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Hancock AM, Datta SS. Interplay between environmental yielding and dynamic forcing modulates bacterial growth. Biophys J 2024; 123:957-967. [PMID: 38454600 PMCID: PMC11052696 DOI: 10.1016/j.bpj.2024.03.008] [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: 12/05/2023] [Revised: 02/22/2024] [Accepted: 03/04/2024] [Indexed: 03/09/2024] Open
Abstract
Many bacterial habitats-ranging from gels and tissues in the body to cell-secreted exopolysaccharides in biofilms-are rheologically complex, undergo dynamic external forcing, and have unevenly distributed nutrients. How do these features jointly influence how the resident cells grow and proliferate? Here, we address this question by studying the growth of Escherichia coli dispersed in granular hydrogel matrices with defined and highly tunable structural and rheological properties, under different amounts of external forcing imposed by mechanical shaking, and in both aerobic and anaerobic conditions. Our experiments establish a general principle: that the balance between the yield stress of the environment that the cells inhabit, σy, and the external stress imposed on the environment, σ, modulates bacterial growth by altering transport of essential nutrients to the cells. In particular, when σy<σ, the environment is easily fluidized and mixed over large scales, providing nutrients to the cells and sustaining complete cellular growth. By contrast, when σy>σ, the elasticity of the environment suppresses large-scale fluid mixing, limiting nutrient availability and arresting cellular growth. Our work thus reveals a new mechanism, beyond effects that change cellular behavior via local forcing, by which the rheology of the environment may modulate microbial physiology in diverse natural and industrial settings.
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Affiliation(s)
- Anna M Hancock
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - Sujit S Datta
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey.
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Thomas B, Koh MS, O'Callaghan C, Allen JC, Rutman A, Hirst RA, Connolly J, Low SY, Thun How O, Chian Min L, Lim WT, Lin Ean Oon L, He Q, Teoh OH, Lapperre TS. Dysfunctional Bronchial Cilia Are a Feature of Chronic Obstructive Pulmonary Disease (COPD). COPD 2021; 18:657-663. [PMID: 34468237 DOI: 10.1080/15412555.2021.1963695] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Impaired mucociliary clearance may increase COPD exacerbation risk. We aimed to compare bronchial ciliary function and epithelial ultrastructure of COPD patients to healthy controls and explore its relationship to exacerbator phenotypes (frequent [FE] and infrequent [IFE] exacerbator). In this cross-sectional study, 16 COPD patients and 12 controls underwent bronchial brushings. Ciliary beat frequency (CBF) and dyskinesia index (DI; % of dyskinetic cilia) were assessed using digital high-speed video microscopy, and epithelial ultrastructure using transmission electron microscopy (TEM). Bronchial epithelium in COPD showed lower CBF and higher DI, compared to controls (median [IQR] CBF: 6.8 (6.1-7.2) Hz vs 8.5 (7.7-8.9) Hz, p<0.001 and DI: 73.8 (60.7-89.8) % vs 14.5 (11.2-16.9) %, p<0.001, respectively). This was true for FE and IFE phenotypes of COPD, which were similar in terms of bronchial CBF or DI. Subgroup analyses demonstrated lower CBF and higher DI in FE and IFE COPD phenotypes compared to controls, irrespective of smoking status. TEM showed more loss of cilia, extrusion of cells, cytoplasmic blebs and dead cells in COPD patients versus controls. Profound dysfunction of bronchial cilia is a feature of COPD irrespective of exacerbation phenotype and smoking status, which is likely to contribute to poor mucus clearance in COPD.Supplemental data for this article is available online at https://doi.org/10.1080/15412555.2021.1963695 .
