151
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Noble PB, Jones RL, Cairncross A, Elliot JG, Mitchell HW, James AL, McFawn PK. Airway narrowing and bronchodilation to deep inspiration in bronchial segments from subjects with and without reported asthma. J Appl Physiol (1985) 2013; 114:1460-71. [PMID: 23493364 DOI: 10.1152/japplphysiol.01489.2012] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study presents preliminary findings on how structural/functional abnormalities of the airway wall relate to excessive airway narrowing and reduced bronchodilatory response to deep inspiration (DI) in subjects with a history of asthma. Bronchial segments were acquired from subjects undergoing surgery, mostly to remove pulmonary neoplasms. Subjects reported prior doctor-diagnosed asthma ( n = 5) or had no history of asthma ( n = 8). In vitro airway narrowing in response to acetylcholine was assessed to determine maximal bronchoconstriction and sensitivity, under static conditions and during simulated tidal and DI maneuvers. Fixed airway segments were sectioned for measurement of airway wall dimensions, particularly the airway smooth muscle (ASM) layer. Airways from subjects with a history of asthma had increased ASM ( P = 0.014), greater maximal airway narrowing under static conditions ( P = 0.003), but no change in sensitivity. Maximal airway narrowing was positively correlated with the area of the ASM layer ( r = 0.58, P = 0.039). In tidally oscillating airways, DI produced bronchodilation in airways from the control group ( P = 0.0001) and the group with a history of asthma ( P = 0.001). While bronchodilation to DI was reduced with increased airway narrowing ( P = 0.02; r = −0.64)), when the level of airway narrowing was matched, there was no difference in magnitude of bronchodilation to DI between groups. Results suggest that greater ASM mass in asthma contributes to exaggerated airway narrowing in vivo. In comparison, the airway wall in asthma may have a normal response to mechanical stretch during DI. We propose that increased maximal airway narrowing and the reduced bronchodilatory response to DI in asthma are independent.
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Affiliation(s)
- Peter B. Noble
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Perth, Western Australia, Australia
- Centre for Neonatal Research and Education, School of Paediatrics and Child Health, University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - Robyn L. Jones
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Perth, Western Australia, Australia; and
- School of Medicine and Pharmacology, University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - Alvenia Cairncross
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - John G. Elliot
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Perth, Western Australia, Australia; and
- School of Medicine and Pharmacology, University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - Howard W. Mitchell
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - Alan L. James
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Perth, Western Australia, Australia; and
- School of Medicine and Pharmacology, University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - Peter K. McFawn
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Perth, Western Australia, Australia
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152
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Katsumoto TR, Kudo M, Chen C, Sundaram A, Callahan EC, Zhu JW, Lin J, Rosen CE, Manz BN, Lee JW, Matthay MA, Huang X, Sheppard D, Weiss A. The phosphatase CD148 promotes airway hyperresponsiveness through SRC family kinases. J Clin Invest 2013; 123:2037-48. [PMID: 23543053 DOI: 10.1172/jci66397] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 02/07/2013] [Indexed: 01/10/2023] Open
Abstract
Increased airway smooth muscle (ASM) contractility and the development of airway hyperresponsiveness (AHR) are cardinal features of asthma, but the signaling pathways that promote these changes are poorly understood. Tyrosine phosphorylation is tightly regulated by the opposing actions of protein tyrosine kinases and phosphatases, but little is known about whether tyrosine phosphatases influence AHR. Here, we demonstrate that genetic inactivation of receptor-like protein tyrosine phosphatase J (Ptprj), which encodes CD148, protected mice from the development of increased AHR in two different asthma models. Surprisingly, CD148 deficiency minimally affected the inflammatory response to allergen, but significantly altered baseline pulmonary resistance. Mice specifically lacking CD148 in smooth muscle had decreased AHR, and the frequency of calcium oscillations in CD148-deficient ASM was substantially attenuated, suggesting that signaling pathway alterations may underlie ASM contractility. Biochemical analysis of CD148-deficient ASM revealed hyperphosphorylation of the C-terminal inhibitory tyrosine of SRC family kinases (SFKs), implicating CD148 as a critical positive regulator of SFK signaling in ASM. The effect of CD148 deficiency on ASM contractility could be mimicked by treatment of both mouse trachea and human bronchi with specific SFK inhibitors. Our studies identify CD148 and the SFKs it regulates in ASM as potential targets for the treatment of AHR.
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Affiliation(s)
- Tamiko R Katsumoto
- Division of Rheumatology and Rosalind Russell Medical Research Center for Arthritis, University of California San Francisco (UCSF), San Francisco, California, USA
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153
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Song Y, Hong J, Liu D, Lin Q, Lai G. 1,25-dihydroxyvitamin D3 inhibits nuclear factor kappa B activation by stabilizing inhibitor IκBα via mRNA stability and reduced phosphorylation in passively sensitized human airway smooth muscle cells. Scand J Immunol 2013; 77:109-16. [PMID: 23126502 DOI: 10.1111/sji.12006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/10/2012] [Indexed: 10/27/2022]
Abstract
Excessive activation of nuclear transcription factor-κB (NF-κB) is involved in human airway smooth muscle cells (HASMCs) activities in asthma. We investigated the effects of 1,25 - dihydroxyvitamin D3 [1,25 - (OH) 2D3] on the NF- κB signaling pathway in passively sensitized HASMCs and the molecular mechanisms involved. HASMCs were treated with either healthy controls' serum, asthma patients' serum or pretreated with 1,25 - (OH) 2D3 prior to treatment with asthmatics' serum. At 1 h after serum treatment: electrophoretic mobility shift assay (EMSA) was used to detect NF-κB DNA binding activity; immunocytochemical staining was used to observe the nuclear translocation of NF-κB p65; Western blots were used for NF-κB p65, IκBα, and phospho-IκBα protein levels and the nuclear translocation of NF-κB p65; real-time quantitative PCR was used for NF-κB p65 and IκBα mRNA expressions; and actinomycin D treatment was used to determine IκBα mRNA stability. Our major findings were: (1) 1,25 - (OH) 2D3 significantly reduced asthma serum passively sensitized HASMCs NF-κB DNA binding activity and inhibited the nuclear translocation of NF-κB p65; (2) 1,25 - (OH) 2D3 increased the stability of IκBα mRNA with reduced IκBα phosphorylation in asthma serum passively sensitized HASMCs and significantly increased IκBα expression in these HASMCs. Inhibiting NF-κB signalling with 1,25 - dihydroxyvitamin D3 may be a therapeutic approach for controlling HASMC-related remodelling in asthma.
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Affiliation(s)
- Y Song
- Department of Pulmonary and Critical Care Medicine, Fuzhou General Hospital of Nanjing Military Command, Dongfang Hospital, Xiamen University, Fuzhou, China
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154
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Xue Z, Zhang W, Desai LP, Gao H, Gunst SJ, Tepper RS. Increased mechanical strain imposed on murine lungs during ventilation in vivo depresses airway responsiveness and activation of protein kinase Akt. J Appl Physiol (1985) 2013; 114:1506-10. [PMID: 23493362 DOI: 10.1152/japplphysiol.01460.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Continuous positive airway pressure (CPAP) administered to tracheostomized rabbits and ferrets for 4 days or 2 wk suppresses bronchial reactivity in vivo and suppresses airway reactivity in lobes and tracheal segments isolated from these animals. In vitro studies of canine tracheal smooth muscle tissues indicate that mechanical loading suppresses the activation of the growth regulatory kinase, Akt, and that Akt is a negative regulator of smooth muscle differentiation. The transduction of mechanical signals in the tracheal tissues in vitro is mediated by integrin-associated adhesion complexes. To determine whether airway responsiveness and Akt activation are modulated by mechanical loads applied for short time periods to the airways of living animals in vivo, mice were mechanically ventilated for 2 h with high (5 cmH2O) or low (0-1 cmH2O) positive end-expiratory pressure (PEEP) and then ventilated at low PEEP for 30 min. Ventilation of mice with PEEP in vivo for 2 h depressed airway responsiveness to methacholine measured in vivo subsequent to the PEEP treatment. Airway narrowing in vitro in intraparenchymal airways in isolated lung slices and contractile responses of isolated tracheal segments in vitro were suppressed for at least 6 h subsequent to the in vivo exposure to PEEP. Tracheal segments isolated from high PEEP-treated mice exhibited significantly lower levels of Akt activation than tracheae from low PEEP-treated mice. The results indicate that mechanical loads imposed in vivo result in physiological and biochemical changes in the airway tissues after a relatively short 2-h period of in vivo loading.
