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Nudelman R, Alhmoud H, Delalat B, Kaur I, Vitkin A, Bourgeois L, Goldfarb I, Cifuentes-Rius A, Voelcker NH, Richter S. From nanoparticles to crystals: one-pot programmable biosynthesis of photothermal gold structures and their use for biomedical applications. J Nanobiotechnology 2022; 20:482. [PMID: 36384747 PMCID: PMC9670439 DOI: 10.1186/s12951-022-01680-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/18/2022] [Indexed: 11/17/2022] Open
Abstract
Inspired by nature, green chemistry uses various biomolecules, such as proteins, as reducing agents to synthesize metallic nanostructures. This methodology provides an alternative route to conventional harsh synthetic processes, which include polluting chemicals. Tuning the resulting nanostructure properties, such as their size and shape, is challenging as the exact mechanism involved in their formation is still not well understood. This work reports a well-controlled method to program gold nanostructures' shape, size, and aggregation state using only one protein type, mucin, as a reduction and capping material in a one-pot bio-assisted reaction. Using mucin as a gold reduction template while varying its tertiary structure via the pH of the synthesis, we demonstrate that spherical, coral-shaped, and hexagonal gold crystals can be obtained and that the size can be tuned over three orders of magnitude. This is achieved by leveraging the protein's intrinsic reducing properties and pH-induced conformational changes. The systematic study of the reaction kinetics and growth steps developed here provides an understanding of the mechanism behind this phenomenon. We further show that the prepared gold nanostructures exhibit tunable photothermal properties that can be optimized for various hyperthermia-induced antibacterial applications.
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2
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Ford AG, Cao XZ, Papanikolas MJ, Kato T, Boucher RC, Markovetz MR, Hill DB, Freeman R, Forest MG. Molecular Dynamics Simulations to Explore the Structure and Rheological Properties of Normal and Hyperconcentrated Airway Mucus. STUDIES IN APPLIED MATHEMATICS (CAMBRIDGE, MASS.) 2021; 147:1369-1387. [PMID: 35221375 PMCID: PMC8871504 DOI: 10.1111/sapm.12433] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Indexed: 06/14/2023]
Abstract
We develop the first molecular dynamics model of airway mucus based on the detailed physical properties and chemical structure of the predominant gel-forming mucin MUC5B. Our airway mucus model leverages the LAMMPS open-source code [https://lammps.sandia.gov], based on the statistical physics of polymers, from single molecules to networks. On top of the LAMMPS platform, the chemical structure of MUC5B is used to superimpose proximity-based, non-covalent, transient interactions within and between the specific domains of MUC5B polymers. We explore feasible ranges of hydrophobic and electrostatic interaction strengths between MUC5B domains with 9 nanometer spatial and 1 nanosecond temporal resolution. Our goal here is to propose and test a mechanistic hypothesis for a striking clinical observation with respect to airway mucus: a 10-fold increase in non-swellable, dense structures called flakes during progression of cystic fibrosis disease. Among the myriad possible effects that might promote self-organization of MUC5B networks into flake structures, we hypothesize and confirm that the clinically confirmed increase in mucin concentration, from 1.5 to 5 mg/mL, alone is sufficient to drive the structure changes observed with scanning electron microscopy images from experimental samples. We post-process the LAMMPS simulated datasets at 1.5 and 5 mg/mL, both to image the structure transition and compare with scanning electron micrographs and to show that the 3.33-fold increase in concentration induces closer proximity of interacting electrostatic and hydrophobic domains, thereby amplifying the proximity-based strength of the interactions.
