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The lung surfactant activity probed with molecular dynamics simulations. Adv Colloid Interface Sci 2022; 304:102659. [PMID: 35421637 DOI: 10.1016/j.cis.2022.102659] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 03/18/2022] [Accepted: 03/31/2022] [Indexed: 01/17/2023]
Abstract
The surface of pulmonary alveolar subphase is covered with a mixture of lipids and proteins. This lung surfactant plays a crucial role in lung functioning. It shows a complex phase behavior which can be altered by the interaction with third molecules such as drugs or pollutants. For studying multicomponent biological systems, it is of interest to couple experimental approach with computational modelling yielding atomic-scale information. Simple two, three, or four-component model systems showed to be useful for getting more insight in the interaction between lipids, lipids and proteins or lipids and proteins with drugs and impurities. These systems were studied theoretically using molecular dynamic simulations and experimentally by means of the Langmuir technique. A better understanding of the structure and behavior of lung surfactants obtained from this research is relevant for developing new synthetic surfactants for efficient therapies, and may contribute to public health protection.
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Islam MZ, Krajewska M, Hossain SI, Prochaska K, Anwar A, Deplazes E, Saha SC. Concentration-Dependent Effect of the Steroid Drug Prednisolone on a Lung Surfactant Monolayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4188-4199. [PMID: 35344368 DOI: 10.1021/acs.langmuir.1c02817] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The lung surfactant monolayer (LSM) is the main barrier for particles entering the lung, including steroid drugs used to treat lung diseases. The present study combines Langmuir experiments and coarse-grained (CG) molecular dynamics simulations to investigate the concentration-dependent effect of steroid drug prednisolone on the structure and morphology of a model LSM. The surface pressure-area isotherms for the Langmuir monolayers reveal a concentration-dependent decrease in area per lipid (APL). Results from simulations at a fixed surface tension, representing inhalation and exhalation conditions, suggest that at high drug concentrations, prednisolone induces a collapse of the LSM, which is likely caused by the inability of the drug to diffuse into the bilayer. Overall, the monolayer is most susceptible to drug-induced collapse at surface tensions representing exhalation conditions. The presence of cholesterol also exacerbates the instability. The findings of this investigation might be helpful for better understanding the interaction between steroid drug prednisolone and lung surfactants in relation to off-target effects.
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Affiliation(s)
- Mohammad Zohurul Islam
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia
| | - Martyna Krajewska
- Institute of Chemical Technology and Engineering, Poznan University of Technology, Berdychowo 4, 60-965 Poznań, Poland
| | - Sheikh I Hossain
- School of Life Sciences, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia
| | - Krystyna Prochaska
- Institute of Chemical Technology and Engineering, Poznan University of Technology, Berdychowo 4, 60-965 Poznań, Poland
| | - Azraf Anwar
- Independent Researcher, Dhaka 1000, Bangladesh
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia
| | - Suvash C Saha
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia
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A Simulation Study on the Interaction Between Pollutant Nanoparticles and the Pulmonary Surfactant Monolayer. Int J Mol Sci 2019; 20:ijms20133281. [PMID: 31277358 PMCID: PMC6651701 DOI: 10.3390/ijms20133281] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 06/29/2019] [Accepted: 07/01/2019] [Indexed: 01/09/2023] Open
Abstract
A good understanding of the mechanism of interaction between inhaled pollutant nanoparticles (NPs) and the pulmonary surfactant monolayer is useful to study the impact of fine particulate matter on human health. In this work, we established coarse-grained models of four representative NPs with different hydrophilicity properties in the air (i.e., CaSO4, C, SiO2, and C6H14O2 NPs) and the pulmonary surfactant monolayer. Molecular dynamic simulations of the interaction during exhalation and inhalation breathing states were performed. The effects of NP hydrophilicity levels, NP structural properties, and cholesterol content in the monolayer on the behaviors of NP embedment or the transmembrane were analyzed by calculating the changes in potential energy, NP displacement, monolayer orderliness, and surface tension. Results showed that NPs can inhibit the ability of the monolayer to adjust surface tension. For all breathing states, the hydrophobic C NP cannot translocate across the monolayer and had the greatest influence on the structural properties of the monolayer, whereas the strongly hydrophilic SiO2 and C6H14O2 NPs can cross the monolayer with little impact. The semi-hydrophilic CaSO4 NP can penetrate the monolayer only during the inhalation breathing state. The hydrophilic flaky NP shows the best penetration ability, followed by the rod-shaped NP and spherical NP in turn. An increase in cholesterol content of the monolayer led to improved orderliness and decreased fluidity of the membrane system due to enhanced intermolecular forces. Consequently, difficulty in crossing the monolayer increased for the NPs.
