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Henry C, Biardel S, Boucher M, Godbout K, Chakir J, Côté A, Laviolette M, Bossé Y. Bronchial thermoplasty attenuates bronchodilator responsiveness. Respir Med 2023; 217:107340. [PMID: 37422022 DOI: 10.1016/j.rmed.2023.107340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/31/2023] [Accepted: 06/25/2023] [Indexed: 07/10/2023]
Abstract
INTRODUCTION Bronchial thermoplasty is an effective intervention to improve respiratory symptoms and to reduce the rate of exacerbations in uncontrolled severe asthma. A reduction in airway smooth muscle is arguably the most widely discussed mechanisms accounting for these clinical benefits. Yet, this smooth muscle reduction should also translate into an impaired response to bronchodilator drugs. This study was designed to address this question. METHODS Eight patients with clinical indication for thermoplasty were studied. They were uncontrolled severe asthmatics despite optimal environmental control, treatment of comorbidities, and the use of high-dose inhaled corticosteroids and long-acting β2-agonists. Lung function measured by spirometry and respiratory mechanics measured by oscillometry were examined pre- and post-bronchodilator (salbutamol, 400 μg), both before and at least 1 year after thermoplasty. RESULTS Consistent with previous studies, thermoplasty yielded no benefits in terms of baseline lung function and respiratory mechanics, despite improving symptoms based on two asthma questionnaires (ACQ-5 and ACT-5). The response to salbutamol was also not affected by thermoplasty based on spirometric readouts, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio. However, a significant interaction was observed between thermoplasty and salbutamol for two oscillometric readouts, namely reactance at 5 Hz (Xrs5) and reactance area (Ax), showing an attenuated response to salbutamol after thermoplasty. CONCLUSIONS Thermoplasty attenuates the response to a bronchodilator. We argue that this result is a physiological proof of therapeutic efficacy, consistent with the well-described effect of thermoplasty in reducing the amount of airway smooth muscle.
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Affiliation(s)
- Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Sabrina Biardel
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Krystelle Godbout
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Jamila Chakir
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Andréanne Côté
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Michel Laviolette
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada.
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Henry C, Boucher M, Boulay MÈ, Côté A, Boulet LP, Bossé Y. The cumulative effect of methacholine on large and small airways when deep inspirations are avoided. Respirology 2023; 28:226-235. [PMID: 36210352 DOI: 10.1111/resp.14387] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 09/20/2022] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND OBJECTIVE The effect of serial incremental concentrations of methacholine is only slightly cumulative when assessed by spirometry. This limited cumulative effect may be attributed to the bronchodilator effect of deep inspirations that are required between concentrations to measure lung function. Using oscillometry, the response to methacholine can be measured without deep inspirations. Conveniently, oscillometry can also dissociate the contribution of large versus small airways. Herein, oscillometry was used to assess the cumulative effect of methacholine in the absence of deep inspirations on large and small airways. METHODS Healthy and asthmatic volunteers underwent a multiple-concentration methacholine challenge on visit 1 and a single-concentration challenge on visit 2 using the highest concentration of visit 1. The maximal response was compared between visits to assess the cumulative effect of methacholine. The lung volume was also measured after the final concentration to assess hyperinflation. RESULTS In both healthy and asthmatic subjects, increases in resistance at 19 Hz (Rrs19 ), reflecting large airway narrowing, did not differ between the multiple- and the single-concentration challenge. However, increases in resistance at 5 Hz (Rrs5 ) minus Rrs19 , reflecting small airway narrowing, were 117 and 270% greater in the multiple- than the single-concentration challenge in healthy (p = 0.006) and asthmatic (p < 0.0001) subjects, respectively. Hyperinflation occurred with both challenges and was greater in the multiple- than the single-concentration challenge in both groups. CONCLUSION Without deep inspirations, the effect of methacholine is cumulative on small airways but not on large airways. Lung hyperinflation and derecruitment may partially explain these different responses.
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Affiliation(s)
- Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
| | - Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
| | - Marie-Ève Boulay
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
| | - Andréanne Côté
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
| | | | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
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Boucher M, Henry C, Bossé Y. Force adaptation through the intravenous route in naïve mice. Exp Lung Res 2023; 49:131-141. [PMID: 37477352 DOI: 10.1080/01902148.2023.2237127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/15/2023] [Accepted: 07/11/2023] [Indexed: 07/22/2023]
Abstract
Aim of the study: Force adaptation is a process whereby the contractile capacity of the airway smooth muscle increases during a sustained contraction (aka tone). Tone also increases the response to a nebulized challenge with methacholine in vivo, presumably through force adaptation. Yet, due to its patchy pattern of deposition, nebulized methacholine often spurs small airway narrowing heterogeneity and closure, two important enhancers of the methacholine response. This raises the possibility that the potentiating effect of tone on the methacholine response is not due to force adaptation but by furthering heterogeneity and closure. Herein, methacholine was delivered homogenously through the intravenous (i.v.) route. Materials and Methods: Female and male BALB/c mice were subjected to one of two i.v. methacholine challenges, each of the same cumulative dose but starting by a 20-min period either with or without tone induced by serial i.v. boluses. Changes in respiratory mechanics were monitored throughout by oscillometry, and the response after the final dose was compared between the two challenges to assess the effect of tone. Results: For the elastance of the respiratory system (Ers), tone potentiated the methacholine response by 64 and 405% in females (37.4 ± 10.7 vs. 61.5 ± 15.1 cmH2O/mL; p = 0.01) and males (33.0 ± 14.3 vs. 166.7 ± 60.6 cmH2O/mL; p = 0.0004), respectively. For the resistance of the respiratory system (Rrs), tone potentiated the methacholine response by 129 and 225% in females (9.7 ± 3.5 vs. 22.2 ± 4.3 cmH2O·s/mL; p = 0.0003) and males (10.7 ± 3.1 vs. 34.7 ± 7.9 cmH2O·s/mL; p < 0.0001), respectively. Conclusions: As previously reported with nebulized challenges, tone increases the response to i.v. methacholine in both sexes; albeit sexual dimorphisms were obvious regarding the relative resistive versus elastic nature of this potentiation. This represents further support that tone increases the lung response to methacholine through force adaptation.
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Affiliation(s)
- Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
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4
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Boucher M, Dufour-Mailhot A, Tremblay-Pitre S, Khadangi F, Rojas-Ruiz A, Henry C, Bossé Y. In mice of both sexes, repeated contractions of smooth muscle in vivo greatly enhance the response of peripheral airways to methacholine. Respir Physiol Neurobiol 2022; 304:103938. [PMID: 35716869 DOI: 10.1016/j.resp.2022.103938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/10/2022] [Accepted: 06/12/2022] [Indexed: 10/18/2022]
Abstract
BALB/c mice from both sexes underwent one of two nebulized methacholine challenges that were preceded by a period of 20 min either with or without tone induced by repeated contractions of the airway smooth muscle. Impedance was monitored throughout and the constant phase model was used to dissociate the impact of tone on conducting airways (RN - Newtonian resistance) versus the lung periphery (G and H - tissue resistance and elastance). The effect of tone on smooth muscle contractility was also tested on excised tracheas. While tone markedly potentiated the methacholine-induced gains in H and G in both sexes, the gain in RN was only potentiated in males. The contractility of female and male tracheas was also potentiated by tone. Inversely, the methacholine-induced gain in hysteresivity (G/H) was mitigated by tone in both sexes. Therefore, the tone-induced muscle hypercontractility impacts predominantly the lung periphery in vivo, but also promotes further airway narrowing in males while protecting against narrowing heterogeneity in both sexes.
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Affiliation(s)
- Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada
| | - Alexis Dufour-Mailhot
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada
| | - Sophie Tremblay-Pitre
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada
| | - Fatemeh Khadangi
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada
| | - Andrés Rojas-Ruiz
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec - Université Laval, Québec, Canada.
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5
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Papi A, Fabbri LM, Kerstjens HAM, Rogliani P, Watz H, Singh D. Inhaled long-acting muscarinic antagonists in asthma - A narrative review. Eur J Intern Med 2021; 85:14-22. [PMID: 33563506 DOI: 10.1016/j.ejim.2021.01.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 01/20/2021] [Accepted: 01/24/2021] [Indexed: 12/13/2022]
Abstract
Long-acting muscarinic antagonists (LAMAs) have a recognised role in the management of chronic obstructive pulmonary disease. In asthma, muscarinic antagonists (both short- and long-acting) were historically considered less effective than β2-agonists; only relatively recently have studies been conducted to evaluate the efficacy of LAMAs, as add-on to either inhaled corticosteroid (ICS) monotherapy or ICS/long-acting β2-agonist (LABA) combinations. These studies led to the approval of the first LAMA, tiotropium, as an add-on therapy in patients with poorly controlled asthma. Subsequently, a number of single-inhaler ICS/LABA/LAMA triple therapies have been approved or are in clinical development for the management of asthma. There is now substantial evidence of the efficacy and safety of LAMAs in asthma that is uncontrolled despite treatment with an ICS/LABA combination. This regimen is recommended by GINA as an optimisation step for patients with severe asthma before any biologic or systemic corticosteroid treatment is initiated. This narrative review summarises the potential mechanisms of action of LAMAs in asthma, together with the initial clinical evidence supporting this use. We also discuss the studies that led to the approval of tiotropium for asthma and the data evaluating the efficacy and safety of the various triple therapies, before considering other potential uses for triple therapy.
