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Gélinas L, Rojas-Ruiz A, Boucher M, Henry C, Bossé Y. Sensitivity of the airway smooth muscle in terms of force, shortening and stiffness. Respir Physiol Neurobiol 2024; 325:104264. [PMID: 38599345 DOI: 10.1016/j.resp.2024.104264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/02/2024] [Accepted: 04/06/2024] [Indexed: 04/12/2024]
Abstract
Eight pig tracheal strips were stimulated to contract with log increments of methacholine from 10-8 to 10-5 M. For each strip, the concentration-response was repeated four times in a randomized order to measure isometric force, isotonic shortening against a load corresponding to either 5 or 10 % of a reference force, and average force, stiffness, elastance and resistance over one cycle while the strip length was oscillating sinusoidally by 5 % at 0.2 Hz. For each readout, the logEC50 was calculated and compared. Isotonic shortening with a 5 % load had the lowest logEC50 (-7.13), yielding a greater sensitivity than any other contractile readout (p<0.05). It was followed by isotonic shortening with a 10 % load (-6.66), elastance (-6.46), stiffness (-6.46), resistance (-6.38), isometric force (-6.32), and average force (-6.30). Some of these differences were significant. For example, the EC50 with the average force was 44 % greater than with the elastance (p=0.001). The methacholine sensitivity is thus affected by the contractile readout being measured.
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Affiliation(s)
- Louis Gélinas
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, QC, Canada
| | - Andrés Rojas-Ruiz
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, QC, Canada
| | - Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, QC, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, QC, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, QC, Canada.
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2
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Hackmann MJ, Cairncross A, Elliot JG, Mulrennan S, Nilsen K, Thompson BR, Li Q, Karnowski K, Sampson DD, McLaughlin RA, Cense B, James AL, Noble PB. Quantification of smooth muscle in human airways by polarization-sensitive optical coherence tomography requires correction for perichondrium. Am J Physiol Lung Cell Mol Physiol 2024; 326:L393-L408. [PMID: 38261720 DOI: 10.1152/ajplung.00254.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/05/2023] [Accepted: 01/12/2024] [Indexed: 01/25/2024] Open
Abstract
Quantifying airway smooth muscle (ASM) in patients with asthma raises the possibility of improved and personalized disease management. Endobronchial polarization-sensitive optical coherence tomography (PS-OCT) is a promising quantitative imaging approach that is in the early stages of clinical translation. To date, only animal tissues have been used to assess the accuracy of PS-OCT to quantify absolute (rather than relative) ASM in cross sections with directly matched histological cross sections as validation. We report the use of whole fresh human and pig airways to perform a detailed side-by-side qualitative and quantitative validation of PS-OCT against gold-standard histology. We matched and quantified 120 sections from five human and seven pig (small and large) airways and linked PS-OCT signatures of ASM to the tissue structural appearance in histology. Notably, we found that human cartilage perichondrium can share with ASM the properties of birefringence and circumferential alignment of fibers, making it a significant confounder for ASM detection. Measurements not corrected for perichondrium overestimated ASM content several-fold (P < 0.001, paired t test). After careful exclusion of perichondrium, we found a strong positive correlation (r = 0.96, P < 0.00001) of ASM area measured by PS-OCT and histology, supporting the method's application in human subjects. Matching human histology further indicated that PS-OCT allows conclusions on the intralayer composition and in turn potential contractile capacity of ASM bands. Together these results form a reliable basis for future clinical studies.NEW & NOTEWORTHY Polarization-sensitive optical coherence tomography (PS-OCT) may facilitate in vivo measurement of airway smooth muscle (ASM). We present a quantitative validation correlating absolute ASM area from PS-OCT to directly matched histological cross sections using human tissue. A major confounder for ASM quantification was observed and resolved: fibrous perichondrium surrounding hyaline cartilage in human airways presents a PS-OCT signature similar to ASM for birefringence and optic axis orientation. Findings impact the development of automated methods for ASM segmentation.
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Affiliation(s)
- Michael J Hackmann
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
- Department of Electrical, Electronic, and Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia
| | - Alvenia Cairncross
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
- Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Western Australia, Australia
| | - John G Elliot
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
- Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Western Australia, Australia
| | - Siobhain Mulrennan
- Department of Respiratory Medicine, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
- Institute of Respiratory Health, The University of Western Australia, Crawley, Western Australia, Australia
- Medical School, The University of Western Australia, Crawley, Western Australia, Australia
| | - Kris Nilsen
- Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Bruce R Thompson
- Melbourne School of Health Sciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Qingyun Li
- Department of Electrical, Electronic, and Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia
| | - Karol Karnowski
- Department of Electrical, Electronic, and Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - David D Sampson
- School of Computer Science and Electronic Engineering, University of Surrey, Guildford, United Kingdom
| | - Robert A McLaughlin
- Department of Electrical, Electronic, and Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia
- Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
- Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, South Australia, Australia
| | - Barry Cense
- Department of Electrical, Electronic, and Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia
- Department of Mechanical Engineering, Yonsei University, Seoul, South Korea
| | - Alan L James
- Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Western Australia, Australia
- Medical School, The University of Western Australia, Crawley, Western Australia, Australia
| | - Peter B Noble
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
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3
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Atia L, Fredberg JJ. A life off the beaten track in biomechanics: Imperfect elasticity, cytoskeletal glassiness, and epithelial unjamming. BIOPHYSICS REVIEWS 2023; 4:041304. [PMID: 38156333 PMCID: PMC10751956 DOI: 10.1063/5.0179719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/17/2023] [Indexed: 12/30/2023]
Abstract
Textbook descriptions of elasticity, viscosity, and viscoelasticity fail to account for certain mechanical behaviors that typify soft living matter. Here, we consider three examples. First, strong empirical evidence suggests that within lung parenchymal tissues, the frictional stresses expressed at the microscale are fundamentally not of viscous origin. Second, the cytoskeleton (CSK) of the airway smooth muscle cell, as well as that of all eukaryotic cells, is more solid-like than fluid-like, yet its elastic modulus is softer than the softest of soft rubbers by a factor of 104-105. Moreover, the eukaryotic CSK expresses power law rheology, innate malleability, and fluidization when sheared. For these reasons, taken together, the CSK of the living eukaryotic cell is reminiscent of the class of materials called soft glasses, thus likening it to inert materials such as clays, pastes slurries, emulsions, and foams. Third, the cellular collective comprising a confluent epithelial layer can become solid-like and jammed, fluid-like and unjammed, or something in between. Esoteric though each may seem, these discoveries are consequential insofar as they impact our understanding of bronchospasm and wound healing as well as cancer cell invasion and embryonic development. Moreover, there are reasons to suspect that certain of these phenomena first arose in the early protist as a result of evolutionary pressures exerted by the primordial microenvironment. We have hypothesized, further, that each then became passed down virtually unchanged to the present day as a conserved core process. These topics are addressed here not only because they are interesting but also because they track the journey of one laboratory along a path less traveled by.
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Affiliation(s)
- Lior Atia
- Ben Gurion University of the Negev, Beer Sheva, Israel
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4
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Tjong J, Pendlmayr S, Barter J, Chen J, Maksym GN, Quinn TA, Frampton JP. Cell-contact-mediated assembly of contractile airway smooth muscle rings. Biomed Mater 2023; 18. [PMID: 36801856 DOI: 10.1088/1748-605x/acbd09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 02/17/2023] [Indexed: 02/19/2023]
Abstract
Microtissues in the shape of toroidal rings provide an ideal geometry to better represent the structure and function of the airway smooth muscle present in the small airways, and to better understand diseases such as asthma. Here, polydimethylsiloxane devices consisting of a series of circular channels surrounding central mandrels are used to form microtissues in the shape of toroidal rings by way of the self-aggregation and -assembly of airway smooth muscle cell (ASMC) suspensions. Over time, the ASMCs present in the rings become spindle-shaped and axially align along the ring circumference. Ring strength and elastic modulus increase over 14 d in culture, without significant changes in ring size. Gene expression analysis indicates stable expression of mRNA for extracellular matrix-associated proteins, including collagen I and lamininsα1 andα4 over 21 d in culture. Cells within the rings respond to TGF-β1 treatment, leading to dramatic decreases in ring circumference, with increases in mRNA and protein levels for extracellular matrix and contraction-associated markers. These data demonstrate the utility of ASMC rings as a platform for modeling diseases of the small airways such as asthma.
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Affiliation(s)
- Jonathan Tjong
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada
| | - Stefan Pendlmayr
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada
| | - Jena Barter
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada.,Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Canada
| | - Julie Chen
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada
| | - Geoffrey N Maksym
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada.,Department of Physics & Atmospheric Science, Dalhousie University, Halifax, Canada
| | - T Alexander Quinn
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada.,Department of Physiology & Biophysics, Dalhousie University, Halifax, Canada
| | - John P Frampton
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada.,Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Canada
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5
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Xiong D(JP, Martin JG, Lauzon AM. Airway smooth muscle function in asthma. Front Physiol 2022; 13:993406. [PMID: 36277199 PMCID: PMC9581182 DOI: 10.3389/fphys.2022.993406] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/14/2022] [Indexed: 11/27/2022] Open
Abstract
Known to have affected around 340 million people across the world in 2018, asthma is a prevalent chronic inflammatory disease of the airways. The symptoms such as wheezing, dyspnea, chest tightness, and cough reflect episodes of reversible airway obstruction. Asthma is a heterogeneous disease that varies in clinical presentation, severity, and pathobiology, but consistently features airway hyperresponsiveness (AHR)—excessive airway narrowing due to an exaggerated response of the airways to various stimuli. Airway smooth muscle (ASM) is the major effector of exaggerated airway narrowing and AHR and many factors may contribute to its altered function in asthma. These include genetic predispositions, early life exposure to viruses, pollutants and allergens that lead to chronic exposure to inflammatory cells and mediators, altered innervation, airway structural cell remodeling, and airway mechanical stress. Early studies aiming to address the dysfunctional nature of ASM in the etiology and pathogenesis of asthma have been inconclusive due to the methodological limitations in assessing the intrapulmonary airways, the site of asthma. The study of the trachealis, although convenient, has been misleading as it has shown no alterations in asthma and it is not as exposed to inflammatory cells as intrapulmonary ASM. Furthermore, the cartilage rings offer protection against stress and strain of repeated contractions. More recent strategies that allow for the isolation of viable intrapulmonary ASM tissue reveal significant mechanical differences between asthmatic and non-asthmatic tissues. This review will thus summarize the latest techniques used to study ASM mechanics within its environment and in isolation, identify the potential causes of the discrepancy between the ASM of the extra- and intrapulmonary airways, and address future directions that may lead to an improved understanding of ASM hypercontractility in asthma.