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Affiliation(s)
- Z Xue
- Department of Pediatrics Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
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155
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Billington CK, Ojo OO, Penn RB, Ito S. cAMP regulation of airway smooth muscle function. Pulm Pharmacol Ther 2013; 26:112-20. [PMID: 22634112 PMCID: PMC3574867 DOI: 10.1016/j.pupt.2012.05.007] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/14/2012] [Accepted: 05/17/2012] [Indexed: 12/11/2022]
Abstract
Agonists activating β(2)-adrenoceptors (β(2)ARs) on airway smooth muscle (ASM) are the drug of choice for rescue from acute bronchoconstriction in patients with both asthma and chronic obstructive pulmonary disease (COPD). Moreover, the use of long-acting β-agonists combined with inhaled corticosteroids constitutes an important maintenance therapy for these diseases. β-Agonists are effective bronchodilators due primarily to their ability to antagonize ASM contraction. The presumed cellular mechanism of action involves the generation of intracellular cAMP, which in turn can activate the effector molecules cAMP-dependent protein kinase (PKA) and Epac. Other agents such as prostaglandin E(2) and phosphodiesterase inhibitors that also increase intracellular cAMP levels in ASM, can also antagonize ASM contraction, and inhibit other ASM functions including proliferation and migration. Therefore, β(2)ARs and cAMP are key players in combating the pathophysiology of airway narrowing and remodeling. However, limitations of β-agonist therapy due to drug tachyphylaxis related to β(2)AR desensitization, and recent findings regarding the manner in which β(2)ARs and cAMP signal, have raised new and interesting questions about these well-studied molecules. In this review we discuss current concepts regarding β(2)ARs and cAMP in the regulation of ASM cell functions and their therapeutic roles in asthma and COPD.
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Affiliation(s)
- Charlotte K Billington
- Division of Therapeutics and Molecular Medicine, The University of Nottingham, Nottingham NG7 2UH, UK.
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156
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Doeing DC, Solway J. Airway smooth muscle in the pathophysiology and treatment of asthma. J Appl Physiol (1985) 2013; 114:834-43. [PMID: 23305987 DOI: 10.1152/japplphysiol.00950.2012] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Airway smooth muscle (ASM) plays an integral part in the pathophysiology of asthma. It is responsible for acute bronchoconstriction, which is potentiated by constrictor hyperresponsiveness, impaired relaxation and length adaptation. ASM also contributes to airway remodeling and inflammation in asthma. In light of this, ASM is an important target in the treatment of asthma.
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Affiliation(s)
- Diana C Doeing
- Department of Medicine, University of Chicago, Chicago, IL, USA.
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157
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Kumawat K, Menzen MH, Bos IST, Baarsma HA, Borger P, Roth M, Tamm M, Halayko AJ, Simoons M, Prins A, Postma DS, Schmidt M, Gosens R. Noncanonical WNT-5A signaling regulates TGF-β-induced extracellular matrix production by airway smooth muscle cells. FASEB J 2012; 27:1631-43. [PMID: 23254341 DOI: 10.1096/fj.12-217539] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Transforming growth factor β (TGF-β), a key mediator of fibrotic responses, is increased in asthma and drives airway remodeling by inducing expression of extracellular matrix (ECM) proteins. We investigated the molecular mechanisms underlying TGF-β-induced ECM expression by airway smooth muscle cells and demonstrate a novel link between TGF-β and Wingless/integrase 1 (WNT) signaling in ECM deposition. Airway smooth muscle expresses abundant WNT ligands, with the noncanonical WNT-5A being the most profoundly expressed. Interestingly, WNT-5A shows ∼2-fold higher abundance in airway smooth muscle cells isolated from individuals with asthma than individuals without asthma. WNT-5A is markedly induced in response to TGF-β (4-16-fold; EC₅₀ 0.3 ng/ml) and is required for collagen and fibronectin expression by airway smooth muscle. WNT-5A engages noncanonical WNT signaling pathways, as inhibition of Ca(2+) and c-Jun N-terminal kinase (JNK) signaling attenuated this TGF-β response, whereas the canonical WNT antagonist Dickkopf 1 (DKK-1) did not. Accordingly, WNT-5A induced JNK phosphorylation and nuclear translocation of nuclear factor of activated T cells c1 (NFATc1). Furthermore, silencing of the WNT-5A receptors Frizzled 8 (FZD8) and RYK attenuated TGF-β-induced ECM expression. Collectively, these findings demonstrate that noncanonical WNT-5A signaling is activated by and necessary for TGF-β-induced ECM production by airway smooth muscle cells, which could have significance in asthma pathogenesis.
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Affiliation(s)
- Kuldeep Kumawat
- Department of Molecular Pharmacology, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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158
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Zhang CH, Li Y, Zhao W, Lifshitz LM, Li H, Harfe BD, Zhu MS, ZhuGe R. The transmembrane protein 16A Ca(2+)-activated Cl- channel in airway smooth muscle contributes to airway hyperresponsiveness. Am J Respir Crit Care Med 2012; 187:374-81. [PMID: 23239156 DOI: 10.1164/rccm.201207-1303oc] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RATIONALE Asthma is a chronic inflammatory disorder with a characteristic of airway hyperresponsiveness (AHR). Ca(2+)-activated Cl(-) [Cl((Ca))] channels are inferred to be involved in AHR, yet their molecular nature and the cell type they act within to mediate this response remain unknown. OBJECTIVES Transmembrane protein 16A (TMEM16A) and TMEM16B are Cl((Ca)) channels, and activation of Cl((Ca)) channels in airway smooth muscle (ASM) contributes to agonist-induced airway contraction. We hypothesized that Tmem16a and/or Tmem16b encode Cl((Ca)) channels in ASM and mediate AHR. METHODS We assessed the expression of the TMEM16 family, and the effects of niflumic acid and benzbromarone on AHR and airway contraction, in an ovalbumin-sensitized mouse model of chronic asthma. We also cloned TMEM16A from ASM and examined the Cl(-) currents it produced in HEK293 cells. We further studied the impacts of TMEM16A deletion on Ca(2+) agonist-induced cell shortening, and on Cl((Ca)) currents activated by Ca(2+) sparks (localized, short-lived Ca(2+) transients due to the opening of ryanodine receptors) in mouse ASM cells. MEASUREMENTS AND MAIN RESULTS TMEM16A, but not TMEM16B, is expressed in ASM cells and its expression in these cells is up-regulated in ovalbumin-sensitized mice. Niflumic acid and benzbromarone prevent AHR and contraction evoked by methacholine in ovalbumin-sensitized mice. TMEM16A produces Cl((Ca)) currents with kinetics similar to native Cl((Ca)) currents. TMEM16A deletion renders Ca(2+) sparks unable to activate Cl((Ca)) currents, and weakens caffeine- and methacholine-induced cell shortening. CONCLUSIONS Tmem16a encodes Cl((Ca)) channels in ASM and contributes to Ca(2+) agonist-induced contraction. In addition, up-regulation of TMEM16A and its augmented activation contribute to AHR in an ovalbumin-sensitized mouse model of chronic asthma. TMEM16A may represent a potential therapeutic target for asthma.
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Affiliation(s)
- Cheng-Hai Zhang
- Model Animal Research Center, Nanjing University, Nanjing, China
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159
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Muscarinic receptors and their antagonists in COPD: anti-inflammatory and antiremodeling effects. Mediators Inflamm 2012; 2012:409580. [PMID: 23226927 PMCID: PMC3512336 DOI: 10.1155/2012/409580] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/12/2012] [Indexed: 01/15/2023] Open
Abstract
Muscarinic receptors are expressed by most cell types and mediate cellular signaling of their natural ligand acetylcholine. Thereby, they control numerous central and peripheral physiological organ responses to neuronal activity. In the human lung, muscarinic receptors are predominantly expressed by smooth muscle cells, epithelial cells, and fibroblasts. Antimuscarinic agents are used for the treatment of chronic obstructive pulmonary disease and to a lesser extent for asthma. They are primarily used as bronchodilators, but it is now accepted that they are also associated with anti-inflammatory, antiproliferative, and antiremodeling effects. Remodeling of the small airways is a major pathology in COPD and impairs lung function through changes of the extracellular matrix. Glycosaminoglycans, particularly hyaluronic acid, and matrix metalloproteases are among extracellular matrix molecules that have been associated with tissue inflammation and remodeling in lung diseases, including chronic obstructive pulmonary disease and asthma. Since muscarinic receptors have been shown to influence the homeostasis of glycosaminoglycans and matrix metalloproteases, these molecules may be proved valuable endpoint targets in clinical studies for the pharmacological exploitation of the anti-inflammatory and antiremodeling effects of muscarinic inhibitors in the treatment of chronic obstructive pulmonary disease and asthma.
