1
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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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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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3
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Airway Smooth Muscle and Asthma. Cells 2023; 12:cells12060882. [PMID: 36980223 PMCID: PMC10047161 DOI: 10.3390/cells12060882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
Airway smooth muscle (ASM) was first described in 1804 by Franz Daniel Reisseisen (as related by Otis (1983)) [...]
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4
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Immunohistochemical Study of Smooth Muscle Cells and Elastin in Goose Lungs. FOLIA VETERINARIA 2022. [DOI: 10.2478/fv-2022-0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
There are many differences (morphological, physiological and mechanical) between the lungs of birds and the lungs of mammals. Birds have a more efficient exchange of oxygen and carbon dioxide than mammals. In this article, we studied the presence of four antibodies (actin, α-smooth muscle actin, desmin and elastin) in the lungs of geese. Smooth muscle cells (SMCs) immunoreactive to actin, α-SMA and desmin were observed in the primary and secondary bronchi and arranged as a continuous layer. In the tertiary bronchus (parabronchus), immunoreactive cells on α-SMA and desmin were observed as aggregations of smooth muscle cells in the septum tips in atrial opening. A small number of α-SMA and desmin-positive cells were observed on the periphery of the parabronchi and between the air and blood capillaries. The elastic fibres were found in the large bronchi in connection with smooth muscle bands. In the parabronchi the elastic fibres form an elastic membrane lining the parabronchial lumen. In the blood vessels, the elastic fibres form the inner and outer elastic membrane. The individual elastic membranes connect neighbouring blood vessels.
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5
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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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6
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Otero-Sabio C, Centelleghe C, Corain L, Graïc JM, Cozzi B, Rivero M, Consoli F, Peruffo A. Microscopic anatomical, immunohistochemical, and morphometric characterization of the terminal airways of the lung in cetaceans. J Morphol 2020; 282:291-308. [PMID: 33338275 DOI: 10.1002/jmor.21304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/16/2020] [Accepted: 11/19/2020] [Indexed: 11/08/2022]
Abstract
The lungs of cetaceans undergo anatomical and physiological adaptations that facilitate extended breath-holding during dives. Here, we present new insights on the ontogeny of the microscopic anatomy of the terminal portion of the airways of the lungs in five cetacean species: the fin whale (Balaenoptera physalus); the sperm whale (Physeter macrocephalus), the Cuvier's beaked whale (Ziphius cavirostris); the bottlenose dolphin (Tursiops truncatus); and the striped dolphin (Stenella coeruleoalba). We (a) studied the histology of the terminal portion of the airways; (b) used immunohistochemistry (IHC) to characterize the muscle fibers with antibodies against smooth muscle (sm-) actin, sm-myosin, and desmin; (c) the innervation of myoelastic sphincters (MESs) with an antibody against neurofilament protein; and (d) defined the diameter of the terminal bronchioles, the diameter and length of the alveoli, the thickness of the septa, the major and minor axis, perimeter and section area of the cartilaginous rings by quantitative morphometric analyses in partially inflated lung tissue. As already reported in the literature, in bottlenose and striped dolphins, a system of MESs was observed in the terminal bronchioles. Immunohistochemistry confirmed the presence of smooth muscle in the terminal bronchioles, alveolar ducts, and alveolar septa in all the examined species. Some neurofilaments were observed close to the MESs in both bottlenose and striped dolphins. In fin, sperm, and Cuvier's beaked whales, we noted a layer of longitudinal smooth muscle going from the terminal bronchioles to the alveolar sacs. The morphometric analysis allowed to quantify the structural differences among cetacean species by ranking them into groups according to the adjusted mean values of the morphometric parameters measured. Our results contribute to the current understanding of the anatomy of the terminal airways of the cetacean lung and the role of the smooth muscle in the alveolar collapse reflex, crucial for prolonged breath-holding diving.
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Affiliation(s)
- Cristina Otero-Sabio
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Padova, Italy
| | - Cinzia Centelleghe
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Padova, Italy
| | - Livio Corain
- Department of Management and Engineering, University of Padova, Vicenza, Padova, Italy
| | - Jean-Marie Graïc
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Padova, Italy
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Padova, Italy
| | - Miguel Rivero
- Veterinary Histology and Pathology, Institute of Animal Health and Food Safety (IUSA), Veterinary School, University of Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Francesco Consoli
- Veterinary Histology and Pathology, Institute of Animal Health and Food Safety (IUSA), Veterinary School, University of Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Antonella Peruffo
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Padova, Italy
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7
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Anthracopoulos MB, Everard ML. Asthma: A Loss of Post-natal Homeostatic Control of Airways Smooth Muscle With Regression Toward a Pre-natal State. Front Pediatr 2020; 8:95. [PMID: 32373557 PMCID: PMC7176812 DOI: 10.3389/fped.2020.00095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/24/2020] [Indexed: 12/20/2022] Open
Abstract
The defining feature of asthma is loss of normal post-natal homeostatic control of airways smooth muscle (ASM). This is the key feature that distinguishes asthma from all other forms of respiratory disease. Failure to focus on impaired ASM homeostasis largely explains our failure to find a cure and contributes to the widespread excessive morbidity associated with the condition despite the presence of effective therapies. The mechanisms responsible for destabilizing the normal tight control of ASM and hence airways caliber in post-natal life are unknown but it is clear that atopic inflammation is neither necessary nor sufficient. Loss of homeostasis results in excessive ASM contraction which, in those with poor control, is manifest by variations in airflow resistance over short periods of time. During viral exacerbations, the ability to respond to bronchodilators is partially or almost completely lost, resulting in ASM being "locked down" in a contracted state. Corticosteroids appear to restore normal or near normal homeostasis in those with poor control and restore bronchodilator responsiveness during exacerbations. The mechanism of action of corticosteroids is unknown and the assumption that their action is solely due to "anti-inflammatory" effects needs to be challenged. ASM, in evolutionary terms, dates to the earliest land dwelling creatures that required muscle to empty primitive lungs. ASM appears very early in embryonic development and active peristalsis is essential for the formation of the lungs. However, in post-natal life its only role appears to be to maintain airways in a configuration that minimizes resistance to airflow and dead space. In health, significant constriction is actively prevented, presumably through classic negative feedback loops. Disruption of this robust homeostatic control can develop at any age and results in asthma. In order to develop a cure, we need to move from our current focus on immunology and inflammatory pathways to work that will lead to an understanding of the mechanisms that contribute to ASM stability in health and how this is disrupted to cause asthma. This requires a radical change in the focus of most of "asthma research."
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Affiliation(s)
| | - Mark L. Everard
- Division of Paediatrics & Child Health, Perth Children's Hospital, University of Western Australia, Perth, WA, Australia
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8
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Abstract
Bronchial thermoplasty is an advanced therapy for severe asthma. It is a bronchoscopic procedure in which radiofrequency energy is applied to the airway wall, resulting in decreased airway smooth muscle burden. Human trials have shown that bronchial thermoplasty may reduce asthma exacerbations and improve quality of life in patients with severe uncontrolled asthma. It has been demonstrated to be a safe procedure, with most adverse events being early and mild. More studies are required to understand the precise effects of bronchial thermoplasty on the asthmatic airway and optimal parameters to appropriately select patients for this novel procedure.
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Affiliation(s)
- Anne S Mainardi
- Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520, USA
| | - Mario Castro
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, 4523 Clayton Avenue, St Louis, MO 63110, USA
| | - Geoffrey Chupp
- Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520, USA.
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9
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Regulation of Airway Smooth Muscle Contraction in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:381-422. [PMID: 31183836 DOI: 10.1007/978-981-13-5895-1_16] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Airway smooth muscle (ASM) extends from the trachea throughout the bronchial tree to the terminal bronchioles. In utero, spontaneous phasic contraction of fetal ASM is critical for normal lung development by regulating intraluminal fluid movement, ASM differentiation, and release of key growth factors. In contrast, phasic contraction appears to be absent in the adult lung, and regulation of tonic contraction and airflow is under neuronal and humoral control. Accumulating evidence suggests that changes in ASM responsiveness contribute to the pathophysiology of lung diseases with lifelong health impacts.Functional assessments of fetal and adult ASM and airways have defined pharmacological responses and signaling pathways that drive airway contraction and relaxation. Studies using precision-cut lung slices, in which contraction of intrapulmonary airways and ASM calcium signaling can be assessed simultaneously in situ, have been particularly informative. These combined approaches have defined the relative importance of calcium entry into ASM and calcium release from intracellular stores as drivers of spontaneous phasic contraction in utero and excitation-contraction coupling.Increased contractility of ASM in asthma contributes to airway hyperresponsiveness. Studies using animal models and human ASM and airways have characterized inflammatory and other mechanisms underlying increased reactivity to contractile agonists and reduced bronchodilator efficacy of β2-adrenoceptor agonists in severe diseases. Novel bronchodilators and the application of bronchial thermoplasty to ablate increased ASM within asthmatic airways have the potential to overcome limitations of current therapies. These approaches may directly limit excessive airway contraction to improve outcomes for difficult-to-control asthma and other chronic lung diseases.
