid mixture (SM) of similar composition to natural lung surfactant phospholipids. SM phospholipids were also combined and studied biophysically with another purified surfactant-associated protein, SAP-35. The biophysical activity of synthetic phospholipid-apoprotein combinants was assessed by measurements of adsorption facility and dynamic surface tension lowering ability at 37 degrees C. The SM-SAP-6 combinants had adsorption facility equivalent to natural lung surfactant, and to the surfactant extract preparations CLSE and surfactant-TA used in exogenous surfactant replacement therapy for the neonatal Respiratory Distress Syndrome (RDS). The synthetic phospholipid-SAP-6 combinants also lowered surface tension to less than 1 dyne/cm under dynamic compression in an oscillating bubble apparatus at concentrations as low as 0.5 mg phospholipid/ml. A striking finding was that this excellent dynamic surface activity was preserved as SAP-6 composition was reduced to values as low as 5 micrograms/5 mg SM phospholipid (0.1% SAP-6 protein), an order of magnitude less than the 1% protein content of CLSE and surfactant-TA. Mixtures of SM phospholipids plus SAP-35, the major surfactant glycoprotein, had significantly lower biophysical activity, which did not approach that of a functional lung surfactant. These results suggest that synthetic exogenous surfactants of potential utility for replacement therapy in RDS can be formulated by combining synthetic phospholipids in vitro with specifically purified, hydrophobic surfactant-associated protein, SAP-6.
Collapse
|
29
|
Ross GF, Notter RH, Meuth J, Whitsett JA. Phospholipid binding and biophysical activity of pulmonary surfactant-associated protein (SAP)-35 and its non-collagenous COOH-terminal domains. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67016-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|