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Affiliation(s)
- Dora (Jun Ping) Xiong
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
| | - James G. Martin
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
| | - Anne-Marie Lauzon
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
- *Correspondence: Anne-Marie Lauzon,
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Wang X, Xu R, Chi D, Dai C, Sheng M. Role of NEAT1/MiR-9-5p/SLC26A2 Pathway on Human Airway Smooth Muscle Cell. Yonsei Med J 2021; 62:858-867. [PMID: 34427073 PMCID: PMC8382724 DOI: 10.3349/ymj.2021.62.9.858] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 06/09/2021] [Accepted: 06/13/2021] [Indexed: 12/28/2022] Open
Abstract
PURPOSE Asthma is a serious inflammatory disease of the respiratory system in which airway smooth muscle cells (ASMCs) play a key role. This study aimed to investigate the expression of SLC26A2 in human ASMCs (HASMCs) and the regulatory mechanism of SLC26A2 in the proliferation and inflammatory factor production of HASMCs. MATERIALS AND METHODS We obtained the asthma-associated differential mRNA SLC26A2 by bioinformatics analysis in childhood acute asthma samples. To investigate its role in airway inflammation and airway remodeling, we treated HASMCs with platelet-derived growth factor (PDGF) in an in vitro model and determined SLC26A2 expression in cells using western blotting. Cell proliferation was detected by MTT and EdU assays, and cell contractile phenotype marker proteins were measured. Cell migration and production of inflammatory factors were determined by Transwell and ELISA assays. Additionally, the upstream regulatory miRNA and LncRNA of SLC26A2 were identified by bioinformatics, luciferase reporter gene, and RIP analyses. RESULTS SLC26A2 was significantly upregulated in bioinformatics analysis of pediatric asthma-related sample. PDGF treatment up-regulated SLC26A2 expression in HASMCs, whereas the knockdown of SLC26A2 inhibited PDGF-stimulated proliferation, migration, and production of inflammatory factors, and enhanced the expression of cell contractile phenotype marker proteins in HASMCs. Luciferase reporter and RIP experiments validated that NEAT1 targeted miR-9-5p to regulate SLC26A2, thereby influencing the biological function of PDGF-induced HASMCs. CONCLUSION These findings indicate that NEAT1-mediated miR-9-5p targeting of SLC26A2 inhibits the PDGF-induced proliferation and production of inflammatory factors in HASMCs. These findings highlight potential therapeutic targets for asthma and airway inflammation.
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Affiliation(s)
- Xiangying Wang
- Department of Rheumatology and Immunology in Children, Hangzhou Children's Hospital, Hangzhou, China
| | - Ruju Xu
- Department of Rheumatology and Immunology in Children, Hangzhou Children's Hospital, Hangzhou, China
| | - Di Chi
- Department of Rheumatology and Immunology in Children, Hangzhou Children's Hospital, Hangzhou, China
| | - Chufeng Dai
- Department of Rheumatology and Immunology in Children, Hangzhou Children's Hospital, Hangzhou, China
| | - Meiling Sheng
- Department of Rheumatology and Immunology in Children, Hangzhou Children's Hospital, Hangzhou, China.
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7
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van den Bosch WB, James AL, Tiddens HAWM. Structure and function of small airways in asthma patients revisited. Eur Respir Rev 2021; 30:30/159/200186. [PMID: 33472958 DOI: 10.1183/16000617.0186-2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/27/2020] [Indexed: 12/21/2022] Open
Abstract
Small airways (<2 mm in diameter) are probably involved across almost all asthma severities and they show proportionally more structural and functional abnormalities with increasing asthma severity. The structural and functional alterations of the epithelium, extracellular matrix and airway smooth muscle in small airways of people with asthma have been described over many years using in vitro studies, animal models or imaging and modelling methods. The purpose of this review was to provide an overview of these observations and to outline several potential pathophysiological mechanisms regarding the role of small airways in asthma.
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Affiliation(s)
- Wytse B van den Bosch
- Dept of Paediatric Pulmonology and Allergology, Erasmus MC - Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Dept of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Alan L James
- Dept of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Perth, Australia
| | - Harm A W M Tiddens
- Dept of Paediatric Pulmonology and Allergology, Erasmus MC - Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Dept of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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8
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Abstract
This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.
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Affiliation(s)
- David A Kaminsky
- University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - David G Chapman
- University of Technology Sydney, Sydney, New South Wales, Australia
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9
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Malmberg LP, Malmström K, Kotaniemi‐Syrjänen A, Lohi J, Pelkonen AS, Sarna S, Mäkelä MJ. Early bronchial inflammation and remodeling and airway hyperresponsiveness at school age. Allergy 2020; 75:1765-1768. [PMID: 31984505 DOI: 10.1111/all.14198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/13/2019] [Accepted: 01/19/2020] [Indexed: 01/06/2023]
Affiliation(s)
- Leo Pekka Malmberg
- Department of Allergy, Skin and Allergy Hospital University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Kristiina Malmström
- Department of Allergy, Skin and Allergy Hospital University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Anne Kotaniemi‐Syrjänen
- Department of Allergy, Skin and Allergy Hospital University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Jouko Lohi
- Department of Pathology University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Anna S. Pelkonen
- Department of Allergy, Skin and Allergy Hospital University of Helsinki and Helsinki University Hospital Helsinki Finland
| | - Seppo Sarna
- Department of Public Health University of Helsinki Finland Helsinki Finland
| | - Mika J. Mäkelä
- Department of Allergy, Skin and Allergy Hospital University of Helsinki and Helsinki University Hospital Helsinki Finland
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10
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Yap HM, Israf DA, Harith HH, Tham CL, Sulaiman MR. Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia. Front Pharmacol 2019; 10:1148. [PMID: 31649532 PMCID: PMC6794426 DOI: 10.3389/fphar.2019.01148] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/06/2019] [Indexed: 12/14/2022] Open
Abstract
Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.
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Affiliation(s)
- Hui Min Yap
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Daud Ahmad Israf
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Hanis Hazeera Harith
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Chau Ling Tham
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Mohd Roslan Sulaiman
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
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11
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Bossé Y. The Strain on Airway Smooth Muscle During a Deep Inspiration to Total Lung Capacity. JOURNAL OF ENGINEERING AND SCIENCE IN MEDICAL DIAGNOSTICS AND THERAPY 2019; 2:0108021-1080221. [PMID: 32328568 PMCID: PMC7164505 DOI: 10.1115/1.4042309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/06/2018] [Indexed: 02/05/2023]
Abstract
The deep inspiration (DI) maneuver entices a great deal of interest because of its ability to temporarily ease the flow of air into the lungs. This salutary effect of a DI is proposed to be mediated, at least partially, by momentarily increasing the operating length of airway smooth muscle (ASM). Concerningly, this premise is largely derived from a growing body of in vitro studies investigating the effect of stretching ASM by different magnitudes on its contractility. The relevance of these in vitro findings remains uncertain, as the real range of strains ASM undergoes in vivo during a DI is somewhat elusive. In order to understand the regulation of ASM contractility by a DI and to infer on its putative contribution to the bronchodilator effect of a DI, it is imperative that in vitro studies incorporate levels of strains that are physiologically relevant. This review summarizes the methods that may be used in vivo in humans to estimate the strain experienced by ASM during a DI from functional residual capacity (FRC) to total lung capacity (TLC). The strengths and limitations of each method, as well as the potential confounders, are also discussed. A rough estimated range of ASM strains is provided for the purpose of guiding future in vitro studies that aim at quantifying the regulatory effect of DI on ASM contractility. However, it is emphasized that, owing to the many limitations and confounders, more studies will be needed to reach conclusive statements.
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Affiliation(s)
- Ynuk Bossé
- Université Laval, Faculty of Medicine, Department of Medicine, IUCPQ, M2694, Pavillon Mallet, Chemin Sainte-Foy, Québec, QC G1V 4G5, Canada e-mail:
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12
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O'Sullivan MJ, Lan B. The Aftermath of Bronchoconstriction. ACTA ACUST UNITED AC 2019; 2:0108031-108036. [PMID: 32328569 DOI: 10.1115/1.4042318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 10/30/2018] [Indexed: 11/08/2022]
Abstract
Asthma is characterized by chronic airway inflammation, airway remodeling, and excessive constriction of the airway. Detailed investigation exploring inflammation and the role of immune cells has revealed a variety of possible mechanisms by which chronic inflammation drives asthma development. However, the underlying mechanisms of asthma pathogenesis still remain poorly understood. New evidence now suggests that mechanical stimuli that arise during bronchoconstriction may play a critical role in asthma development. In this article, we review the mechanical effect of bronchoconstriction and how these mechanical stresses contribute to airway remodeling independent of inflammation.
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Affiliation(s)
- Michael J O'Sullivan
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, 665 Huntington Avenue, 1-G07, Boston, MA 02115
| | - Bo Lan
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, 665 Huntington Avenue, 1-G07, Boston, MA 02115 e-mail:
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13
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Bond S, Léguillette R, Richard EA, Couetil L, Lavoie JP, Martin JG, Pirie RS. Equine asthma: Integrative biologic relevance of a recently proposed nomenclature. J Vet Intern Med 2018; 32:2088-2098. [PMID: 30294851 PMCID: PMC6271326 DOI: 10.1111/jvim.15302] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 05/11/2018] [Accepted: 07/24/2018] [Indexed: 12/29/2022] Open
Abstract
The term “equine asthma” has been proposed as a unifying descriptor of inflammatory airway disease (IAD), recurrent airway obstruction (RAO), and summer pasture‐associated obstructive airway disease. Whilst the term will increase comprehensibility for both the lay and scientific communities, its biologic relevance must be compared and contrasted to asthma in human medicine, recognizing the limited availability of peer‐reviewed equine‐derived data, which are largely restricted to clinical signs, measures of airway obstruction and inflammation and response to therapy. Such limitations constrain meaningful comparisons with human asthma phenotypes. Suggested minimum inclusion criteria supporting the term asthma, as well as similarities and differences between IAD, RAO, and multiple human asthma phenotypes are discussed. Furthermore, differences between phenotype and severity are described, and typical features for equine asthma subcategories are proposed. Based on shared features, we conclude that mild/moderate (IAD) and severe (RAO) equine asthma are biologically appropriate models for both allergic and non‐allergic human asthma, with RAO (severe equine asthma) also being an appropriate model for late‐onset asthma. With the development of new biologic treatments in humans and the application of more targeted therapeutic approaches in the horse, it would appear appropriate to further investigate the allergic (Th‐2) and non‐allergic (non‐Th‐2) phenotypes of equine asthma. Further research is required to more fully determine the potential clinical utility of phenotype classification.