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10
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Jaslove JM, Nelson CM. Smooth muscle: a stiff sculptor of epithelial shapes. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170318. [PMID: 30249770 PMCID: PMC6158200 DOI: 10.1098/rstb.2017.0318] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2018] [Indexed: 12/11/2022] Open
Abstract
Smooth muscle is increasingly recognized as a key mechanical sculptor of epithelia during embryonic development. Smooth muscle is a mesenchymal tissue that surrounds the epithelia of organs including the gut, blood vessels, lungs, bladder, ureter, uterus, oviduct and epididymis. Smooth muscle is stiffer than its adjacent epithelium and often serves its morphogenetic function by physically constraining the growth of a proliferating epithelial layer. This constraint leads to mechanical instabilities and epithelial morphogenesis through buckling. Smooth muscle stiffness alone, without smooth muscle cell shortening, seems to be sufficient to drive epithelial morphogenesis. Fully understanding the development of organs that use smooth muscle stiffness as a driver of morphogenesis requires investigating how smooth muscle develops, a key aspect of which is distinguishing smooth muscle-like tissues from one another in vivo and in culture. This necessitates a comprehensive appreciation of the genetic, anatomical and functional markers that are used to distinguish the different subtypes of smooth muscle (for example, vascular versus visceral) from similar cell types (including myofibroblasts and myoepithelial cells). Here, we review how smooth muscle acts as a mechanical driver of morphogenesis and discuss ways of identifying smooth muscle, which is critical for understanding these morphogenetic events.This article is part of the Theo Murphy meeting issue 'Mechanics of Development'.
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Affiliation(s)
- Jacob M Jaslove
- Department of Molecular Biology, Princeton University, 303 Hoyt Laboratory, William Street, Princeton, NJ 08544, USA
- Graduate School of Biomedical Sciences, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Celeste M Nelson
- Department of Molecular Biology, Princeton University, 303 Hoyt Laboratory, William Street, Princeton, NJ 08544, USA
- Department of Chemical and Biological Engineering, Princeton University, 303 Hoyt Laboratory, William Street, Princeton, NJ 08544, USA
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11
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Calzetta L, Matera MG, Rogliani P, Cazzola M. Multifaceted activity of N-acetyl-l-cysteine in chronic obstructive pulmonary disease. Expert Rev Respir Med 2018; 12:693-708. [DOI: 10.1080/17476348.2018.1495562] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Luigino Calzetta
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, Rome, Italy
| | - Maria Gabriella Matera
- Department of Experimental Medicine, Unit of Pharmacology, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Paola Rogliani
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, Rome, Italy
| | - Mario Cazzola
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, Rome, Italy
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12
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Chernyavsky IL, Russell RJ, Saunders RM, Morris GE, Berair R, Singapuri A, Chachi L, Mansur AH, Howarth PH, Dennison P, Chaudhuri R, Bicknell S, Rose FRAJ, Siddiqui S, Brook BS, Brightling CE. In vitro, in silico and in vivo study challenges the impact of bronchial thermoplasty on acute airway smooth muscle mass loss. Eur Respir J 2018; 51:13993003.01680-2017. [PMID: 29700102 PMCID: PMC6003767 DOI: 10.1183/13993003.01680-2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 03/29/2018] [Indexed: 11/05/2022]
Abstract
Bronchial thermoplasty is a treatment for asthma. It is currently unclear whether its histopathological impact is sufficiently explained by the proportion of airway wall that is exposed to temperatures necessary to affect cell survival. Airway smooth muscle and bronchial epithelial cells were exposed to media (37–70°C) for 10 s to mimic thermoplasty. In silico we developed a mathematical model of airway heat distribution post-thermoplasty. In vivo we determined airway smooth muscle mass and epithelial integrity pre- and post-thermoplasty in 14 patients with severe asthma. In vitro airway smooth muscle and epithelial cell number decreased significantly following the addition of media heated to ≥65°C. In silico simulations showed a heterogeneous heat distribution that was amplified in larger airways, with <10% of the airway wall heated to >60°C in airways with an inner radius of ∼4 mm. In vivo at 6 weeks post-thermoplasty, there was an improvement in asthma control (measured via Asthma Control Questionnaire-6; mean difference 0.7, 95% CI 0.1–1.3; p=0.03), airway smooth muscle mass decreased (absolute median reduction 5%, interquartile range (IQR) 0–10; p=0.03) and epithelial integrity increased (14%, IQR 6–29; p=0.007). Neither of the latter two outcomes was related to improved asthma control. Integrated in vitro and in silico modelling suggest that the reduction in airway smooth muscle post-thermoplasty cannot be fully explained by acute heating, and nor did this reduction confer a greater improvement in asthma control. Bronchial thermoplasty treatment for asthma has unexpected possible mechanisms of actionhttp://ow.ly/ZcuE30jsaSa
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Affiliation(s)
- Igor L Chernyavsky
- School of Mathematics, University of Manchester, Manchester, UK.,These authors contributed equally to the study
| | - Richard J Russell
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK.,These authors contributed equally to the study
| | - Ruth M Saunders
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK.,These authors contributed equally to the study
| | - Gavin E Morris
- Dept of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Rachid Berair
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Amisha Singapuri
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Latifa Chachi
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | | | - Peter H Howarth
- Clinical and Experimental Sciences, University of Southampton, Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Trust, Southampton, UK
| | - Patrick Dennison
- Clinical and Experimental Sciences, University of Southampton, Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Trust, Southampton, UK
| | - Rekha Chaudhuri
- Gartnavel General Hospital, Glasgow, UK.,Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | | | | | - Salman Siddiqui
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, Nottingham, UK.,Co-senior authors
| | - Christopher E Brightling
- Dept of Infection, Immunity and Inflammation, Institute for Lung Health, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK.,Co-senior authors
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13
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Cazzola M, Calzetta L, Facciolo F, Rogliani P, Matera MG. Pharmacological investigation on the anti-oxidant and anti-inflammatory activity of N-acetylcysteine in an ex vivo model of COPD exacerbation. Respir Res 2017; 18:26. [PMID: 28118826 PMCID: PMC5260037 DOI: 10.1186/s12931-016-0500-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/29/2016] [Indexed: 12/20/2022] Open
Abstract
Background Oxidative stress is recognized to be one of predisposing factor in the pathogenesis of COPD. The oxidant/antioxidant imbalance is significantly pronounced in patients with COPD exacerbation. N-acetylcysteine (NAC) seems to be able to reduce COPD exacerbations by modulating the oxidative stress in addition to its well-known mucolytic activity, but there are discordant findings on the actual anti-oxidant activity of NAC. Methods The anti-oxidant effect of NAC and its impact on the inflammatory response have been pharmacologically characterized on a human ex vivo model of COPD exacerbation induced by lipopolysaccharide (LPS). Results NAC prevented the desensitization induced by LPS incubation on the contractile tone in linear concentration-response manner. Concentrations of NAC ≥1 μM reduced the pro-oxidant response (peroxidase activity, hydrogen peroxide, malondialdehyde, nitric oxide), and improved the anti-oxidant response (total anti-oxidant capacity, glutathione, superoxide dismutase) induced by LPS. Lower concentrations of NAC (<1 μM) did not modulate the bronchial oxidative imbalance. Concentrations of NAC ≥300 μM inhibited the inflammatory response (release of IL-1β, IL-8, and TNF-α) of human airways induced by the overnight stimulation with LPS, whereas lower concentrations of NAC (≥1 μM) were sufficient to reduce the release of IL-6 elicited by LPS. Both the anti-oxidant effect and the anti-inflammatory effect of NAC were inversely correlated with the release of NKA. Conclusions The findings of this study suggest that NAC may have a role in modulating the detrimental effect induced by LPS in course of COPD exacerbation. It may elicit both anti-oxidant and anti-inflammatory effects when administered at high concentrations.
