1
|
Chiba Y, Yamane Y, Sato T, Suto W, Hanazaki M, Sakai H. Extracellular acidification attenuates bronchial contraction via an autocrine activation of EP 2 receptor: Its diminishment in murine experimental asthma. Respir Physiol Neurobiol 2024; 324:104251. [PMID: 38492830 DOI: 10.1016/j.resp.2024.104251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/03/2024] [Accepted: 03/09/2024] [Indexed: 03/18/2024]
Abstract
PURPOSE Extracellular acidification is a major component of tissue inflammation, including airway inflammation in asthmatics. However, its physiological/pathophysiological significance in bronchial function is not fully understood. Currently, the functional role of extracellular acidification on bronchial contraction was explored. METHODS Left main bronchi were isolated from male BALB/c mice. Epithelium-removed tissues were exposed to acidic pH under submaximal contraction induced by 10-5 M acetylcholine in the presence or absence of a COX inhibitor indomethacin (10-6 M). Effects of AH6809 (10-6 M, an EP2 receptor antagonist), BW A868C (10-7 M, a DP receptor antagonist) and CAY10441 (3×10-6 M, an IP receptor antagonist) on the acidification-induced change in tension were determined. The release of prostaglandin E2 (PGE2) from epithelium-denuded tissues in response to acidic pH was assessed using an ELISA. RESULTS In the bronchi stimulated with acetylcholine, change in the extracellular pH from 7.4 to 6.8 caused a transient augmentation of contraction followed by a sustained relaxing response. The latter inhibitory response was abolished by indomethacin and AH6809 but not by BW A868C or CAY10441. Both indomethacin and AH6809 significantly increased potency and efficacy of acetylcholine at pH 6.8. Stimulation with low pH caused an increase in PGE2 release from epithelium-denuded bronchi. Interestingly, the acidic pH-induced bronchial relaxation was significantly reduced in a murine asthma model that had a bronchial hyperresponsiveness to acetylcholine. CONCLUSION Taken together, extracellular acidification could inhibit the bronchial contraction via autocrine activation of EP2 receptors. The diminished acidic pH-mediated inhibition of bronchial tone may contribute to excessive bronchoconstriction in inflamed airways such as asthma.
Collapse
Affiliation(s)
| | - Yamato Yamane
- Laboratory of Molecular Biology and Physiology, Japan
| | - Tsubasa Sato
- Laboratory of Molecular Biology and Physiology, Japan
| | - Wataru Suto
- Laboratory of Molecular Biology and Physiology, Japan
| | - Motohiko Hanazaki
- Department of Anesthesiology and Intensive Care Medicine, School of Medicine, International University of Health and Welfare, Narita, Japan
| | - Hiroyasu Sakai
- Laboratory of Biomolecular Pharmacology, Hoshi University School of Pharmacy, Tokyo, Japan
| |
Collapse
|
2
|
Beqiraj-Zeqiraj Q, Thaçi Q, Sahiti F, Kovač Z, Raffay TM, Sopi RB. Rho-kinase inhibitors protect against neonatal hyperoxia-induced airway hyperreactivity in a rat pup model: Role of prostaglandin F 2α. Pediatr Pulmonol 2022; 57:1229-1237. [PMID: 35088947 DOI: 10.1002/ppul.25848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 01/06/2022] [Accepted: 01/26/2022] [Indexed: 11/06/2022]
Abstract