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Affiliation(s)
- Stephanie Bond
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta
| | | | - Eric A Richard
- Equine Immunity & Inflammation, LABÉO Frank Duncombe, Caen, France.,BIOTARGEN, Normandie Univ, UniCaen, Biotargen, France
| | - Laurent Couetil
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana
| | - Jean-Pierre Lavoie
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec
| | - James G Martin
- Meakins Christie Laboratories, McGill University Health Center Research Institute, McGill University, Montreal, Quebec
| | - R Scott Pirie
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, Easter Bush Campus, University of Edinburgh, Midlothian, Scotland, United Kingdom
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14
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Mailhot-Larouche S, Bossé Y. Interval between simulated deep inspirations on the dynamics of airway smooth muscle contraction in guinea pig bronchi. Respir Physiol Neurobiol 2018; 259:136-142. [PMID: 30217723 DOI: 10.1016/j.resp.2018.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/06/2018] [Accepted: 09/10/2018] [Indexed: 11/26/2022]
Abstract
A certain amount of time is required to achieve a maximal contraction from airway smooth muscle (ASM) and stretches of substantial magnitude, such as the ones imparted by deep inspirations (DIs), interfere with contraction. The duration of ASM contraction without interference may thus affect its shortening, its mechanical response to DIs and the overall toll it exerts on the respiratory system. In this study, the effect of changing the interval between DIs on the dynamics of ASM was examined in vitro. Isolated bronchi derived from guinea pigs were held isotonically and stimulated to both contract and relax, in a randomized order, in response to 10-5 M of methacholine and 10-6 M of isoproterenol, respectively. Interference to ASM was inflicted after 2, 5, 10 and 30 min in a randomized order, by imposing a stretch that simulated a DI. The shortening before the stretch, the stiffness before and during the stretch, the post-stretch elongation of ASM and the ensuing re-shortening were measured. These experiments were also performed in the presence of simulated tidal breathing achieved through force fluctuations. The results demonstrate that, with or without force fluctuations, increasing the interval between simulated DIs increased shortening and post-stretch elongation, but not stiffness and re-shortening. These time-dependent effects were not observed when ASM was held in the relaxed state. These findings may help understand to which extent ASM shortening and the regulatory effect of DI are affected by changing the interval between DIs. The potential consequences of these findings on airway narrowing are also discussed.
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15
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Yu Q, Yu X, Zhao W, Zhu M, Wang Z, Zhang J, Huang M, Zeng X. Inhibition of H3K27me3 demethylases attenuates asthma by reversing the shift in airway smooth muscle phenotype. Clin Exp Allergy 2018; 48:1439-1452. [PMID: 30084510 DOI: 10.1111/cea.13244] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/11/2018] [Accepted: 07/25/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND The shift in airway smooth muscle cells (ASMCs) phenotype between proliferation and contraction during asthma has been reported recently, highlighting a role of ASMCs plasticity in the pathophysiology of asthma. As an event involved in epigenetic post-translational modification, histone H3 lysine27 (H3K27) demethylation has attracted significant attention with respect to the epigenetic changes in diverse cells; however, little is known about its contribution to the switching of ASMCs phenotype in asthma. OBJECTIVE To investigate the role of trimethylated H3K27 (H3k27me3) demethylation in ASM remodelling as well as the underling mechanism. METHODS Mice were exposed five times a week to house dust mite (HDM) extract for 5 weeks. Lung function was measured following the final HDM challenge. Airway inflammation and remodelling were then assessed in lungs of individual mice. Human ASMCs were purchased from Sciencell Research Laboratories. Proliferation, synthesis, migration and contraction of ASMCs were analysed, respectively. RESULTS We observed demethylation at H3k27me3 sites in lungs harvested from mice exposed to HDM extract. Administration of a selective inhibitor of H3K27 demethylase (GSK-J4) could ameliorate the classical hallmarks of asthma, such as airway hyperresponsiveness, airway inflammation and remodelling. We established a proliferative as well as a contractive model of human ASMCs to explore the impacts of H3K27 demethylase inhibition on ASMCs phenotype. Our results indicated that GSK-J4 decreased ASMCs proliferation and migration elicited by PDGF through the Akt/JNK signalling; GSK-J4 also prevented the upregulation of contractile proteins in ASMCs induced by TGF-β through the Smad3 pathway. CONCLUSIONS Inhibition of H3K27me3 demethylation alleviated the development of asthmatic airway disease in vivo and modulated ASMCs phenotype in vitro. Collectively, our findings highlight a role of H3K27me3 demethylation in experimental asthma and ASMCs phenotype switch.
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Affiliation(s)
- Qijun Yu
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaowei Yu
- Department of Respiratory Medicine, Changzhou Second People's Hospital, Nanjing Medical University, Changzhou, Jiangsu, China
| | - Wenxue Zhao
- Department of Medicine, Lung Biology Center, University of California San Francisco, San Francisco, California
| | - Manni Zhu
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Zhengxia Wang
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jiaxiang Zhang
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Mao Huang
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaoning Zeng
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
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16
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Chen F, Shao F, Hinds A, Yao S, Ram-Mohan S, Norman TA, Krishnan R, Fine A. Retinoic acid signaling is essential for airway smooth muscle homeostasis. JCI Insight 2018; 3:120398. [PMID: 30135301 DOI: 10.1172/jci.insight.120398] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/11/2018] [Indexed: 12/18/2022] Open
Abstract
Airway smooth muscle (ASM) is a dynamic and complex tissue involved in regulation of bronchomotor tone, but the molecular events essential for the maintenance of ASM homeostasis are not well understood. Observational and genome-wide association studies in humans have linked airway function to the nutritional status of vitamin A and its bioactive metabolite retinoic acid (RA). Here, we provide evidence that ongoing RA signaling is critical for the regulation of adult ASM phenotype. By using dietary, pharmacologic, and genetic models in mice and humans, we show that (a) RA signaling is active in adult ASM in the normal lung, (b) RA-deficient ASM cells are hypertrophic, hypercontractile, profibrotic, but not hyperproliferative, (c) TGF-β signaling, known to cause ASM hypertrophy and airway fibrosis in human obstructive lung diseases, is hyperactivated in RA-deficient ASM, (d) pharmacologic and genetic inhibition of the TGF-β activity in ASM prevents the development of the aberrant phenotype induced by RA deficiency, and (e) the consequences of transient RA deficiency in ASM are long-lasting. These results indicate that RA signaling actively maintains adult ASM homeostasis, and disruption of RA signaling leads to aberrant ASM phenotypes similar to those seen in human chronic airway diseases such as asthma.
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Affiliation(s)
- Felicia Chen
- The Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Fengzhi Shao
- The Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Anne Hinds
- The Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Sean Yao
- Center for Vascular Biology Research, Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Sumati Ram-Mohan
- Center for Vascular Biology Research, Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Timothy A Norman
- The Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Ramaswamy Krishnan
- Center for Vascular Biology Research, Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Alan Fine
- The Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA.,Division of Pulmonary, Critical Care, and Allergy, West Roxbury Veterans Hospital, West Roxbury, Massachusetts, USA
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17
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Gazzola M, Mailhot-Larouche S, Beucher C, Bossé Y. The underlying physiological mechanisms whereby anticholinergics alleviate asthma. Can J Physiol Pharmacol 2018; 96:433-441. [PMID: 29414243 DOI: 10.1139/cjpp-2017-0448] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mechanisms whereby anticholinergics improve asthma outcomes, such as lung function, symptoms, and rate of exacerbation, can be numerous. The most obvious is by affecting the contraction of airway smooth muscle (ASM). The acetylcholine released from the cholinergic nerves is the most important bronchoconstrictor that sets the baseline degree of contractile activation of ASM in healthy individuals. Although the degree of ASM's contractile activation can also be fine-tuned by a plethora of other bronchoconstrictors and bronchodilators in asthma, blocking the ceaseless effect of acetylcholine on ASM by anticholinergics reduces, at any given moment, the overall degree of contractile activation. Because the relationships that exist between the degree of contractile activation, ASM force, ASM shortening, airway narrowing, airflow resistance, and respiratory resistance are not linear, small decreases in the contractile activation of ASM can be greatly amplified and thus translate into important benefits to a patient's well-being. Plus, many inflammatory and remodeling features that are often found in asthmatic lungs synergize with the contractile activation of ASM to increase respiratory resistance. This review recalls that the proven effectiveness of anticholinergics in the treatment of asthma could be merely attributed to a small reduction in the contractile activation of ASM.
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Affiliation(s)
- Morgan Gazzola
- Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada.,Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada
| | - Samuel Mailhot-Larouche
- Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada.,Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada
| | - Clémentine Beucher
- Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada.,Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada
| | - Ynuk Bossé
- Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada.,Quebec Heart and Lung Institute, affiliated with Université Laval, Quebec City, Quebec G1V 4G5, Canada
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18
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Lan B, Krishnan R, Park CY, Watanabe RA, Panganiban R, Butler JP, Lu Q, Cole WC, Fredberg JJ. Transient stretch induces cytoskeletal fluidization through the severing action of cofilin. Am J Physiol Lung Cell Mol Physiol 2018; 314:L799-L807. [PMID: 29345194 DOI: 10.1152/ajplung.00326.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
With every deep inspiration (DI) or sigh, the airway wall stretches, as do the airway smooth muscle cells in the airway wall. In response, the airway smooth muscle cell undergoes rapid stretch-induced cytoskeletal fluidization. As a molecular mechanism underlying the cytoskeletal fluidization response, we demonstrate a key role for the actin-severing protein cofilin. Using primary human airway smooth muscle cells, we simulated a DI by imposing a transient stretch of physiological magnitude and duration. We used traction microscopy to measure the resulting changes in contractile forces. After a transient stretch, cofilin-knockdown cells exhibited a 29 ± 5% decrease in contractile force compared with prestretch conditions. By contrast, control cells exhibited a 67 ± 6% decrease ( P < 0.05, knockdown vs. control). Consistent with these contractile force changes with transient stretch, actin filaments in cofilin-knockdown cells remained largely intact, whereas actin filaments in control cells were rapidly disrupted. Furthermore, in cofilin-knockdown cells, contractile force at baseline was higher and rate of remodeling poststretch was slower than in control cells. Additionally, the severing action of cofilin was restricted to the release phase of the transient stretch. We conclude that the actin-severing activity of cofilin is an important factor in stretch-induced cytoskeletal fluidization and may account for an appreciable part of the bronchodilatory effects of a DI.
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Affiliation(s)
- Bo Lan
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts.,Smooth Muscle Research Group and Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Ramaswamy Krishnan
- Center for Vascular Biology Research, Department of Emergency Medicine, Beth Israel Deaconess Medical Center , Boston, Massachusetts
| | - Chan Yong Park
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts
| | - Rodrigo A Watanabe
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts
| | - Ronald Panganiban
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts
| | - James P Butler
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts.,Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts
| | - Quan Lu
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts
| | - William C Cole
- Smooth Muscle Research Group and Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Jeffrey J Fredberg
- Department of Environmental Health, Harvard T. H. Chan School of Public Health , Boston, Massachusetts
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19
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King GG, James A, Harkness L, Wark PAB. Pathophysiology of severe asthma: We've only just started. Respirology 2018; 23:262-271. [PMID: 29316003 DOI: 10.1111/resp.13251] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 11/14/2017] [Accepted: 12/07/2017] [Indexed: 12/01/2022]
Abstract
Severe asthma is defined by the high treatment requirements to partly or fully control the clinical manifestations of disease. It remains a problem worldwide with a large burden for individuals and health services. The key to improving targeted treatments, reducing disease burden and improving patient outcomes is a better understanding of the pathophysiology and mechanisms of severe disease. The heterogeneity, complexity and difficulties in undertaking clinical studies in severe asthma remain challenges to achieving better understanding and better outcomes. In this review, we focus on the structural, mechanical and inflammatory abnormalities that are relevant in severe asthma.