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160
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Lai G, Wu C, Hong J, Song Y. 1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) attenuates airway remodeling in a murine model of chronic asthma. J Asthma 2012; 50:133-40. [PMID: 23157452 DOI: 10.3109/02770903.2012.738269] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVES 1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) has immune- and inflammation-modulating properties in asthma, but its possible effects on asthmatic airway remodeling remain uncertain. In this study, we investigated the effects of 1,25-(OH)(2)D(3) on airway remodeling in a murine model of chronic asthma and investigated its role in regulating nuclear factor-κB (NF-κB) activation. METHODS BALB/c mice were sensitized to ovalbumin (OVA) and subsequently exposed to intranasal OVA challenges for 9 weeks. Some mice also received an intraperitoneal injection of 1,25-(OH)(2)D(3) at the time of challenge. At the end of the challenge period, mice were evaluated for chronic airway inflammation and airway remodeling. Nuclear translocation of NF-κB p65 in lung tissue was examined by Western blot. Inhibitor of NF-κB alpha (IκBα) expression was determined by real-time quantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR) and Western blot. Phosphorylated IκBα protein expression was also determined by Western blot. RESULTS 1,25-(OH)(2)D(3) treatment reduced OVA-induced chronic inflammation in lung tissue and attenuated established structural changes of the airways, including subepithelial collagen deposition, goblet cell hyperplasia, and increased airway smooth muscle mass. 1,25-(OH)(2)D(3) also inhibited the nuclear translocation of NF-κB p65 in lung tissue. Concurrently, 1,25-(OH)(2)D(3) induced increased IκBα protein levels via inducing increased IκBα mRNA levels and decreased IκBα phosphorylation. CONCLUSION 1,25-(OH)(2)D(3) could attenuate asthmatic airway remodeling and its inhibition of NF-κB activation may underlie this protective effect.
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Affiliation(s)
- Guoxiang Lai
- Department of Respiratory Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, PR China
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161
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The importance of synergy between deep inspirations and fluidization in reversing airway closure. PLoS One 2012; 7:e48552. [PMID: 23144901 PMCID: PMC3493561 DOI: 10.1371/journal.pone.0048552] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 09/27/2012] [Indexed: 11/19/2022] Open
Abstract
Deep inspirations (DIs) and airway smooth muscle fluidization are two widely studied phenomena in asthma research, particularly for their ability (or inability) to counteract severe airway constriction. For example, DIs have been shown effectively to reverse airway constriction in normal subjects, but this is impaired in asthmatics. Fluidization is a connected phenomenon, wherein the ability of airway smooth muscle (ASM, which surrounds and constricts the airways) to exert force is decreased by applied strain. A maneuver which sufficiently strains the ASM, then, such as a DI, is thought to reduce the force generating capacity of the muscle via fluidization and hence reverse or prevent airway constriction. Understanding these two phenomena is considered key to understanding the pathophysiology of asthma and airway hyper-responsiveness, and while both have been extensively studied, the mechanism by which DIs fail in asthmatics remains elusive. Here we show for the first time the synergistic interaction between DIs and fluidization which allows the combination to provide near complete reversal of airway closure where neither is effective alone. This relies not just on the traditional model of airway bistability between open and closed states, but also the critical addition of previously-unknown oscillatory and chaotic dynamics. It also allows us to explore the types of subtle change which can cause this interaction to fail, and thus could provide the missing link to explain DI failure in asthmatics.
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162
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Airway Smooth Muscle Dynamics and Hyperresponsiveness: In and outside the Clinic. J Allergy (Cairo) 2012; 2012:157047. [PMID: 23118774 PMCID: PMC3483736 DOI: 10.1155/2012/157047] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/05/2012] [Indexed: 11/18/2022] Open
Abstract
The primary functional abnormality in asthma is airway hyperresponsiveness (AHR)-excessive airway narrowing to bronchoconstrictor stimuli. Our understanding of the underlying mechanism(s) producing AHR is incomplete. While structure-function relationships have been evoked to explain AHR (e.g., increased airway smooth muscle (ASM) mass in asthma) more recently there has been a focus on how the dynamic mechanical environment of the lung impacts airway responsiveness in health and disease. The effects of breathing movements such as deep inspiration reveal innate protective mechanisms in healthy individuals that are likely mediated by dynamic ASM stretch but which may be impaired in asthmatic patients and thereby facilitate AHR. This perspective considers the evidence for and against a role of dynamic ASM stretch in limiting the capacity of airways to narrow excessively. We propose that lung function measured after bronchial provocation in the laboratory and changes in lung function perceived by the patient in everyday life may be quite different in their dependence on dynamic ASM stretch.
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163
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Al-Moamary MS, Alhaider SA, Al-Hajjaj MS, Al-Ghobain MO, Idrees MM, Zeitouni MO, Al-Harbi AS, Al Dabbagh MM, Al-Matar H, Alorainy HS. The Saudi initiative for asthma - 2012 update: Guidelines for the diagnosis and management of asthma in adults and children. Ann Thorac Med 2012; 7:175-204. [PMID: 23189095 PMCID: PMC3506098 DOI: 10.4103/1817-1737.102166] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 09/19/2012] [Indexed: 11/15/2022] Open
Abstract
This an updated guidelines for the diagnosis and management of asthma, developed by the Saudi Initiative for Asthma (SINA) group, a subsidiary of the Saudi Thoracic Society. The main objective of SINA is to have updated guidelines, which are simple to understand and easy to use by non-asthma specialists, including primary care and general practice physicians. This new version includes updates of acute and chronic asthma management, with more emphasis on the use of Asthma Control Test in the management of asthma, and a new section on "difficult-to-treat asthma." Further, the section on asthma in children was re-written to cover different aspects in this age group. The SINA panel is a group of Saudi experts with well-respected academic backgrounds and experience in the field of asthma. The guidelines are formatted based on the available evidence, local literature, and the current situation in Saudi Arabia. There was an emphasis on patient-doctor partnership in the management that also includes a self-management plan. The approach adopted by the SINA group is mainly based on disease control as it is the ultimate goal of treatment.
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Affiliation(s)
- Mohamed S. Al-Moamary
- Department of Medicine, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Sami A. Alhaider
- Department of Pediatrics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Mohamed S. Al-Hajjaj
- Respiratory Division, Department of Medicine, Medical College, King Saud University, Riyadh, Saudi Arabia
| | - Mohammed O. Al-Ghobain
- Department of Medicine, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Majdy M. Idrees
- Pulmonary Division, Department of Medicine, Military Hospital, Riyadh, Saudi Arabia
| | - Mohammed O. Zeitouni
- Department of Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Adel S. Al-Harbi
- Department of Pediatrics, Military Hospital, Riyadh, Saudi Arabia
| | - Maha M. Al Dabbagh
- Department of Pediatrics, King Fahd Armed Forces Hospital, Jeddah, Saudi Arabia
| | - Hussain Al-Matar
- Department of Medicine, Imam Abdulrahman Al Faisal, Dammam, Saudi Arabia
| | - Hassan S. Alorainy
- Department of Respiratory Care, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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164
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Integrin and GPCR Crosstalk in the Regulation of ASM Contraction Signaling in Asthma. J Allergy (Cairo) 2012; 2012:341282. [PMID: 23056062 PMCID: PMC3465959 DOI: 10.1155/2012/341282] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 07/24/2012] [Indexed: 12/15/2022] Open
Abstract
Airway hyperresponsiveness (AHR) is one of the cardinal features of asthma. Contraction of airway smooth muscle (ASM) cells that line the airway wall is thought to influence aspects of AHR, resulting in excessive narrowing or occlusion of the airway. ASM contraction is primarily controlled by agonists that bind G protein-coupled receptor (GPCR), which are expressed on ASM. Integrins also play a role in regulating ASM contraction signaling. As therapies for asthma are based on symptom relief, better understanding of the crosstalk between GPCRs and integrins holds good promise for the design of more effective therapies that target the underlying cellular and molecular mechanism that governs AHR. In this paper, we will review current knowledge about integrins and GPCRs in their regulation of ASM contraction signaling and discuss the emerging concept of crosstalk between the two and the implication of this crosstalk on the development of agents that target AHR.