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Affiliation(s)
- Mario Cazzola
- Department of Systems Medicine, Chair of Respiratory Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Luigino Calzetta
- Department of Systems Medicine, Chair of Respiratory Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133, Rome, Italy.
| | - Francesco Facciolo
- Regina Elena National Cancer Institute, Thoracic Surgery Unit, Rome, Italy
| | - Paola Rogliani
- Department of Systems Medicine, Chair of Respiratory Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Maria Gabriella Matera
- Department of Experimental Medicine, Unit of Pharmacology, Second University of Naples, Naples, Italy
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14
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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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15
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Singh SK, Tiwari KK. Bronchial thermoplasty: a non-pharmacological approach. CLINICAL RESPIRATORY JOURNAL 2015; 11:13-20. [PMID: 25919949 DOI: 10.1111/crj.12315] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 02/12/2015] [Accepted: 04/21/2015] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Asthma is a chronic inflammatory disorder of the airway characterized by the episodic symptoms of breathlessness, wheezes and cough. Even with the use of maximum anti-asthmatic pharmacological treatment sometimes it remains uncontrolled. For such patients, bronchial thermoplasty is the new mode of treatment. OBJECTIVE To review published article on bronchial thermoplasty. METHODS We identified 102 English articles on PubMed, and 56 were excluded by the abstract. The remaining articles were retrieved for full-text detailed evaluation by authors, and 28 relevant articles were selected for final review. RESULTS Bronchial thermoplasty is the radiofrequency ablation of the airway smooth muscle with the help of flexible fiberoptic bronchoscope. It reduces the smooth muscle mass of the bronchial wall and decreases its contractility. CONCLUSION Bronchial thermoplasty causes improvement in the quality of life, and causes reduction in the emergency room visit and exacerbation due to asthma. Long-term safety has been established by various prospective studies.
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Affiliation(s)
- Saurabh Kumar Singh
- Department of Pulmonary Medicine, Gajra Raja Medical College, Jayarogya Group of Hospitals, Gwalior, Madhya Pradesh, India
| | - Kamlesh Kumar Tiwari
- Department of Pulmonary Medicine, Gajra Raja Medical College, Jayarogya Group of Hospitals, Gwalior, Madhya Pradesh, India
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16
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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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17
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Hardin C, Rajendran K, Manomohan G, Tambe DT, Butler JP, Fredberg JJ, Martinelli R, Carman CV, Krishnan R. Glassy dynamics, cell mechanics, and endothelial permeability. J Phys Chem B 2013; 117:12850-6. [PMID: 23638866 DOI: 10.1021/jp4020965] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A key feature of all inflammatory processes is disruption of the vascular endothelial barrier. Such disruption is initiated in part through active contraction of the cytoskeleton of the endothelial cell (EC). Because contractile forces are propagated from cell to cell across a great many cell-cell junctions, this contractile process is strongly cooperative and highly nonlocal. We show here that the characteristic length scale of propagation is modulated by agonists and antagonists that impact permeability of the endothelial barrier. In the presence of agonists including thrombin, histamine, and H2O2, force correlation length increases, whereas in the presence of antagonists including sphingosine-1-phosphate, hepatocyte growth factor, and the rho kinase inhibitor, Y27632, force correlation length decreases. Intercellular force chains and force clusters are also evident, both of which are reminiscent of soft glassy materials approaching a glass transition.
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Affiliation(s)
- Corey Hardin
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital , Boston, Massachusetts
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18
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Marruchella G, Bernabò N, Valbonetti L. Quantitative assessment of bronchiolar smooth muscle in healthy and diseased porcine lungs. Res Vet Sci 2012; 94:641-3. [PMID: 23151463 DOI: 10.1016/j.rvsc.2012.10.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/19/2012] [Accepted: 10/20/2012] [Indexed: 10/27/2022]
Abstract
Smooth muscle cells are major components of bronchiolar wall. Bronchiolar smooth muscle is reported to increase in some veterinary pulmonary disorders, but such assumption is not supported by detailed morphometric analyses. The present investigation aimed at quantitatively evaluating bronchiolar smooth muscle in healthy and diseased pig lungs. Our results suggest that bronchiolar smooth muscle cells significantly modify in size and number under different disease conditions, namely parasitic bronchopneumonia and Mycoplasma hyopneumoniae-induced enzootic pneumonia. Further studies are needed in order to understand the pathogenesis and the functional impact of such changes.
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Affiliation(s)
- G Marruchella
- University of Teramo, Faculty of Veterinary Medicine, Department of Comparative Biomedical Sciences, Piazza A. Moro 45, 64100 Teramo, Italy.
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19
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Airway smooth muscle as a target in asthma and the beneficial effects of bronchial thermoplasty. J Allergy (Cairo) 2012; 2012:593784. [PMID: 23024662 PMCID: PMC3457660 DOI: 10.1155/2012/593784] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 08/01/2012] [Indexed: 11/17/2022] Open
Abstract
Airflow within the airways is determined directly by the lumenal area of that airway. In this paper, we consider several factors which can reduce airway lumenal area, including thickening and/or active constriction of the airway smooth muscle (ASM). The latter cell type can also contribute in part to inflammation, another feature of asthma, through its ability to take on a synthetic/secretory phenotype. The ASM therefore becomes a strategically important target in the treatment of asthma, given these key contributions to the pathophysiology of that disease. Pharmacological approaches have been developed to elicit relaxation of the ASM, but these are not always effective in all patients, nor do they address the long-term structural changes which impinge on the airway lumen. The recent discovery that thermal energy can be used to ablate smooth muscle has led to the development of a novel physical intervention—bronchial thermoplasty—in the treatment of asthma. Here, we review the evolution of this novel approach, consider some of the possible mechanisms that account for its salutary effects, and pose new questions which may lead to even better therapies for asthma.
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20
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Krishnan R, Fredberg JJ. In Bronchospasm, Fluctuations Come to Life. Am J Respir Crit Care Med 2011; 184:1321-2. [DOI: 10.1164/rccm.201106-1002ed] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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21
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Chitano P. Models to understand contractile function in the airways. Pulm Pharmacol Ther 2011; 24:444-51. [PMID: 21511049 DOI: 10.1016/j.pupt.2011.04.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 11/25/2022]
Abstract
Although the role of contractile function in the airways is controversial, there is general consensus on the importance of airway smooth muscle (ASM) as a therapeutic target for diseases characterized by airway obstruction, such as asthma or chronic obstructive pulmonary disease. Indeed, the use of bronchodilators to relax ASM is the most common and effective practice to treat airflow obstruction. Excessive pathologic bronchoconstriction may originate from primary alterations of ASM mechanical function and/or from the effects exerted on ASM function by disease processes, such as inflammation and remodeling. An in depth knowledge of the potentially multiple mechanisms that distinctively regulate primary and secondary alterations in ASM contractile function would be essential for the development of new therapeutic approaches aimed at preventing the occurrence or reducing the severity of bronchoconstriction. The present review discusses studies that have addressed the mechanisms of altered ASM contractile function in models of airway hyperresponsiveness. Although not comprehensively, in the present review, animal models of intrinsic airway hyperresponsiveness, normal ontogenesis, and allergic sensitization are analyzed in the attempt to summarize the current knowledge on regulatory mechanisms of ASM contractile function in health and disease. Studies in human ASM and the need for additional models to understand contractile function in the airways are also discussed.
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Affiliation(s)
- Pasquale Chitano
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA.