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Affiliation(s)
- Gregory G King
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, NSW, Australia.,The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
| | - Alan James
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Perth, WA, Australia.,School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia
| | - Louise Harkness
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
| | - Peter A B Wark
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, University of Newcastle, Newcastle, NSW, Australia.,Department of Respiratory Medicine, John Hunter Hospital, Newcastle, NSW, Australia
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20
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Ioan I, Tatopoulos A, Metche S, Coutier L, Houriez E, Kiefer S, Blondé A, Bonabel C, Marchal F, Derelle J, Schweitzer CE, Demoulin-Alexikova S. More Relaxation by Deep Breath on Methacholine- Than on Exercise-Induced bronchoconstriction during the Routine Testing of Asthmatic Children. Front Physiol 2017; 8:768. [PMID: 29046644 PMCID: PMC5632680 DOI: 10.3389/fphys.2017.00768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 09/20/2017] [Indexed: 01/11/2023] Open
Abstract
Deep inspiration (DI) dilates normal airway precontracted with methacholine. The fact that this effect is diminished or absent in asthma could be explained by the presence of bronchial inflammation. The hypothesis was tested that DI induces more relaxation in methacholine induced bronchoconstriction—solely determined by the smooth muscle contraction—than in exercise induced bronchoconstriction, which is contributed to by both smooth muscle contraction and airway wall inflammation. The respiratory conductance (Grs) response to DI was monitored in asthmatic children presenting a moderately positive airway response to challenge by methacholine (n = 36) or exercise (n = 37), and expressed as the post- to pre-DI Grs ratio (GrsDI). Both groups showed similar change in FEV1 after challenge and performed a DI of similar amplitude. GrsDI however was significantly larger in methacholine than in exercise induced bronchoconstriction (p < 0.02). The bronchodilatory effect of DI is thus less during exercise- than methacholine-induced bronchoconstriction. The observation is consistent with airway wall inflammation—that characterizes exercise induced bronchoconstriction—rendering the airways less responsive to DI. More generally, it is surmised that less relief of bronchoconstriction by DI is to be expected during indirect than direct airway challenge. The current suggestion that airway smooth muscle constriction and airway wall inflammation may result in opposing effects on the bronchomotor action of DI opens important perspective to the routine testing of asthmatic children. New crossover research protocols comparing the mechanical consequences of the DI maneuver are warranted during direct and indirect bronchial challenges.
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Affiliation(s)
- Iulia Ioan
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France.,EA 3450 DevAH, Faculté de Médecine, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Aurélie Tatopoulos
- Service de Pédiatrie, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Stéphanie Metche
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Laurianne Coutier
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Emmanuelle Houriez
- Service de Pédiatrie, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Sébastien Kiefer
- Service de Pédiatrie, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Aurore Blondé
- Service de Pédiatrie, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Claude Bonabel
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France.,EA 3450 DevAH, Faculté de Médecine, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - François Marchal
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France.,EA 3450 DevAH, Faculté de Médecine, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Jocelyne Derelle
- Service de Pédiatrie, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Cyril E Schweitzer
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France.,EA 3450 DevAH, Faculté de Médecine, Université de Lorraine, Vandœuvre-lès-Nancy, France.,Service de Pédiatrie, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France
| | - Silvia Demoulin-Alexikova
- Service d'explorations Fonctionnelles Pédiatriques, Hôpital d'enfants, CHRU de Nancy, Vandœuvre-lès-Nancy, France.,EA 3450 DevAH, Faculté de Médecine, Université de Lorraine, Vandœuvre-lès-Nancy, France
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21
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Ojiaku CA, Yoo EJ, Panettieri RA. Transforming Growth Factor β1 Function in Airway Remodeling and Hyperresponsiveness. The Missing Link? Am J Respir Cell Mol Biol 2017; 56:432-442. [PMID: 27854509 DOI: 10.1165/rcmb.2016-0307tr] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The pathogenesis of asthma includes a complex interplay among airway inflammation, hyperresponsiveness, and remodeling. Current evidence suggests that airway structural cells, including bronchial smooth muscle cells, myofibroblasts, fibroblasts, and epithelial cells, mediate all three aspects of asthma pathogenesis. Although studies show a connection between airway remodeling and changes in bronchomotor tone, the relationship between the two remains unclear. Transforming growth factor β1 (TGF-β1), a growth factor elevated in the airway of patients with asthma, plays a role in airway remodeling and in the shortening of various airway structural cells. However, the role of TGF-β1 in mediating airway hyperresponsiveness remains unclear. In this review, we summarize the literature addressing the role of TGF-β1 in airway remodeling and shortening. Through our review, we aim to further elucidate the role of TGF-β1 in asthma pathogenesis and the link between airway remodeling and airway hyperresponsiveness in asthma and to define TGF-β1 as a potential therapeutic target for reducing asthma morbidity and mortality.
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Affiliation(s)
- Christie A Ojiaku
- 1 Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and.,2 Rutgers Institute for Translational Medicine and Science, Child Health Institute, Rutgers University, New Brunswick, New Jersey
| | - Edwin J Yoo
- 1 Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and.,2 Rutgers Institute for Translational Medicine and Science, Child Health Institute, Rutgers University, New Brunswick, New Jersey
| | - Reynold A Panettieri
- 2 Rutgers Institute for Translational Medicine and Science, Child Health Institute, Rutgers University, New Brunswick, New Jersey
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22
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Mailhot-Larouche S, Lortie K, Marsolais D, Flamand N, Bossé Y. An in vitro study examining the duration between deep inspirations on the rate of renarrowing. Respir Physiol Neurobiol 2017; 243:13-19. [PMID: 28487171 DOI: 10.1016/j.resp.2017.04.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/07/2017] [Accepted: 04/29/2017] [Indexed: 12/12/2022]
Abstract
The factors altering the bronchodilatory response to a deep inspiration (DI) in asthma are important to decipher. In this in vitro study, we investigated the effect of changing the duration between DIs on the rate of force recovery post-DI in guinea pig bronchi. The airway smooth muscle (ASM) within the main bronchi were submitted to length oscillation that simulated tidal breathing in different contractile states during 2, 5, 10 or 30min prior to a larger length excursion that simulated a DI. The contractile states of ASM were determined by adding either methacholine or isoproterenol. Irrespective of the contractile state, the duration between DIs neither affected the measured force during length oscillation nor the bronchodilator effect of DI. Contrastingly, the rate of force recovery post-DI in contracted state increased as the duration between DIs decreased. Similar results were obtained with contracted parenchymal strips. These findings suggest that changing the duration between DIs may alter the rate of ASM force recovery post-DI and thereby affect the rate of renarrowing and the duration of the respiratory relief afforded by DI.
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Affiliation(s)
- Samuel Mailhot-Larouche
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Katherine Lortie
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - David Marsolais
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Nicolas Flamand
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada.
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23
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Rosner SR, Pascoe CD, Blankman E, Jensen CC, Krishnan R, James AL, Elliot JG, Green FH, Liu JC, Seow CY, Park JA, Beckerle MC, Paré PD, Fredberg JJ, Smith MA. The actin regulator zyxin reinforces airway smooth muscle and accumulates in airways of fatal asthmatics. PLoS One 2017; 12:e0171728. [PMID: 28278518 PMCID: PMC5344679 DOI: 10.1371/journal.pone.0171728] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/24/2017] [Indexed: 01/21/2023] Open
Abstract
Bronchospasm induced in non-asthmatic human subjects can be easily reversed by a deep inspiration (DI) whereas bronchospasm that occurs spontaneously in asthmatic subjects cannot. This physiological effect of a DI has been attributed to the manner in which a DI causes airway smooth muscle (ASM) cells to stretch, but underlying molecular mechanisms-and their failure in asthma-remain obscure. Using cells and tissues from wild type and zyxin-/- mice we report responses to a transient stretch of physiologic magnitude and duration. At the level of the cytoskeleton, zyxin facilitated repair at sites of stress fiber fragmentation. At the level of the isolated ASM cell, zyxin facilitated recovery of contractile force. Finally, at the level of the small airway embedded with a precision cut lung slice, zyxin slowed airway dilation. Thus, at each level zyxin stabilized ASM structure and contractile properties at current muscle length. Furthermore, when we examined tissue samples from humans who died as the result of an asthma attack, we found increased accumulation of zyxin compared with non-asthmatics and asthmatics who died of other causes. Together, these data suggest a biophysical role for zyxin in fatal asthma.
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Affiliation(s)
- Sonia R. Rosner
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Christopher D. Pascoe
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Elizabeth Blankman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
| | - Christopher C. Jensen
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
| | - Ramaswamy Krishnan
- Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Alan L. James
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, West Australia, Australia
- School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Australia
| | - John G. Elliot
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, West Australia, Australia
| | - Francis H. Green
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jeffrey C. Liu
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Chun Y. Seow
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Jin-Ah Park
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Mary C. Beckerle
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Peter D. Paré
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Jeffrey J. Fredberg
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Mark A. Smith
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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24
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Pascoe CD, Seow CY, Hackett TL, Paré PD, Donovan GM. Heterogeneity of airway wall dimensions in humans: a critical determinant of lung function in asthmatics and nonasthmatics. Am J Physiol Lung Cell Mol Physiol 2017; 312:L425-L431. [PMID: 28062484 DOI: 10.1152/ajplung.00421.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/13/2016] [Accepted: 12/30/2016] [Indexed: 11/22/2022] Open
Abstract
Airway remodeling, a key feature of asthma, alters every layer of the airway wall but most strikingly the airway smooth muscle (ASM) layer. Airway remodeling in asthmatics contributes to fixed airflow obstruction and can amplify airway narrowing caused by ASM activation. Previous modeling studies have shown that the increase in ASM mass has the largest effect on increasing maximal airway narrowing. Simulated heterogeneity in the dimensions and properties of the airway wall can further amplify airway narrowing. Using measurements made on histological sections from donor lungs, we show for the first time that there is profound heterogeneity of ASM area and wall area in both nonasthmatics and asthmatics. Using a mathematical model, we found that this heterogeneity, together with changes in the mean values, contributes to an increased baseline resistance and elastance in asthmatics as well as a leftward shift in the responsiveness of the airways to a simulated agonist in both nonasthmatics and asthmatics. The ability of heterogeneous wall dimensions to shift the dose-response curve is largely due to an increased susceptibility for the small airways to close. This research confirms that heterogeneity of airway wall dimensions can contribute to exaggerated airway narrowing and provides an actual assessment of the magnitude of these effects.