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Affiliation(s)
- Alberto Papi
- Respiratory Medicine Unit, University of Ferrara, University Hospital S.Anna, Ferrara, Italy.
| | - Leonardo M Fabbri
- Section of Respiratory Medicine, Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Huib A M Kerstjens
- University of Groningen, University Medical Center Groningen, and Groningen Research Institute for Asthma and COPD, Groningen, The Netherlands
| | - Paola Rogliani
- Unit of Respiratory Medicine, Department of Experimental Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Henrik Watz
- Pulmonary Research Institute at Lung Clinic Grosshansdorf, Airway Research Center North (ARCN), German Center for Lung Research (DZL), Grosshansdorf, Germany
| | - Dave Singh
- Medicines Evaluation Unit, The University of Manchester, Manchester University NHS Foundation Trust, Manchester, UK
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6
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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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7
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Abstract
This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.
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Affiliation(s)
- David A Kaminsky
- University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - David G Chapman
- University of Technology Sydney, Sydney, New South Wales, Australia
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8
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Gazzola M, Henry C, Lortie K, Khadangi F, Park CY, Fredberg JJ, Bossé Y. Airway smooth muscle tone increases actin filamentogenesis and contractile capacity. Am J Physiol Lung Cell Mol Physiol 2020; 318:L442-L451. [PMID: 31850799 DOI: 10.1152/ajplung.00205.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Force adaptation of airway smooth muscle (ASM) is a process whereby the presence of tone (i.e., a sustained contraction) increases the contractile capacity. For example, tone has been shown to increase airway responsiveness in both healthy mice and humans. The goal of the present study is to elucidate the underlying molecular mechanisms. The maximal force generated by mouse tracheas was measured in response to 10-4 M of methacholine following a 30-min period with or without tone elicited by the EC30 of methacholine. To confirm the occurrence of force adaptation at the cellular level, traction force generated by cultured human ASM cells was also measured following a similar protocol. Different pharmacological inhibitors were used to investigate the role of Rho-associated coiled-coil containing protein kinase (ROCK), protein kinase C (PKC), myosin light chain kinase (MLCK), and actin polymerization in force adaptation. The phosphorylation level of the regulatory light chain (RLC) of myosin, the amount of actin filaments, and the activation level of the actin-severing protein cofilin were also quantified. Although ROCK, PKC, MLCK, and RLC phosphorylation was not implicated, force adaptation was prevented by inhibiting actin polymerization. Interestingly, the presence of tone blocked the activation of cofilin in addition to increasing the amount of actin filaments to a maximal level. We conclude that actin filamentogenesis induced by tone, resulting from both actin polymerization and the prevention of cofilin-mediated actin cleavage, is the main molecular mechanism underlying force adaptation.
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Affiliation(s)
- Morgan Gazzola
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| | - Katherine Lortie
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| | - Fatemeh Khadangi
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| | - Chan Young Park
- Harvard School of Public Health, Harvard University, Boston, Massachusetts
| | - Jeffrey J Fredberg
- Harvard School of Public Health, Harvard University, Boston, Massachusetts
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
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9
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Lutchen KR, Paré PD, Seow CY. Hyperresponsiveness: Relating the Intact Airway to the Whole Lung. Physiology (Bethesda) 2018; 32:322-331. [PMID: 28615315 DOI: 10.1152/physiol.00008.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/10/2017] [Accepted: 05/10/2017] [Indexed: 11/22/2022] Open
Abstract
We relate changes of the airway wall to the response of the intact airway and the whole lung. We address how mechanical conditions and specific structural changes for an airway contribute to hyperresponsiveness resistant to deep inspiration. This review conveys that the origins of hyperresponsiveness do not devolve into an abnormality at single structural level but require examination of the complex interplay of all the parts.
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Affiliation(s)
- Kenneth R Lutchen
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Peter D Paré
- Department of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart Lung Innovation-St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Chun Y Seow
- Centre for Heart Lung Innovation-St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada; and.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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10
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Hill MR, Philp CJ, Billington CK, Tatler AL, Johnson SR, O'Dea RD, Brook BS. A theoretical model of inflammation- and mechanotransduction-driven asthmatic airway remodelling. Biomech Model Mechanobiol 2018; 17:1451-1470. [PMID: 29968161 PMCID: PMC6154265 DOI: 10.1007/s10237-018-1037-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 05/22/2018] [Indexed: 12/28/2022]
Abstract
Inflammation, airway hyper-responsiveness and airway remodelling are well-established hallmarks of asthma, but their inter-relationships remain elusive. In order to obtain a better understanding of their inter-dependence, we develop a mechanochemical morphoelastic model of the airway wall accounting for local volume changes in airway smooth muscle (ASM) and extracellular matrix in response to transient inflammatory or contractile agonist challenges. We use constrained mixture theory, together with a multiplicative decomposition of growth from the elastic deformation, to model the airway wall as a nonlinear fibre-reinforced elastic cylinder. Local contractile agonist drives ASM cell contraction, generating mechanical stresses in the tissue that drive further release of mitogenic mediators and contractile agonists via underlying mechanotransductive signalling pathways. Our model predictions are consistent with previously described inflammation-induced remodelling within an axisymmetric airway geometry. Additionally, our simulations reveal novel mechanotransductive feedback by which hyper-responsive airways exhibit increased remodelling, for example, via stress-induced release of pro-mitogenic and pro-contractile cytokines. Simulation results also reveal emergence of a persistent contractile tone observed in asthmatics, via either a pathological mechanotransductive feedback loop, a failure to clear agonists from the tissue, or a combination of both. Furthermore, we identify various parameter combinations that may contribute to the existence of different asthma phenotypes, and we illustrate a combination of factors which may predispose severe asthmatics to fatal bronchospasms.
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Affiliation(s)
- Michael R Hill
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Room C25, Mathematical Sciences Building, University Park, Nottingham, NG7 2RD, UK.
| | - Christopher J Philp
- Division of Respiratory Medicine, Nottingham Biomedical Research Centre, University of Nottingham, D Floor, South Block, Queen's Medical Centre Campus, Nottingham, NG7 2UH, UK
| | - Charlotte K Billington
- Division of Respiratory Medicine, Nottingham Biomedical Research Centre, University of Nottingham, D Floor, South Block, Queen's Medical Centre Campus, Nottingham, NG7 2UH, UK
| | - Amanda L Tatler
- Division of Respiratory Medicine, Nottingham Biomedical Research Centre, Nottingham City Hospital, University of Nottingham, Hucknall Road, Nottingham, NG5 1PB, UK
| | - Simon R Johnson
- Division of Respiratory Medicine, Nottingham Biomedical Research Centre, University of Nottingham, D Floor, South Block, Queen's Medical Centre Campus, Nottingham, NG7 2UH, UK
| | - Reuben D O'Dea
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Room C28, Mathematical Sciences Building, University Park, Nottingham, NG7 2RD, UK
| | - Bindi S Brook
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Room C26, Mathematical Sciences Building, University Park, Nottingham, NG7 2RD, UK
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11
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Jo-Avila MJ, Al-Jumaily AM. Superimposed pressure oscillations: An alternative to treat airway hyperresponsiveness in an acute sensitized airways mouse model. Respir Physiol Neurobiol 2016; 238:1-6. [PMID: 28027938 DOI: 10.1016/j.resp.2016.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
The main driving mechanism during an asthma attack is the hyper-constrictions of airway smooth muscle (ASM), which reduces the airway lumen and makes normal breathing difficult. In spite of some noticeable side effects, bronchodilator drugs such as salbutamol are used to alleviate these symptoms by inducing temporary relaxation of the contracted ASM. In vitro studies have shown that mechanical oscillation can induce relaxation in isolated contracted ASM obtained from healthy subjects but not from asthmatics. To date, little is known about in vivo ASM behaviours, in particular in asthmatic subjects. This in vivo study aims at determining the effect of various superimposed pressure oscillation (SIPO) patterns (different to those occurring during normal breathing) on sensitized airways during an ACh challenge (mimicking an asthmatic attack) and comparing it with the effect of a widely studied broncho-relaxant drug, Isoproterenol (ISO). The study shows that superimposed pressure oscillation in the range of 5-15Hz induces approximately 50% relaxation on pre-constricted sensitized airways in vivo; however, this behaviour was not observed at 20Hz. Our finding suggests that mechanical oscillation, particularly SIPO, may act as a bronchodilator and achieve ASM relaxation.
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Affiliation(s)
- M J Jo-Avila
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
| | - A M Al-Jumaily
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand.