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165
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Chronic exposure to sulfur dioxide enhances airway hyperresponsiveness only in ovalbumin-sensitized rats. Toxicol Lett 2012; 214:320-7. [PMID: 23010223 DOI: 10.1016/j.toxlet.2012.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 09/12/2012] [Accepted: 09/14/2012] [Indexed: 11/21/2022]
Abstract
Sulfur dioxide (SO(2)) is a common air pollutant that triggers asthmatic symptoms, but its toxicological mechanisms are not fully understood. Specifically, it is unclear how airborne SO(2) affects airway hyperresponsiveness (AHR) - a hallmark feature of asthma. To this end, we investigated the effects of chronic exposure to SO(2) on AHR, airway inflammation, tissue remodeling, cell stiffness (G') and contractility of the airway smooth muscle cell (ASMC). Newborn Sprague-Dawley (SD) rats sensitized to ovalbumin (OVA) was used as the model to mimic asthmatic symptoms. The experimental results show that exposure to SO(2): (1) significantly increased Penh (an indicator of AHR) in the OVA-sensitized rats (p<0.01) but not in the normal rats (p>0.05), which correlated with the increase of airway smooth muscle mass; (2) increased IL-4 production in BALF of both the normal (p<0.05) and OVA-sensitized rats (p<0.001), but decreased IFN-γ in BALF of only the normal rats, and in serum only increased IL-4 production of the OVA-sensitized rats (p<0.001); (3) increased ASMC stiffness (G') and contractility only in the OVA-sensitized rats (p<0.001, p<0.05, respectively). Taken together, these results demonstrate that SO(2) may be a universal airway inflammatory factor, but more importantly, specific to exacerbating AHR in asthmatics only. These findings uncover a potential mechanism of SO(2)-induced health effects and may provide a basis for therapeutic targets.
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166
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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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167
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Gaga M, Zervas E, Samitas K, Bel EH. Severe asthma in adults: an orphan disease? Clin Chest Med 2012; 33:571-83. [PMID: 22929103 DOI: 10.1016/j.ccm.2012.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Severe asthma affects fewer than 10% of patients with asthma, is associated with a severe risk of death and disability, has a great impact on health and quality of life, and represents a huge cost to patients and society. Given the poor response to treatment and the side effects associated with medications for severe asthma, more efficient, cost-effective, and phenotype-specific medications are needed. Considering severe asthma as an orphan disease could encourage the pharmaceutical industry to stratify studies based on a more detailed characterization of study subjects at baseline, resulting in the development of novel therapeutic approaches.
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Affiliation(s)
- Mina Gaga
- 7th Respiratory Department and Asthma Centre, Athens Chest Hospital, 152 Mesogion Avenue, Athens 11527, Greece.
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168
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Black JL, Panettieri RA, Banerjee A, Berger P. Airway smooth muscle in asthma: just a target for bronchodilation? Clin Chest Med 2012; 33:543-58. [PMID: 22929101 DOI: 10.1016/j.ccm.2012.05.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Airway smooth muscle (ASM) has long been recognized as the main cell type responsible for bronchial hyperresponsiveness. It has, thus, been considered as a target for bronchodilation. In asthma, however, there is a complex relationship between ASM and inflammatory cells, such as mast cells and T lymphocytes. Moreover, the increased ASM mass in asthmatic airways is one of the key features of airway remodeling. This article aims to review the main concepts about the 3 possible roles of ASM in asthma: (1) contractile tone, (2) inflammatory response, and (3) remodeling.
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Affiliation(s)
- Judith L Black
- University of Sydney, Discipline of Pharmacology and Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, 2006, Australia
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169
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Abstract
To define the role of semaphorin 4A (Sema4A) in allergic response, we employed Sema4A⁻/⁻ and wild-type (WT) mice in the experimental model of ovalbumin (OVA)-induced allergic airway inflammation. We observed a selective increase in eosinophilic airway infiltration accompanied by bronchial epithelial cell hyperplasia in allergen-treated Sema4A⁻/⁻ mice relative to WT mice. This enhanced inflammatory response was associated with a selective increase in bronchoalveolar lavage (BAL) interleukin 13 (IL-13) content, augmented airway hyperreactivity, and lower regulatory T cell (Treg) numbers. In vivo allergen-primed Sema4A⁻/⁻ CD4+ T cells were more effective in transferring T helper type 2 (Th2) response to naive mice as compared with WT CD4+ T cells. T-cell proliferation and IL-13 productions in OVA₃₂₃₋₃₃₉-restimulated Sema4A⁻/⁻ cell cultures were upregulated. Generated bone marrow chimeras showed an equal importance of both lung-resident cell and inflammatory cell Sema4A expression in optimal disease regulation. These data provide a new insight into Sema4A biology and define Sema4A as an important regulator of Th2-driven lung pathophysiology.
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170
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Breen BJ, Donovan GM, Sneyd J, Tawhai MH. Quantifying parenchymal tethering in a finite element simulation of a human lung slice under bronchoconstriction. Respir Physiol Neurobiol 2012; 183:85-90. [PMID: 22732325 DOI: 10.1016/j.resp.2012.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 06/12/2012] [Accepted: 06/12/2012] [Indexed: 01/09/2023]
Abstract
Airway hyper-responsiveness (AHR), a hallmark of asthma, is a highly complex phenomenon characterised by multiple processes manifesting over a large range of length and time scales. Multiscale computational models have been derived to embody the experimental understanding of AHR. While current models differ in their derivation, a common assumption is that the increase in parenchymal tethering pressure P(teth) during airway constriction can be described using the model proposed by Lai-Fook (1979), which is based on intact lung experimental data for elastic moduli over a range of inflation pressures. Here we reexamine this relationship for consistency with a nonlinear elastic material law that has been parameterised to the pressure-volume behaviour of the intact lung. We show that the nonlinear law and Lai-Fook's relationship are consistent for small constrictions, but diverge when the constriction becomes large.
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Affiliation(s)
- Barbara J Breen
- Auckland Bioengineering Institute, University of Auckland, Private Bag 92019 Auckland Mail Centre, Auckland 1142, New Zealand.
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171
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Regulator of G protein signaling 2 is a key modulator of airway hyperresponsiveness. J Allergy Clin Immunol 2012; 130:968-76.e3. [PMID: 22704538 DOI: 10.1016/j.jaci.2012.05.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Revised: 03/29/2012] [Accepted: 05/01/2012] [Indexed: 01/28/2023]
Abstract
BACKGROUND Drugs targeting individual G protein-coupled receptors are used as asthma therapies, but this strategy is limited because of G protein-coupled receptor signal redundancy. Regulator of G protein signaling 2 (RGS2), an intracellular selective inhibitor of multiple bronchoconstrictor receptors, may play a central role in the pathophysiology and treatment of asthma. OBJECTIVE We defined functions and mechanisms of RGS2 in regulating airway hyperresponsiveness (AHR), the pathophysiologic hallmark of asthma. METHODS Real-time PCR and Western blot were used to determine changes in RGS2 expression in ovalbumin-sensitized/-challenged mice. We also used immunohistochemistry and real-time PCR to compare RGS2 expression between human asthmatic and control subjects. The AHR of RGS2 knockout mice was assessed by using invasive tracheostomy and unrestrained plethysmography. Effects of loss of RGS2 on mouse airway smooth muscle (ASM) remodeling, contraction, intracellular Ca(2+), and mitogenic signaling were determined in vivo and in vitro. RESULTS RGS2 was highly expressed in human and murine bronchial epithelium and ASM and was markedly downregulated in lungs of ovalbumin-sensitized/-challenged mice. Lung tissues and blood monocytes from asthma patients expressed significantly lower RGS2 protein (lung) and mRNA (monocytes) than from nonasthma subjects. The extent of reduction of RGS2 on human monocytes correlated with increased AHR. RGS2 knockout caused spontaneous AHR in mice. Loss of RGS2 augmented Ca(2+) mobilization and contraction of ASM cells. Loss of RGS2 also increased ASM mass and stimulated ASM cell growth via extracellular signal-regulated kinase and phosphatidylinositol 3-kinase pathways. CONCLUSION We identified RGS2 as a potent modulator of AHR and a potential novel therapeutic target for asthma.