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Affiliation(s)
- Christopher D Pascoe
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada; .,Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
| | - Chun Y Seow
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada; and
| | - Tillie L Hackett
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada.,UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada; and
| | - Peter D Paré
- Respiratory Division, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada; and
| | - Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, New Zealand
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Duan Y, Long J, Chen J, Jiang X, Zhu J, Jin Y, Lin F, Zhong J, Xu R, Mao L, Deng L. Overexpression of soluble ADAM33 promotes a hypercontractile phenotype of the airway smooth muscle cell in rat. Exp Cell Res 2016; 349:109-118. [PMID: 27720670 DOI: 10.1016/j.yexcr.2016.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 10/01/2016] [Accepted: 10/03/2016] [Indexed: 12/28/2022]
Abstract
A disintegrin and metalloproteinase 33 (ADAM33) has been identified as a susceptibility gene for asthma, but details of the causality are not fully understood. We hypothesize that soluble ADAM33 (sADAM33) overexpression can alter the mechanical behaviors of airway smooth muscle cells (ASMCs) via regulation of the cell's contractile phenotype, and thus contributes to airway hyperresponsiveness (AHR) in asthma. To test this hypothesis, we either overexpressed or knocked down the sADAM33 in rat ASMCs by transfecting the cells with sADAM33 coding sequence or a small interfering RNA (siRNA) that specifically targets the ADAM33 disintegrin domain, and subsequently assessed the cells for stiffness, contractility and traction force, together with the expression level of contractile and proliferative phenotype markers. We also investigated whether these changes were dependent on Rho/ROCK pathway by culturing the ASMCs either in the absence or presence of ROCK inhibitor (H1152). The results showed that the ASMCs with sADAM33 overexpression were stiffer and more contractile, generated greater traction force, exhibited increased expression levels of contractile phenotype markers and markedly enhanced Rho activation. Furthermore these changes were largely attenuated when the cells were cultured in the presence of H-1152. However, the knock-down of ADAM33 seemed insufficient to influence majority of the mechanical behaviors of the ASMCs. Taken together, we demonstrated that sADAM33 overexpression altered the mechanical behaviors of ASMCs in vitro, which was most likely by promoting a hypercontractile phenotype transition of ASMCs through Rho/ROCK pathway. This revelation may establish the previously missing link between ADAM33 expression and AHR, and also provide useful insight for targeting sADAM33 in asthma prevention and therapy.
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Affiliation(s)
- Yiyuan Duan
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Jiaoyue Long
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Jun Chen
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Xuemei Jiang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Jian Zhu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Yang Jin
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Feng Lin
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Jun Zhong
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Rong Xu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China
| | - Lizheng Mao
- Jiangsu Asialand Biomed-Technology Co. Ltd., Changzhou, Jiangsu 213164, China
| | - Linhong Deng
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, Shapingba, Chongqing 400030, China; Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, China.
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26
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Donovan GM. Systems-level airway models of bronchoconstriction. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2016; 8:459-67. [PMID: 27348217 DOI: 10.1002/wsbm.1349] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/23/2016] [Accepted: 05/18/2016] [Indexed: 01/26/2023]
Abstract
Understanding lung and airway behavior presents a number of challenges, both experimental and theoretical, but the potential rewards are great in terms of both potential treatments for disease and interesting biophysical phenomena. This presents an opportunity for modeling to contribute to greater understanding, and here, we focus on modeling efforts that work toward understanding the behavior of airways in vivo, with an emphasis on asthma. We look particularly at those models that address not just isolated airways but many of the important ways in which airways are coupled both with each other and with other structures. This includes both interesting phenomena involving the airways and the layer of airway smooth muscle that surrounds them, and also the emergence of spatial ventilation patterns via dynamic airway interaction. WIREs Syst Biol Med 2016, 8:459-467. doi: 10.1002/wsbm.1349 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, New Zealand
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Hiorns JE, Jensen OE, Brook BS. Nonlinear compliance modulates dynamic bronchoconstriction in a multiscale airway model. Biophys J 2016; 107:3030-3042. [PMID: 25517167 PMCID: PMC4269780 DOI: 10.1016/j.bpj.2014.10.067] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 10/28/2014] [Accepted: 10/29/2014] [Indexed: 02/02/2023] Open
Abstract
The role of breathing and deep inspirations (DI) in modulating airway hyperresponsiveness remains poorly understood. In particular, DIs are potent bronchodilators of constricted airways in nonasthmatic subjects but not in asthmatic subjects. Additionally, length fluctuations (mimicking DIs) have been shown to reduce mean contractile force when applied to airway smooth muscle (ASM) cells and tissue strips. However, these observations are not recapitulated on application of transmural pressure (PTM) oscillations (that mimic tidal breathing and DIs) in isolated intact airways. To shed light on this paradox, we have developed a biomechanical model of the intact airway, accounting for strain-stiffening due to collagen recruitment (a large component of the extracellular matrix (ECM)), and dynamic actomyosin-driven force generation by ASM cells. In agreement with intact airway studies, our model shows that PTM fluctuations at particular mean transmural pressures can lead to only limited bronchodilation. However, our model predicts that moving the airway to a more compliant point on the static pressure-radius relationship (which may involve reducing mean PTM), before applying pressure fluctuations, can generate greater bronchodilation. This difference arises from competition between passive strain-stiffening of ECM and force generation by ASM yielding a highly nonlinear relationship between effective airway stiffness and PTM, which is modified by the presence of contractile agonist. Effectively, the airway at its most compliant may allow for greater strain to be transmitted to subcellular contractile machinery. The model predictions lead us to hypothesize that the maximum possible bronchodilation of an airway depends on its static compliance at the PTM about which the fluctuations are applied. We suggest the design of additional experimental protocols to test this hypothesis.
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Affiliation(s)
- Jonathan E Hiorns
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Oliver E Jensen
- School of Mathematics, University of Manchester, Manchester, United Kingdom
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, United Kingdom.
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Hiorns JE, Jensen OE, Brook BS. Static and dynamic stress heterogeneity in a multiscale model of the asthmatic airway wall. J Appl Physiol (1985) 2016; 121:233-47. [PMID: 27197860 DOI: 10.1152/japplphysiol.00715.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 05/15/2016] [Indexed: 12/13/2022] Open
Abstract
Airway hyperresponsiveness (AHR) is a key characteristic of asthma that remains poorly understood. Tidal breathing and deep inspiration ordinarily cause rapid relaxation of airway smooth muscle (ASM) (as demonstrated via application of length fluctuations to tissue strips) and are therefore implicated in modulation of AHR, but in some cases (such as application of transmural pressure oscillations to isolated intact airways) this mechanism fails. Here we use a multiscale biomechanical model for intact airways that incorporates strain stiffening due to collagen recruitment and dynamic force generation by ASM cells to show that the geometry of the airway, together with interplay between dynamic active and passive forces, gives rise to large stress and compliance heterogeneities across the airway wall that are absent in tissue strips. We show further that these stress heterogeneities result in auxotonic loading conditions that are currently not replicated in tissue-strip experiments; stresses in the strip are similar to hoop stress only at the outer airway wall and are under- or overestimates of stresses at the lumen. Taken together these results suggest that a previously underappreciated factor, stress heterogeneities within the airway wall and consequent ASM cellular response to this micromechanical environment, could contribute to AHR and should be explored further both theoretically and experimentally.
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Affiliation(s)
- J E Hiorns
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom; and
| | - O E Jensen
- School of Mathematics, University of Manchester, Manchester, United Kingdom
| | - B S Brook
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom; and
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29
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Lu KD, Manoukian K, Radom-Aizik S, Cooper DM, Galant SP. Obesity, Asthma, and Exercise in Child and Adolescent Health. Pediatr Exerc Sci 2016; 28:264-274. [PMID: 26618409 PMCID: PMC5904022 DOI: 10.1123/pes.2015-0122] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Obesity increases the risk of asthma throughout life but the underlying mechanisms linking these all too common threats to child health are poorly understood. Acute bouts of exercise, aerobic fitness, and levels of physical activity clearly play a role in the pathogenesis and/or management of both childhood obesity and asthma. Moreover, both obesity and physical inactivity are associated with asthma symptomatology and response to therapy (a particularly challenging feature of obesity-related asthma). In this article, we review current understandings of the link between physical activity, aerobic fitness and the asthma-obesity link in children and adolescents (e.g., the impact of chronic low-grade inflammation, lung mechanics, and direct effects of metabolic health on the lung). Gaps in our knowledge regarding the physiological mechanisms linking asthma, obesity and exercise are often compounded by imprecise estimations of adiposity and challenges of assessing aerobic fitness in children. Addressing these gaps could lead to practical interventions and clinical approaches that could mitigate the profound health care crisis of the increasing comorbidity of asthma, physical inactivity, and obesity in children.
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Affiliation(s)
- Kim D. Lu
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
| | | | - Shlomit Radom-Aizik
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
| | - Dan M. Cooper
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
| | - Stanley P. Galant
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
- Children’s Hospital of Orange County, Orange, California
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30
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Smooth muscle in human bronchi is disposed to resist airway distension. Respir Physiol Neurobiol 2016; 229:51-8. [PMID: 27095271 DOI: 10.1016/j.resp.2016.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/11/2016] [Accepted: 04/14/2016] [Indexed: 11/21/2022]
Abstract
Studying airway smooth muscle (ASM) in conditions that emulate the in vivo environment within which the bronchi normally operate may provide important clues regarding its elusive physiological function. The present study examines the effect of lengthening and shortening of ASM on tension development in human bronchial segments. ASM from each bronchial segment was set at a length approximating in situ length (Linsitu). Bronchial tension was then measured during a slow cyclical strain (0.004Hz, from 0.7Linsitu to 1.3Linsitu) in the relaxed state and at graded levels of activation by methacholine. In all cases, tension was greater at longer ASM lengths, and greater during lengthening than shortening. The threshold of methacholine concentration that was required for ASM to account for bronchial tension across the entire range of ASM lengths tested was on average smaller by 2.8 logs during lengthening than during shortening. The length-dependency of ASM tension, together with this lower threshold of methacholine concentration during lengthening versus shortening, suggest that ASM has a greater ability to resist airway dilation during lung inflation than to narrow the airways during lung deflation. More than serving to narrow the airway, as has long been thought, these data suggest that the main function of ASM contraction is to limit airway wall distension during lung inflation.