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22
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Xu CB, Lei Y, Chen Q, Pehrson C, Larsson L, Edvinsson L. Cigarette smoke extracts promote vascular smooth muscle cell proliferation and enhances contractile responses in the vasculature and airway. Basic Clin Pharmacol Toxicol 2010; 107:940-8. [PMID: 20618305 DOI: 10.1111/j.1742-7843.2010.00610.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cigarette smoke exposure is a strong risk factor for cardiovascular and respiratory diseases. However, the knowledge about how cigarette smoke induces damage to vasculature and airway is limited. The present study was designed to examine the effects of cigarette smoke particles extracted by heptane (heptane-soluble smoke particles, HSP), by water (water-soluble smoke particles, WSP) and by DMSO (DMSO-soluble smoke particles, DSP), which represent lipophilic, hydrophilic and ambiphoteric constituents from the cigarette smoke, respectively. Human aortic smooth muscle cell (HASMC) proliferation was assessed in cell culture. Rat resistance artery and airway contractile responses to serotonin, U46619, phenylephrine, noradrenaline, acetylcholine, des-Arg⁹-bradykinin, bradykinin, sarafotoxin 6c and endothelin-1 were monitored by a sensitive myograph system. Immunocytochemistry and cell-based phosphoELISA assay were used to demonstrate activation of extracellular signal-regulated kinases 1/2 (ERK1/2). For the first time, our results demonstrate that although all the three extracts promote HASMC proliferation, the HSP and DSP effects occur earlier. HSP and DSP, but not WSP, increase the contractile responses to sarafotoxin 6c, U46619 or bradykinin in rat mesenteric artery and/or in bronchi. ERK1/2 is activated by HSP and DSP in HASMCs and inhibition of ERK1/2 abrogated the smoke extracts-induced HASMC proliferation, while blockage of nicotinic receptors had no effects, suggesting that the toxic effects of the smoke extracts occur via activation of intracellular ERK1/2 signalling, but not nicotinic receptors.
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Affiliation(s)
- Cang-Bao Xu
- Division of Experimental Vascular Research, Institute of Clinical Science in Lund, Lund University, Lund, Sweden.
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23
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Amrani Y. Airway smooth muscle modulation and airway hyper-responsiveness in asthma: new cellular and molecular paradigms. Expert Rev Clin Immunol 2010; 2:353-64. [PMID: 20476907 DOI: 10.1586/1744666x.2.3.353] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There is growing evidence indicating the existence of a causal relationship between abnormal airway smooth muscle (ASM) function and airway hyper-responsiveness, a poorly understood feature of asthma that can be defined as an excessive bronchospastic response. In recent years, there has been a veritable explosion of articles suggesting that ASM exposed to proasthmatic cytokines can elicit a hyper-responsive state to contractile G-protein-coupled receptor (GPCR) agonists. Aberrant airway responsiveness could result from abnormal calcium signaling, with changes occurring at various levels of GPCR-associated signal transduction. This review presents the latest observations describing novel mechanistic models that could explain the involvement of ASM in airway hyper-responsiveness. This review will discuss the role of ASM in beta(2)-agonist-mediated bronchial hyper-responsiveness and the clinical significance of cell-cell contact between ASM and mast cells recently described to be intimately infiltrated within the ASM tissues in asthmatic patients. The possibility that allergens could trigger airway hyper-responsiveness by directly acting on ASM via activation of immunoglobulin E receptors, FcepsilonRI and FCepsilonRII will also be discussed. These important findings further support the notion that targeting ASM could offer new treatment for many features of asthma, including airway hyper-responsiveness. Future therapeutic intervention includes: the prevention of ASM-inflammatory cell physical and/or functional interaction, the inhibition of Immunoglobulin E receptor-dependent signal transduction, and the abrogation of cytokine-dependent pathways that modulate receptor-associated calcium metabolism.
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Affiliation(s)
- Yassine Amrani
- University of Pennsylvania Medical Center, Pulmonary, Allergy and Critical Care Division, Department of Medicine, BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104, USA.
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24
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Martin N, Pavord ID. Bronchial thermoplasty for the treatment of asthma. Curr Allergy Asthma Rep 2009; 9:88-95. [PMID: 19063830 DOI: 10.1007/s11882-009-0013-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Asthma is an increasingly prevalent disease, particularly in industrialized countries. With modern treatment, many patients can expect good asthma control; however, a significant minority continue to have excessive symptoms. Bronchial thermoplasty is a novel approach to treating asthma in which the hypertrophied airway smooth muscle present in the asthmatic airway is specifically targeted and depleted using thermal energy. In this article, we review the early animal and human development of the technique, summarize the randomized trials carried out in patients to date, discuss proposed mechanisms of action, and suggest directions for future work.
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Affiliation(s)
- Neil Martin
- Department of Respiratory Medicine, Allergy and Thoracic Surgery, Institute for Lung Health, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom
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25
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Lavoie TL, Dowell ML, Lakser OJ, Gerthoffer WT, Fredberg JJ, Seow CY, Mitchell RW, Solway J. Disrupting actin-myosin-actin connectivity in airway smooth muscle as a treatment for asthma? PROCEEDINGS OF THE AMERICAN THORACIC SOCIETY 2009; 6:295-300. [PMID: 19387033 PMCID: PMC2677405 DOI: 10.1513/pats.200808-078rm] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2008] [Accepted: 01/27/2009] [Indexed: 11/20/2022]
Abstract
Breathing is known to functionally antagonize bronchoconstriction caused by airway muscle contraction. During breathing, tidal lung inflation generates force fluctuations that are transmitted to the contracted airway muscle. In vitro, experimental application of force fluctuations to contracted airway smooth muscle strips causes them to relengthen. Such force fluctuation-induced relengthening (FFIR) likely represents the mechanism by which breathing antagonizes bronchoconstriction. Thus, understanding the mechanisms that regulate FFIR of contracted airway muscle could suggest novel therapeutic interventions to increase FFIR, and so to enhance the beneficial effects of breathing in suppressing bronchoconstriction. Here we propose that the connectivity between actin filaments in contracting airway myocytes is a key determinant of FFIR, and suggest that disrupting actin-myosin-actin connectivity by interfering with actin polymerization or with myosin polymerization merits further evaluation as a potential novel approach for preventing prolonged bronchoconstriction in asthma.
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Affiliation(s)
- Tera L Lavoie
- Department of Medicine, University of Chicago, MC6026, 5841 S. Maryland Ave., Chicago, IL 60637, USA
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26
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Abstract
Very little is known regarding the function, origin, and turnover of airway smooth muscle (ASM). In this article, we discuss the embryological development of ASM, and provide information regarding candidate mesenchymal ASM progenitor cell populations specifically in relation to airway remodeling. This review also highlights the current limitations in studying ASM biology, and underscores the need for novel molecular tools and markers that will refine our understanding of this cell type in lung homeostasis and disease.
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27
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Abstract
A novel physical perspective of molecular interactions within the cytoskeleton of the airway smooth muscle cell may help to explain why the most efficacious of all known bronchodilatory agencies-a simple deep inspiration-becomes abrogated during the spontaneous asthma attack and leads thereby to excessive airway narrowing. This perspective invites us to think of airway smooth muscle not only biochemically as a nidus of traditional cell signaling and immune modulation or mechanically as a motor for generation of active forces but also physically as a phase of soft condensed matter that can restrict airway stretch and dilation. This is perhaps a risky path and is surely an unconventional one, but it is where the trail of evidence leads. This line of investigation is unlikely by itself to provide an asthma cure but will lead to a new conceptual framework without which novel pathways, unsuspected phase transitions, and unanticipated mechanisms of action of target molecules would almost surely remain hidden. Glassy dynamics of the cytoskeleton are likely to be important in a wide range of biological functions and disease processes, but had it not been for their preeminent role in bronchospasm, they might never have been discovered.
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28
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Abstract
Airway hyperresponsiveness is the excessive narrowing of the airway lumen caused by stimuli that would cause little or no narrowing in the normal individual. It is one of the cardinal features of asthma, but its mechanisms remain unexplained. In asthma, the key end-effector of acute airway narrowing is contraction of the airway smooth muscle cell that is driven by myosin motors exerting their mechanical effects within an integrated cytoskeletal scaffolding. In just the past few years, however, our understanding of the rules that govern muscle biophysics has dramatically changed, as has their classical relationship to airway mechanics. It has become well established, for example, that muscle length is equilibrated dynamically rather than statically, and that in a dynamic setting nonclassical features of muscle biophysics come to the forefront, including unanticipated interactions between the muscle and its time-varying load, as well as the ability of the muscle cell to adapt (remodel) its internal microstructure rapidly in response to its ever-changing mechanical environment. Here, we consider some of these emerging concepts and, in particular, focus on structural remodeling of the airway smooth muscle cell as it relates to excessive airway narrowing in asthma.
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Affiliation(s)
- Steven S An
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Room E-7616, Baltimore, MD 21205, USA.