BACKGROUND Oxygen therapy in preterm neonates is associated with airway hyperreactivity. The role of Rho/Rho-kinase smooth muscle signaling in hyperoxia-induced airway hyperreactivity remains understudied. We hypothesized that inhibition of Rho-kinase will attenuate airway hyperreactivity induced by neonatal hyperoxia. METHODS Newborn rats were raised in hyperoxia (>95% O2 ) or ambient air (AA) for 7 days. Subgroups were injected with a Rho-kinase inhibitor: Y-27632 (10 mg·kg-1 ·day-1 ) or fasudil (10 mg·kg-1 ·day-1 ), or a FP receptor antagonist - AS604872 (30 mg·kg-1 ·day-1 ). After exposures, tracheal cylinders were prepared for in vitro wire myography. Contraction to methacholine or PGF2α was measured in the presence or absence of tissue-bath Y-27632, fasudil, or AS604872. Lung PGF2α levels, Rho-kinase protein level and Rho-kinase 1 activity were measured by ELISA. RESULTS Tracheal smooth muscle contraction was significantly greater in hyperoxic compared to AA groups. Both, Y-27632 and fasudil significantly decreased contractility to MCh or PGF2α in hyperoxic groups versus hyperoxic controls (p < 0.001), but did not alter AA group responses. Inhibition of FP receptors attenuated responses to PGF2α . Hyperoxia significantly increased lung PGF2α compared to AA (p < 0.01), but Rho-kinase inhibition did not influence PGF2α level. Rho-kinase protein level (p < 0.001) and activity (p < 0.01), were increased by hyperoxia, but blockade of FP receptor reduced the Rho-kinase 1 activity (p < 0.05) under hyperoxic condition. CONCLUSIONS This study demonstrates an active role of Rho/Rho-kinase signaling on hyperoxia-induced airway hyperreactivity. These findings suggest that Rho-kinase inhibitors might serve as an effective therapy for hyperoxia-induced airway hyperreactivity.
Collapse
Affiliation(s)
- Qendresa Beqiraj-Zeqiraj
- Department of Pathophysiology, Faculty of Medicine, University of Prishtina, Prishtina, Kosovo.,Pediatric Clinic, University Clinical Centre of Kosovo, Prishtina, Kosovo
| | - Qëndrim Thaçi
- Department of Premedical Courses, Faculty of Medicine, University of Prishtina, Prishtina, Kosovo
| | - Floran Sahiti
- Department of Premedical Courses, Faculty of Medicine, University of Prishtina, Prishtina, Kosovo.,Comprehensive Heart Failure Center, University and University Hospital Würzburg, Würzburg, Germany
| | - Zdenko Kovač
- Department of Pathophysiology, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Thomas M Raffay
- Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio, USA
| | - Ramadan B Sopi
- Department of Premedical Courses, Faculty of Medicine, University of Prishtina, Prishtina, Kosovo
| |
Collapse
|
3
|
Fayon M, Beaufils F. The lower respiratory airway wall in children in health and disease. ERJ Open Res 2021; 7:00874-2020. [PMID: 34322550 PMCID: PMC8311136 DOI: 10.1183/23120541.00874-2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 03/24/2021] [Indexed: 02/06/2023] Open
Abstract
Alone or in association with other lung or thorax component disorders, the airway wall (AWW) remains one of the most frequently involved elements in paediatric lung diseases. A myriad of AWW disorders will present with similar symptomatology. It is thus important for the clinician to reappraise the normal development and structure of the AWW to better understand the underlying disease patterns. We herein provide an overview of the structure of the AWW and a description of its development from the fetal period to adulthood. We also detail the most common AWW changes observed in several acute and chronic respiratory disorders as well as after cigarette smoke or chronic pollution exposure. We then describe the relationship between the AWW structure and lung function. In addition, we present the different ways of investigating the AWW structure, from biopsies and histological analyses to the most recent noninvasive airway (AW) imaging techniques. Understanding the pathophysiological processes involved in an individual patient will lead to the judicious choice of nonspecific or specific personalised treatments, in order to prevent irreversible AW damage.