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Affiliation(s)
- Andrew G Ford
- Dept. of Mathematics, University of North Carolina at Chapel Hill
| | | | - Micah J Papanikolas
- Dept. of Applied Physical Sciences, University of North Carolina at Chapel Hill
| | - Takafumi Kato
- Marsico Lung Institute, University of North Carolina at Chapel Hill
| | | | | | - David B Hill
- Marsico Lung Institute, University of North Carolina at Chapel Hill
- Dept. of Physics and Astronomy, University of North Carolina at Chapel Hill
| | - Ronit Freeman
- Dept. of Applied Physical Sciences, University of North Carolina at Chapel Hill
| | - M Gregory Forest
- Dept. of Mathematics, University of North Carolina at Chapel Hill
- Dept. of Applied Physical Sciences, University of North Carolina at Chapel Hill
- Dept. of Biomedical Engineering, University of North Carolina at Chapel Hill
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3
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Andrews B, Long K, Urbanc B. Soluble State of Villin Headpiece Protein as a Tool in the Assessment of MD Force Fields. J Phys Chem B 2021; 125:6897-6911. [PMID: 34143637 DOI: 10.1021/acs.jpcb.1c04589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Protein self-assembly plays an important role in cellular processes. Whereas molecular dynamics (MD) represents a powerful tool in studying assembly mechanisms, its predictions depend on the accuracy of underlying force fields, which are known to overly promote protein assembly. We here examine villin headpiece domain, HP36, which remains soluble at concentrations amenable to MD studies. The experimental characterization of soluble HP36 at concentrations of 0.05 to 1 mM reveals concentration-independent 90% monomeric and 10% dimeric populations. Extensive all-atom MD simulations at two protein concentrations, 0.9 and 8.5 mM, probe the HP36 dimer population, stability, and kinetics of dimer formation within two MD force fields, Amber ff14SB and CHARMM36m. MD results demonstrate that whereas CHARMM36m captures experimental HP36 monomer populations at the lower concentration, both force fields overly promote HP36 association at the higher concentration. Moreover, contacts stabilizing HP36 dimers are force-field-dependent. CHARMM36m produces consistently higher HP36 monomer populations, lower association rates, and weaker dependence of these quantities on the protein concentration than Amber ff14SB. Nonetheless, the highest monomer populations and dissociation constants are observed when the TIP3P water model in Amber ff14SB is replaced by TIP4P/2005, showcasing the critical role of the water model in addressing the protein solubility problem in MD.
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Affiliation(s)
- Brian Andrews
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Kaho Long
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
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4
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Olăreț E, Bălănucă B, Onaș AM, Ghițman J, Iovu H, Stancu IC, Serafim A. Double-Cross-Linked Networks Based on Methacryloyl Mucin. Polymers (Basel) 2021; 13:1706. [PMID: 34071088 PMCID: PMC8197136 DOI: 10.3390/polym13111706] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/14/2021] [Accepted: 05/20/2021] [Indexed: 01/09/2023] Open
Abstract
Mucin is a glycoprotein with proven potential in the biomaterials field, but its use is still underexploited for such applications. The present work aims to produce a synthesis of methacryloyl mucin single-network (SN) hydrogels and their double-cross-linked-network (DCN) counterparts. Following the synthesis of the mucin methacryloyl derivative, various SN hydrogels are prepared through the photopolymerization of methacrylate bonds, using reaction media with different pH values. The SN hydrogels are converted into DCN systems via supplementary cross-linking in tannic acid aqueous solution. The chemical modification of mucin is described, and the obtained product is characterized; the structural modification of mucin is assessed through FTIR spectroscopy, and the circular dichroism and the isoelectric point of methacryloyl mucin is evaluated. The affinity for aqueous media of both SN and DCN hydrogels is estimated, and the mechanical properties of the systems are assessed, both at macroscale through uniaxial compression and rheology tests and also at microscale through nanoindentation tests.
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Affiliation(s)
- Elena Olăreț
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
| | - Brîndușa Bălănucă
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
- Department of Organic Chemistry Costin Nenitescu, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania
| | - Andra Mihaela Onaș
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
| | - Jana Ghițman
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
| | - Horia Iovu
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
- Academy of Romanian Scientists, 54 Splaiul Independentei, 050094 Bucharest, Romania
| | - Izabela-Cristina Stancu
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
- Faculty of Medical Engineering, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania
| | - Andrada Serafim
- Advanced Polymer Materials Group, University Politehnica of Bucharest, 1–7 Ghe. Polizu Street, 011061 Bucharest, Romania; (E.O.); (B.B.); (A.M.O.); (J.G.); (H.I.); (I.-C.S.)