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Baoukina S, Tieleman DP. Computer simulations of lung surfactant. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2431-2440. [PMID: 26922885 DOI: 10.1016/j.bbamem.2016.02.030] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/21/2016] [Accepted: 02/23/2016] [Indexed: 01/26/2023]
Abstract
Lung surfactant lines the gas-exchange interface in the lungs and reduces the surface tension, which is necessary for breathing. Lung surfactant consists mainly of lipids with a small amount of proteins and forms a monolayer at the air-water interface connected to bilayer reservoirs. Lung surfactant function involves transfer of material between the monolayer and bilayers during the breathing cycle. Lipids and proteins are organized laterally in the monolayer; selected species are possibly preferentially transferred to bilayers. The complex 3D structure of lung surfactant and the exact roles of lipid organization and proteins remain important goals for research. We review recent simulation studies on the properties of lipid monolayers, monolayers with phase coexistence, monolayer-bilayer transformations, lipid-protein interactions, and effects of nanoparticles on lung surfactant. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
| | - D Peter Tieleman
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
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Huston KJ, Larson RG. Reversible and Irreversible Adsorption Energetics of Poly(ethylene glycol) and Sorbitan Poly(ethoxylate) at a Water/Alkane Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7503-7511. [PMID: 26079039 DOI: 10.1021/acs.langmuir.5b00398] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We simulate poly(ethylene glycol) (PEG) oligomers and model Tween 80 (polyoxyethylene sorbitan monooleate) molecules at water/alkane interfaces. Using the weighted histogram analysis method (WHAM), including an extension of WHAM to two reaction coordinates to remove hysteresis, we calculate interfacial potentials of mean force (PMFs) for PEG and Tween 80 using three force fields: the atomistic GROMOS 53a6OXY+D and two coarse-grained (CG) MARTINI force fields. Because the force fields have not yet been validated for PEO adsorption to hydrophobic interfaces, we calculate PMFs for alcohol ethoxylates C12E2 and C12E8 and find that they agree with semiempirical results of Mulqueen and Blankschtein [Langmuir 2002, 18 (2), 365-376] for the GROMOS 53a6OXY+D force field, whereas for both MARTINI force fields, PEO adsorbs too weakly to a clean hydrophobic interface. One MARTINI force field incorrectly shows depletion rather than adsorption to a clean hydrophobic interface. We find that the adsorption free energy for PEG oligomers at a clean, planar water/alkane interface is around 1.3 kBT per monomer for the atomistic force field but is less than half of this for the two CG force fields. With the newly validated GROMOS 53a6OXY+D force field, we bracket the dilute adsorption free energy for a model Tween 80 molecule at the clean water/squalane interface. We also calculate the pressure-area isotherm. We exploit these data with the Nikas-Mulqueen-Blankschtein (NMB) theory and a simple transport model to demonstrate a transition from irreversible to reversible adsorption with increasing surface coverage, consistent with experimental results of Reichert and Walker [Langmuir 2013, 29 (6), 1857-1867].
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Affiliation(s)
- Kyle J Huston
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States
| | - Ronald G Larson
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States
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XUE W, WANG D, ZENG Z, GAO X. Conformation and Orientation of Phospholipid Molecule in Pure Phospholipid Monolayer During Compressing. Chin J Chem Eng 2013. [DOI: 10.1016/s1004-9541(13)60456-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
A lipid monolayer lining a boundary between two immiscible phases forms a complex interface with inhomogeneous distribution of forces. Unlike lipid bilayers, monolayers are formed in asymmetric environment and their properties depend strongly on lipid surface density. The monolayer properties are also affected significantly by the representation of the pure interface. Here we give a brief theoretical introduction and describe methods to simulate lipid monolayers starting from force-fields and system setup to reproducing state points on the surface tension (pressure)-area isotherms and transformations between them.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada.
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Shinoda W, DeVane R, Klein ML. Zwitterionic lipid assemblies: molecular dynamics studies of monolayers, bilayers, and vesicles using a new coarse grain force field. J Phys Chem B 2010; 114:6836-49. [PMID: 20438090 PMCID: PMC2876730 DOI: 10.1021/jp9107206] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new coarse-grained (CG) intermolecular force field is presented for a series of zwitterionic lipids. The model is an extension of our previous work on nonionic surfactants and is designed to reproduce experimental surface/interfacial properties as well as distribution functions from all-atom molecular dynamics (MD) simulations. Using simple functional forms, the force field parameters are optimized for multiple lipid molecules, simultaneously. The resulting CG lipid bilayers have reasonable molecular areas, chain order parameters, and elastic properties. The computed surface pressure vs area (pi-A) curve for a dipalmitoyl phosphatidylcholine (DPPC) monolayer demonstrates a significant improvement over the previous CG models. The DPPC monolayer has a longer persistence length than a polyethyleneglycol (PEG) lipid monolayer, exhibiting a long-lived curved monolayer surface under negative tension. The bud ejected from an oversaturated DPPC monolayer has a large bicelle-like structure, which is different from the micellar bud formed from an oversaturated PEG lipid monolayer. We have successfully observed vesicle formation during CG-MD simulations, starting from an aggregate of dimyristoyl phosphatidylcholine (DMPC) molecules. Depending on the aggregate size, the lipid assembly spontaneously transforms into a closed vesicle or a bicelle. None of the various intermediate structures between these extremes seem to be stable. An attempt to observe fusion of two vesicles through the application of an external adhesion force was not successful. The present CG force field also supports stable multilamellar DMPC vesicles.