Collapse
Affiliation(s)
- Michael Fayon
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM U1045, Bordeaux Imaging Center, Bordeaux, France
- CHU de Bordeaux, Département de Pédiatrie, Service d'Exploration Fonctionnelle Respiratoire, Bordeaux, France
- INSERM, Centre d'Investigation Clinique (CIC1401), Bordeaux, France
| | - Fabien Beaufils
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM U1045, Bordeaux Imaging Center, Bordeaux, France
- CHU de Bordeaux, Département de Pédiatrie, Service d'Exploration Fonctionnelle Respiratoire, Bordeaux, France
| |
Collapse
|
4
|
Menezes PMN, Brito MC, de Paiva GO, Dos Santos CO, de Oliveira LM, de Araújo Ribeiro LA, de Lima JT, Lucchese AM, Silva FS. Relaxant effect of Lippia origanoides essential oil in guinea-pig trachea smooth muscle involves potassium channels and soluble guanylyl cyclase. JOURNAL OF ETHNOPHARMACOLOGY 2018; 220:16-25. [PMID: 29609011 DOI: 10.1016/j.jep.2018.03.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 03/17/2018] [Accepted: 03/29/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Lippia origanoides H.B.K. is an aromatic species used in folk medicine to treat respiratory diseases, including asthma. AIM OF THE STUDY The aim of this work was to evaluate the relaxing potential and mechanism of action of the L. origanoides (LOO) essential oil in isolated guinea-pig trachea. MATERIALS AND METHODS Leaves from L. origanoides were collected at experimental fields under organic cultivation, at the Forest Garden of Universidade Estadual de Feira de Santana. Essential oil was extracted by hydrodistillation, analyzed by GC/FID and GC/MS and the volatile constituents were identified. Spasmolytic activity and relaxant mechanism of LOO were assayed in isolated guinea-pig trachea contracted with histamine, carbachol or hyperpolarizing KCl. RESULTS Chemical analysis revealed the presence of carvacrol (53.89%) as major constituent. LOO relaxed isolated guinea-pig trachea pre-contracted with KCl 60 mM [EC50 = 30.02 μg/mL], histamine 1 µM [EC50 = 9.28 μg/mL] or carbachol 1 µM [EC50 = 51.80 μg/mL]. The pre-incubation of glibenclamide, CsCl, propranolol, indomethacin, hexamethonium, aminophylline or L-NAME in histamine-induced contractions did not alter significantly the relaxant effect of LOO. However, the presence of 4-aminopyridine, tetraethylammonium or methylene blue reduced LOO effect, while the presence of dexamethasone or atropine potentialized the LOO relaxant effect. LOO pre-incubation inhibited carbachol-evoked contractions, with this effect potentialized in the presence of sodium nitroprusside and blocked in the presence of ODQ. CONCLUSIONS The relaxant mechanism of LOO on the tracheal smooth muscle possibly involves stimulating of soluble guanylyl cyclase with consequent activation of the voltage-gated and Ca2+-activated K+ channels.
Collapse
Affiliation(s)
| | - Mariana Coelho Brito
- Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| | | | | | - Lenaldo Muniz de Oliveira
- Horto Florestal, Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana (UEFS), Brazil.
| | - Luciano Augusto de Araújo Ribeiro
- Pós-graduação em Recursos Naturais do Semiárido, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil; Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| | - Julianeli Tolentino de Lima
- Pós-graduação em Recursos Naturais do Semiárido, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil; Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| | - Angélica Maria Lucchese
- Laboratório de Química de Produtos Naturais e Bioativos, Departamento de Ciências Exatas, Universidade Estadual de Feira de Santana (UEFS), Brazil.
| | - Fabrício Souza Silva
- Pós-graduação em Recursos Naturais do Semiárido, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil; Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| |
Collapse
|
5
|
Ijpma G, Kachmar L, Matusovsky OS, Bates JHT, Benedetti A, Martin JG, Lauzon AM. Human trachealis and main bronchi smooth muscle are normoresponsive in asthma. Am J Respir Crit Care Med 2015; 191:884-93. [PMID: 25695616 DOI: 10.1164/rccm.201407-1296oc] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
RATIONALE Airway smooth muscle (ASM) plays a key role in airway hyperresponsiveness (AHR) but it is unclear whether its contractility is intrinsically changed in asthma. OBJECTIVES To investigate whether key parameters of ASM contractility are altered in subjects with asthma. METHODS Human trachea and main bronchi were dissected free of epithelium and connective tissues and suspended in a force-length measurement set-up. After equilibration each tissue underwent a series of protocols to assess its methacholine dose-response relationship, shortening velocity, and response to length oscillations equivalent to tidal breathing and deep inspirations. MEASUREMENTS AND MAIN RESULTS Main bronchi and tracheal ASM were significantly hyposensitive in subjects with asthma compared with control subjects. Trachea and main bronchi did not show significant differences in reactivity to methacholine and unloaded tissue shortening velocity (Vmax) compared with control subjects. There were no significant differences in responses to deep inspiration, with or without superimposed tidal breathing oscillations. No significant correlations were found between age, body mass index, or sex and sensitivity, reactivity, or Vmax. CONCLUSIONS Our data show that, in contrast to some animal models of AHR, human tracheal and main bronchial smooth muscle contractility is not increased in asthma. Specifically, our results indicate that it is highly unlikely that ASM half-maximum effective concentration (EC50) or Vmax contribute to AHR in asthma, but, because of high variability, we cannot conclude whether or not asthmatic ASM is hyperreactive.