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12
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Gazzola M, Lortie K, Henry C, Mailhot-Larouche S, Chapman DG, Couture C, Seow CY, Paré PD, King GG, Boulet LP, Bossé Y. Airway smooth muscle tone increases airway responsiveness in healthy young adults. Am J Physiol Lung Cell Mol Physiol 2016; 312:L348-L357. [PMID: 27941076 DOI: 10.1152/ajplung.00400.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 12/06/2016] [Accepted: 12/07/2016] [Indexed: 11/22/2022] Open
Abstract
Force adaptation, a process whereby sustained spasmogenic activation (viz., tone) of airway smooth muscle (ASM) increases its contractile capacity, has been reported in isolated ASM tissues in vitro, as well as in mice in vivo. The objective of the present study was to assess the effect of tone on airway responsiveness in humans. Ten healthy volunteers underwent methacholine challenge on two occasions. One challenge consisted of six serial doses of saline followed by a single high dose of methacholine. The other consisted of six low doses of methacholine 5 min apart followed by a higher dose. The cumulative dose was identical for both challenges. After both methacholine challenges, subjects took a deep inspiration (DI) to total lung capacity as another way to probe ASM mechanics. Responses to methacholine and the DI were measured using a multifrequency forced oscillation technique. Compared with a single high dose, the challenge preceded by tone led to an elevated response measured by respiratory system resistance (Rrs) and reactance at 5 Hz. However, there was no difference in the increase in Rrs at 19 Hz, suggesting a predominant effect on smaller airways. Increased tone also reduced the efficacy of DI, measured by an attenuated maximal dilation during the DI and an increased renarrowing post-DI. We conclude that ASM tone increases small airway responsiveness to inhaled methacholine and reduces the effectiveness of DI in healthy humans. This suggests that force adaptation may contribute to airway hyperresponsiveness and the reduced bronchodilatory effect of DI in asthma.
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Affiliation(s)
- Morgan Gazzola
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Katherine Lortie
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Samuel Mailhot-Larouche
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - David G Chapman
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont
| | - Christian Couture
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Chun Y Seow
- University of British Columbia Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Peter D Paré
- University of British Columbia Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Gregory G King
- Woolcock Institute of Medical Research, Sydney, Australia.,University of Sydney, Sydney, Australia; and.,Cooperative Research Centre for Asthma, Sydney, Australia
| | - Louis-Philippe Boulet
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada;
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13
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Chapman DG, Irvin CG. Mechanisms of airway hyper-responsiveness in asthma: the past, present and yet to come. Clin Exp Allergy 2015; 45:706-19. [PMID: 25651937 DOI: 10.1111/cea.12506] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Airway hyper-responsiveness (AHR) has long been considered a cardinal feature of asthma. The development of the measurement of AHR 40 years ago initiated many important contributions to our understanding of asthma and other airway diseases. However, our understanding of AHR in asthma remains complicated by the multitude of potential underlying mechanisms which in reality are likely to have different contributions amongst individual patients. Therefore, the present review will discuss the current state of understanding of the major mechanisms proposed to contribute to AHR and highlight the way in which AHR testing is beginning to highlight distinct abnormalities associated with clinically relevant patient populations. In doing so we aim to provide a foundation by which future research can begin to ascribe certain mechanisms to specific patterns of bronchoconstriction and subsequently match phenotypes of bronchoconstriction with clinical phenotypes. We believe that this approach is not only within our grasp but will lead to improved mechanistic understanding of asthma phenotypes and we hoped to better inform the development of phenotype-targeted therapy.
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Affiliation(s)
- D G Chapman
- Woolcock Institute of Medical Research, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Department of Medicine, University of Vermont College of Medicine, Burlington, VT, USA
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14
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Auger L, Mailhot-Larouche S, Tremblay F, Poirier M, Farah C, Bossé Y. The contractile lability of smooth muscle in asthmatic airway hyperresponsiveness. Expert Rev Respir Med 2015; 10:19-27. [PMID: 26561333 DOI: 10.1586/17476348.2016.1111764] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The contractile capacity of airway smooth muscle is not fixed but modulated by an impressive number of extracellular inflammatory mediators. Targeting the transient component of airway hyperresponsiveness ascribed to this contractile lability of ASM is a quest of great promises in order to alleviate asthma symptoms during inflammatory flares. However, owing to the plethora of mediators putatively involved and the molecular heterogeneity of asthma, it is more likely that many mediators conspire to increase the contractile capacity of ASM, each of which contributing to a various extent and in a time-varying fashion in individuals suffering from asthma. The task of identifying a common mend for a tissue rendered hypercontractile by imponderable assortments of inflammatory mediators is puzzling.
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Affiliation(s)
- Laurence Auger
- a Institut Universitaire de Cardiologie et de Pneumologie de Québec , Université Laval , Québec , Canada
| | - Samuel Mailhot-Larouche
- a Institut Universitaire de Cardiologie et de Pneumologie de Québec , Université Laval , Québec , Canada
| | - Francis Tremblay
- a Institut Universitaire de Cardiologie et de Pneumologie de Québec , Université Laval , Québec , Canada
| | - Mathilde Poirier
- a Institut Universitaire de Cardiologie et de Pneumologie de Québec , Université Laval , Québec , Canada
| | - Claude Farah
- a Institut Universitaire de Cardiologie et de Pneumologie de Québec , Université Laval , Québec , Canada
| | - Ynuk Bossé
- a Institut Universitaire de Cardiologie et de Pneumologie de Québec , Université Laval , Québec , Canada
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15
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Le Guen M, Naline E, Grassin-Delyle S, Devillier P, Faisy C. Effectiveness of a load-imposing device for cyclic stretching of isolated human bronchi: a validation study. PLoS One 2015; 10:e0127765. [PMID: 26011598 PMCID: PMC4444237 DOI: 10.1371/journal.pone.0127765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 04/18/2015] [Indexed: 11/19/2022] Open
Abstract
Background Mechanical ventilation may induce harmful effects in the airways of critically ill patients. Nevertheless, the effects of cyclic stretching caused by repetitive inflation-deflation of the bronchial compartment have not been well characterized in humans. The objective of the present study was to assess the effectiveness of a load-imposing device for the cyclic stretching of human bronchi. Methods Intact bronchial segments were removed from 128 thoracic surgery patients. After preparation and equilibration in an organ bath, bronchi were stretched repetitively and cyclically with a motorized transducer. The peak force imposed on the bronchi was set to 80% of each individual maximum contraction in response to acetylcholine and the minimal force corresponded to the initial basal tone before stretching. A 1-min cycle (stretching for 15 sec, relaxing for 15 sec and resting for 30 sec) was applied over a time period ranging from 5 to 60 min. The device's performance level was assessed and the properties of the stretched bronchi were compared with those of paired, non-stretched bronchi. Results Despite the intrinsic capacities of the device, the targets of the tension adjustments remained variable for minimal tension (156–178%) while the peak force set point was unchanged (87–115%). In the stretched bronchi, a time-dependent rise in basal tone (P <.05 vs. non-stretched) was apparent after as little as 5 min of cyclic stretching. The stretch-induced rise in basal tone continued to increase (P <.01) after the stretching had ended. Only 60 min of cyclic stretching was associated with a significant (P <.05) increase in responsiveness to acetylcholine, relative to non-stretched bronchi. Conclusions Low-frequency, low-force, cyclic loading of human bronchi is associated with elevated basal tone and acetylcholine responsiveness. The present experimental model is likely to be a useful tool for future investigations of the bronchial response to repetitive stress during mechanical ventilation.
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Affiliation(s)
- Morgan Le Guen
- Research Unit UPRES EA220, University Versailles Saint–Quentin, Hôpital Foch, 40 rue Worth, F-92150, Suresnes, France
- Departement of Anesthesiology, Hôpital Foch, 40 rue Worth, F-92150, Suresnes, France
| | - Emmanuel Naline
- Research Unit UPRES EA220, University Versailles Saint–Quentin, Hôpital Foch, 40 rue Worth, F-92150, Suresnes, France
| | - Stanislas Grassin-Delyle
- Research Unit UPRES EA220, University Versailles Saint–Quentin, Hôpital Foch, 40 rue Worth, F-92150, Suresnes, France
| | - Philippe Devillier
- Research Unit UPRES EA220, University Versailles Saint–Quentin, Hôpital Foch, 40 rue Worth, F-92150, Suresnes, France
| | - Christophe Faisy
- Research Unit UPRES EA220, University Versailles Saint–Quentin, Hôpital Foch, 40 rue Worth, F-92150, Suresnes, France
- Medical Intensive Care Unit, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, University Sorbonne Paris Cité, 20 rue Leblanc, F-75908, Paris, Cedex 15, France
- * E-mail:
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16
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Harvey BC, Parameswaran H, Lutchen KR. Can breathing-like pressure oscillations reverse or prevent narrowing of small intact airways? J Appl Physiol (1985) 2015; 119:47-54. [PMID: 25953836 DOI: 10.1152/japplphysiol.01100.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 05/01/2015] [Indexed: 01/20/2023] Open
Abstract
Periodic length fluctuations of airway smooth muscle during breathing are thought to modulate airway responsiveness in vivo. Recent animal and human intact airway studies have shown that pressure fluctuations simulating breathing can only marginally reverse airway narrowing and are ineffective at protecting against future narrowing. However, these previous studies were performed on relatively large (>5 mm diameter) airways, which are inherently stiffer than smaller airways for which a preponderance of airway constriction in asthma likely occurs. The goal of this study was to determine the effectiveness of breathing-like transmural pressure oscillations to reverse induced narrowing and/or protect against future narrowing of smaller, more compliant intact airways. We constricted smaller (luminal diameter = 2.92 ± 0.29 mm) intact airway segments twice with ACh (10(-6) M), once while applying tidal-like pressure oscillations (5-15 cmH2O) before, during, and after inducing constriction (Pre + Post) and again while only imposing the tidal-like pressure oscillation after induced constriction (Post Only). Smaller airways were 128% more compliant than previously studied larger airways. This increased compliance translated into 196% more strain and 76% greater recovery (41 vs. 23%) because of tidal-like pressure oscillations. Larger pressure oscillations (5-25 cmH2O) caused more recovery (77.5 ± 16.5%). However, pressure oscillations applied before and during constriction resulted in the same steady-state diameter as when pressure oscillations were only applied after constriction. These data show that reduced straining of the airways before a challenge likely does not contribute to the emergence of airway hyperreactivity observed in asthma but may serve to sustain a given level of constriction.