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172
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Lauzon AM, Bates JHT, Donovan G, Tawhai M, Sneyd J, Sanderson MJ. A multi-scale approach to airway hyperresponsiveness: from molecule to organ. Front Physiol 2012; 3:191. [PMID: 22701430 PMCID: PMC3371674 DOI: 10.3389/fphys.2012.00191] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 05/21/2012] [Indexed: 12/13/2022] Open
Abstract
Airway hyperresponsiveness (AHR), a characteristic of asthma that involves an excessive reduction in airway caliber, is a complex mechanism reflecting multiple processes that manifest over a large range of length and time scales. At one extreme, molecular interactions determine the force generated by airway smooth muscle (ASM). At the other, the spatially distributed constriction of the branching airways leads to breathing difficulties. Similarly, asthma therapies act at the molecular scale while clinical outcomes are determined by lung function. These extremes are linked by events operating over intermediate scales of length and time. Thus, AHR is an emergent phenomenon that limits our understanding of asthma and confounds the interpretation of studies that address physiological mechanisms over a limited range of scales. A solution is a modular computational model that integrates experimental and mathematical data from multiple scales. This includes, at the molecular scale, kinetics, and force production of actin-myosin contractile proteins during cross-bridge and latch-state cycling; at the cellular scale, Ca2+ signaling mechanisms that regulate ASM force production; at the tissue scale, forces acting between contracting ASM and opposing viscoelastic tissue that determine airway narrowing; at the organ scale, the topographic distribution of ASM contraction dynamics that determine mechanical impedance of the lung. At each scale, models are constructed with iterations between theory and experimentation to identify the parameters that link adjacent scales. This modular model establishes algorithms for modeling over a wide range of scales and provides a framework for the inclusion of other responses such as inflammation or therapeutic regimes. The goal is to develop this lung model so that it can make predictions about bronchoconstriction and identify the pathophysiologic mechanisms having the greatest impact on AHR and its therapy.
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Affiliation(s)
- Anne-Marie Lauzon
- Meakins-Christie Laboratories, Department of Medicine, McGill University Montreal, QC, Canada
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173
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Maniatis NA, Chernaya O, Shinin V, Minshall RD. Caveolins and lung function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012. [PMID: 22411320 DOI: 10.1007/978-1-4614-1222-911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The primary function of the mammalian lung is to facilitate diffusion of oxygen to venous blood and to ventilate carbon dioxide produced by catabolic reactions within cells. However, it is also responsible for a variety of other important functions, including host defense and production of vasoactive agents to regulate not only systemic blood pressure, but also water, electrolyte and acid-base balance. Caveolin-1 is highly expressed in the majority of cell types in the lung, including epithelial, endothelial, smooth muscle, connective tissue cells, and alveolar macrophages. Deletion of caveolin-1 in these cells results in major functional aberrations, suggesting that caveolin-1 may be crucial to lung homeostasis and development. Furthermore, generation of mutant mice that under-express caveolin-1 results in severe functional distortion with phenotypes covering practically the entire spectrum of known lung diseases, including pulmonary hypertension, fibrosis, increased endothelial permeability, and immune defects. In this Chapter, we outline the current state of knowledge regarding caveolin-1-dependent regulation of pulmonary cell functions and discuss recent research findings on the role of caveolin-1 in various pulmonary disease states, including obstructive and fibrotic pulmonary vascular and inflammatory diseases.
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Affiliation(s)
- Nikolaos A Maniatis
- 2nd Department of Critical Care, National and Kapodistrian University of Athens Medical School, Athens, Greece
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174
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Jiang H, Xie Y, Abel PW, Toews ML, Townley RG, Casale TB, Tu Y. Targeting phosphoinositide 3-kinase γ in airway smooth muscle cells to suppress interleukin-13-induced mouse airway hyperresponsiveness. J Pharmacol Exp Ther 2012; 342:305-11. [PMID: 22543031 DOI: 10.1124/jpet.111.189704] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We recently reported that phosphoinositide 3-kinase γ (PI3Kγ) directly regulates airway smooth muscle (ASM) contraction by modulating Ca(2+) oscillations. Because ASM contraction plays a critical role in airway hyperresponsiveness (AHR) of asthma, the aim of the present study was to determine whether targeting PI3Kγ in ASM cells could suppress AHR in vitro and in vivo. Intranasal administration into mice of interleukin-13 (IL-13; 10 μg per mouse), a key pathophysiologic cytokine in asthma, induced AHR after 48 h, as assessed by invasive tracheostomy. Intranasal administration of a broad-spectrum PI3K inhibitor or a PI3Kγ-specific inhibitor 1 h before AHR assessment attenuated IL-13 effects. Airway responsiveness to bronchoconstrictor agonists was also examined in precision-cut mouse lung slices pretreated without or with IL-13 for 24 h. Acetylcholine and serotonin dose-response curves indicated that IL-13-treated lung slices had a 40 to 50% larger maximal airway constriction compared with controls. Furthermore, acetylcholine induced a larger initial Ca(2+) transient and increased Ca(2+) oscillations in IL-13-treated primary mouse ASM cells compared with control cells, correlating with increased cell contraction. As expected, PI3Kγ inhibitor treatment attenuated IL-13-augmented airway contractility of lung slices and ASM cell contraction. In both control and IL-13-treated ASM cells, small interfering RNA-mediated knockdown of PI3Kγ by 70% only reduced the initial Ca(2+) transient by 20 to 30% but markedly attenuated Ca(2+) oscillations and contractility of ASM cells by 50 to 60%. This report is the first to demonstrate that PI3Kγ in ASM cells is important for IL-13-induced AHR and that acute treatment with a PI3Kγ inhibitor can ameliorate AHR in a murine model of asthma.
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Affiliation(s)
- Haihong Jiang
- Department of Pharmacology, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178, USA
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175
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Gunst SJ, Panettieri RA. Point: alterations in airway smooth muscle phenotype do/do not cause airway hyperresponsiveness in asthma. J Appl Physiol (1985) 2012; 113:837-9. [PMID: 22518830 DOI: 10.1152/japplphysiol.00483.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- Susan J Gunst
- Department of Cell and Integrated Physiology Indianapolis, Indiana University School of Medicine, Indiana, USA.
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176
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Ma B, Bates JHT. Continuum vs. spring network models of airway-parenchymal interdependence. J Appl Physiol (1985) 2012; 113:124-9. [PMID: 22500006 DOI: 10.1152/japplphysiol.01578.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The outward tethering forces exerted by the lung parenchyma on the airways embedded within it are potent modulators of the ability of the airway smooth muscle to shorten. Much of our understanding of these tethering forces is based on treating the parenchyma as an elastic continuum; yet, on a small enough scale, the lung parenchyma in two dimensions would seem to be more appropriately described as a discrete spring network. We therefore compared how the forces and displacements in the parenchyma surrounding a contracting airway are predicted to differ depending on whether the parenchyma is modeled as an elastic continuum or as a spring network. When the springs were arranged hexagonally to represent alveolar walls, the predicted parenchymal stresses and displacements propagated substantially farther away from the airway than when the springs were arranged in a triangular pattern or when the parenchyma was modeled as a continuum. Thus, to the extent that the parenchyma in vivo behaves as a hexagonal spring network, our results suggest that the range of interdependence forces due to airway contraction may have a greater influence than was previously thought.
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Affiliation(s)
- Baoshun Ma
- Department of Medicine, University of Vermont, Burlington, Vermont 05405, USA
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177
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Yick CY, Ferreira DS, Annoni R, Thüsen JH, Kunst PW, Bel EH, Lutter R, Mauad T, Sterk PJ. Extracellular matrix in airway smooth muscle is associated with dynamics of airway function in asthma. Allergy 2012; 67:552-9. [PMID: 22229658 DOI: 10.1111/j.1398-9995.2011.02773.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2011] [Indexed: 11/30/2022]
Abstract
BACKGROUND Altered deposition of extracellular matrix (ECM) in the airway smooth muscle (ASM) layer as observed in asthma may influence ASM mechanical properties. We hypothesized that ECM in ASM is associated with airway function in asthma. First, we investigated the difference in ECM expression in ASM between asthma and controls. Second, we examined whether ECM expression is associated with bronchoconstriction and bronchodilation in vivo. METHODS Our cross-sectional study comprised 19 atopic mild asthma patients, 15 atopic and 12 nonatopic healthy subjects. Spirometry, methacholine responsiveness, deep-breath-induced bronchodilation (ΔR(rs) ) and bronchoscopy with endobronchial biopsies were performed. Positive staining of elastin, collagen I, III and IV, decorin, versican, fibronectin, laminin and tenascin in ASM was quantified as fractional area and mean density. Data were analysed using Pearson's or Spearman's correlation coefficient. RESULTS Extracellular matrix expression in ASM was not different between asthma and controls. In asthmatics, fractional area and mean density of collagen I and III were correlated with methacholine dose-response slope and ΔR(rs) , respectively (r = 0.71, P < 0.01; r = 0.60, P = 0.02). Furthermore, ASM collagen III and laminin in asthma were correlated with FEV(1) reversibility (r = -0.65, P = 0.01; r = -0.54, P = 0.04). CONCLUSION In asthma, ECM in ASM is related to the dynamics of airway function in the absence of differences in ECM expression between asthma and controls. This indicates that the ASM layer in its full composition is a major structural component in determining variable airways obstruction in asthma.