Collapse
|
6
|
Chitano P, Wang L, Degan S, Worthington CL, Pozzato V, Hussaini SH, Turner WC, Dorscheid DR, Murphy TM. Ovalbumin sensitization of guinea pig at birth prevents the ontogenetic decrease in airway smooth muscle responsiveness. Physiol Rep 2014; 2:2/12/e12241. [PMID: 25501429 PMCID: PMC4332219 DOI: 10.14814/phy2.12241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Airway smooth muscle (ASM) displays a hyperresponsive phenotype at young age and becomes less responsive in adulthood. We hypothesized that allergic sensitization, which causes ASM hyperresponsiveness and typically occurs early in life, prevents the ontogenetic loss of the ASM hyperresponsive phenotype. We therefore studied whether neonatal allergic sensitization, not followed by later allergen challenges, alters the ontogenesis of ASM properties. We neonatally sensitized guinea pigs to ovalbumin and studied them at 1 week, 3 weeks, and 3 months (adult). A Schultz‐Dale response in isolated tracheal rings confirmed sensitization. The occurrence of inflammation was evaluated in the blood and in the submucosa of large airways. We assessed ASM function in tracheal strips as ability to produce force and shortening. ASM content of vimentin was also studied. A Schultz‐Dale response was observed in all 3‐week or older sensitized animals. A mild inflammatory process was characterized by eosinophilia in the blood and in the airway submucosa. Early life sensitization had no effect on ASM force generation, but prevented the ontogenetic decline of shortening velocity and the increase in resistance to shortening. Vimentin increased with age in control but not in sensitized animals. Allergic sensitization at birth without subsequent allergen exposures is sufficient to prevent normal ASM ontogenesis, inducing persistence to adulthood of an ASM hyperresponsive phenotype. Airway smooth muscle (ASM) displays a hyperresponsive phenotype at young age and becomes less responsive in adulthood. In this study, we found that allergic sensitization at birth without subsequent allergen exposures is sufficient to prevent normal ASM ontogenesis, inducing persistence to adulthood of an ASM hyperresponsive phenotype.
Collapse
Affiliation(s)
- Pasquale Chitano
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina James Hogg Research Centre, Institute for Heart and Lung Innovation and Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lu Wang
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina James Hogg Research Centre, Institute for Heart and Lung Innovation and Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Simone Degan
- Duke Center for Molecular and Biomolecular Imaging, Duke University Medical Center, Durham, North Carolina Duke Department of Radiology, Duke University Medical Center, Durham, North Carolina
| | - Charles L Worthington
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina
| | - Valeria Pozzato
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina
| | - Syed H Hussaini
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina
| | - Wesley C Turner
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina
| | - Delbert R Dorscheid
- James Hogg Research Centre, Institute for Heart and Lung Innovation and Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Thomas M Murphy
- Division of Pediatric Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina
| |
Collapse
|
7
|
Accumulating evidence for increased velocity of airway smooth muscle shortening in asthmatic airway hyperresponsiveness. J Allergy (Cairo) 2012; 2012:156909. [PMID: 23319963 PMCID: PMC3540810 DOI: 10.1155/2012/156909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 12/06/2012] [Indexed: 11/18/2022] Open
Abstract
It remains unclear whether airway smooth muscle (ASM) mechanics is altered in asthma. While efforts have originally focussed on contractile force, some evidence points to an increased velocity of shortening. A greater rate of airway renarrowing after a deep inspiration has been reported in asthmatics compared to controls, which could result from a shortening velocity increase. In addition, we have recently shown in rats that increased shortening velocity correlates with increased muscle shortening, without increasing muscle force. Nonetheless, establishing whether or not asthmatic ASM shortens faster than that of normal subjects remains problematic. Endobronchial biopsies provide excellent tissue samples because the patients are well characterized, but the size of the samples allows only cell level experiments. Whole human lungs from transplant programs suffer primarily from poor patient characterization, leading to high variability. ASM from several animal models of asthma has shown increased shortening velocity, but it is unclear whether this is representative of human asthma. Several candidates have been suggested as responsible for increased shortening velocity in asthma, such as alterations in contractile protein expression or changes in the contractile apparatus structure. There is no doubt that more remains to be learned about the role of shortening velocity in asthma.