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Affiliation(s)
- Brian C Harvey
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | | | - Kenneth R Lutchen
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
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17
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Ansell TK, McFawn PK, McLaughlin RA, Sampson DD, Eastwood PR, Hillman DR, Mitchell HW, Noble PB. Does smooth muscle in an intact airway undergo length adaptation during a sustained change in transmural pressure? J Appl Physiol (1985) 2015; 118:533-43. [DOI: 10.1152/japplphysiol.00724.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In isolated airway smooth muscle (ASM) strips, an increase or decrease in ASM length away from its current optimum length causes an immediate reduction in force production followed by a gradual time-dependent recovery in force, a phenomenon termed length adaptation. In situ, length adaptation may be initiated by a change in transmural pressure (Ptm), which is a primary physiological determinant of ASM length. The present study sought to determine the effect of sustained changes in Ptm and therefore, ASM perimeter, on airway function. We measured contractile responses in whole porcine bronchial segments in vitro before and after a sustained inflation from a baseline Ptm of 5 cmH2O to 25 cmH2O, or deflation to −5 cmH2O, for ∼50 min in each case. In one group of airways, lumen narrowing and stiffening in response to electrical field stimulation (EFS) were assessed from volume and pressure signals using a servo-controlled syringe pump with pressure feedback. In a second group of airways, lumen narrowing and the perimeter of the ASM in situ were determined by anatomical optical coherence tomography. In a third group of airways, active tension was determined under isovolumic conditions. Both inflation and deflation reduced the contractile response to EFS. Sustained Ptm change resulted in a further decrease in contractile response, which returned to baseline levels upon return to the baseline Ptm. These findings reaffirm the importance of Ptm in regulating airway narrowing. However, they do not support a role for ASM length adaptation in situ under physiological levels of ASM lengthening and shortening.
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Affiliation(s)
- Thomas K. Ansell
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Peter K. McFawn
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Robert A. McLaughlin
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - David D. Sampson
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, Western Australia, Australia
| | - Peter R. Eastwood
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
- West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; and
| | - David R. Hillman
- West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; and
| | - Howard W. Mitchell
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Peter B. Noble
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
- Centre for Neonatal Research and Education, School of Paediatrics and Child Health, University of Western Australia, Crawley, Western Australia, Australia
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18
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Lee-Gosselin A, Gendron D, Blanchet MR, Marsolais D, Bossé Y. The gain of smooth muscle's contractile capacity induced by tone on in vivo airway responsiveness in mice. J Appl Physiol (1985) 2015; 118:692-8. [PMID: 25571989 DOI: 10.1152/japplphysiol.00645.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Airway hyperresponsiveness to a spasmogenic challenge such as methacholine, and an increased baseline tone measured by the reversibility of airway obstruction with a bronchodilator, are two common features of asthma. However, whether the increased tone influences the degree of airway responsiveness to a spasmogen is unclear. Herein, we hypothesized that increased tone augments airway responsiveness in vivo by increasing the contractile capacity of airway smooth muscle (ASM). Anesthetized, tracheotomized, paralyzed, and mechanically ventilated mice were either exposed (experimental group) or not (control group) to tone for 20 min, which was elicited by nebulizing serial small doses of methacholine. Respiratory system resistance was monitored during this period and the peak response to a large cumulative dose of methacholine was then measured at the end of 20 min to assess and compare the level of airway responsiveness between groups. To confirm direct ASM involvement, the contractile capacity of excised murine tracheas was measured with and without preexposure to tone elicited by either methacholine or a thromboxane A2 mimetic (U46619). Distinct spasmogens were tested because the spasmogens liable for increased tone in asthma are likely to differ. The results indicate that preexposure to tone increases airway responsiveness in vivo by 126 ± 37% and increases the contractile capacity of excised tracheas ex vivo by 23 ± 4% for methacholine and 160 ± 63% for U46619. We conclude that an increased tone, regardless of whether it is elicited by a muscarinic agonist or a thromboxane A2 mimetic, may contribute to airway hyperresponsiveness by increasing the contractile capacity of ASM.
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Affiliation(s)
- Audrey Lee-Gosselin
- Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - David Gendron
- Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Marie-Renée Blanchet
- Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - David Marsolais
- Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Ynuk Bossé
- Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Québec, Canada
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19
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Lan B, Norris BA, Liu JCY, Paré PD, Seow CY, Deng L. Development and maintenance of force and stiffness in airway smooth muscle. Can J Physiol Pharmacol 2014; 93:163-9. [PMID: 25615545 DOI: 10.1139/cjpp-2014-0404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Airway smooth muscle (ASM) plays a central role in the excessive narrowing of the airway that characterizes the primary functional impairment in asthma. This phenomenon is known as airway hyper-responsiveness (AHR). Emerging evidence suggests that the development and maintenance of ASM force involves dynamic reorganization of the subcellular filament network in both the cytoskeleton and the contractile apparatus. In this review, evidence is presented to support the view that regulation of ASM contraction extends beyond the classical actomyosin interaction and involves processes within the cytoskeleton and at the interfaces between the cytoskeleton, the contractile apparatus, and the extracellular matrix. These processes are initiated when the muscle is activated, and collectively they cause the cytoskeleton and the contractile apparatus to undergo structural transformation, resulting in a more connected and solid state that allows force generated by the contractile apparatus to be transmitted to the extracellular domain. Solidification of the cytoskeleton also serves to stiffen the muscle and hence the airway. Oscillatory strain from tidal breathing and deep inspiration is believed to be the counter balance that prevents hypercontraction and stiffening of ASM in vivo. Dysregulation of this balance could lead to AHR seen in asthma.
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Affiliation(s)
- Bo Lan
- Bioengineering College, Chongqing University, Chongqing, China., Centre for Heart and Lung Innovation, St Paul's Hospital and University of British Columbia, 1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada
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20
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Pascoe CD, Donovan GM, Bossé Y, Seow CY, Paré PD. Bronchoprotective effect of simulated deep inspirations in tracheal smooth muscle. J Appl Physiol (1985) 2014; 117:1502-13. [PMID: 25324512 DOI: 10.1152/japplphysiol.00713.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Deep inspirations (DIs) taken before an inhaled challenge with a spasmogen limit airway responsiveness in nonasthmatic subjects. This phenomenon is called bronchoprotection and is severely impaired in asthmatic subjects. The ability of DIs to prevent a decrease in forced expiratory volume in 1 s (FEV1) was initially attributed to inhibition of airway narrowing. However, DIs taken before methacholine challenge limit airway responsiveness only when a test of lung function requiring a DI is used (FEV1). Therefore, it has been suggested that prior DIs enhance the compliance of the airways or airway smooth muscle (ASM). This would increase the strain the airway wall undergoes during the subsequent DI, which is part of the FEV1 maneuver. To investigate this phenomenon, we used ovine tracheal smooth muscle strips that were subjected to shortening elicited by acetylcholine with or without prior strain mimicking two DIs. The compliance of the shortened strip was then measured in response to a stress mimicking one DI. Our results show that the presence of "DIs" before acetylcholine-induced shortening resulted in 11% greater relengthening in response to the third DI, compared with the prior DIs. This effect, although small, is shown to be potentially important for the reopening of closed airways. The effect of prior DIs was abolished by the adaptation of ASM to either shorter or longer lengths or to a low baseline tone. These results suggest that DIs confer bronchoprotection because they increase the compliance of ASM, which, consequently, promotes greater strain from subsequent DI and fosters the reopening of closed airways.
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Affiliation(s)
- Christopher D Pascoe
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Center for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, New Zealand
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada; and
| | - Chun Y Seow
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Center for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Peter D Paré
- Department of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada; Center for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
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21
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Abstract
Asthma is a prevalent respiratory disorder triggered by a variety of inhaled environmental factors, such as allergens, viruses, and pollutants. Asthma is characterized by an elevated activation of the smooth muscle surrounding the airways, as well as a propensity of the airways to narrow excessively in response to a spasmogen (i.e. contractile agonist), a feature called airway hyperresponsiveness. The level of airway smooth muscle (ASM) activation is putatively controlled by mediators released in its vicinity. In asthma, many mediators that affect ASM contractility originate from inflammatory cells that are mobilized into the airways, such as eosinophils. However, mounting evidence indicates that mediators released by remote organs can also influence the level of activation of ASM, as well as its level of responsiveness to spasmogens and relaxant agonists. These remote mediators are transported through circulating blood to act either directly on ASM or indirectly via the nervous system by tuning the level of cholinergic activation of ASM. Indeed, mediators generated from diverse organs, including the adrenals, pancreas, adipose tissue, gonads, heart, intestines, and stomach, affect the contractility of ASM. Together, these results suggest that, apart from a paracrine mode of regulation, ASM is subjected to an endocrine mode of regulation. The results also imply that defects in organs other than the lungs can contribute to asthma symptoms and severity. In this review, I suggest that the endocrine mode of regulation of ASM contractility is overlooked.