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5
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Ruiz-Pulido G, Medina DI. An overview of gastrointestinal mucus rheology under different pH conditions and introduction to pH-dependent rheological interactions with PLGA and chitosan nanoparticles. Eur J Pharm Biopharm 2020; 159:123-136. [PMID: 33387633 DOI: 10.1016/j.ejpb.2020.12.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 11/28/2020] [Accepted: 12/15/2020] [Indexed: 02/07/2023]
Abstract
This review discusses the physicochemical and mechanical properties of porcine gastrointestinal mucus from a rheological point of view. Considering mucus as a viscoelastic gel that functions as a biological barrier by limiting particles passage, lubricating the gastrointestinal tract, and protecting the stomach from gastric acids. The viscoelastic and protective properties of mucus are mainly produced by its mucin network, which is stabilized through electrostatic, hydrophobic and hydrogen bonding interactions. Otherwise, mucus rheology is determined by its polyanionic nature at physiological pH. At neutral pH, mucus presents a viscous behavior produced by chains crosslinking. While, at acidic pH, mucus exhibits an elastic behavior related with the extended conformation that produces mucus gelation at the stomach. Additionally, rheology studies the degree of adhesion between a polymer-mucus mixture through rheological synergism, and how it varies at different pH conditions. Finally, mucoadhesion phenomenon is exemplified with chitosan (cationic) and poly (lactic-co-glycolic) acid (anionic) polymers.
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Affiliation(s)
- Gustavo Ruiz-Pulido
- Tecnologico de Monterrey, School of Engineering and Sciences, Atizapan de Zaragoza, Estado de Mexico 52926, Mexico
| | - Dora I Medina
- Tecnologico de Monterrey, School of Engineering and Sciences, Atizapan de Zaragoza, Estado de Mexico 52926, Mexico.
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Sharma A, Kwak JG, Kolewe KW, Schiffman JD, Forbes NS, Lee J. In Vitro Reconstitution of an Intestinal Mucus Layer Shows That Cations and pH Control the Pore Structure That Regulates Its Permeability and Barrier Function. ACS APPLIED BIO MATERIALS 2020; 3:2897-2909. [PMID: 34322659 PMCID: PMC8315583 DOI: 10.1021/acsabm.9b00851] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dysfunction of the intestinal mucus barrier causes disorders such as ulcerative colitis and Crohn's disease. The function of this essential barrier may be affected by the periodically changing luminal environment. We hypothesized that the pH and ion concentration in mucus control its porosity, molecular permeability, and the penetration of microbes. To test this hypothesis, we developed a scalable method to extract porcine small intestinal mucus (PSIM). The aggregation and porosity of PSIM were determined using rheometry, spectrophotometry, and microscopy. Aggregation of PSIM at low pH increased both the elastic (G') and viscous (G″) moduli, and it slowed the transmigration of pathogenic Salmonella. Molecular transport was dependent on ion concentration. At moderate concentrations, many microscopic aggregates (2-5 μm in diameter) impeded diffusion. At higher concentrations, PSIM formed aggregate islands, increasing both porosity and diffusion. This in vitro model could lead to a better understanding of mucus barrier functions and improve the treatment of intestinal diseases.