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29
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Bossé Y, Rola-Pleszczynski M. FGF2 in asthmatic airway-smooth-muscle-cell hyperplasia. Trends Mol Med 2007; 14:3-11. [PMID: 18055262 DOI: 10.1016/j.molmed.2007.11.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 11/09/2007] [Accepted: 11/09/2007] [Indexed: 01/25/2023]
Abstract
Airway smooth muscle (ASM)-cell hyperplasia is a cardinal feature of the remodeled airways in asthma and contributes to airway hyper-responsiveness. Several upregulated mediators are potentially involved in this architectural change. Recently, many investigators have turned their interest toward fibroblast growth factor (FGF)2. This opinion article describes the current knowledge on the biology of this growth factor, reviews the papers that have measured its baseline or allergen-induced expression in human asthmatics and summarizes observations supporting its role as an ASM cell mitogen. The possibility that FGF2 is involved in ASM-cell hyperplasia is raised, not only because it induces ASM-cell proliferation by itself but because of recent findings showing that FGF2 confers to ASM cells the ability to proliferate in response to different asthma mediators.
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Affiliation(s)
- Ynuk Bossé
- Immunology Division, Department of Pediatrics, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada.
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30
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Lenormand G, Bursac P, Butler JP, Fredberg JJ. Out-of-equilibrium dynamics in the cytoskeleton of the living cell. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:041901. [PMID: 17995020 DOI: 10.1103/physreve.76.041901] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Revised: 07/09/2007] [Indexed: 05/05/2023]
Abstract
We report here measurements of rheological properties of the human airway smooth muscle cell using forced nanoscale motions of Arg-Gly-Asp RGD-coated microbeads tightly bound to the cytoskeleton. With changes of forcing amplitude, the storage modulus showed small but systematic nonlinearities, especially after treatment with a contractile agonist. In a dose-dependent manner, a large oscillatory shear applied from a few seconds up to 400 s caused the cytoskeleton matrix to soften, a behavior comparable to physical rejuvenation observed in certain inert soft materials; the stiffness remained constant for as long as the large oscillatory shear was maintained, but suddenly fell with shear cessation. Stiffness then followed a slow scale-free recovery, a phenomenon comparable to physical aging. However, acetylated low-density lipoprotein acLDL-coated microbeads, which connect mainly to scavenger receptors, did not show similar out-of-equilibrium behaviors. Taken together, these data demonstrate in the cytoskeleton of the living cell behaviors with all the same signatures as that of soft inert condensed systems. This unexpected intersection of condensed matter physics and cytoskeletal biology suggests that trapping, intermittency, and approach to kinetic arrest represent central mesoscale features linking underlying molecular events to integrative cellular functions.
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Affiliation(s)
- Guillaume Lenormand
- Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts 02115, USA
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31
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Abstract
Impaired lung development afflicts a range of newborns cared for by paediatric surgeons. As a result the speciality has led in the development of surgical models that illustrate the biomechanical regulation of lung growth. Using transgenic mutants, biologists have similarly discovered much about the biochemical regulation of prenatal lung growth. Airway smooth muscle (ASM) and its prenatal contractility airway peristalsis (AP) represent a novel link between these areas: ASM progenitors produce an essential biochemical factor for lung morphogenesis, whilst calcium-driven biomechanical ASM activity appears to regulate the same. In this invited paper, I take the opportunity both to review our recent findings on lung growth and prenatal ASM, and also to discuss mechanisms by which ASM contractility can regulate growth. Finally, I will introduce some novel ideas for exploration: ASM contractility could help to schedule parturition (pulmonary parturition clock) and could even be a generic model for smooth muscle regulation of morphogenesis in similar organs.
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Affiliation(s)
- Edwin C Jesudason
- Academy of Medical Sciences Clinician Scientist/Consultant Paediatric Surgeon, Alder Hey Children's Hospital, The Division of Child Health, University of Liverpool, Liverpool L12 2AP, UK. .
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33
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An S, Bai T, Bates J, Black J, Brown R, Brusasco V, Chitano P, Deng L, Dowell M, Eidelman D, Fabry B, Fairbank N, Ford L, Fredberg J, Gerthoffer W, Gilbert S, Gosens R, Gunst S, Halayko A, Ingram R, Irvin C, James A, Janssen L, King G, Knight D, Lauzon A, Lakser O, Ludwig M, Lutchen K, Maksym G, Martin J, Mauad T, McParland B, Mijailovich S, Mitchell H, Mitchell R, Mitzner W, Murphy T, Paré P, Pellegrino R, Sanderson M, Schellenberg R, Seow C, Silveira P, Smith P, Solway J, Stephens N, Sterk P, Stewart A, Tang D, Tepper R, Tran T, Wang L. Airway smooth muscle dynamics: a common pathway of airway obstruction in asthma. Eur Respir J 2007; 29:834-60. [PMID: 17470619 PMCID: PMC2527453 DOI: 10.1183/09031936.00112606] [Citation(s) in RCA: 279] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Excessive airway obstruction is the cause of symptoms and abnormal lung function in asthma. As airway smooth muscle (ASM) is the effecter controlling airway calibre, it is suspected that dysfunction of ASM contributes to the pathophysiology of asthma. However, the precise role of ASM in the series of events leading to asthmatic symptoms is not clear. It is not certain whether, in asthma, there is a change in the intrinsic properties of ASM, a change in the structure and mechanical properties of the noncontractile components of the airway wall, or a change in the interdependence of the airway wall with the surrounding lung parenchyma. All these potential changes could result from acute or chronic airway inflammation and associated tissue repair and remodelling. Anti-inflammatory therapy, however, does not "cure" asthma, and airway hyperresponsiveness can persist in asthmatics, even in the absence of airway inflammation. This is perhaps because the therapy does not directly address a fundamental abnormality of asthma, that of exaggerated airway narrowing due to excessive shortening of ASM. In the present study, a central role for airway smooth muscle in the pathogenesis of airway hyperresponsiveness in asthma is explored.
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Affiliation(s)
- S.S. An
- Division of Physiology, Dept of Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health
| | - T.R. Bai
- James Hogg iCAPTURE Centre, University of British Columbia, Vancouver
| | - J.H.T. Bates
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, VT
| | - J.L. Black
- Dept of Pharmacology, University of Sydney, Sydney
| | - R.H. Brown
- Dept of Anesthesiology and Critical Care medicine, Johns Hopkins Medical Institutions, Baltimore, MD
| | - V. Brusasco
- Dept of Internal Medicine, University of Genoa, Genoa
| | - P. Chitano
- Dept of Paediatrics, Duke University Medical Center, Durham, NC
| | - L. Deng
- Program in Molecular and Integrative Physiological Sciences, Dept of Environmental Health, Harvard School of Public Health
- Bioengineering College, Chongqing University, Chongqing, China
| | - M. Dowell
- Section of Pulmonary and Critical Care Medicine
| | - D.H. Eidelman
- Meakins-Christie Laboratories, Dept of Medicine, McGill University, Montreal
| | - B. Fabry
- Center for Medical Physics and Technology, Erlangen, Germany
| | - N.J. Fairbank
- School of Biomedical Engineering, Dalhousie University, Halifax
| | | | - J.J. Fredberg
- Program in Molecular and Integrative Physiological Sciences, Dept of Environmental Health, Harvard School of Public Health
| | - W.T. Gerthoffer
- Dept of Pharmacology, University of Nevada School of Medicine, Reno, NV
| | | | - R. Gosens
- Dept of Physiology, University of Manitoba, Winnipeg
| | - S.J. Gunst
- Dept of Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - A.J. Halayko
- Dept of Physiology, University of Manitoba, Winnipeg
| | - R.H. Ingram
- Dept of Medicine, Emory University School of Medicine, Atlanta, GA
| | - C.G. Irvin
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, VT
| | - A.L. James
- West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands
| | - L.J. Janssen
- Dept of Medicine, McMaster University, Hamilton, Canada
| | - G.G. King
- Woolcock Institute of Medical Research, Camperdown
| | - D.A. Knight
- James Hogg iCAPTURE Centre, University of British Columbia, Vancouver
| | - A.M. Lauzon
- Meakins-Christie Laboratories, Dept of Medicine, McGill University, Montreal
| | - O.J. Lakser