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Affiliation(s)
- Biju Thomas
- Department of Respiratory Medicine, KK Women's and Children's Hospital, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore
| | - Mariko Siyue Koh
- Duke-NUS Medical School, Singapore, Singapore.,Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore, Singapore
| | - Christopher O'Callaghan
- Respiratory, Critical Care and Anaesthesia, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - John Carson Allen
- Department of Quantitative Medicine, Duke-NUS Medical School, Singapore, Singapore
| | - Andrew Rutman
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Robert Anthony Hirst
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - John Connolly
- A*STAR, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Su Ying Low
- Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore, Singapore
| | - Ong Thun How
- Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore, Singapore
| | - Loo Chian Min
- Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore, Singapore
| | - Wan Teck Lim
- Duke-NUS Medical School, Singapore, Singapore.,A*STAR, Institute of Molecular and Cell Biology, Singapore, Singapore.,Singhealth Investigational Medicine Unit, Singapore General Hospital, Singapore, Singapore
| | - Lynette Lin Ean Oon
- Duke-NUS Medical School, Singapore, Singapore.,Department of Molecular Pathology, Singapore General Hospital, Singapore, Singapore
| | - Qixian He
- Department of Respiratory Medicine, KK Women's and Children's Hospital, Singapore, Singapore
| | - Oon Hoe Teoh
- Department of Respiratory Medicine, KK Women's and Children's Hospital, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore
| | - Therese Sophie Lapperre
- Duke-NUS Medical School, Singapore, Singapore.,Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore, Singapore.,Department of Pulmonology, University Hospital Antwerp, Antwerp, Belgium.,Laboratory of Experimental Medicine and Paediatrics, Faculty of Medicine & Health Sciences, University of Antwerp, Antwerp, Belgium
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Tam A, Wadsworth S, Dorscheid D, Man SFP, Sin DD. The airway epithelium: more than just a structural barrier. Ther Adv Respir Dis 2011; 5:255-73. [PMID: 21372121 DOI: 10.1177/1753465810396539] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian airway is lined by a variety of specialized epithelial cells that not only serve as a physical barrier but also respond to environment-induced damage through the release of biologically active factors and constant cellular renewal. The lung epithelium responds to environmental insults such as pathogens, cigarette smoke and pollution by secreting inflammatory mediators and antimicrobial peptides, and by recruiting immune cells to the site of infection or damage. When the epithelium is severely damaged, basal cells and Clara cells that have stem-cell-like properties are capable of self-renewal and proliferation in the affected area, to repair the damage. In order to effectively fight off infections, the epithelium requires the assistance of neutrophils recruited from the peripheral circulation through transendothelial followed by transepithelial migration events. Activated neutrophils migrate across the epithelium through a series of ligand-receptor interactions to the site of injury, where they secrete proteolytic enzymes and oxidative radicals for pathogen destruction. However, chronic activation and recruitment of neutrophils in airway diseases such as chronic obstructive pulmonary disease and asthma has been associated with tissue damage and disease severity. In this paper, we review the current understanding of the airway epithelial response to injury and its interaction with inflammatory cells, in particular the neutrophil.
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Affiliation(s)
- Anthony Tam
- The UBC James Hogg Research Centre, Providence Heart and Lung Centre and Department of Medicine, University of British Columbia, UBC, Vancouver, BC, Canada
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Norton MM, Robinson RJ, Weinstein SJ. Model of ciliary clearance and the role of mucus rheology. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:011921. [PMID: 21405727 DOI: 10.1103/physreve.83.011921] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Indexed: 05/30/2023]
Abstract
It has been observed that the transportability of mucus by cilial mats is dependent on the rheological properties of the mucus. Mucus is a non-Newtonian fluid that exhibits a plethora of phenomena such as stress relaxation, tensile stresses, shear thinning, and yielding behavior. These observations motivate the analysis in this paper that considers the first two attributes in order to construct a transport model. The model developed here assumes that the mucus is transported as a rigid body, the metachronal wave exhibits symplectic behavior, that the mucus is thin compared to the metachronal wavelength, and that the effects of individual cilia can be lumped together to impart an average strain to the mucus during contact. This strain invokes a stress in the mucus, whose non-Newtonian rheology creates tensile forces that persist into unsheared regions and allow the unsupported mucus to move as a rigid body whereas a Newtonian fluid would retrograde. This work focuses primarily on the Doi-Edwards model but results are generalized to the Jeffrey's and Maxwell fluids as well. The model predicts that there exists an optimal mucus rheology that maximizes the shear stress imparted to the mucus by the cilia for a given cilia motion. We propose that this is the rheology that the body strives for in order to minimize energy consumption. Predicted optimal rheologies are consistent with results from previous experimental studies when reasonable model parameters are chosen.