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Affiliation(s)
- Abhinav Sharma
- Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Jun-Goo Kwak
- Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Kristopher W Kolewe
- Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Jessica D Schiffman
- Department of Chemical Engineering and Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Neil S Forbes
- Department of Chemical Engineering, Molecular and Cellular Biology Graduate Program, and Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Jungwoo Lee
- Department of Chemical Engineering, Molecular and Cellular Biology Graduate Program, and Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
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7
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Dash R, Choi HJ, Moon IS. Mechanistic insights into the deleterious roles of Nasu-Hakola disease associated TREM2 variants. Sci Rep 2020; 10:3663. [PMID: 32107424 PMCID: PMC7046722 DOI: 10.1038/s41598-020-60561-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 02/13/2020] [Indexed: 02/06/2023] Open
Abstract
Recently, the critical roles played by genetic variants of TREM2 (Triggering Receptor Expressed on Myeloid cells 2) in Alzheimer's disease have been aggressively highlighted. However, few studies have focused on the deleterious roles of Nasu-Hakola disease (NHD) associated TREM2 variants. In order to get insights into the contributions made by these variants to neurodegeneration, we investigated the influences of four NHD associated TREM2 mutations (Y38C, W50C, T66M, and V126G) on loss-of-function, and followed this with in silico prediction and conventional molecular dynamics simulation. NHD mutations were predicted to be highly deleterious by eight different in silico bioinformatics tools and found to induce conformational changes by molecular dynamics simulation. As compared with the wild-type, the four variants produced substantial differences in the collective motions of loop regions, which not only promoted structural remodeling in the CDR2 (complementarity-determining region 2) loop but also in the CDR1 loop, by changing inter- and intra-loop hydrogen bonding networks. In addition, structural studies in a free energy landscape analysis showed that Y38, T66, and V126 are crucial for maintaining the structural features of CDR1 and CDR2 loops, and that mutations in these positions produced steric clashes and loss of ligand binding. These results showed the presence of mutations in the TREM2 ectodomain induced flexibility and caused structural alterations. Dynamical scenarios, as provided by the present study, may be critical to our understanding of the roles of these TREM2 mutations in neurodegenerative diseases.
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Affiliation(s)
- Raju Dash
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea
| | - Ho Jin Choi
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea
| | - Il Soo Moon
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea.
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8
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Dinu V, Gillis RB, MacCalman T, Lim M, Adams GG, Harding SE, Fisk ID. Submaxillary Mucin: its Effect on Aroma Release from Acidic Drinks and New Insight into the Effect of Aroma Compounds on its Macromolecular Integrity. FOOD BIOPHYS 2019; 14:278-286. [PMID: 31402849 PMCID: PMC6658575 DOI: 10.1007/s11483-019-09574-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 03/12/2019] [Indexed: 11/28/2022]
Abstract
Submaxillary mucin is a major component that defines the makeup and functionality of saliva. Understanding its structure and function during food intake is key to designing appropriate strategies for enhancing the delivery of flavour. In the present study, the hydrodynamic integrity of bovine submaxillary mucin was characterised under physiological and acidic conditions and it was shown to have a broad molecular weight distribution with species ranging from 100 kDa to over 2000 kDa, and a random coil type of conformation. A decrease in the pH of mucin appeared to result in aggregation and a broader molecular weight distribution, which was shown to correlate with a release of flavour compounds. Our study also provides indications that p-cresol may have an effect on the macromolecular integrity of mucin.
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Affiliation(s)
- Vlad Dinu
- National Centre for Macromolecular Hydrodynamics, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, UK
| | - Richard B. Gillis
- School of Health Sciences, Faculty of Medicine and Health Sciences, Queen’s Medical Centre, Clifton Boulevard, Nottingham, UK
| | - Thomas MacCalman
- National Centre for Macromolecular Hydrodynamics, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
| | - Mui Lim
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, UK
| | - Gary G. Adams
- School of Health Sciences, Faculty of Medicine and Health Sciences, Queen’s Medical Centre, Clifton Boulevard, Nottingham, UK
| | - Stephen E. Harding
- National Centre for Macromolecular Hydrodynamics, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
- Kulturhistorisk Museum, Universitetet i Oslo, Postboks 6762, St. Olavs plass, 0130 Oslo, Norway
| | - Ian D. Fisk
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, UK
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9
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Zhang S, Fox DM, Urbanc B. Elucidating the Role of Hydroxylated Phenylalanine in the Formation and Structure of Cross-Linked Aβ Oligomers. J Phys Chem B 2019; 123:1068-1084. [DOI: 10.1021/acs.jpcb.8b12120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Shuting Zhang
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Dillion M. Fox
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
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10
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Zhang S, Fox DM, Urbanc B. Insights into Formation and Structure of Aβ Oligomers Cross-Linked via Tyrosines. J Phys Chem B 2017; 121:5523-5535. [DOI: 10.1021/acs.jpcb.7b02495] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Shuting Zhang
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Dillion M. Fox
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Brigita Urbanc
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
- Faculty
of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
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11
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Urbanc B. Flexible N‐Termini of Amyloid β‐Protein Oligomers: A Link between Structure and Activity? Isr J Chem 2017. [DOI: 10.1002/ijch.201600097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Brigita Urbanc
- Department of Physics Drexel University Philadelphia, PA 19104 USA
- Faculty of Mathematics and Physics Jadranska ulica 19 1000 Ljubljana Slovenia
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12
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Žganec M, Žerovnik E, Urbanc B. Assembly of Stefin B into Polymorphic Oligomers Probed by Discrete Molecular Dynamics. J Chem Theory Comput 2016; 11:2355-66. [PMID: 26574430 DOI: 10.1021/acs.jctc.5b00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Assembly of an amyloidogenic protein stefin B into molten globule oligomers is studied by efficient discrete molecular dynamics. Consistent with in vitro findings, tetramers form primarily through dimer association, resulting in a decreased trimer abundance. Oligomers up to heptamers display elongated rod-like morphologies akin to protofibrils, whereas larger oligomers, decamers through dodecamers, form elongated, branched, as well as annular structures, providing structural insights into pore forming ability and toxicity of amyloidogenic proteins.