- Section of Paediatric Pulmonary Medicine, University of Chicago, Chicago, IL
| | - M.S. Ludwig
- Meakins-Christie Laboratories, Dept of Medicine, McGill University, Montreal
| | - K.R. Lutchen
- Dept of Biomedical Engineering, Boston University, Boston
| | - G.N. Maksym
- School of Biomedical Engineering, Dalhousie University, Halifax
| | - J.G. Martin
- Meakins-Christie Laboratories, Dept of Medicine, McGill University, Montreal
| | - T. Mauad
- Dept of Pathology, Sao Paulo University Medical School, Sao Paulo, Brazil
| | | | - S.M. Mijailovich
- Program in Molecular and Integrative Physiological Sciences, Dept of Environmental Health, Harvard School of Public Health
| | - H.W. Mitchell
- Discipline of Physiology, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, Perth
| | | | - W. Mitzner
- Division of Physiology, Dept of Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health
| | - T.M. Murphy
- Dept of Paediatrics, Duke University Medical Center, Durham, NC
| | - P.D. Paré
- James Hogg iCAPTURE Centre, University of British Columbia, Vancouver
| | - R. Pellegrino
- Dept of Respiratory Physiopathology, S. Croce e Carle Hospital, Cuneo, Italy
| | - M.J. Sanderson
- Dept of Physiology, University of Massachusetts Medical School, Worcester, MA
| | - R.R. Schellenberg
- James Hogg iCAPTURE Centre, University of British Columbia, Vancouver
| | - C.Y. Seow
- James Hogg iCAPTURE Centre, University of British Columbia, Vancouver
| | - P.S.P. Silveira
- Dept of Pathology, Sao Paulo University Medical School, Sao Paulo, Brazil
| | - P.G. Smith
- Dept of Paediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - J. Solway
- Section of Pulmonary and Critical Care Medicine
| | - N.L. Stephens
- Dept of Physiology, University of Manitoba, Winnipeg
| | - P.J. Sterk
- Dept of Pulmonology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - A.G. Stewart
- Dept of Pharmacology, University of Melbourne, Parkville, Australia
| | - D.D. Tang
- Center for Cardiovascular Sciences, Albany Medical College, Albany, NY, USA
| | - R.S. Tepper
- Dept of Paediatrics, Indiana University School of Medicine, Indianapolis, IN
| | - T. Tran
- Dept of Physiology, University of Manitoba, Winnipeg
| | - L. Wang
- Dept of Paediatrics, Duke University Medical Center, Durham, NC
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Abstract
In this review we discuss the potential of a new procedure, termed Bronchial Thermoplasty to prevent serious consequences resulting from excessive airway narrowing. The most important factor in minimizing an asthmatic attack is limiting the degree of smooth muscle shortening. The premise that airway smooth muscle can be either inactivated or obliterated without any long-term alteration of other lung tissues, and that airway function will remain normal, albeit with reduced bronchoconstriction, has now been demonstrated in dogs, a subset of normal subjects, and mild asthmatics. Bronchial Thermoplasty may thus develop into a useful clinical procedure to effectively impair the ability for airway smooth muscle to reach the levels of pathologic narrowing that characterizes an asthma attack. It may also enable more successful treatment of asthma patients who are unresponsive to more conventional therapies. Whether this will remain stable for the lifetime of the patient still remains to be determined, but at the present time, there are no indications that the smooth muscle contractility will return. This successful preliminary experience showing that Bronchial Thermoplasty could be safely performed in patients with asthma has led to an ongoing clinical trial at a number of sites in Europe and North America designed to examine the effectiveness of this procedure in subjects with moderately severe asthma.
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Affiliation(s)
- Wayne Mitzner
- Department of Environmental Health Sciences, Johns Hopkins University, MD 21204, USA.
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37
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Gil FR, Zitouni NB, Azoulay E, Maghni K, Lauzon AM. Smooth muscle myosin isoform expression and LC20 phosphorylation in innate rat airway hyperresponsiveness. Am J Physiol Lung Cell Mol Physiol 2006; 291:L932-40. [PMID: 16766577 DOI: 10.1152/ajplung.00339.2004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Four smooth muscle myosin heavy chain (SMMHC) isoforms are generated by alternative mRNA splicing of a single gene. Two of these isoforms differ by the presence [(+)insert] or absence [(-)insert] of a 7-amino acid insert in the motor domain. The rate of actin filament propulsion of the (+)insert SMMHC isoform, as measured in the in vitro motility assay, is twofold greater than that of the (-)insert isoform. We hypothesized that a greater expression of the (+)insert SMMHC isoform and greater regulatory light chain (LC(20)) phosphorylation contribute to airway hyperresponsiveness. We measured airway responsiveness to methacholine in Fischer hyperresponsive and Lewis normoresponsive rats and determined SMMHC isoform mRNA and protein expression, as well as essential light chain (LC(17)) isoforms, h-caldesmon, and alpha-actin protein expression in their tracheae. We also measured tracheal muscle strip contractility in response to methacholine and corresponding LC(20) phosphorylation. We found Fischer rats have more (+)insert mRNA (69.4 +/- 2.0%) (mean +/- SE) than Lewis rats (53.0 +/- 2.4%; P < 0.05) and a 44% greater content of (+)insert isoform relative to total myosin protein. No difference was found for LC(17) isoform, h-caldesmon, and alpha-actin expression. The contractility experiments revealed a greater isometric force for Fischer trachealis segments (4.2 +/- 0.8 mN) than Lewis (1.9 +/- 0.4 mN; P < 0.05) and greater LC(20) phosphorylation level in Fischer (55.1 +/- 6.4) than in Lewis (41.4 +/- 6.1; P < 0.05) rats. These results further support the contention that innate airway hyperresponsiveness is a multifactorial disorder in which increased expression of the fast (+)insert SMMHC isoform and greater activation of LC(20) lead to smooth muscle hypercontractility.
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Affiliation(s)
- Fulvio R Gil
- Meakins-Christie Laboratories, Department of Medicine, McGill University, 3626 St-Urbain St., Montréal, Québec, Canada H2X 2P2
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38
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Abstract
Gas exchange, the primary function of the lung, can come about only with the application of physical forces on the macroscale and their transmission to the scale of small airway, small blood vessel, and alveolus, where they serve to distend and stabilize structures that would otherwise collapse. The pathway for force transmission then continues down to the level of cell, nucleus, and molecule; moreover, to lesser or greater degrees most cell types that are resident in the lung have the ability to generate contractile forces. At these smallest scales, physical forces serve to distend the cytoskeleton, drive cytoskeletal remodeling, expose cryptic binding domains, and ultimately modulate reaction rates and gene expression. Importantly, evidence has now accumulated suggesting that multiscale phenomena span these scales and govern integrative lung behavior.
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Affiliation(s)
- Jeffrey J Fredberg
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
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39
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Kim N, Vu TH. Parabronchial smooth muscle cells and alveolar myofibroblasts in lung development. ACTA ACUST UNITED AC 2006; 78:80-9. [PMID: 16622850 DOI: 10.1002/bdrc.20062] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Epithelial-mesenchymal interactions and extracellular matrix remodeling are key processes of embryonic lung development. Lung smooth muscle cells, which are derived from the mesenchyme, form a sheath around bronchi and blood vessels. During lung organogenesis, smooth muscle differentiation coincides with epithelial branching morphogenesis and closely follows developing airways spatially and temporally. The precise function of parabronchial smooth muscle (PBSM) cells in healthy adult lung remains unclear. However, PBSM may regulate epithelial branching morphogenesis during lung development by the induction of mechanical stress or through regulation of paracrine signaling pathways. Alveolar myofibroblasts are interstitial contractile cells that share features and may share an origin with smooth muscle cells. Alveolar myofibroblasts are essential for secondary septation, a process critical for the development of the gas-exchange region of the lung. Dysregulation of PBSM or alveolar myofibroblast development is thought to underlie the pathogenesis of many lung diseases, including bronchopulmonary dysplasia, asthma, and interstitial fibrosis. We review the current understanding of the regulation of PBSM and alveolar myofibroblast development, and discuss the role of PBSM in lung development. We specifically focus on the role of these cells in the context of fibroblast growth factor-10, sonic hedgehog, bone morphogenetic protein-4, retinoic acid, and Wnt signaling pathways in the regulation of lung branching morphogenesis.