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Affiliation(s)
- C. Y. Yick
- Department of Respiratory Medicine; Academic Medical Centre; Amsterdam; the Netherlands
| | - D. S. Ferreira
- Department of Pathology; São Paulo University Medical School; USP; São Paulo; Brazil
| | - R. Annoni
- Department of Pathology; São Paulo University Medical School; USP; São Paulo; Brazil
| | | | - P. W. Kunst
- Department of Respiratory Medicine; Academic Medical Centre; Amsterdam; the Netherlands
| | - E. H. Bel
- Department of Respiratory Medicine; Academic Medical Centre; Amsterdam; the Netherlands
| | - R. Lutter
- Department of Respiratory Medicine; Academic Medical Centre; Amsterdam; the Netherlands
| | - T. Mauad
- Department of Pathology; São Paulo University Medical School; USP; São Paulo; Brazil
| | - P. J. Sterk
- Department of Respiratory Medicine; Academic Medical Centre; Amsterdam; the Netherlands
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178
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Regulation of airway inflammation and remodeling by muscarinic receptors: perspectives on anticholinergic therapy in asthma and COPD. Life Sci 2012; 91:1126-33. [PMID: 22406302 DOI: 10.1016/j.lfs.2012.02.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 02/09/2012] [Accepted: 02/13/2012] [Indexed: 12/15/2022]
Abstract
Acetylcholine is the primary parasympathetic neurotransmitter in the airways and an autocrine/paracrine secreted hormone from non-neuronal origins including inflammatory cells and airway structural cells. In addition to the well-known functions of acetylcholine in regulating bronchoconstriction and mucus secretion, it is increasingly evident that acetylcholine regulates inflammatory cell chemotaxis and activation, and also participates in signaling events leading to chronic airway wall remodeling that is associated with chronic obstructive airway diseases including asthma and COPD. As muscarinic receptors appear responsible for most of the pro-inflammatory and remodeling effects of acetylcholine, these findings have significant implications for anticholinergic therapy in asthma and COPD, which is selective for muscarinic receptors. Here, the regulatory role of acetylcholine in inflammation and remodeling in asthma and COPD will be discussed including the perspectives that these findings offer for anticholinergic therapy in these diseases.
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179
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Bates JHT, Stevenson CA, Aliyeva M, Lundblad LKA. Airway responsiveness depends on the diffusion rate of methacholine across the airway wall. J Appl Physiol (1985) 2012; 112:1670-7. [PMID: 22383507 DOI: 10.1152/japplphysiol.00703.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
During methacholine challenge tests of airway responsiveness, it is invariably assumed that the administered dose of agonist is accurately reflected in the dose that eventually reaches the airway smooth muscle (ASM). However, agonist must traverse a variety of tissue obstacles to reach the ASM, during which the agonist is subjected to both enzymatic breakdown and removal by the bronchial and pulmonary circulations. This raises the possibility that a significant fraction of the deposited agonist may never actually make it to the ASM. To understand the nature of this effect, we measured the time course of changes in airway resistance elicited by various durations of methacholine aerosol in mice. We fit to these data a computational model of a dynamically contracting airway responding to agonist that diffuses through an airway compartment, thereby obtaining rate constants that reflect the diffusive barrier to methacholine. We found that these barriers can contribute significantly to the time course of airway narrowing, raising the important possibility that alterations in the diffusive barrier presented by the airway wall may play a role in pathologically altered airway responsiveness.
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Affiliation(s)
- Jason H T Bates
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, USA.
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180
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Cyclin D1 in ASM Cells from Asthmatics Is Insensitive to Corticosteroid Inhibition. J Allergy (Cairo) 2012; 2012:307838. [PMID: 22500182 PMCID: PMC3303636 DOI: 10.1155/2012/307838] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 11/17/2011] [Indexed: 02/02/2023] Open
Abstract
Hyperplasia of airway smooth muscle (ASM) is a feature of the remodelled airway in asthmatics. We examined the antiproliferative effectiveness of the corticosteroid dexamethasone on expression of the key regulator of G1 cell cycle progression—cyclin D1—in ASM cells from nonasthmatics and asthmatics stimulated with the mitogen platelet-derived growth factor BB. While cyclin D1 mRNA and protein expression were repressed in cells from nonasthmatics in contrast, cyclin D1 expression in asthmatics was resistant to inhibition by dexamethasone. This was independent of a repressive effect on glucocorticoid receptor translocation. Our results corroborate evidence demonstrating that corticosteroids inhibit mitogen-induced proliferation only in ASM cells from subjects without asthma and suggest that there are corticosteroid-insensitive proliferative pathways in asthmatics.
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181
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Yang Z, Balenga N, Cooper PR, Damera G, Edwards R, Brightling CE, Panettieri RA, Druey KM. Regulator of G-protein signaling-5 inhibits bronchial smooth muscle contraction in severe asthma. Am J Respir Cell Mol Biol 2012; 46:823-32. [PMID: 22281988 DOI: 10.1165/rcmb.2011-0110oc] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Severe asthma is associated with fixed airway obstruction attributable to inflammation, copious luminal mucus, and increased airway smooth muscle (ASM) mass. Paradoxically, studies demonstrated that the hypertrophic and hyperplastic ASM characteristic of severe asthma has reduced contractile capacity. We compared the G-protein-coupled receptor (GPCR)-induced Ca(2+) mobilization and expression of GPCRs and signaling proteins related to procontractile signaling in ASM derived postmortem from subjects who died of nonrespiratory causes, with cells from subjects who died of asthma. Despite the increased or comparable expression of contraction-promoting GPCRs (bradykinin B2 or histamine H1 and protease-activated receptor 1, respectively) in asthmatic ASM cells relative to cells from healthy donors, asthmatic ASM cells exhibited reduced histamine-induced Ca(2+) mobilization and comparable responses to bradykinin and thrombin, suggesting a postreceptor signaling defect. Accordingly, the expression of regulator of G-protein signaling-5 (RGS5), an inhibitor of ASM contraction, was increased in cultured, asthmatic ASM cells and in bronchial smooth muscle bundles of both human subjects with asthma and allergen-challenged mice, relative to those of healthy human subjects or naive mice. The overexpression of RGS5 impaired the release of Ca(2+) to thrombin, histamine, and carbachol, and reduced the contraction of precision-cut lung slices to carbachol. These results suggest that increased RGS5 expression contributes to decreased myocyte shortening in severe and fatal asthma.
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Affiliation(s)
- Zhao Yang
- Molecular Signal Transduction Section, Laboratory of Allergic Diseases, National Insitute of Allergy and Infectious Diseases/NIH, 10 Center Drive, Bethesda, MD 20982, USA.
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182
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Vinchurkar S, Backer LD, Vos W, Holsbeke CV, Backer JD, Backer WD. A case series on lung deposition analysis of inhaled medication using functional imaging based computational fluid dynamics in asthmatic patients: effect of upper airway morphology and comparison with in vivo data. Inhal Toxicol 2012; 24:81-8. [PMID: 22260527 DOI: 10.3109/08958378.2011.644351] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONTEXT Asthma affects 20 million Americans resulting in an economic burden of approximately $18 billion in the US alone (Allergies and Asthma Foundation 2000; National Center for Environmental Health (NCEH) 1999). Research studies based on differences in patient-specific airway morphology for asthma and the associated effect on deposition of inhaled aerosols are currently not available in the literature. Therefore, the role of morphological variations such as upper airway (extrathoracic) occlusion is not well documented. OBJECTIVE Functional imaging based computational fluid dynamics (CFD) of the respiratory airways for five asthmatic subjects is performed in this study using computed tomography (CT) based patient-specific airway models and boundary conditions. METHODS CT scans for 5 asthma patients were used to reconstruct 3D lung models using segmentation software. An averaged inhalation profile and patient-specific lobar flow distribution were used to perform the simulation. The simulations were used to obtain deposition for BDP/Formoterol® HFA pMDI in the patient-specific airway models. RESULTS The lung deposition obtained using CFD was in excellent agreement with available in vivo data using the same product. Specifically, CFD resulted in 30% lung deposition, whereas in vivo lung deposition was reported to be approximately 31%. CONCLUSION It was concluded that a combination of patient-specific airway models and lobar boundary conditions can be used to obtain accurate lung deposition estimates. Lower lung deposition can be expected for patients with higher extrathoracic resistance. Novel respiratory drug delivery devices need to accommodate population sub-groups based on these morphological and anatomical differences in addition to subject age.