Collapse
|
8
|
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.
Collapse
Affiliation(s)
- Adrian R West
- School of Biomedical Engineering, Dalhousie University, Nova Scotia, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Chitano P. Models to understand contractile function in the airways. Pulm Pharmacol Ther 2011; 24:444-51. [PMID: 21511049 DOI: 10.1016/j.pupt.2011.04.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 11/25/2022]
Abstract
Although the role of contractile function in the airways is controversial, there is general consensus on the importance of airway smooth muscle (ASM) as a therapeutic target for diseases characterized by airway obstruction, such as asthma or chronic obstructive pulmonary disease. Indeed, the use of bronchodilators to relax ASM is the most common and effective practice to treat airflow obstruction. Excessive pathologic bronchoconstriction may originate from primary alterations of ASM mechanical function and/or from the effects exerted on ASM function by disease processes, such as inflammation and remodeling. An in depth knowledge of the potentially multiple mechanisms that distinctively regulate primary and secondary alterations in ASM contractile function would be essential for the development of new therapeutic approaches aimed at preventing the occurrence or reducing the severity of bronchoconstriction. The present review discusses studies that have addressed the mechanisms of altered ASM contractile function in models of airway hyperresponsiveness. Although not comprehensively, in the present review, animal models of intrinsic airway hyperresponsiveness, normal ontogenesis, and allergic sensitization are analyzed in the attempt to summarize the current knowledge on regulatory mechanisms of ASM contractile function in health and disease. Studies in human ASM and the need for additional models to understand contractile function in the airways are also discussed.
Collapse
Affiliation(s)
- Pasquale Chitano
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA.
| |
Collapse
|
10
|
Bossé Y, Paré PD, Seow CY. Airway wall remodeling in asthma: from the epithelial layer to the adventitia. Curr Allergy Asthma Rep 2008; 8:357-66. [PMID: 18606090 DOI: 10.1007/s11882-008-0056-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Asthma is an episodic respiratory syndrome caused by several pathogenic processes. This recurrent syndrome is associated with an accelerated decline in lung function and increase in airway obstruction over time. The reduced lung function is a consequence of tissue restructuring of all the components of the airway wall: 1) epithelium metaplasia; 2) altered quantity, composition, and distribution of extracellular matrix components; 3) microvascular remodeling; and 4) increase of airway smooth muscle mass. How these structural changes affect lung functions is not entirely clear. Deeper understandings of the altered structure and related functional impairment are important for gaining insights into the mechanisms underlying asthma. This review describes the tissue remodeling observed in different compartments of the asthmatic airway wall, from the airway lumen to adventitia. The underlying mechanisms driving the remodeling processes are also briefly reviewed.