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Affiliation(s)
- Namjin Kim
- Department of Medicine and Lung Biology Center, University of California, San Francisco, California 94143-2911, USA
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40
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Jesudason EC, Smith NP, Connell MG, Spiller DG, White MRH, Fernig DG, Losty PD. Peristalsis of airway smooth muscle is developmentally regulated and uncoupled from hypoplastic lung growth. Am J Physiol Lung Cell Mol Physiol 2006; 291:L559-65. [PMID: 16603591 DOI: 10.1152/ajplung.00498.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Prenatal airway smooth muscle (ASM) peristalsis appears coupled to lung growth. Moreover, ASM progenitors produce fibroblast growth factor-10 (FGF-10) for lung morphogenesis. Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia, FGF-10 deficiency, and postnatal ASM dysfunction. We hypothesized ASM dysfunction emerges in tandem with, and may contribute toward, the primordial lung hypoplasia that precedes experimental CDH. Spatial origin and frequency of ASM peristaltic waves were measured in normal and hypoplastic rat lungs cultured from day 13.5 of gestation (lung hypoplasia was generated by nitrofen dosing of pregnant dams). Longitudinal lung growth was assayed by bud counts and tracing photomicrographs of cultures. Coupling of lung growth and peristalsis was tested by stimulation studies using serum, FGF-10, or nicotine and inhibition studies with nifedipine or U0126 (MEK1/2 inhibitor). In normal lung, ASM peristalsis is developmentally regulated: proximal ASM becomes quiescent (while retaining capacity for cholinergic-stimulated peristalsis). However, in hypoplastic lung, spontaneous proximal ASM activity persists. FGF-10 corrects this aberrant ASM activity in tandem with improved growth. Stimulation and inhibition studies showed that, unlike normal lung, changes in growth or peristalsis are not consistently accompanied by parallel modulation of the other. ASM peristalsis undergoes FGF-10-regulated spatiotemporal development coupled to lung growth: this process is disrupted early in lung hypoplasia. ASM dysfunction emerges in tandem with and may therefore contribute toward lung hypoplasia in CDH.
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Affiliation(s)
- E C Jesudason
- Division of Child Health, Centre for Cell Imaging, The Molecular Medicine Group, University of Liverpool, Institute of Child Health, Alder Hey Children's Hospital, Eaton Road, Liverpool, United Kingdom.
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41
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Silveira PSP, Butler JP, Fredberg JJ. Length adaptation of airway smooth muscle: a stochastic model of cytoskeletal dynamics. J Appl Physiol (1985) 2005; 99:2087-98. [PMID: 16081628 DOI: 10.1152/japplphysiol.00159.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
To account for cytoskeleton remodeling as well as smooth muscle length adaptation, here we represent the cytoskeleton as a two-dimensional network of links (contractile filaments or stress fibers) that connect nodes (dense plaques or focal adhesions). The network evolves in continuous turnover with probabilities of link formation and dissolution. The probability of link formation increases with the available fraction of contractile units, increases with the degree of network activation, and decreases with increasing distance between nodes, d, as 1/d(s), where s controls the distribution of link lengths. The probability of link dissolution decays with time to mimic progressive cytoskeleton stabilization. We computed network force (F) as the vector summation of link forces exerted at all nodes, unloaded shortening velocity (V) as being proportional to the average link length, and network compliance (C) as the change in network length per change in elastic force. Imposed deformation caused F to decrease transiently and then recover dynamically; recovery ability decreased with increasing time after activation, mimicking observed biological behavior. Isometric contractions showed small sensitivity of F to network length, thus maintaining high force over a wide range of lengths; V and C increased with increasing length. In these behaviors, link length regulation, as described by the parameter s, was found to be crucial. Concerning length adaptation, all phenomena reported thus far in the literature were captured by this extremely simple network model.
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Affiliation(s)
- Paulo S P Silveira
- Harvard School of Public Health, Department of Environmental Health, Boston, MA 02115, USA.
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42
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McParland BE, Tait RR, Paré PD, Seow CY. The role of airway smooth muscle during an attack of asthma simulated in vitro. Am J Respir Cell Mol Biol 2005; 33:500-4. [PMID: 16055669 DOI: 10.1165/rcmb.2005-0183oc] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Excessive narrowing of airways in response to contractile agonists is a characteristic feature of asthma. We hypothesized that airway smooth muscle (ASM) adaptation to short lengths could contribute to exaggerated airway narrowing during an acute attack of asthma by allowing the muscle to regain its ability to generate maximal force at a shortened length. To test this hypothesis we mimicked, in vitro, the sequence of contractile events that would occur during a spontaneous attack of asthma. Trachealis muscle was challenged with carbachol (300 nM, submaximal dose) and allowed to shorten to approximately half of its original length. After 30 min of adaptation at the shortened length in the presence of carbachol, muscle force, amount and rate of shortening in response to electrical stimulation were compared with corresponding values obtained from control experiments during which the ASM was not adapted to the short length. After adaptation at the shortened length the developed force, amount and rate of shortening increased by 1.93 +/- 0.08-, 1.57 +/- 0.12-, and 1.75 +/- 0.2-fold, respectively. Shortening of ASM in response to contractile agonists can lead to adaptation of the muscle to the shortened length that, in turn, can result in further shortening and the potential for airway closure.
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Affiliation(s)
- Brent E McParland
- Department of Medicine, James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research, St. Paul's Hospital/Providence Health Care, University of British Columbia, Vancouver, British Columbia, Canada
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43
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Kim JH, Jain D, Tliba O, Yang B, Jester WF, Panettieri RA, Amrani Y, Puré E. TGF-beta potentiates airway smooth muscle responsiveness to bradykinin. Am J Physiol Lung Cell Mol Physiol 2005; 289:L511-20. [PMID: 15923209 DOI: 10.1152/ajplung.00027.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The molecular mechanisms by which bradykinin induces excessive airway obstruction in asthmatics remain unknown. Transforming growth factor (TGF)-beta has been involved in regulating airway inflammation and remodeling in asthma, although it is unknown whether TGF-beta can modulate bradykinin-associated bronchial hyperresponsiveness. To test whether TGF-beta directly modulates airway smooth muscle (ASM) responsiveness to bradykinin, isolated murine tracheal rings were used to assess whether TGF-beta alters ASM contractile responsiveness to bradykinin. Interestingly, we found TGF-beta-treated murine rings (12.5 ng/ml, 18 h) exhibited increased expression of bradykinin 2 (B(2)) receptors and became hyperreactive to bradykinin, as shown by increases in maximal contractile responses and receptor distribution. We investigated the effect of TGF-beta on bradykinin-evoked calcium signals since calcium is a key molecule regulating ASM excitation-contraction coupling. We reported that TGF-beta, in a dose- (0.5-10 ng/ml) and time- (2-24 h) dependent manner, increased mRNA and protein expression of the B(2) receptor in cultured human ASM cells. Maximal B(2) receptor protein expression that colocalized with CD44, a marker of membrane cell surface, occurred after 18 h of TGF-beta treatment and was further confirmed using fluorescence microscopy. TGF-beta (2.5 ng/ml, 18 h) also increased bradykinin-induced intracellular calcium mobilization in fura-2-loaded ASM cells. TGF-beta-mediated enhancement of calcium mobilization was not attenuated with indomethacin, a cyclooxygenase inhibitor. These data demonstrate for the first time that TGF-beta may play a role in mediating airway hyperresponsiveness to bradykinin seen in asthmatics by enhancing ASM contractile responsiveness to bradykinin, possibly as a result of increased B(2) receptor expression and signaling.