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183
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Rosenkranz SK, Rosenkranz RR, Hastmann TJ, Harms CA. High-intensity training improves airway responsiveness in inactive nonasthmatic children: evidence from a randomized controlled trial. J Appl Physiol (1985) 2012; 112:1174-83. [PMID: 22241059 DOI: 10.1152/japplphysiol.00663.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
PURPOSE the relationship between physical activity and airway health in children is not well understood. The purpose of this study was to determine whether 8 wk of high-intensity exercise training would improve airway responsiveness in prepubescent, nonasthmatic, inactive children. METHODS 16 healthy, prepubescent children were randomized [training group (TrG) n = 8, control group (ConG) n = 8]. Prior to and following 8 wk of training (or no training), children completed pulmonary function tests (PFTs): forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF(25-75)), and exhaled nitric oxide (FENO). Children completed an incremental cycle Vo(2max) test, eucapnic voluntary hyperventilation (EVH), anthropometric tests, and blood tests to determine fasting blood glucose, total cholesterol, HDL, LDL, and triglycerides. Body fat percentage was determined using dual-energy X-ray absorptiometry pretraining and bioelectrical impedance pre- and posttraining. RESULTS there were no differences (P > 0.05) in anthropometric measures or PFTs between TrG and ConG at baseline. In the TrG, there was a significant increase in Vo(2max) (∼24%) and a decrease in total cholesterol (∼13%) and LDL cholesterol (∼35%) following training. There were improvements (P < 0.05) in ΔFEV(1) both postexercise (pre: -7.60 ± 2.10%, post: -1.10 ± 1.80%) and post-EVH (pre: -6.71 ± 2.21%, post: -1.41 ± 1.58%) with training. The ΔFEF(25-75) pre-post exercise also improved with training (pre: -16.10 ± 2.10%, post: -6.80 ± 1.80%; P < 0.05). Lower baseline body fat percentages were associated with greater improvements in pre-post exercise ΔFEV(1) following training (r = -0.80, P < 0.05). CONCLUSION these results suggest that in nonasthmatic prepubescent children, inactivity negatively impacts airway responsiveness, which can be improved with high-intensity training. Excess adiposity, however, may constrain these improvements.
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Affiliation(s)
- Sara K Rosenkranz
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA.
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Abstract
The primary function of the mammalian lung is to facilitate diffusion of oxygen to venous blood and to ventilate carbon dioxide produced by catabolic reactions within cells. However, it is also responsible for a variety of other important functions, including host defense and production of vasoactive agents to regulate not only systemic blood pressure, but also water, electrolyte and acid-base balance. Caveolin-1 is highly expressed in the majority of cell types in the lung, including epithelial, endothelial, smooth muscle, connective tissue cells, and alveolar macrophages. Deletion of caveolin-1 in these cells results in major functional aberrations, suggesting that caveolin-1 may be crucial to lung homeostasis and development. Furthermore, generation of mutant mice that under-express caveolin-1 results in severe functional distortion with phenotypes covering practically the entire spectrum of known lung diseases, including pulmonary hypertension, fibrosis, increased endothelial permeability, and immune defects. In this Chapter, we outline the current state of knowledge regarding caveolin-1-dependent regulation of pulmonary cell functions and discuss recent research findings on the role of caveolin-1 in various pulmonary disease states, including obstructive and fibrotic pulmonary vascular and inflammatory diseases.
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185
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Waters CM, Roan E, Navajas D. Mechanobiology in lung epithelial cells: measurements, perturbations, and responses. Compr Physiol 2012; 2:1-29. [PMID: 23728969 PMCID: PMC4457445 DOI: 10.1002/cphy.c100090] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Epithelial cells of the lung are located at the interface between the environment and the organism and serve many important functions including barrier protection, fluid balance, clearance of particulate, initiation of immune responses, mucus and surfactant production, and repair following injury. Because of the complex structure of the lung and its cyclic deformation during the respiratory cycle, epithelial cells are exposed to continuously varying levels of mechanical stresses. While normal lung function is maintained under these conditions, changes in mechanical stresses can have profound effects on the function of epithelial cells and therefore the function of the organ. In this review, we will describe the types of stresses and strains in the lungs, how these are transmitted, and how these may vary in human disease or animal models. Many approaches have been developed to better understand how cells sense and respond to mechanical stresses, and we will discuss these approaches and how they have been used to study lung epithelial cells in culture. Understanding how cells sense and respond to changes in mechanical stresses will contribute to our understanding of the role of lung epithelial cells during normal function and development and how their function may change in diseases such as acute lung injury, asthma, emphysema, and fibrosis.
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186
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Koziol-White CJ, Damera G, Panettieri RA. Targeting airway smooth muscle in airways diseases: an old concept with new twists. Expert Rev Respir Med 2011; 5:767-77. [PMID: 22082163 PMCID: PMC3276206 DOI: 10.1586/ers.11.77] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Airway smooth muscle (ASM) manifests a hyper-responsive phenotype in airway disorders such as asthma. ASM also modulates immune responses by secreting mediators and expressing cell-surface molecules that promote recruitment of inflammatory cells to the lungs. The aim of the current article is to highlight therapeutics that may modulate ASM responses in airway disorders and exacerbations.
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Affiliation(s)
- Cynthia J Koziol-White
- Pulmonary, Allergy and Critical Care Division, Airways Biology Initiative, University of Pennsylvania, Philadelphia, PA 19104-3413, USA
| | - Gautam Damera
- Pulmonary, Allergy and Critical Care Division, Airways Biology Initiative, University of Pennsylvania, Philadelphia, PA 19104-3413, USA
| | - Reynold A Panettieri
- Pulmonary, Allergy and Critical Care Division, Airways Biology Initiative, University of Pennsylvania, Philadelphia, PA 19104-3413, USA
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187
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Ijpma G, Lauzon AM. The rise of passive airway smooth muscle mechanics. J Appl Physiol (1985) 2011; 112:335-6. [PMID: 22052866 DOI: 10.1152/japplphysiol.01338.2011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Xu J, Chen C, Jiang X, Xu R, Tambe D, Zhang X, Liu L, Lan B, Cai K, Deng L. Effects of micropatterned curvature on the motility and mechanical properties of airway smooth muscle cells. Biochem Biophys Res Commun 2011; 415:591-6. [PMID: 22074822 DOI: 10.1016/j.bbrc.2011.10.111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 10/25/2011] [Indexed: 11/29/2022]
Abstract
Geometric features such as size and shape of the microenvironment are known to alter cell behaviors such as growth, differentiation, apoptosis, and migration. Little is known, however, about the effect of curvature on cell behaviors despite that many cells reside in curved space of tubular organs such as the bronchial airways. To address this question, we fabricated micropatterned strips that mimic airway walls with varying curvature. Then, we cultured airway smooth muscle cells (ASMCs) on these strips and investigated the cells' motility and mechanical properties using time-lapse imaging microscopy and optical magnetic twisting cytometry (OMTC). We found that both motility and mechanical properties of the ASMCs were influenced by the curvature. In particular, when the curvature increased from 0 to 1/150 μm(-1), the velocity of cell migration first decreased (0-1/750 μm(-1)), and then increased (1/750-1/150 μm(-1)). In contrast, the cell stiffness increased and then decreased. Thus, at the intermediate curvature (1/750 μm(-1)) the ASMCs were the least motile, but most stiff. The contractility instead decreased consistently as the curvature increased. The level of F-actin, and vinculin expression within the ASMCs appeared to correlate with the contractility and motility, respectively, in relation to the curvature. These results may provide valuable insights to understanding the heterogeneity of airway constrictions in asthma as well as the developing and functioning of other tubular organs and tissue engineering.