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Affiliation(s)
- Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de QuébecUniversité Laval, Québec, Québec, Canada G1V 4G5
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22
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Noble PB, Pascoe CD, Lan B, Ito S, Kistemaker LEM, Tatler AL, Pera T, Brook BS, Gosens R, West AR. Airway smooth muscle in asthma: linking contraction and mechanotransduction to disease pathogenesis and remodelling. Pulm Pharmacol Ther 2014; 29:96-107. [PMID: 25062835 DOI: 10.1016/j.pupt.2014.07.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 07/12/2014] [Accepted: 07/15/2014] [Indexed: 02/07/2023]
Abstract
Asthma is an obstructive airway disease, with a heterogeneous and multifactorial pathogenesis. Although generally considered to be a disease principally driven by chronic inflammation, it is becoming increasingly recognised that the immune component of the pathology poorly correlates with the clinical symptoms of asthma, thus highlighting a potentially central role for non-immune cells. In this context airway smooth muscle (ASM) may be a key player, as it comprises a significant proportion of the airway wall and is the ultimate effector of acute airway narrowing. Historically, the contribution of ASM to asthma pathogenesis has been contentious, yet emerging evidence suggests that ASM contractile activation imparts chronic effects that extend well beyond the temporary effects of bronchoconstriction. In this review article we describe the effects that ASM contraction, in combination with cellular mechanotransduction and novel contraction-inflammation synergies, contribute to asthma pathogenesis. Specific emphasis will be placed on the effects that ASM contraction exerts on the mechanical properties of the airway wall, as well as novel mechanisms by which ASM contraction may contribute to more established features of asthma such as airway wall remodelling.
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Affiliation(s)
- Peter B Noble
- School of Anatomy, Physiology and Human Biology, University of Western Australia, WA, Australia
| | - Chris D Pascoe
- Center for Heart Lung Innovation, University of British Columbia, BC, Canada
| | - Bo Lan
- Center for Heart Lung Innovation, University of British Columbia, BC, Canada; Bioengineering College, Chongqing University, Chongqing, China
| | - Satoru Ito
- Department of Respiratory Medicine, Nagoya University, Aichi, Japan
| | - Loes E M Kistemaker
- Department of Molecular Pharmacology, University of Groningen, The Netherlands
| | - Amanda L Tatler
- Division of Respiratory Medicine, University of Nottingham, United Kingdom
| | - Tonio Pera
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, United Kingdom
| | - Reinoud Gosens
- Department of Molecular Pharmacology, University of Groningen, The Netherlands
| | - Adrian R West
- Department of Physiology, University of Manitoba, MB, Canada; Biology of Breathing, Manitoba Institute of Child Health, MB, Canada.
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23
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Stamatiou R, Paraskeva E, Vasilaki A, Mylonis I, Molyvdas PA, Gourgoulianis K, Hatziefthimiou A. Long-term exposure to muscarinic agonists decreases expression of contractile proteins and responsiveness of rabbit tracheal smooth muscle cells. BMC Pulm Med 2014; 14:39. [PMID: 24607024 PMCID: PMC3995846 DOI: 10.1186/1471-2466-14-39] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 02/25/2014] [Indexed: 12/23/2022] Open
Abstract
Background Chronic airway diseases, like asthma or COPD, are characterized by excessive acetylcholine release and airway remodeling. The aim of this study was to investigate the long-term effect of muscarinic agonists on the phenotype and proliferation of rabbit tracheal airway smooth muscle cells (ASMCs). Methods ASMCs were serum starved before treatment with muscarinic agonists. Cell phenotype was studied by optical microscopy and indirect immunofluorescence, using smooth muscle α-actin, desmin and SM-Myosin Heavy Chain (SM-MHC) antibodies. [N-methyl-3H]scopolamine binding studies were performed in order to assess M3 muscarinic receptor expression on isolated cell membranes. Contractility studies were performed on isolated ASMCs treated with muscarinic agonists. Proliferation was estimated using methyl-[3H]thymidine incorporation, MTT or cell counting methods. Involvement of PI3K and MAPK signalling pathways was studied by cell incubation with the pathway inhibitors LY294002 and PD98059 respectively. Results Prolonged culture of ASMCs with acetylcholine, carbachol or FBS, reduced the expression of α-actin, desmin and SM-MHC compared to cells cultured in serum free medium. Treatment of ASMCs with muscarinic agonists for 3-15 days decreased muscarinic receptor expression and their responsiveness to muscarinic stimulation. Acetylcholine and carbachol induced DNA synthesis and increased cell number, of ASMCs that had acquired a contractile phenotype by 7 day serum starvation. This effect was mediated via a PI3K and MAPK dependent mechanism. Conclusions Prolonged exposure of rabbit ASMCs to muscarinic agonists decreases the expression of smooth muscle specific marker proteins, down-regulates muscarinic receptors and decreases ASMC contractile responsiveness. Muscarinic agonists are mitogenic, via the PI3K and MAPK signalling pathways.
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Affiliation(s)
| | | | | | | | | | | | - Apostolia Hatziefthimiou
- Laboratory of Physiology, Department of Medicine, School of Health Sciences, University of Thessaly, 3 Panepistimiou Str, 41500 BIOPOLIS Larissa, Greece.
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24
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Hulme KM, Salome CM, Brown NJ, Berend N, Agus HM, Horlyck KR, King GG, Chapman DG. Deep inspiration volume and the impaired reversal of bronchoconstriction in asthma. Respir Physiol Neurobiol 2013; 189:506-12. [PMID: 23994826 DOI: 10.1016/j.resp.2013.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/26/2013] [Accepted: 08/21/2013] [Indexed: 01/08/2023]
Abstract
It is unclear whether the failure to reverse bronchoconstriction with deep inspiration (DI) in asthma is due to reduced maximal dilatation of the DI. We compared the effect of different DI volumes on maximal dilatation and reversal of bronchoconstriction in nine asthmatics and ten non-asthmatics. During bronchoconstriction, subjects took DI to 40%, 70% and 100% inspiratory capacity, on separate days. Maximal dilatation was measured as respiratory system resistance (Rrs) at end-inspiration and residual dilatation as Rrs at end-expiration, both expressed as percent of Rrs at end-tidal expiration prior to DI. DI volume was positively associated with maximal dilatation in non-asthmatics (ANOVA p=0.055) and asthmatics (p=0.023). DI volume was positively associated with residual dilatation in non-asthmatics (p=0.004) but not in asthmatics (p=0.53). The degree of maximal dilatation independently predicted residual dilatation in non-asthmatics but not asthmatics. These findings suggest that the failure to reverse bronchoconstriction with DI in asthma is not due to reduced maximal dilatation, but rather due to increased airway narrowing during expiration.
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25
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Lee-Gosselin A, Pascoe CD, Couture C, Paré PD, Bossé Y. Does the length dependency of airway smooth muscle force contribute to airway hyperresponsiveness? J Appl Physiol (1985) 2013; 115:1304-15. [PMID: 23970527 DOI: 10.1152/japplphysiol.01480.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Airway wall remodeling and lung hyperinflation are two typical features of asthma that may alter the contractility of airway smooth muscle (ASM) by affecting its operating length. The aims of this study were as follows: 1) to describe in detail the "length dependency of ASM force" in response to different spasmogens; and 2) to predict, based on morphological data and a computational model, the consequence of this length dependency of ASM force on airway responsiveness in asthmatic subjects who have both remodeled airway walls and hyperinflated lungs. Ovine tracheal ASM strips and human bronchial rings were isolated and stimulated to contract in response to increasing concentrations of spasmogens at three different lengths. Ovine tracheal strips were more sensitive and generated greater force at longer lengths in response to acetylcholine (ACh) and K(+). Equipotent concentrations of ACh were approximately a log less for ASM stretched by 30% and approximately a log more for ASM shortened by 30%. Similar results were observed in human bronchi in response to methacholine. Morphometric and computational analyses predicted that the ASM of asthmatic subjects may be elongated by 6.6-10.4% (depending on airway generation) due to remodeling and/or hyperinflation, which could increase ACh-induced force by 1.8-117.8% (depending on ASM length and ACh concentration) and enhance the increased resistance to airflow by 0.4-4,432.8%. In conclusion, elongation of ASM imposed by airway wall remodeling and/or hyperinflation may allow ASM to operate at a longer length and to consequently generate more force and respond to lower concentration of spasmogens. This phenomenon could contribute to airway hyperresponsiveness.
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Affiliation(s)
- Audrey Lee-Gosselin
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Université Laval, Québec City, Québec, Canada
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Tuna BG, Bakker ENTP, VanBavel E. Relation between active and passive biomechanics of small mesenteric arteries during remodeling. J Biomech 2013; 46:1420-6. [DOI: 10.1016/j.jbiomech.2013.03.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/07/2013] [Accepted: 03/10/2013] [Indexed: 11/30/2022]
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A Brief History of Airway Smooth Muscle's Role in Airway Hyperresponsiveness. J Allergy (Cairo) 2012; 2012:768982. [PMID: 23118776 PMCID: PMC3483821 DOI: 10.1155/2012/768982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 09/21/2012] [Indexed: 11/18/2022] Open
Abstract
A link between airway smooth muscle (ASM) and airway hyperresponsiveness (AHR) in asthma was first postulated in the midnineteenth century, and the suspected link has garnered ever increasing interest over the years. AHR is characterized by excessive narrowing of airways in response to nonspecific stimuli, and it is the ASM that drives this narrowing. The stimuli that can be used to demonstrate AHR vary widely, as do the potential mechanisms by which phenotypic changes in ASM or nonmuscle factors can contribute to AHR. In this paper, we review the history of research on airway smooth muscle's role in airway hyperresponsiveness. This research has ranged from analyzing the quantity of ASM in the airways to testing for alterations in the plastic behavior of smooth muscle, which distinguishes it from skeletal and cardiac muscles. This long history of research and the continued interest in this topic mean that the precise role of ASM in airway responsiveness remains elusive, which makes it a pertinent topic for this collection of articles.