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MESH Headings
- Animals
- Anti-Inflammatory Agents, Non-Steroidal/pharmacology
- Bradykinin/pharmacology
- Calcium/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Cells, Cultured
- Drug Synergism
- In Vitro Techniques
- Indomethacin/pharmacology
- Isometric Contraction/drug effects
- Isometric Contraction/physiology
- Lung/drug effects
- Lung/physiology
- Mice
- Mice, Inbred BALB C
- Muscle, Smooth/cytology
- Muscle, Smooth/drug effects
- Muscle, Smooth/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Receptor, Bradykinin B2/metabolism
- Respiratory Hypersensitivity/physiopathology
- Transforming Growth Factor beta/pharmacology
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Affiliation(s)
- Jenny H Kim
- Pulmonary, Allergy, and Critical Care Division, Dept. of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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44
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Ong HL, Barritt GJ. Transient receptor potential and other ion channels as pharmaceutical targets in airway smooth muscle cells. Respirology 2005; 9:448-57. [PMID: 15612955 DOI: 10.1111/j.1440-1843.2004.00651.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Regardless of the triggering stimulus in asthma, contraction of the airway smooth muscle (ASM) is considered to be an important pathway leading to the manifestation of asthmatic symptoms. Therefore, the various ion channels that modulate ASM contraction and relaxation are particularly attractive targets for therapy. Although voltage-operated Ca2+ channels (VOCC) are the most extensively characterised Ca(2+)-permeable channels in ASM cells and are obvious pharmacological targets, blockers of VOCC have not been successful in alleviating ASM contraction in asthma. Similarly, although the Cl- and K+ channels also modulate ASM contraction and relaxation by regulating plasma membrane potential, pharmacological interventions directed against these channels have failed to abrogate ASM contraction in asthma. A large body of evidence suggests that store-operated Ca2+ channels (SOCC) and Ca(2+)-permeable second messenger-activated non-selective cation channels (NSCC) predominantly mediate ASM contraction. However, development of pharmacological interventions involving these channels has been hampered by the paucity of information regarding their molecular identity. Members of the mammalian transient receptor potential (TRP) protein family, which form voltage-independent channels with variable Ca2+ selectivity that are activated by store depletion and/or by intracellular messengers, are potential molecular candidates for SOCC and NSCC in ASM cells. While the function of TRP channels in ASM cells remains to be elucidated and there are, at present, essentially no good TRP channel antagonists, this group of proteins is a potentially valuable pharmaceutical target for the treatment of asthma.
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Affiliation(s)
- Hwei L Ong
- Department of Medical Biochemistry, School of Medicine, Flinders University, Adelaide, South Australia, Australia
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45
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Fernandes DJ, McConville JF, Stewart AG, Kalinichenko V, Solway J. Can we differentiate between airway and vascular smooth muscle? Clin Exp Pharmacol Physiol 2005; 31:805-10. [PMID: 15566398 DOI: 10.1111/j.1440-1681.2004.04084.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1. Airway smooth muscle (ASM) has recently been termed the 'frustrated' cell of the lung given that contraction of ASM has no proven useful physiological function in adults and yet is indelibly associated with pathological conditions by virtue of its unwanted airflow-limiting actions in asthma. In contrast, pulmonary vascular smooth muscle contraction plays an essential role in the control of blood flow through the lung. 2. Little is known of the differences in phenotype between human ASM and pulmonary vascular smooth muscle (VSM) tissues, but differences in contractile protein and transcription factor expression and regulation of contractile protein promoter activity have been documented. Similarly, the embryological signals in mice required for differentiation of ASM versus pulmonary VSM are distinct. 3. Bronchoconstriction in asthma is currently treated with beta2-adrenoceptor agonists, which relax contracted ASM cells. An additional approach may be to use gene therapy to render ASM unable to contract (via disruption of their contractile apparatus organization). 4. Application of ASM-specific gene therapies would rely on minimal actions on other lung smooth muscle tissues, including pulmonary and bronchial vascular smooth muscle. The combination of mRNA analysis of laser-captured microdissected tissue with in situ immunohistochemical staining for protein should be very useful in terms of being able to characterize definitively the differences in mRNA and protein expression between the smooth muscle species of the lung. Any discovery of an ASM-selective target could provide a novel lead for ASM-directed anti-asthma therapy.
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Affiliation(s)
- Darren J Fernandes
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia.
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46
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Sylvester JT. The tone of pulmonary smooth muscle: ROK and Rho music? Am J Physiol Lung Cell Mol Physiol 2004; 287:L624-30. [PMID: 15355859 DOI: 10.1152/ajplung.00215.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- J T Sylvester
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
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47
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Affiliation(s)
- Wayne Mitzner
- Department of Enviromental Health Sciences, Division of Physiology, Johns Hopkins University, Baltimore, MD 21205, USA.
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48
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Fredberg JJ. Bronchospasm and its biophysical basis in airway smooth muscle. Respir Res 2004; 5:2. [PMID: 15084229 PMCID: PMC387531 DOI: 10.1186/1465-9921-5-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2003] [Accepted: 02/26/2004] [Indexed: 11/10/2022] Open
Abstract
Airways hyperresponsiveness is a cardinal feature of asthma but remains unexplained. In asthma, the airway smooth muscle cell is the key end-effector of bronchospasm and acute airway narrowing, but in just the past five years our understanding of the relationship of responsiveness to muscle biophysics has dramatically changed. It has become well established, for example, that muscle length is equilibrated dynamically rather than statically, and that non-classical features of muscle biophysics come to the forefront, including unanticipated interactions between the muscle and its time-varying load, as well as the ability of the muscle cell to adapt rapidly to changes in its dynamic microenvironment. These newly discovered phenomena have been described empirically, but a mechanistic basis to explain them is only beginning to emerge.
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Affiliation(s)
- Jeffrey J Fredberg
- Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA.
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49
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Lambert RK, Paré PD, Seow CY. Mathematical description of geometric and kinematic aspects of smooth muscle plasticity and some related morphometrics. J Appl Physiol (1985) 2004; 96:469-76. [PMID: 14506098 DOI: 10.1152/japplphysiol.00736.2003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite considerable investigation, the mechanisms underlying the functional properties of smooth muscle are poorly understood. This can be attributed, at least in part, to a lack of knowledge about the structure and organization of the contractile apparatus inside the muscle cell. Recent observations of the plasticity of smooth muscle and of morphometry of the cell have provided enough information for us to propose a quantitative, although highly simplified, model for the geometric arrangement of contractile units and their collective kinematic functions in smooth muscle, particularly airway smooth muscle. We propose that, to a considerable extent, contractile machinery restructures upon activation of the muscle and adapts to cell geometry at the time of activation. We assume that, under steady-state conditions, the geometric arrangement of contractile units and the filaments within these units determines the kinematic characteristics of the muscle. The model successfully predicts the results of experiments on airway smooth muscle plasticity relating to maximal force generation, maximal velocity of shortening, and the variation of compliance with adapted length. The model is also concordant with morphometric observations that show an increase in myosin filament density when muscle is adapted to a longer length. The model provides a framework for design of experiments to quantitatively test various aspects of smooth muscle plasticity in terms of geometric arrangement of contractile units and the muscle's mechanical properties.
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Affiliation(s)
- R K Lambert
- Institute of Fundamental Sciences-Physics, Massey University, Palmerston North, New Zealand
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50
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An SS, Fabry B, Mellema M, Bursac P, Gerthoffer WT, Kayyali US, Gaestel M, Shore SA, Fredberg JJ. Role of heat shock protein 27 in cytoskeletal remodeling of the airway smooth muscle cell. J Appl Physiol (1985) 2004; 96:1701-13. [PMID: 14729728 DOI: 10.1152/japplphysiol.01129.2003] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Remodeling of the airway smooth muscle (ASM) cell has been proposed to play an important role in airway hyperresponsiveness. Using a functional assay, we have assessed remodeling of the cultured rat ASM cell and the role of heat shock protein (HSP) 27 in that process. To probe remodeling dynamics, we measured spontaneous motions of an individual Arg-Gly-Asp-coated microbead that was anchored to the cytoskeleton. We reasoned that the bead could not move unless the microstructure to which it is attached rearranged; if so, then its mean square displacement (MSD) would report ongoing internal reorganizations over time. Each bead displayed a random, superdiffusive motion; MSD increased with time as approximately t(1.7), whereas an exponent of unity would be expected for a simple passive diffusion. Increasing concentrations of cytochalasin-D or latrunculin-A caused marked increases in the MSD, whereas colchicine did not. Treatments with PDGF or IL-1beta, but not transforming growth factor-beta, caused decreases in the MSD, the extent of which rank-ordered with the relative potency of these agents in eliciting the phosphorylation of HSP27. The chemical stressors anisomycin and arsenite each increased the levels of HSP27 phosphorylation and, at the same time, decreased bead motions. In particular, arsenite prevented and even reversed the effects of cytochalasin-D on bead motions. Finally, ASM cells overexpressing phospho-mimicking human HSP27, but not wild-type or phosphorylation-deficient HSP27, exhibited decreases in bead motions that were comparable to the arsenite response. Taken together, these results show that phosphorylated HSP27 favors reduced bead motions that are probably due to stabilization of the actin cytoskeleton.
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Affiliation(s)
- Steven S An
- Physiology Program, Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115.
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