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Affiliation(s)
- Michael M Norton
- Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, New York 14623, USA.
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Thomas B, Rutman A, Hirst RA, Haldar P, Wardlaw AJ, Bankart J, Brightling CE, O'Callaghan C. Ciliary dysfunction and ultrastructural abnormalities are features of severe asthma. J Allergy Clin Immunol 2010; 126:722-729.e2. [PMID: 20673980 DOI: 10.1016/j.jaci.2010.05.046] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 04/20/2010] [Accepted: 05/21/2010] [Indexed: 11/17/2022]
Abstract
BACKGROUND Epithelial dysfunction has been implicated in asthma pathophysiology, but no studies have directly assessed ciliary function in asthma. OBJECTIVE To study the ciliary function and epithelial ultrastructure of patients with asthma and healthy controls. METHODS We studied ciliary beat frequency and beat pattern by using digital high-speed video imaging and ultrastructure by transmission electron microscopy of bronchial epithelial strips from 7 subjects with mild, 7 with moderate, and 19 with severe asthma and 9 healthy controls. RESULTS The median (interquartile range) ciliary beat frequency was decreased in moderate (6.5 [4.4-8.5] Hz) and severe asthma (6.7 [6.1-7.6] Hz) compared with controls (10.5 [9.7-11.8] Hz; P < .01). Dyskinesia and immotility indices were higher in severe asthma (65% [43%-75%]; 6.3% [1%-9.5%], respectively) compared with controls (4% [0%-6.7%; 0%, respectively; P < .01). These abnormalities were related to disease severity (ciliary beat frequency, r(s) = -0.68; dyskinesia index, r(s) = 0.86; immotility index, r(s) = 0.65; P < .0001). The ultrastructure of the epithelium was abnormal in severe asthma with a reduction in ciliated cells, an increase in dead cells, and ciliary disorientation compared with all other groups (P < .05). Compared with patients with mild asthma and healthy controls, patients with severe asthma showed increased ciliary depletion, microtubular defects, mitochondrial damage, and cytoplasmic blebbing (P < .01). All of these changes were related to disease severity. CONCLUSION Ciliary dysfunction and ultrastructural abnormalities are closely related to asthma severity. Ciliary dysfunction is a feature of moderate to severe asthma, and profound ultrastructural abnormalities are restricted to severe disease. Whether these changes contribute to the development of severe asthma phenotype remains to be determined.
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Affiliation(s)
- Biju Thomas
- Institute for Lung Health, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom
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Cheung AT, Kurland G, Miller ME, Ford EW, Ayin SA, Walsh EM. Host Defense Deficiency in Newborn Nonhuman Primate Lungs. J Med Primatol 1986. [DOI: 10.1111/j.1600-0684.1986.tb00189.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anthony T.W. Cheung
- Department of PediatricsUniveristy of California Davis School of MedicineDavisCAUSA
- California Primate Research CenterUniversity of California at DavisDavisCAUSA
| | - Geoffrey Kurland
- Department of PediatricsUniveristy of California Davis School of MedicineDavisCAUSA
| | - Michael E. Miller
- Department of PediatricsUniveristy of California Davis School of MedicineDavisCAUSA
| | - Elizabeth W. Ford
- California Primate Research CenterUniversity of California at DavisDavisCAUSA
| | - Susan A. Ayin
- Department of PediatricsUniveristy of California Davis School of MedicineDavisCAUSA
| | - Erin M. Walsh
- California Primate Research CenterUniversity of California at DavisDavisCAUSA
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