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Affiliation(s)
- Matjaž Žganec
- Faculty of Mathematics and Physics, University of Ljubljana , 1000 Ljubljana, Slovenia.,Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute , 1000 Ljubljana, Slovenia
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute , 1000 Ljubljana, Slovenia
| | - Brigita Urbanc
- Faculty of Mathematics and Physics, University of Ljubljana , 1000 Ljubljana, Slovenia.,Department of Physics, Drexel University , Philadelphia, Pennsylvania 19104, United States
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13
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Targeted chitosan-based bionanocomposites for controlled oral mucosal delivery of chlorhexidine. Int J Pharm 2016; 509:408-418. [DOI: 10.1016/j.ijpharm.2016.06.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/18/2016] [Accepted: 06/06/2016] [Indexed: 12/20/2022]
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14
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Tang XX, Ostedgaard LS, Hoegger MJ, Moninger TO, Karp PH, McMenimen JD, Choudhury B, Varki A, Stoltz DA, Welsh MJ. Acidic pH increases airway surface liquid viscosity in cystic fibrosis. J Clin Invest 2016; 126:879-91. [PMID: 26808501 DOI: 10.1172/jci83922] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 12/08/2015] [Indexed: 12/21/2022] Open
Abstract
Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3- concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator-dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF.
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16
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Bansil R, Celli JP, Hardcastle JM, Turner BS. The Influence of Mucus Microstructure and Rheology in Helicobacter pylori Infection. Front Immunol 2013; 4:310. [PMID: 24133493 PMCID: PMC3794295 DOI: 10.3389/fimmu.2013.00310] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/16/2013] [Indexed: 12/24/2022] Open
Abstract
The bacterium Helicobacter pylori (H. pylori), has evolved to survive in the highly acidic environment of the stomach and colonize on the epithelial surface of the gastric mucosa. Its pathogenic effects are well known to cause gastritis, peptic ulcers, and gastric cancer. In order to infect the stomach and establish colonies on the mucus epithelial surface, the bacterium has to move across the gel-like gastric mucus lining of the stomach under acidic conditions. In this review we address the question of how the bacterium gets past the protective mucus barrier from a biophysical perspective. We begin by reviewing the molecular structure of gastric mucin and discuss the current state of understanding concerning mucin polymerization and low pH induced gelation. We then focus on the viscoelasticity of mucin in view of its relevance to the transport of particles and bacteria across mucus, the key first step in H. pylori infection. The second part of the review focuses on the motility of H. pylori in mucin solutions and gels, and how infection with H. pylori in turn impacts the viscoelastic properties of mucin. We present recent microscopic results tracking the motion of H. pylori in mucin solutions and gels. We then discuss how the biochemical strategy of urea hydrolysis required for survival in the acid is also relevant to the mechanism that enables flagella-driven swimming across the mucus gel layer. Other aspects of the influence of H. pylori infection such as, altering gastric mucin expression, its rate of production and its composition, and the influence of mucin on factors controlling H. pylori virulence and proliferation are briefly discussed with references to relevant literature.
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Affiliation(s)
- Rama Bansil
- Department of Physics, Boston University , Boston, MA , USA
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