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Bossé Y. Asthmatic airway hyperresponsiveness: the ants in the tree. Trends Mol Med 2012; 18:627-33. [PMID: 23062358 DOI: 10.1016/j.molmed.2012.09.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 08/28/2012] [Accepted: 09/10/2012] [Indexed: 01/27/2023]
Abstract
Airways from asthmatics have a propensity to narrow excessively in response to spasmogens (i.e., contractile agonists), a feature called airway hyperresponsiveness (AHR). AHR is an important contributor to asthma symptoms because the degree of responsiveness dictates the amount of airway narrowing that occurs in response to inflammation-derived spasmogens produced endogenously following exposure to environmental triggers, such as allergens, viruses, or pollutants. The smooth muscle encircling the airways is responsible for responsiveness because it constricts the airway lumen when commanded to contract by spasmogens. However, whether AHR seen in asthmatics is due to stronger muscle is equivocal. In this opinion article, I propose that environmental triggers and other inflammatory molecules released during asthma attacks contribute to AHR by increasing muscle force.
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Affiliation(s)
- Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, G1V 4G5, Canada.
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West AR, Syyong HT, Siddiqui S, Pascoe CD, Murphy TM, Maarsingh H, Deng L, Maksym GN, Bossé Y. Airway contractility and remodeling: links to asthma symptoms. Pulm Pharmacol Ther 2012; 26:3-12. [PMID: 22989721 DOI: 10.1016/j.pupt.2012.08.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/14/2012] [Accepted: 08/16/2012] [Indexed: 02/07/2023]
Abstract
Respiratory symptoms are largely caused by obstruction of the airways. In asthma, airway narrowing mediated by airway smooth muscle (ASM) contraction contributes significantly to obstruction. The spasmogens produced following exposure to environmental triggers, such as viruses or allergens, are initially responsible for ASM activation. However, the extent of narrowing of the airway lumen due to ASM shortening can be influenced by many factors and it remains a real challenge to decipher the exact role of ASM in causing asthmatic symptoms. Innovative tools, such as the forced oscillation technique, continue to develop and have been proven useful to assess some features of ASM function in vivo. Despite these technologic advances, it is still not clear whether excessive narrowing in asthma is driven by ASM abnormalities, by other alterations in non-muscle factors or simply because of the overexpression of spasmogens. This is because a multitude of forces are acting on the airway wall, and because not only are these forces constantly changing but they are also intricately interconnected. To counteract these limitations, investigators have utilized in vitro and ex vivo systems to assess and compare asthmatic and non-asthmatic ASM contractility. This review describes: 1- some muscle and non-muscle factors that are altered in asthma that may lead to airway narrowing and asthma symptoms; 2- some technologies such as the forced oscillation technique that have the potential to unveil the role of ASM in airway narrowing in vivo; and 3- some data from ex vivo and in vitro methods that probe the possibility that airway hyperresponsiveness is due to the altered environment surrounding the ASM or, alternatively, to a hypercontractile ASM phenotype that can be either innate or acquired.
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Affiliation(s)
- Adrian R West
- School of Biomedical Engineering, Dalhousie University, Nova Scotia, Canada
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Functional phenotype of airway myocytes from asthmatic airways. Pulm Pharmacol Ther 2012; 26:95-104. [PMID: 22921313 DOI: 10.1016/j.pupt.2012.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 08/08/2012] [Accepted: 08/08/2012] [Indexed: 11/23/2022]
Abstract
In asthma, the airway smooth muscle (ASM) cell plays a central role in disease pathogenesis through cellular changes which may impact on its microenvironment and alter ASM response and function. The answer to the long debated question of what makes a 'healthy' ASM cell become 'asthmatic' still remains speculative. What is known of an 'asthmatic' ASM cell, is its ability to contribute to the hallmarks of asthma such as bronchoconstriction (contractile phenotype), inflammation (synthetic phenotype) and ASM hyperplasia (proliferative phenotype). The phenotype of healthy or diseased ASM cells or tissue for the most part is determined by expression of key phenotypic markers. ASM is commonly accepted to have different phenotypes: the contractile (differentiated) state versus the synthetic (dedifferentiated) state (with the capacity to synthesize mediators, proliferate and migrate). There is now accumulating evidence that the synthetic functions of ASM in culture derived from asthmatic and non-asthmatic donors differ. Some of these differences include an altered profile and increased production of extracellular matrix proteins, pro-inflammatory mediators and adhesion receptors, collectively suggesting that ASM cells from asthmatic subjects have the capacity to alter their environment, actively participate in repair processes and functionally respond to changes in their microenvironment.
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31
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Seow CY. Passive stiffness of airway smooth muscle: the next target for improving airway distensibility and treatment for asthma? Pulm Pharmacol Ther 2012; 26:37-41. [PMID: 22776694 DOI: 10.1016/j.pupt.2012.06.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 06/25/2012] [Accepted: 06/27/2012] [Indexed: 10/28/2022]
Abstract
Reduced airway distensibility due to increased airway stiffness is a characteristic of asthma. Airway stiffness is determined by the property and structural organization of the various elements of the airway wall, and is often divided into active and passive components. Active stiffness is thought to be associated with activation of muscle cells in the airway wall. This component of stiffness can be inhibited when active force produced by the muscle is abolished. Passive stiffness, on the other hand, is thought to stem from non-muscle component of the airway wall, especially the collagen/elastin fibrous network of the extracellular matrix within which the muscle cells are embedded. In this brief review, the notion that passive stiffness is exclusively extracellular in origin is challenged. Recent evidence suggests that a substantial portion of the passive stiffness of an in vitro preparation of tracheal smooth muscle is calcium sensitive and is regulated by Rho-kinase, although the underlying mechanism and the details of regulation for the development of this intracellular passive stiffness are still largely unknown. To reduce airway stiffness different lines of attack must be tailored to different components of the stiffness. The regulatable passive stiffness is distinct from the relatively permanent stiffness of the extracellular matrix and the stiffness associated with active muscle contraction. To improve airway distensibility during asthma exacerbation, a comprehensive approach to reduce overall airway stiffness should therefore include a strategy for targeting the regulatable passive stiffness.
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Affiliation(s)
- Chun Y Seow
- Department of Pathology and Laboratory Medicine, The James Hogg Research Centre/St. Paul's Hospital, University of British Columbia, 1081 Burrard Street, Rm. 166, Vancouver, BC V6Z 1Y6, Canada.
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Speich JE, Wilson CW, Almasri AM, Southern JB, Klausner AP, Ratz PH. Carbachol-induced volume adaptation in mouse bladder and length adaptation via rhythmic contraction in rabbit detrusor. Ann Biomed Eng 2012; 40:2266-76. [PMID: 22614640 DOI: 10.1007/s10439-012-0590-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 05/07/2012] [Indexed: 10/28/2022]
Abstract
The length-tension (L-T) relationships in rabbit detrusor smooth muscle (DSM) are similar to those in vascular and airway smooth muscles and exhibit short-term length adaptation characterized by L-T curves that shift along the length axis as a function of activation and strain history. In contrast to skeletal muscle, the length-active tension (L-T(a)) curve for rabbit DSM strips does not have a unique peak tension value with a single ascending and descending limb. Instead, DSM can exhibit multiple ascending and descending limbs, and repeated KCl-induced contractions at a particular muscle length on an ascending or descending limb display increasingly greater tension. In the present study, mouse bladder strips with and without urothelium exhibited KCl-induced and carbachol-induced length adaptation, and the pressure-volume relationship in mouse whole bladder displayed short-term volume adaptation. Finally, prostaglandin-E(2)-induced low-level rhythmic contraction produced length adaptation in rabbit DSM strips. A likely role of length adaptation during bladder filling is to prepare DSM cells to contract efficiently over a broad range of volumes. Mammalian bladders exhibit spontaneous rhythmic contraction (SRC) during the filling phase and SRC is elevated in humans with overactive bladder (OAB). The present data identify a potential physiological role for SRC in bladder adaptation and motivate the investigation of a potential link between short-term volume adaptation and OAB with impaired contractility.
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Affiliation(s)
- John E Speich
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University, Richmond, 23284-3015, USA.
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Pascoe C, Jiao Y, Seow CY, Paré PD, Bossé Y. Force oscillations simulating breathing maneuvers do not prevent force adaptation. Am J Respir Cell Mol Biol 2012; 47:44-9. [PMID: 22323367 DOI: 10.1165/rcmb.2011-0429oc] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Airway inflammation in patients with asthma exposes the airway smooth muscle (ASM) to a variety of spasmogens. These spasmogens increase ASM tone, which can lead to force adaptation. Length oscillations of ASM, which occur in vivo due to breathing maneuvers, can attenuate force adaptation. However, in the presence of tone, the force oscillations required to achieve these length oscillations may be unphysiologic (i.e., magnitude greater than the ones achieved due to the swings in transpulmonary pressure required for breathing). In the present study, we applied force oscillations simulating the tension oscillations experienced by the wall of a fourth-generation airway during tidal breathing with or without deep inspirations (DI) to ASM. The goal was to investigate whether force adaptation occurs in conditions mimicking breathing maneuvers. Tone was induced by carbachol (average, 20 nM), and the force-generating capacity of the ASM was assessed at 5-minute intervals before and after carbachol administration using electrical field stimulations (EFS). The results show that force oscillations applied before the introduction of tone had a small effect on the force produced by EFS (declined to 96.8% [P > 0.05] and 92.3% [P < 0.05] with and without DI, respectively). The tone induced by carbachol transiently decreased after a DI and declined significantly (P < 0.05) due to tidal breathing oscillations (25%). These force oscillations did not prevent force adaptation (gain of force of 11.2 ± 2.2 versus 13.5 ± 2.7 and 11.2 ± 3.0% in static versus dynamic conditions with or without DI, respectively). The lack of effect of simulated breathing maneuvers on force adaptation suggests that this gain in ASM force may occur in vivo and could contribute to the development of airway hyperresponsiveness.