Collapse
Affiliation(s)
- Ynuk Bossé
- James Hogg iCAPTURE Centre/St. Paul's Hospital, Room 166, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada.
| | | | | |
Collapse
|
11
|
Wang L, Pozzato V, Turato G, Madamanchi A, Murphy TM, Chitano P. Reduced spontaneous relaxation in immature guinea pig airway smooth muscle is associated with increased prostanoid release. Am J Physiol Lung Cell Mol Physiol 2008; 294:L964-73. [PMID: 18326825 DOI: 10.1152/ajplung.00401.2007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway smooth muscle (ASM) from infant guinea pigs has less spontaneous relaxation during stimulation than ASM from adults. Inhibition of cyclooxygenase (COX), which catalyzes the production of prostanoids, increases this relaxation in infant ASM and abolishes age differences, thus suggesting that prostanoids reduce relaxation in infant ASM. In this study, we investigated whether leukotrienes are also involved in reducing spontaneous relaxation; whether the two COX isoforms, COX-1 and COX-2, differentially regulate spontaneous relaxation; and whether prostanoid release is developmentally regulated in guinea pig ASM. In different age groups, we measured relaxation during and after electrical stimulation in tracheal strips as well as prostanoid release from tracheal segments. Relaxation was studied in the absence and in the presence of a lipoxygenase inhibitor, a cysteinyl leukotriene receptor-1 antagonist, a COX-1 inhibitor, or a COX-2 inhibitor. We found that inhibition of lipoxygenase or cysteinyl leukotriene receptor-1 antagonism did not increase spontaneous relaxation at any age, thus excluding a role for leukotrienes in this phenomenon. Inhibition of COX-2, but not COX-1, promoted spontaneous relaxation. The basal release of prostanoids was more abundant in tissue from infant animals and decreased significantly with age. Thromboxane B2 was the most abundant metabolite released at all ages. Electrical stimulation and epithelium removal did not affect the age difference in prostanoid release. We conclude that increased basal prostanoid release contributes to the reduced spontaneous relaxation in immature guinea pig ASM compared with older animals. By regulating ASM relaxation, prostanoids may play a role in the airway hyperresponsiveness at a young age.
Collapse
Affiliation(s)
- Lu Wang
- Division of Pediatric Pulmonary Medicine, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | | | | | | | | | | |
Collapse
|
12
|
Chitano P, Wang L, Mason SN, Auten RL, Potts EN, Foster WM, Sturrock A, Kennedy TP, Hoidal JR, Murphy TM. Airway smooth muscle relaxation is impaired in mice lacking the p47phox subunit of NAD(P)H oxidase. Am J Physiol Lung Cell Mol Physiol 2007; 294:L139-48. [PMID: 17993584 PMCID: PMC3391573 DOI: 10.1152/ajplung.00384.2007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
NAD(P)H oxidase is one of the critical enzymes mediating cellular production of reactive oxygen species and has a central role in airway smooth muscle (ASM) cell proliferation. Since reactive oxygen species also affect ASM contractile response, we hypothesized a regulatory role of NAD(P)H oxidase in ASM contractility. We therefore studied ASM function in wild-type mice (C57BL/6J) and mice deficient in a component (p47phox) of NAD(P)H oxidase. In histological sections of the trachea, we found that the area occupied by ASM was 17% more in p47(phox-/-) than in wild-type mice. After correcting for the difference in ASM content, we found that force generation did not vary between the two genotypes. Similarly, their ASM shortening velocity, maximal power, and sensitivity to acetylcholine, as well as airway responsiveness to methacholine in vivo, were not significantly different. The main finding of this study was a significantly reduced ASM relaxation in p47phox-/- compared with wild-type mice both during the stimulus and after the end of stimulation. The tension relaxation attained at the 20th second of electric field stimulation was, respectively, 17.6 +/- 2.4 and 9.2 +/- 2.3% in null and wild-type mice (P <0.01 by t-test). Similar significant differences were found in the rate of tension relaxation and the time required to reduce tension by one-half. Our data suggest that NAD(P)H oxidase may have a role in the structural arrangement and mechanical properties of the airway tissue. Most importantly, we report the first evidence that the p47phox subunit of NAD(P)H oxidase plays a role in ASM relaxation.
Collapse
Affiliation(s)
- Pasquale Chitano
- Dept. of Pediatrics and Neonatal Perinatal Research Institute, Duke Univ. Medical Center, Rm. 302, Bell Bldg., Box 2994, Durham, NC 27710, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|