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Abstract
BACKGROUND Bronchial hyperresponsiveness (BHR) is often regarded as a 'hallmark' of asthma and bronchoprovocation testing is frequently performed to support a diagnosis of asthma. However, BHR is also found in a spectrum of other lung diseases and can be provoked by a variety of specific stimuli. AIMS To review the pathophysiology of BHR, discuss various methods of testing for BHR and describe the epidemiology of BHR in a variety of previously studied populations. METHODS We performed a systematic review of references identified using Medline and hand searches of identified articles. Because of space limitations, we have included those reports that seem most representative of the overall BHR literature. RESULTS BHR can be induced by a variety of stimuli that trigger a number of different but overlapping physiological mechanisms. Bronchoprovocation testing can be performed using a variety of stimuli, various protocols and differing test criteria, yielding results that may be discordant. Elevated rates of BHR have been reported in studies of smokers, chronic obstructive pulmonary disease patients, atopics, athletes, exposed workers and the general population. CONCLUSIONS Due to the prevalence of BHR in a spectrum of clinical patients and working populations, clinicians should be aware that BHR is not specific for asthma. When performed correctly, the greatest clinical value of BHR testing is to rule out suspected asthma in patients in whom testing is negative. Assessment of BHR also provides insights into the pathological mechanisms of airway disease.
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Affiliation(s)
- J Borak
- Department of Environmental Health Sciences, Yale School of Public Health, Yale University, New Haven, CT 06510, USA, Department of Internal Medicine (Yale Occupational and Environmental Medicine Program), Yale School of Medicine, Yale University, New Haven, CT 06510, USA.
| | - R Y Lefkowitz
- Department of Internal Medicine (Yale Occupational and Environmental Medicine Program), Yale School of Medicine, Yale University, New Haven, CT 06510, USA
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Bullone M, Beauchamp G, Godbout M, Martin JG, Lavoie JP. Endobronchial Ultrasound Reliably Quantifies Airway Smooth Muscle Remodeling in an Equine Asthma Model. PLoS One 2015; 10:e0136284. [PMID: 26348727 PMCID: PMC4562526 DOI: 10.1371/journal.pone.0136284] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 08/01/2015] [Indexed: 11/18/2022] Open
Abstract
Endobronchial ultrasonography (EBUS) revealed differences in the thickness of the layer representing subepithelial tissues (L2) between human asthmatics and controls, but whether this measurement correlates with airway smooth muscle (ASM) remodeling in asthma is unknown. In this study, we sought to determine the ability of EBUS to predict histological ASM remodeling in normal and equine asthmatic airways. We studied 109 isolated bronchi from the lungs of 13 horses. They underwent EBUS examination using a 30 MHz radial probe before being processed for histology. ASM remodeling parameters were evaluated in EBUS images (L2 thickness, L2 area, L2 area/internal perimeter [Pi] and L2 area/Pi2) and histological cuts (ASM area/Pi2), and compared. EBUS was then performed ex vivo on the lungs of 4 horses with heaves, an asthma-like condition of horses, and 7 controls to determine whether central bronchial remodeling could be detected with this technique. An optimized approach was developed based on data variability within airways, subjects, and groups, and then validated in 7 horses (3 controls, 4 with heaves) that underwent EBUS in vivo. L2 area was significantly associated to ASM area in isolated lungs (p<0.0001), in the absence of significant bias related to the airway size. Bronchial size significantly affected EBUS ASM-related parameters, except for L2 area/Pi2. L2 area/Pi2 was increased in the airways of asthmatic horses compared to controls, both ex vivo and in vivo (p<0.05). Bronchial histology confirmed our findings (AASM/Pi2 was increased in asthmatic horses compared to controls, p<0.05). In both horses with heaves and controls, L2 was composed of ASM for the outer 75% of its thickness and by ECM for the remaining inner 25%. In conclusion, EBUS reliably allows assessment of asthma-associated ASM remodeling of central airways in a non-invasive way.
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Affiliation(s)
- Michela Bullone
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec, Canada
| | - Guy Beauchamp
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec, Canada
| | - Mireille Godbout
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec, Canada
| | - James G. Martin
- Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Jean-Pierre Lavoie
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec, Canada
- * E-mail:
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Lulich SM, Arsikere H. Tracheo-bronchial soft tissue and cartilage resonances in the subglottal acoustic input impedance. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 137:3436-3446. [PMID: 26093432 DOI: 10.1121/1.4921281] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper offers a re-evaluation of the mechanical properties of the tracheo-bronchial soft tissues and cartilage and uses a model to examine their effects on the subglottal acoustic input impedance. It is shown that the values for soft tissue elastance and cartilage viscosity typically used in models of subglottal acoustics during phonation are not accurate, and corrected values are proposed. The calculated subglottal acoustic input impedance using these corrected values reveals clusters of weak resonances due to soft tissues (SgT) and cartilage (SgC) lining the walls of the trachea and large bronchi, which can be observed empirically in subglottal acoustic spectra. The model predicts that individuals may exhibit SgT and SgC resonances to variable degrees, depending on a number of factors including tissue mechanical properties and the dimensions of the trachea and large bronchi. Potential implications for voice production and large pulmonary airway tissue diseases are also discussed.
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Affiliation(s)
- Steven M Lulich
- Department of Speech and Hearing Sciences, Indiana University, Bloomington, Indiana 47405, USA
| | - Harish Arsikere
- Department of Electrical Engineering, UCLA, Los Angeles, California 90095, USA
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Asthma "of horses and men"--how can equine heaves help us better understand human asthma immunopathology and its functional consequences? Mol Immunol 2014; 66:97-105. [PMID: 25547716 DOI: 10.1016/j.molimm.2014.12.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 11/30/2014] [Accepted: 12/07/2014] [Indexed: 12/20/2022]
Abstract
Animal models have been studied to unravel etiological, immunopathological, and genetic attributes leading to asthma. However, while experiments in which the disease is artificially induced have helped discovering biological and molecular pathways leading to allergic airway inflammation, their contribution to the understanding of the causality of the disease has been more limited. Horses naturally suffer from an asthma-like condition called "heaves" which presents sticking similarities with human asthma. It is characterized by reversible airway obstruction, airway neutrophilic inflammation, and a predominant Th2 immune response. This model allows one to investigate the role of neutrophils in asthma, which remains contentious, the regulation of chronic neutrophilic inflammation, and their possible implication in pulmonary allergic responses. Furthermore, the pulmonary remodeling features in heaves closely resemble those of human asthma, which makes this model unique to investigate the kinetics, reversibility, as well as the physiological consequences of tissue remodeling. In conclusion, heaves and asthma share common clinical presentation and also important immunological and tissue remodeling features. This makes heaves an ideal model for the discovery of novel pathways implicated in the asthmatic inflammation and associated tissue remodeling.
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Dekkers BGJ, Naeimi S, Bos IST, Menzen MH, Halayko AJ, Hashjin GS, Meurs H. L-thyroxine promotes a proliferative airway smooth muscle phenotype in the presence of TGF-β1. Am J Physiol Lung Cell Mol Physiol 2014; 308:L301-6. [PMID: 25480330 DOI: 10.1152/ajplung.00071.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hypothyroidism may reduce, whereas hyperthyroidism may aggravate, asthma symptoms. The mechanisms underlying this relationship are largely unknown. Since thyroid hormones have central roles in cell growth and differentiation, we hypothesized that airway remodeling, in particular increased airway smooth muscle (ASM) mass, may be involved. To address this hypothesis, we investigated the effects of triiodothyronine (T3) and l-thyroxine (T4) in the absence and presence of the profibrotic transforming growth factor (TGF)-β1 on human ASM cell phenotype switching. T3 (1-100 nM) and T4 (1-100 nM) did not affect basal ASM proliferation. However, when combined with TGF-β1 (2 ng/ml), T4 synergistically increased the proliferative response, whereas only a minor effect was observed for T3. In line with a switch from a contractile to a proliferative ASM phenotype, T4 reduced the TGF-β1-induced contractile protein expression by ∼50%. Cotreatment with T3 reduced TGF-β1-induced contractile protein expression by ∼25%. The synergistic increase in proliferation was almost fully inhibited by the integrin αvβ3 antagonist tetrac (100 nM), whereas no significant effects of the thyroid receptor antagonist 1-850 (3 μM) were observed. Inhibition of MEK1/2, downstream of the integrin αvβ3, also inhibited the T4- and TGF-β1-induced proliferative responses. Collectively, the results indicate that T4, and to a lesser extent T3, promotes a proliferative ASM phenotype in the presence of TGF-β1, which is predominantly mediated by the membrane-bound T4 receptor αvβ3. These results indicate that thyroid hormones may enhance ASM remodeling in asthma, which could be of relevance for hyperthyroid patients with this disease.
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Affiliation(s)
- Bart G J Dekkers
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands; Groningen Research Institute for Asthma and COPD, University of Groningen, Groningen, The Netherlands;
| | - Saeideh Naeimi
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands; Department of Pharmacology, Faculty of Veterinary Medicine, Semnan University, Semnan, Iran
| | - I Sophie T Bos
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands; Groningen Research Institute for Asthma and COPD, University of Groningen, Groningen, The Netherlands
| | - Mark H Menzen
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands; Groningen Research Institute for Asthma and COPD, University of Groningen, Groningen, The Netherlands
| | - Andrew J Halayko
- Department of Physiology, University of Manitoba, Winnipeg, Canada; and
| | - Goudarz Sadeghi Hashjin
- Department of Pharmacology, Faculty of Veterinary Medicine, University of Tehran, Teheran, Iran
| | - Herman Meurs
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands; Groningen Research Institute for Asthma and COPD, University of Groningen, Groningen, The Netherlands
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36
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Pascoe CD, Donovan GM, Bossé Y, Seow CY, Paré PD. Bronchoprotective effect of simulated deep inspirations in tracheal smooth muscle. J Appl Physiol (1985) 2014; 117:1502-13. [PMID: 25324512 DOI: 10.1152/japplphysiol.00713.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Deep inspirations (DIs) taken before an inhaled challenge with a spasmogen limit airway responsiveness in nonasthmatic subjects. This phenomenon is called bronchoprotection and is severely impaired in asthmatic subjects. The ability of DIs to prevent a decrease in forced expiratory volume in 1 s (FEV1) was initially attributed to inhibition of airway narrowing. However, DIs taken before methacholine challenge limit airway responsiveness only when a test of lung function requiring a DI is used (FEV1). Therefore, it has been suggested that prior DIs enhance the compliance of the airways or airway smooth muscle (ASM). This would increase the strain the airway wall undergoes during the subsequent DI, which is part of the FEV1 maneuver. To investigate this phenomenon, we used ovine tracheal smooth muscle strips that were subjected to shortening elicited by acetylcholine with or without prior strain mimicking two DIs. The compliance of the shortened strip was then measured in response to a stress mimicking one DI. Our results show that the presence of "DIs" before acetylcholine-induced shortening resulted in 11% greater relengthening in response to the third DI, compared with the prior DIs. This effect, although small, is shown to be potentially important for the reopening of closed airways. The effect of prior DIs was abolished by the adaptation of ASM to either shorter or longer lengths or to a low baseline tone. These results suggest that DIs confer bronchoprotection because they increase the compliance of ASM, which, consequently, promotes greater strain from subsequent DI and fosters the reopening of closed airways.