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Affiliation(s)
- Chris Pascoe
- University of British Columbia, James Hogg Research Center, St. Paul’s Hospital Vancouver, Canada
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Wylam ME, Xue A, Sieck GC. Mechanisms of intrinsic force in small human airways. Respir Physiol Neurobiol 2012; 181:99-108. [PMID: 22322114 DOI: 10.1016/j.resp.2012.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 01/24/2012] [Accepted: 01/25/2012] [Indexed: 10/14/2022]
Abstract
We quantified the magnitude and investigated mechanisms regulating intrinsic force (IF) in human airway smooth muscle (hASM). IF was identified by reducing extracellular calcium (Ca2+) concentration to nominally zero in freshly isolated isometrically mounted 2mm human bronchi. Our results show: (1) the magnitude of IF is ∼50% of the maximal total force elicited by acetylcholine (10(-5) M) and is epithelial independent, (2) IF can also be revealed by β-adrenergic activation (isoproterenol), non-specific cationic channel blockade (La3+) or L-type voltage gated Ca2+ channel blockade (nifedipine), (3) atropine, indomethacin, AA-861, or pyrilamine did not affect IF, (4) IF was reduced by the intracellular Ca2+ ([Ca2+]i) chelating agent BAPTA-AM, (5) ω-conotoxin had no effect on IF. In studies in cultured hASM cells nominally zero Ca2+ buffer and BAPTA-AM reduced [Ca2+]i but isoproterenol and nifedipine did not. Taken together these results indicate that rapid reduction of [Ca2+]i reveals a permissive relationship between extracellular Ca2+, [Ca2+]i and IF. However IF can be dissipated by mechanisms effecting Ca2+ sensitivity. We speculate that an increase of IF, a fundamental property of ASM, could be related to human airway clinical hyperresponsiveness and must be accounted for in in vitro studies of hASM.
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Affiliation(s)
- Mark E Wylam
- Division of Pulmonary and Critical Care Medicine, Departments of Medicine, Pediatrics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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A 'Good' muscle in a 'Bad' environment: the importance of airway smooth muscle force adaptation to airway hyperresponsiveness. Respir Physiol Neurobiol 2011; 179:269-75. [PMID: 21939788 DOI: 10.1016/j.resp.2011.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Revised: 08/17/2011] [Accepted: 09/06/2011] [Indexed: 12/31/2022]
Abstract
Asthma is characterized by airway inflammation, with a consequent increase in spasmogens, and exaggerated airway narrowing in response to stimuli, termed airway hyperresponsiveness (AHR). The nature of any relationship between inflammation and AHR is less clear. Recent ex vivo data has suggested a novel mechanism by which inflammation may lead to AHR, in which increased basal ASM-tone, due to the presence of spasmogens in the airways, may "strengthen" the ASM and ultimately lead to exaggerated airway narrowing. This phenomenon was termed "force adaptation" [Bossé, Y., Chin, L.Y., Paré, P.D., Seow, C.Y., 2009. Adaptation of airway smooth muscle to basal tone: relevance to airway hyperresponsiveness. Am. J. Respir. Cell Mol. Biol. 40, 13-18]. However, it is unknown whether the magnitude of the effect of force adaptation ex vivo could contribute to exaggerated airway narrowing in vivo. Our aim was to utilize a computational model of ASM shortening in order to quantify the potential effect of force adaptation on airway narrowing when all other mechanical factors were kept constant. The shortening in the model is dictated by a balance between physiological loads and ASM force-generating capacity at different lengths. The results suggest that the magnitude of the effect of force adaptation on ASM shortening would lead to substantially more airway narrowing during bronchial challenge at any given airway generation. We speculate that the increased basal ASM-tone in asthma, due to the presence of inflammation-derived spasmogens, produces an increase in the force-generating capacity of ASM, predisposing to AHR during subsequent challenge.
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36
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Chapman DG, Brown NJ, Salome CM. The dynamic face of respiratory research: understanding the effect of airway disease on a lung in constant motion. Pulm Pharmacol Ther 2011; 24:505-12. [PMID: 21463699 DOI: 10.1016/j.pupt.2011.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/21/2011] [Accepted: 03/25/2011] [Indexed: 02/01/2023]
Abstract
The lungs are in a constant state of motion. The dynamic nature of tidal breathing, whereby cycles of pressure changes across the lungs cause the chest wall, lung tissue and airways to repeatedly expand and contract, ventilates the lung tissue and allows respiration to occur. However, these regular cycles of tidal inspirations and expirations are punctuated by breaths of differing volumes, most particularly periodic deep inspirations. In normal, healthy subjects, these deep inspirations have a dual effect in reducing airway responsiveness. Firstly, deep inspirations taken under baseline conditions protect the airways against subsequent bronchoconstriction, termed DI bronchoprotection. Secondly, deep inspirations are able to dramatically reverse bronchoconstriction. The ability for deep inspirations to reverse bronchoconstriction appears to be due to both the ability to dilate the airways with a full inspiration to total lung capacity (TLC) and the rate at which the airways re-narrow once tidal breathing is resumed. Deep inspiration reversal is reduced in subjects with asthma and is due both to a reduced ability to dilate the airways as well as an increase in the rate of re-narrowing. On the other hand, DI bronchoprotection is completely absent in asthma. Although the mechanisms behind these abnormalities remain unclear, the inability for deep inspirations to both protect against and fully reverse bronchoconstriction in patients with asthma appears critical in the development of airway hyperresponsiveness. As such, determining the pathophysiology responsible for the malfunction of deep inspirations in asthma remains critical to understanding the disease and is likely to pave the way for novel therapeutic targets.
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Affiliation(s)
- David G Chapman
- Woolcock Institute of Medical Research, Missenden Road, Sydney, NSW 2050, Australia.
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37
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Schlepütz M, Uhlig S, Martin C. Electric field stimulation of precision-cut lung slices. J Appl Physiol (1985) 2010; 110:545-54. [PMID: 21109600 DOI: 10.1152/japplphysiol.00409.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The precision-cut lung slice (PCLS) technique is widely used to examine airway responses in different species. We developed a method to study nerve-dependent bronchoconstriction by the application of electric field stimulation (EFS) to PCLS. PCLS prepared from Wistar rats were placed between two platinum electrodes to apply serial rectangular impulses (5-100 Hz), and bronchoconstriction was studied by videomicroscopy. The extent of airway contractions increased with higher frequencies. Stable repeated airway contractions were obtained at a frequency of 50 Hz, a width of 1 ms, and an output of 200 mA for 2.5 s each minute. Larger airways showed stronger responses. The EFS-triggered contractions were increased by the acetylcholine esterase inhibitor neostigmine (10 μM) and reversed by the muscarinic antagonist atropine (10 μM), whereas the thromboxane protanoid receptor antagonist SQ29548 (10 μM) had no effect. Magnesium ions (10 mM) antagonized airway contractions induced by EFS, but not by methacholine, indicating that nerve endings remain intact in PCLS. Our data further show that the electrically evoked airway contractions in PCLS are mediated by cholinergic nerves, independent of thromboxane and more prominent in larger airways. Taken together these findings show that nerve endings remain intact in PCLS, and they suggest that the present method is useful to study neurogenic responses in airways of different size.
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Affiliation(s)
- Marco Schlepütz
- Institute of Pharmacology and Toxicology, Univ. Hospital Aachen, Wendlingweg 2, 52074 Aachen.
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Raqeeb A, Solomon D, Paré PD, Seow CY. Length oscillation mimicking periodic individual deep inspirations during tidal breathing attenuates force recovery and adaptation in airway smooth muscle. J Appl Physiol (1985) 2010; 109:1476-82. [DOI: 10.1152/japplphysiol.00676.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway smooth muscle (ASM) is able to generate maximal force under static conditions, and this isometric force can be maintained over a large length range due to length adaptation. The increased force at short muscle length could lead to excessive narrowing of the airways. Prolonged exposure of ASM to submaximal stimuli also increases the muscle's ability to generate force in a process called force adaptation. To date, the effects of length and force adaptation have only been demonstrated under static conditions. In the mechanically dynamic environment of the lung, ASM is constantly subjected to periodic stretches by the parenchyma due to tidal breathing and deep inspiration. It is not known whether force recovery due to muscle adaptation to a static environment could occur in a dynamic environment. In this study the effect of length oscillation mimicking tidal breathing and deep inspiration was examined. Force recovery after a length change was attenuated in the presence of length oscillation, except at very short lengths. Force adaptation was abolished by length oscillation. We conclude that in a healthy lung (with intact airway-parenchymal tethering) where airways are not allowed to narrow excessively, large stretches (associated with deep inspiration) may prevent the ability of the muscle to generate maximal force that would occur under static conditions irrespective of changes in mean length; mechanical perturbation on ASM due to tidal breathing and deep inspiration, therefore, is the first line of defense against excessive bronchoconstriction that may result from static length and force adaptation.