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Affiliation(s)
- Wataru Shinoda
- Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Central-2, Umezono 1-1-1, Tsukuba 305-8568, Japan.
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9
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Sanders SA, Panagiotopoulos AZ. Micellization behavior of coarse grained surfactant models. J Chem Phys 2010; 132:114902. [DOI: 10.1063/1.3358354] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Mohammad-Aghaie D, Macé E, Sennoga CA, Seddon JM, Bresme F. Molecular Dynamics Simulations of Liquid Condensed to Liquid Expanded Transitions in DPPC Monolayers. J Phys Chem B 2009; 114:1325-35. [DOI: 10.1021/jp9061303] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Delara Mohammad-Aghaie
- Department of Chemistry, Imperial College London, SW7 2AZ London, United Kingdom, and Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313, Iran
| | - Emilie Macé
- Department of Chemistry, Imperial College London, SW7 2AZ London, United Kingdom, and Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313, Iran
| | - Charles A. Sennoga
- Department of Chemistry, Imperial College London, SW7 2AZ London, United Kingdom, and Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313, Iran
| | - John M. Seddon
- Department of Chemistry, Imperial College London, SW7 2AZ London, United Kingdom, and Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313, Iran
| | - Fernando Bresme
- Department of Chemistry, Imperial College London, SW7 2AZ London, United Kingdom, and Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313, Iran
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11
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Cho HM, Chu JW. Inversion of radial distribution functions to pair forces by solving the Yvon–Born–Green equation iteratively. J Chem Phys 2009; 131:134107. [DOI: 10.1063/1.3238547] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Duncan SL, Larson RG. Comparing experimental and simulated pressure-area isotherms for DPPC. Biophys J 2008; 94:2965-86. [PMID: 18199666 PMCID: PMC2275714 DOI: 10.1529/biophysj.107.114215] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Accepted: 12/03/2007] [Indexed: 11/18/2022] Open
Abstract
Although pressure-area isotherms are commonly measured for lipid monolayers, it is not always appreciated how much they can vary depending on experimental factors. Here, we compare experimental and simulated pressure-area isotherms for dipalmitoylphosphatidylcholine (DPPC) at temperatures ranging between 293.15 K and 323.15 K, and explore possible factors influencing the shape and position of the isotherms. Molecular dynamics simulations of DPPC monolayers using both coarse-grained (CG) and atomistic models yield results that are in rough agreement with some of the experimental isotherms, but with a steeper slope in the liquid-condensed region than seen experimentally and shifted to larger areas. The CG lipid model gives predictions that are very close to those of atomistic simulations, while greatly improving computational efficiency. There is much more variation among experimental isotherms than between isotherms obtained from CG simulations and from the most refined simulation available. Both atomistic and CG simulations yield liquid-condensed and liquid-expanded phase area compressibility moduli that are significantly larger than those typically measured experimentally, but compare well with some experimental values obtained under rapid compression.
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Affiliation(s)
- Susan L Duncan
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, USA
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Baoukina S, Monticelli L, Marrink SJ, Tieleman DP. Pressure-area isotherm of a lipid monolayer from molecular dynamics simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:12617-23. [PMID: 17973510 DOI: 10.1021/la702286h] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We calculated the pressure-area isotherm of a dipalmitoyl-phosphatidylcholine (DPPC) lipid monolayer from molecular dynamics simulations using a coarse-grained molecular model. We characterized the monolayer structure, geometry, and phases directly from the simulations and compared the calculated isotherm to experiments. The calculated isotherm shows liquid-expanded and liquid-condensed phases and their coexistence plateau. At high pressure, the monolayer surface is rippled; upon further compression, the monolayer undergoes a collapse. We studied the effect of temperature and system size on the isotherm slope and phase coexistence region. Thermodynamic and dynamic properties of the monolayer phases were also investigated.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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Marrink SJ, Risselada HJ, Yefimov S, Tieleman DP, de Vries AH. The MARTINI Force Field: Coarse Grained Model for Biomolecular Simulations. J Phys Chem B 2007; 111:7812-24. [PMID: 17569554 DOI: 10.1021/jp071097f] [Citation(s) in RCA: 3594] [Impact Index Per Article: 211.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present an improved and extended version of our coarse grained lipid model. The new version, coined the MARTINI force field, is parametrized in a systematic way, based on the reproduction of partitioning free energies between polar and apolar phases of a large number of chemical compounds. To reproduce the free energies of these chemical building blocks, the number of possible interaction levels of the coarse-grained sites has increased compared to those of the previous model. Application of the new model to lipid bilayers shows an improved behavior in terms of the stress profile across the bilayer and the tendency to form pores. An extension of the force field now also allows the simulation of planar (ring) compounds, including sterols. Application to a bilayer/cholesterol system at various concentrations shows the typical cholesterol condensation effect similar to that observed in all atom representations.
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Affiliation(s)
- Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, Department of Biophysical Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
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