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Affiliation(s)
- Christopher D Pascoe
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Center for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, New Zealand
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada; and
| | - Chun Y Seow
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Center for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Peter D Paré
- Department of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada; Center for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
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Integrins: therapeutic targets in airway hyperresponsiveness and remodelling? Trends Pharmacol Sci 2014; 35:567-74. [PMID: 25441775 DOI: 10.1016/j.tips.2014.09.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/25/2014] [Accepted: 09/15/2014] [Indexed: 12/28/2022]
Abstract
Integrins are a group of transmembrane heterodimeric proteins that mediate cell-cell and cell-extracellular matrix (ECM) interactions. Integrins have been under intense investigation for their role in inflammation in asthma. Clinical trials investigating integrin antagonists, however, have shown that these compounds are relatively ineffective. Airway remodelling is another pathological feature of asthma that is thought to make an important contribution to airway hyperresponsiveness (AHR) and lung function decline. Recent studies have identified integrins as important players in this process, with a particular role for β1 and αv integrins. Here we review the role of these integrins in airway remodelling and hyperresponsiveness in obstructive airway disease and their potential as pharmacological targets for future treatment.
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Elliot JG, Jones RL, Abramson MJ, Green FH, Mauad T, McKay KO, Bai TR, James AL. Distribution of airway smooth muscle remodelling in asthma: relation to airway inflammation. Respirology 2014; 20:66-72. [PMID: 25257809 DOI: 10.1111/resp.12384] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 06/20/2014] [Accepted: 07/16/2014] [Indexed: 01/08/2023]
Abstract
BACKGROUND AND OBJECTIVE Pathological phenotypes of asthma have been based predominantly on inflammation, rather than airway wall remodelling. Differences in the distribution of airway smooth muscle (ASM) remodelling between large and small airways may affect clinical outcomes in asthma. The aim of this study was to examine the distribution of ASM remodelling and its relation to airway inflammation. METHODS Post-mortem cases of asthma (n = 68) were categorized by the distribution of increased thickness of the ASM layer (relative to nonasthmatic controls, n = 37), into 'large only' (LO, n = 15), 'small only' (SO, n = 4) 'large/small' (LS, n = 24) or no increase (NI, n = 25). Subject characteristics, ASM and airway wall dimensions and inflammatory cell numbers were compared between groups. RESULTS Apart from reduced clinical severity of asthma in NI cases (P = 0.002), subject characteristics did not distinguish asthma groups. Compared with control subjects, ASM cell number, reticular basement membrane thickness, airway wall thickness, percent muscle shortening and eosinophil number were increased (P < 0.05) in both large and small airways in LS cases and only the large airways in LO cases. Increased numbers of neutrophils were observed only in the small airways of LO cases. CONCLUSIONS Distinct distributions of ASM remodelling are seen in asthma. Pathology limited to the small airways was uncommon. Increased thickness of the ASM layer was associated with airway remodelling and eosinophilia, but not neutrophilia. These data support the presence of distinct pathological phenotypes based on the site of increased ASM.
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Affiliation(s)
- John G Elliot
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
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Kono Y, Soeda S, Okada Y, Hara H, Araki K, To M, To Y. A surrogate marker of airway hyperresponsiveness in patients with bronchial asthma. Allergol Int 2014; 63:487-8. [PMID: 24851946 DOI: 10.2332/allergolint.13-le-0656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Yuta Kono
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
| | - Seiko Soeda
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
| | - Yuki Okada
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
| | - Hiroko Hara
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
| | - Kosuke Araki
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
| | - Masako To
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
| | - Yasuo To
- Department of Allergy and Respiratory Medicine, The Fraternity Memorial Hospital, Tokyo, Japan
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Jones RL, Elliot JG, James AL. Estimating airway smooth muscle cell volume and number in airway sections. Sources of variability. Am J Respir Cell Mol Biol 2014; 50:246-52. [PMID: 24007332 DOI: 10.1165/rcmb.2013-0029oc] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Hypertrophy and hyperplasia of airway smooth muscle (ASM) cells are features of asthma that can be assessed in airway transverse sections using stereologically derived parameters. However, little is known about the variability of these parameters within and between airways. The aim of the present study was to assess sources of variation in the measurement of the area of the ASM layer (AASM), and the volume fraction of ASM cells (VVASM) and numerical density of ASM cells within that layer. AASM increased by up to 12% in 4-μm sections, and 28% in 30-μm sections, compared with 0.5-μm sections. AASM was greater (P < 0.05) in large than in small airways, and varied by up to 28% along segments of large airways. Numerical density of ASM cell estimates around the airway circumference varied by less than 10% if 40 random high-power fields were sampled. VVASM was most accurately estimated on 0.5-μm, rather than 4- or 30-μm sections, and was less (P < 0.05) in large than in small airways. The coefficients of variation for VVASM were less than 10% along airway segments. We found that variation of parameters used to estimate ASM cell number or size could be minimized with adequate sampling frequency around or along airway segments. Section thickness was positively related to the measured area of ASM on transverse airway sections. Thin (0.5-μm) sections should be used to estimate tissue volume fractions, which vary little within and between airways of similar size. Airway size contributes most to the variation in estimating parameters of the ASM layer.
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Affiliation(s)
- Robyn L Jones
- 1 Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; and
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Pike KC, Davis SA, Collins SA, Lucas JSA, Inskip HM, Wilson SJ, Thomas ER, Wain HA, Keskiväli-Bond PHM, Cooper C, Godfrey KM, Torrens C, Roberts G, Holloway JW. Prenatal development is linked to bronchial reactivity: epidemiological and animal model evidence. Sci Rep 2014; 4:4705. [PMID: 24740086 PMCID: PMC3989559 DOI: 10.1038/srep04705] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/25/2014] [Indexed: 12/13/2022] Open
Abstract
Chronic cardiorespiratory disease is associated with low birthweight suggesting the importance of the developmental environment. Prenatal factors affecting fetal growth are believed important, but the underlying mechanisms are unknown. The influence of developmental programming on bronchial hyperreactivity is investigated in an animal model and evidence for comparable associations is sought in humans. Pregnant Wistar rats were fed either control or protein-restricted diets throughout pregnancy. Bronchoconstrictor responses were recorded from offspring bronchial segments. Morphometric analysis of paraffin-embedded lung sections was conducted. In a human mother-child cohort ultrasound measurements of fetal growth were related to bronchial hyperreactivity, measured at age six years using methacholine. Protein-restricted rats' offspring demonstrated greater bronchoconstriction than controls. Airway structure was not altered. Children with lesser abdominal circumference growth during 11–19 weeks' gestation had greater bronchial hyperreactivity than those with more rapid abdominal growth. Imbalanced maternal nutrition during pregnancy results in offspring bronchial hyperreactivity. Prenatal environmental influences might play a comparable role in humans.
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Affiliation(s)
- Katharine C Pike
- 1] Clinical and Experimental Sciences Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] NIHR Southampton Respiratory Biomedical Research Unit [3]
| | - Shelley A Davis
- 1] Clinical and Experimental Sciences Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [3]
| | - Samuel A Collins
- Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK
| | - Jane S A Lucas
- 1] Clinical and Experimental Sciences Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] NIHR Southampton Respiratory Biomedical Research Unit
| | - Hazel M Inskip
- 1] Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
| | - Susan J Wilson
- Clinical and Experimental Sciences Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK
| | - Elin R Thomas
- Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK
| | - Harris A Wain
- Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK
| | - Piia H M Keskiväli-Bond
- Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK
| | - Cyrus Cooper
- 1] Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK [3] Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
| | - Keith M Godfrey
- 1] Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK [3] Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
| | - Christopher Torrens
- Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK
| | - Graham Roberts
- 1] Clinical and Experimental Sciences Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [3] NIHR Southampton Respiratory Biomedical Research Unit [4]
| | - John W Holloway
- 1] Clinical and Experimental Sciences Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [2] Human Developmental and Health Academic Unit, University of Southampton Faculty of Medicine, Southampton, UK [3]
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Bartolák-Suki E, LaPrad AS, Harvey BC, Suki B, Lutchen KR. Tidal stretches differently regulate the contractile and cytoskeletal elements in intact airways. PLoS One 2014; 9:e94828. [PMID: 24740101 PMCID: PMC3989249 DOI: 10.1371/journal.pone.0094828] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 03/20/2014] [Indexed: 12/24/2022] Open
Abstract
Recent reports suggest that tidal stretches do not cause significant and sustainable dilation of constricted intact airways ex vivo. To better understand the underlying mechanisms, we aimed to map the physiological stretch-induced molecular changes related to cytoskeletal (CSK) structure and contractile force generation through integrin receptors. Using ultrasound, we measured airway constriction in isolated intact airways during 90 minutes of static transmural pressure (Ptm) of 7.5 cmH2O or dynamic variations between Ptm of 5 and 10 cmH20 mimicking breathing. Integrin and focal adhesion kinase activity increased during Ptm oscillations which was further amplified during constriction. While Ptm oscillations reduced β-actin and F-actin formation implying lower CSK stiffness, it did not affect tubulin. However, constriction was amplified when the microtubule structure was disassembled. Without constriction, α-smooth muscle actin (ASMA) level was higher and smooth muscle myosin heavy chain 2 was lower during Ptm oscillations. Alternatively, during constriction, overall molecular motor activity was enhanced by Ptm oscillations, but ASMA level became lower. Thus, ASMA and motor protein levels change in opposite directions due to stretch and contraction maintaining similar airway constriction levels during static and dynamic Ptm. We conclude that physiological Ptm variations affect cellular processes in intact airways with constriction determined by the balance among contractile and CSK molecules and structure.
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Affiliation(s)
- Erzsébet Bartolák-Suki
- Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Adam S. LaPrad
- Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Brian C. Harvey
- Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Béla Suki
- Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Kenneth R. Lutchen
- Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
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Abstract
Isolated tracheal rings have often been used to directly measure the contractile output of airway smooth muscle (ASM). Here, we describe the method for excising murine tracheas, mounting tracheal rings in organ baths, and measuring the isometric forces generated by the ASM when stimulated by drug additions or electric field stimulation. The apparatus for the setup and the pathways responsible for stimulation are detailed. Examples of the responses and analyses of two types of ASM stimulation are illustrated: (1) the carbachol concentration-response curve and (2) the frequency-response curve elicited by electric field stimulation.