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Affiliation(s)
- Abdul Raqeeb
- Department of Pathology and Laboratory Medicine,
- James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dennis Solomon
- James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter D. Paré
- Department of Medicine, and
- James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chun Y. Seow
- Department of Pathology and Laboratory Medicine,
- James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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Sobieszek A, Sarg B, Lindner H, Seow CY. Phosphorylation of caldesmon by myosin light chain kinase increases its binding affinity for phosphorylated myosin filaments. Biol Chem 2010; 391:1091-104. [DOI: 10.1515/bc.2010.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Abstract
Phosphorylation of myosin by myosin light chain kinase (MLCK) is essential for smooth muscle contraction. In this study we show that caldesmon (CaD) is also phosphorylated in vitro by MLCK. The phosphorylation is calcium- and calmodulin (CaM)-dependent and requires a MLCK concentration close to that found in vivo. On average, approximately 2 mol P
i
per mol of CaD are incorporated at Thr-626 and Thr-693, with additional partial phosphorylation at Ser-658 and Ser-702. The phosphorylation rate for CaD is 20- to 50-fold slower than that for filamentous myosin; faster relative rates were obtained with CaD added to purified actomyosin or myosin preparations containing endogenous MLCK/CaM complex. Addition of CaM also augmented CaD phosphorylation. We further demonstrate that [32P] labeled CaD binds much more readily to phosphorylated filamentous myosin than to unphosphorylated myosin. For actomyosin, CaD binding affinity doubles after myosin phosphorylation, without a significant change in binding stoichiometry (approx. one CaD per myosin molecule). Unphosphorylated CaD is ineffective in competing with the phosphorylated protein for the binding site(s) on myosin filaments. The ATPase activity of reconstituted actomyosin is inhibited by unphosphorylated CaD, and this inhibition was removed by CaD phosphorylation. Our results suggest that CaD phosphorylation plays a role in modifying actomyosin interaction in vivo, particularly during prolonged muscle activation.
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40
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Khan MA, Ellis R, Inman MD, Bates JHT, Sanderson MJ, Janssen LJ. Influence of airway wall stiffness and parenchymal tethering on the dynamics of bronchoconstriction. Am J Physiol Lung Cell Mol Physiol 2010; 299:L98-L108. [PMID: 20435686 DOI: 10.1152/ajplung.00011.2010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Understanding how tissue remodeling affects airway responsiveness is of key importance, but experimental data bearing on this issue remain scant. We used lung explants to investigate the effects of enzymatic digestion on the rate and magnitude of airway narrowing induced by acetylcholine. To link the observed changes in narrowing dynamics to the degree of alteration in tissue mechanics, we compared our experimental results with predictions made by a computational model of a dynamically contracting elastic airway embedded in elastic parenchyma. We found that treatment of explanted airways with two different proteases (elastase and collagenase) resulted in differential effects on the dynamics of airway narrowing following application of ACh. Histological corroboration of these different effects is manifest in different patterns of elimination of collagen and elastin from within the airway wall and the surrounding parenchyma. Simulations with a computational model of a dynamically contracting airway embedded in elastic parenchyma suggest that elastase exerts its functional effects predominately through a reduction in parenchymal tethering, while the effects of collagenase are more related to a reduction in airway wall stiffness. We conclude that airway and parenchymal remodeling as a result of protease activity can have varied effects on the loads opposing ASM shortening, with corresponding consequences for airway responsiveness.
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Affiliation(s)
- Mohammad Afzal Khan
- Asthma Research Group, Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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41
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Bossé Y, Solomon D, Chin LYM, Lian K, Paré PD, Seow CY. Increase in passive stiffness at reduced airway smooth muscle length: potential impact on airway responsiveness. Am J Physiol Lung Cell Mol Physiol 2010; 298:L277-87. [DOI: 10.1152/ajplung.00275.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The amplitude of strain in airway smooth muscle (ASM) produced by oscillatory perturbations such as tidal breathing or deep inspiration (DI) influences the force loss in the muscle and is therefore a key determinant of the bronchoprotective and bronchodilatory effects of these breathing maneuvers. The stiffness of unstimulated ASM (passive stiffness) directly influences the amplitude of strain. The nature of the passive stiffness is, however, not clear. In this study, we measured the passive stiffness of ovine ASM at different muscle lengths (relative to in situ length, which was used as a reference length, Lref) and states of adaptation to gain insights into the origin of this muscle property. The results showed that the passive stiffness was relatively independent of muscle length, possessing a constant plateau value over a length range from 0.62 to 1.25 Lref. Following a halving of ASM length, passive stiffness decreased substantially (by 71%) but redeveloped over time (∼30 min) at the shorter length to reach 65% of the stiffness value at Lref, provided that the muscle was stimulated to contract at least once over a ∼30-min period. The redevelopment and maintenance of passive stiffness were dependent on the presence of Ca2+ but unaffected by latrunculin B, an inhibitor of actin filament polymerization. The maintenance of passive stiffness was also not affected by blocking myosin cross-bridge cycling using a myosin light chain kinase inhibitor or by blocking the Rho-Rho kinase (RhoK) pathway using a RhoK inhibitor. Our results suggest that the passive stiffness of ASM is labile and capable of redevelopment following length reduction. Redevelopment and maintenance of passive stiffness following muscle shortening could contribute to airway hyperresponsiveness by attenuating the airway wall strain induced by tidal breathing and DI.
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Affiliation(s)
- Ynuk Bossé
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Providence Health Care/St. Paul's Hospital,
| | - Dennis Solomon
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Providence Health Care/St. Paul's Hospital,
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Leslie Y. M. Chin
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Providence Health Care/St. Paul's Hospital,
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kevin Lian
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Providence Health Care/St. Paul's Hospital,
| | - Peter D. Paré
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Providence Health Care/St. Paul's Hospital,
- Department of Medicine, Respiratory Division, and
| | - Chun Y. Seow
- The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, Providence Health Care/St. Paul's Hospital,
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Bates JHT, Bullimore SR, Politi AZ, Sneyd J, Anafi RC, Lauzon AM. Transient oscillatory force-length behavior of activated airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 2009; 297:L362-72. [PMID: 19525391 DOI: 10.1152/ajplung.00095.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway smooth muscle (ASM) is cyclically stretched during breathing, even in the active state, yet the factors determining its dynamic force-length behavior remain incompletely understood. We developed a model of the activated ASM strip and compared its behavior to that observed in strips of rat trachealis muscle stimulated with methacholine. The model consists of a nonlinear viscoelastic element (Kelvin body) in series with a force generator obeying the Hill force-velocity relationship. Isometric force in the model is proportional to the number of bound crossbridges, the attachment of which follows first-order kinetics. Crossbridges detach at a rate proportional to the rate of change of muscle length. The model accurately accounts for the experimentally observed transient and steady-state oscillatory force-length behavior of both passive and activated ASM. However, the model does not predict the sustained decrement in isometric force seen when activated strips of ASM are subjected briefly to large stretches. We speculate that this force decrement reflects some mechanism unrelated to the cycling of crossbridges, and which may be involved in the reversal of bronchoconstriction induced by a deep inflation of the lungs in vivo.
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Affiliation(s)
- J H T Bates
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, 05405-0075, USA.
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Bossé Y, Chin LYM, Paré PD, Seow CY. Chronic activation in shortened airway smooth muscle: a synergistic combination underlying airway hyperresponsiveness? Am J Respir Cell Mol Biol 2009; 42:341-8. [PMID: 19448153 DOI: 10.1165/rcmb.2008-0448oc] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Airway smooth muscle (ASM) in individuals with asthma is continuously stimulated by spasmogens released as part of chronic airway inflammation. This chronic submaximal stimulation of ASM produces "tone," which may or may not narrow airways sufficiently to induce respiratory symptoms. However, when coupled with a bronchoprovocative challenge with a nonspecific contractile agonist, this increased tone could contribute to the manifestation of airway hyperresponsiveness (AHR). In this study, we examined the effect of chronic acetylcholine (ACh) exposure at different muscle lengths to gain insights into the consequence of increased tone on the mechanical properties of ASM. The total force (the ACh-induced tone plus active force induced by a second stimulus-electric field stimulation [EFS]) increased immediately after induction of muscle tone, and increased further over time in the presence of the tone in a process termed "force adaptation." The phenomenon of force adaptation was observed over a wide range of muscle lengths and did not prevent length adaptation when the muscle was adapted to the tone before being subjected to a length change, suggesting that both length and force adaptations can occur sequentially and in an independent fashion in the same tissue. Together, these results suggest that adaptation of ASM to shortened length in the presence of muscle tone produced a condition that favored excessive force generation in response to a second stimulus (herein EFS) at reduced muscle length. In vivo these changes will be translated into excessive airway narrowing in response to naturally occurring and pharmacological bronchoconstricting stimuli.
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Affiliation(s)
- Ynuk Bossé
- The James Hogg iCAPTURE Centre, Providence Health Care/St. Paul's Hospital, Vancouver, BC, V6Z 1Y6 Canada
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