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Brook BS. Emergence of airway smooth muscle mechanical behavior through dynamic reorganization of contractile units and force transmission pathways. J Appl Physiol (1985) 2014; 116:980-97. [PMID: 24481961 DOI: 10.1152/japplphysiol.01209.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway hyperresponsiveness (AHR) in asthma remains poorly understood despite significant research effort to elucidate relevant underlying mechanisms. In particular, a significant body of experimental work has focused on the effect of tidal fluctuations on airway smooth muscle (ASM) cells, tissues, lung slices, and whole airways to understand the bronchodilating effect of tidal breathing and deep inspirations. These studies have motivated conceptual models that involve dynamic reorganization of both cytoskeletal components as well as contractile machinery. In this article, a biophysical model of the whole ASM cell is presented that combines 1) crossbridge cycling between actin and myosin; 2) actin-myosin disconnectivity, under imposed length changes, to allow dynamic reconfiguration of "force transmission pathways"; and 3) dynamic parallel-to-serial transitions of contractile units within these pathways that occur through a length fluctuation. Results of this theoretical model suggest that behavior characteristic of experimentally observed force-length loops of maximally activated ASM strips can be explained by interactions among the three mechanisms. Crucially, both sustained disconnectivity and parallel-to-serial transitions are necessary to explain the nature of hysteresis and strain stiffening observed experimentally. The results provide strong evidence that dynamic rearrangement of contractile machinery is a likely mechanism underlying many of the phenomena observed at timescales associated with tidal breathing. This theoretical cell-level model captures many of the salient features of mechanical behavior observed experimentally and should provide a useful starting block for a bottom-up approach to understanding tissue-level mechanical behavior.
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Affiliation(s)
- Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
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45
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Abstract
In this article, we discuss the interaction of the lung parenchyma and the airways as well as the physiological and pathophysiological significance of this interaction. These two components of the respiratory organ can be thought of as two independent elastic structures but in fact the mechanical properties of one influence the behavior of the other. Traditionally, the interaction has focused on the effects of the lung on the airways but there is good evidence that the opposite is also true, that is, that the mechanical properties of the airways influence the elastic properties of the parenchyma. The interplay between components of the respiratory system including the airways, parenchyma, and vasculature is often referred to as "interdependence." This interdependence transmits the elastic recoil of the lung to create an effective pressure that dilates the airways as transpulmonary pressure and lung volume increase. By using a continuum mechanics analysis of the lung parenchyma, it is possible to predict the effective pressure between the airways and parenchyma, and these predictions can be empirically evaluated. Normal airway caliber is maintained by this pressure in the adventitial interstitium of the airway, and it attenuates the ability of airway smooth muscle to narrow airways. Interdependence has physiological and pathophysiological significance. Weakening of the forces of interdependence contributes to airway dysfunction and gas exchange impairment in acute and chronic airway diseases including asthma and emphysema.
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Affiliation(s)
- Peter D Paré
- University of British Columbia, Vancouver, British Columbia, Canada.
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46
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Lutchen KR. Airway smooth muscle stretch and airway hyperresponsiveness in asthma: have we chased the wrong horse? J Appl Physiol (1985) 2013; 116:1113-5. [PMID: 24265278 DOI: 10.1152/japplphysiol.00968.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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47
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Gabehart KE, Royce SG, Maselli DJ, Miyasato SK, Davis EC, Tang MLK, Jourdan Le Saux C. Airway hyperresponsiveness is associated with airway remodeling but not inflammation in aging Cav1-/- mice. Respir Res 2013; 14:110. [PMID: 24138138 PMCID: PMC4015038 DOI: 10.1186/1465-9921-14-110] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 10/14/2013] [Indexed: 12/03/2022] Open
Abstract
Background Airway inflammation and airway remodeling are the key contributors to airway hyperresponsiveness (AHR), a characteristic feature of asthma. Both processes are regulated by Transforming Growth Factor (TGF)-β. Caveolin 1 (Cav1) is a membrane bound protein that binds to a variety of receptor and signaling proteins, including the TGF-β receptors. We hypothesized that caveolin-1 deficiency promotes structural alterations of the airways that develop with age will predispose to an increased response to allergen challenge. Methods AHR was measured in Cav1-deficient and wild-type (WT) mice 1 to 12 months of age to examine the role of Cav1 in AHR and the relative contribution of inflammation and airway remodeling. AHR was then measured in Cav1-/- and WT mice after an ovalbumin-allergen challenge performed at either 2 months of age, when remodeling in Cav1-/- and WT mice was equivalent, and at 6 months of age, when the Cav1-/- mice had established airway remodeling. Results Cav1-/- mice developed increased thickness of the subepithelial layer and a correspondingly increased AHR as they aged. In addition, allergen-challenged Cav1-/- mice had an increase in AHR greater than WT mice that was largely independent of inflammation. Cav1-/- mice challenged at 6 months of age have decreased AHR compared to those challenged at 2 months with correspondingly decreased BAL IL-4 and IL-5 levels, inflammatory cell counts and percentage of eosinophils. In addition, in response to OVA challenge, the number of goblet cells and α-SMA positive cells in the airways were reduced with age in response to OVA challenge in contrast to an increased collagen deposition further enhanced in absence of Cav1. Conclusion A lack of Cav1 contributed to the thickness of the subepithelial layer in mice as they aged resulting in an increase in AHR independent of inflammation, demonstrating the important contribution of airway structural changes to AHR. In addition, age in the Cav1-/- mice is a contributing factor to airway remodeling in the response to allergen challenge.
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Affiliation(s)
| | | | | | | | | | | | - Claude Jourdan Le Saux
- Department of Cell and Molecular Biology, John A, Burns School of Medicine, University of Hawaii, Honolulu, HI, USA.
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Up-regulation of KCa3.1 promotes human airway smooth muscle cell phenotypic modulation. Pharmacol Res 2013; 77:30-8. [PMID: 24055799 DOI: 10.1016/j.phrs.2013.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/26/2013] [Accepted: 09/08/2013] [Indexed: 02/06/2023]
Abstract
Airway smooth muscle (ASM) cell phenotype modulation, characterized by reversible switching between contractile and proliferative phenotypes, is considered to contribute to proliferative diseases such as allergic asthma and chronic obstructive pulmonary disease (COPD). KCa3.1 has been suggested to be involved in regulating ASM cell activation, proliferation, and migration. However, little is known regarding the exact role of KCa3.1 in ASM cell phenotypic modulation. To elucidate the role of KCa3.1 in regulating ASM cell phenotypic modulation, we investigated the effects of KCa3.1 channels on ASM contractile marker protein expression, proliferation and migration of primary human bronchial smooth muscle (BSM) cells. We found that PDGF increased KCa3.1 channel expression in BSM cells with a concomitant marked decrease in the expression of contractile phenotypic marker proteins including smooth muscle myosin heavy chain (SMMHC), smooth muscle α-actin (α-SMA), myocardin and KCa1.1. These changes were significantly attenuated by the KCa3.1 blocker, TRAM-34, or gene silencing of KCa3.1. Pharmacological blockade or gene silencing of KCa3.1 also suppressed PDGF-induced human BSM cell migration and proliferation accompanied by a decrease in intracellular free Ca(2+) levels as a consequence of membrane depolarization, resulting in a reduction in cyclin D1 level and cell cycle arrest at G0-G1 phase. Additionally, PDGF-induced up-regulation of KCa3.1 and down-regulation of BSM contractile marker proteins were regulated by the ERK inhibitor U0126 and the AKT inhibitor LY294002. These findings highlight a novel role for the KCa3.1 channel in human BSM cell phenotypic modulation and provide a potential target for therapeutic intervention for proliferative airway diseases.
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Oenema TA, Mensink G, Smedinga L, Halayko AJ, Zaagsma J, Meurs H, Gosens R, Dekkers BGJ. Cross-talk between transforming growth factor-β₁ and muscarinic M₂ receptors augments airway smooth muscle proliferation. Am J Respir Cell Mol Biol 2013; 49:18-27. [PMID: 23449734 DOI: 10.1165/rcmb.2012-0261oc] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Transforming growth factor-β₁ (TGF-β₁) is a central mediator in tissue remodeling processes, including fibrosis and airway smooth muscle (ASM) hyperplasia, as observed in asthma. The mechanisms underlying this response, however, remain unclear because TGF-β₁ exerts only weak mitogenic effects on ASM cells. In this study, we hypothesized that the mitogenic effect of TGF-β₁ on ASM is indirect and requires prolonged exposure to allow for extracellular matrix (ECM) deposition. To address this hypothesis, we investigated the effects of acute and prolonged treatment with TGF-β₁, alone and in combination with the muscarinic receptor agonist methacholine, on human ASM cell proliferation. Acutely, TGF-β₁ exerted no mitogenic effect. However, prolonged treatment (for 7 d) with TGF-β₁ increased ASM cell proliferation and potentiated the platelet-derived growth factor-induced mitogenic response. Muscarinic receptor stimulation with methacholine synergistically enhanced the effect of TGF-β₁. Interestingly, the integrin-blocking peptide Arg-Gly-Asp-Ser, as well as integrin α5β1 function-blocking antibodies, inhibited the effects of TGF-β₁ and its combination with methacholine on cell proliferation. Accordingly, prolonged treatment with TGF-β₁ increased fibronectin expression, which was also synergistically enhanced by methacholine. The synergistic effects of methacholine on TGF-β₁-induced proliferation were reduced by the long-acting muscarinic receptor antagonist tiotropium and the M₂ receptor subtype-selective antagonist gallamine, but not the M₃-selective antagonist DAU5884. In line with these findings, the irreversible Gi protein inhibitor pertussis toxin also prevented the potentiation of TGF-β₁-induced proliferation by methacholine. We conclude that prolonged exposure to TGF-β₁ enhances ASM cell proliferation, which is mediated by extracellular matrix-integrin interactions, and which can be enhanced by muscarinic M₂ receptor stimulation.
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Affiliation(s)
- Tjitske A Oenema
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands.
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50
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Hulme KM, Salome CM, Brown NJ, Berend N, Agus HM, Horlyck KR, King GG, Chapman DG. Deep inspiration volume and the impaired reversal of bronchoconstriction in asthma. Respir Physiol Neurobiol 2013; 189:506-12. [PMID: 23994826 DOI: 10.1016/j.resp.2013.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/26/2013] [Accepted: 08/21/2013] [Indexed: 01/08/2023]
Abstract
It is unclear whether the failure to reverse bronchoconstriction with deep inspiration (DI) in asthma is due to reduced maximal dilatation of the DI. We compared the effect of different DI volumes on maximal dilatation and reversal of bronchoconstriction in nine asthmatics and ten non-asthmatics. During bronchoconstriction, subjects took DI to 40%, 70% and 100% inspiratory capacity, on separate days. Maximal dilatation was measured as respiratory system resistance (Rrs) at end-inspiration and residual dilatation as Rrs at end-expiration, both expressed as percent of Rrs at end-tidal expiration prior to DI. DI volume was positively associated with maximal dilatation in non-asthmatics (ANOVA p=0.055) and asthmatics (p=0.023). DI volume was positively associated with residual dilatation in non-asthmatics (p=0.004) but not in asthmatics (p=0.53). The degree of maximal dilatation independently predicted residual dilatation in non-asthmatics but not asthmatics. These findings suggest that the failure to reverse bronchoconstriction with DI in asthma is not due to reduced maximal dilatation, but rather due to increased airway narrowing during expiration.
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