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Affiliation(s)
- Jimin Xu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Bioengineering College, Chongqing University, 174 Shapingzhengjie Street, Chongqing 400044, China
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Gosens R, Stelmack GL, Bos ST, Dueck G, Mutawe MM, Schaafsma D, Unruh H, Gerthoffer WT, Zaagsma J, Meurs H, Halayko AJ. Caveolin-1 is required for contractile phenotype expression by airway smooth muscle cells. J Cell Mol Med 2011; 15:2430-42. [PMID: 21199324 PMCID: PMC3822954 DOI: 10.1111/j.1582-4934.2010.01246.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 12/14/2010] [Indexed: 12/18/2022] Open
Abstract
Airway smooth muscle cells exhibit phenotype plasticity that underpins their ability to contribute both to acute bronchospasm and to the features of airway remodelling in chronic asthma. A feature of mature, contractile smooth muscle cells is the presence of abundant caveolae, plasma membrane invaginations that develop from the association of lipid rafts with caveolin-1, but the functional role of caveolae and caveolin-1 in smooth muscle phenotype plasticity is unknown. Here, we report a key role for caveolin-1 in promoting phenotype maturation of differentiated airway smooth muscle induced by transforming growth factor (TGF)-β(1). As assessed by Western analysis and laser scanning cytometry, caveolin-1 protein expression was selectively enriched in contractile phenotype airway myocytes. Treatment with TGF-β(1) induced profound increases in the contractile phenotype markers sm-α-actin and calponin in cells that also accumulated abundant caveolin-1; however, siRNA or shRNAi inhibition of caveolin-1 expression largely prevented the induction of these contractile phenotype marker proteins by TGF-β(1). The failure by TGF-β(1) to adequately induce the expression of these smooth muscle specific proteins was accompanied by a strongly impaired induction of eukaryotic initiation factor-4E binding protein(4E-BP)1 phosphorylation with caveolin-1 knockdown, indicating that caveolin-1 expression promotes TGF-β(1) signalling associated with myocyte maturation and hypertrophy. Furthermore, we observed increased expression of caveolin-1 within the airway smooth muscle bundle of guinea pigs repeatedly challenged with allergen, which was associated with increased contractile protein expression, thus providing in vivo evidence linking caveolin-1 expression with accumulation of contractile phenotype myocytes. Collectively, we identify a new function for caveolin-1 in controlling smooth muscle phenotype; this mechanism could contribute to allergic asthma.
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Affiliation(s)
- Reinoud Gosens
- Departments of Physiology & Internal Medicine, University of ManitobaWinnipeg, Manitoba, Canada
- Biology of Breathing Group, Manitoba Institute of Child HealthWinnipeg, Manitoba, Canada
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
| | - Gerald L Stelmack
- Departments of Physiology & Internal Medicine, University of ManitobaWinnipeg, Manitoba, Canada
- Biology of Breathing Group, Manitoba Institute of Child HealthWinnipeg, Manitoba, Canada
| | - Sophie T Bos
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
| | - Gordon Dueck
- Departments of Physiology & Internal Medicine, University of ManitobaWinnipeg, Manitoba, Canada
- Biology of Breathing Group, Manitoba Institute of Child HealthWinnipeg, Manitoba, Canada
| | - Mark M Mutawe
- Departments of Physiology & Internal Medicine, University of ManitobaWinnipeg, Manitoba, Canada
- Biology of Breathing Group, Manitoba Institute of Child HealthWinnipeg, Manitoba, Canada
| | - Dedmer Schaafsma
- Departments of Physiology & Internal Medicine, University of ManitobaWinnipeg, Manitoba, Canada
- Biology of Breathing Group, Manitoba Institute of Child HealthWinnipeg, Manitoba, Canada
| | - Helmut Unruh
- Section of Thoracic Surgery, University of ManitobaWinnipeg, Manitoba, Canada
| | - William T Gerthoffer
- Department of Pharmacology, University of Nevada School of MedicineReno, NV, USA
| | - Johan Zaagsma
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
| | - Herman Meurs
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
| | - Andrew J Halayko
- Departments of Physiology & Internal Medicine, University of ManitobaWinnipeg, Manitoba, Canada
- Biology of Breathing Group, Manitoba Institute of Child HealthWinnipeg, Manitoba, Canada
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Robertson C, Lee SW, Ahn YC, Mahon S, Chen Z, Brenner M, George SC. Investigating in vivo airway wall mechanics during tidal breathing with optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:106011. [PMID: 22029358 PMCID: PMC3210193 DOI: 10.1117/1.3642006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Optical coherence tomography (OCT) is a nondestructive imaging technique offering high temporal and spatial resolution, which makes it a natural choice for assessing tissue mechanical properties. We have developed methods to mechanically analyze the compliance of the rabbit trachea in vivo using tissue deformations induced by tidal breathing, offering a unique tool to assess the behavior of the airways during their normal function. Four-hundred images were acquired during tidal breathing with a custom-built endoscopic OCT system. The surface of the tissue was extracted from a set of these images via image processing algorithms, filtered with a bandpass filter set at respiration frequency to remove cardiac and probe motion, and compared to ventilatory pressure to calculate wall compliance. These algorithms were tested on elastic phantoms to establish reliability and reproducibility. The mean tracheal wall compliance (in five animals) was 1.3±0.3×10(-5) (mm Pa)(-1). Unlike previous work evaluating airway mechanics, this new method is applicable in vivo, noncontact, and loads the trachea in a physiological manner. The technique may have applications in assessing airway mechanics in diseases such as asthma that are characterized by significant airway remodeling.
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Affiliation(s)
- Claire Robertson
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California 92697, USA
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Schaafsma D, McNeill KD, Mutawe MM, Ghavami S, Unruh H, Jacques E, Laviolette M, Chakir J, Halayko AJ. Simvastatin inhibits TGFβ1-induced fibronectin in human airway fibroblasts. Respir Res 2011; 12:113. [PMID: 21864337 PMCID: PMC3173339 DOI: 10.1186/1465-9921-12-113] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 08/24/2011] [Indexed: 01/11/2023] Open
Abstract
Background Bronchial fibroblasts contribute to airway remodelling, including airway wall fibrosis. Transforming growth factor (TGF)-β1 plays a major role in this process. We previously revealed the importance of the mevalonate cascade in the fibrotic response of human airway smooth muscle cells. We now investigate mevalonate cascade-associated signaling in TGFβ1-induced fibronectin expression by bronchial fibroblasts from non-asthmatic and asthmatic subjects. Methods We used simvastatin (1-15 μM) to inhibit 3-hydroxy-3-methlyglutaryl-coenzyme A (HMG-CoA) reductase which converts HMG-CoA to mevalonate. Selective inhibitors of geranylgeranyl transferase-1 (GGT1; GGTI-286, 10 μM) and farnesyl transferase (FT; FTI-277, 10 μM) were used to determine whether GGT1 and FT contribute to TGFβ1-induced fibronectin expression. In addition, we studied the effects of co-incubation with simvastatin and mevalonate (1 mM), geranylgeranylpyrophosphate (30 μM) or farnesylpyrophosphate (30 μM). Results Immunoblotting revealed concentration-dependent simvastatin inhibition of TGFβ1 (2.5 ng/ml, 48 h)-induced fibronectin. This was prevented by exogenous mevalonate, or isoprenoids (geranylgeranylpyrophosphate or farnesylpyrophosphate). The effects of simvastatin were mimicked by GGTI-286, but not FTI-277, suggesting fundamental involvement of GGT1 in TGFβ1-induced signaling. Asthmatic fibroblasts exhibited greater TGFβ1-induced fibronectin expression compared to non-asthmatic cells; this enhanced response was effectively reduced by simvastatin. Conclusions We conclude that TGFβ1-induced fibronectin expression in airway fibroblasts relies on activity of GGT1 and availability of isoprenoids. Our results suggest that targeting regulators of isoprenoid-dependent signaling holds promise for treating airway wall fibrosis.
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Affiliation(s)
- Dedmer Schaafsma
- Department of Physiology, Section of Respiratory Disease, University of Manitoba, Winnipeg, MB, Canada
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Szefler SJ, Dakhama A. New insights into asthma pathogenesis and treatment. Curr Opin Immunol 2011; 23:801-7. [PMID: 21840186 DOI: 10.1016/j.coi.2011.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 07/22/2011] [Indexed: 02/06/2023]
Abstract
Although national asthma guidelines help organize standards for asthma care, current asthma management is still primarily symptom based. Recent reports provide insights on how to improve asthma management through steps to better understand the natural history of asthma, individualize asthma care, reduce asthma exacerbations, manage inner city asthma, and some potential new ways to use available medications to improve asthma control. Despite many significant gains in managing asthma, we must now find improved strategies to prevent asthma exacerbations, alter the natural history of the disease, and to reduce health disparities in asthma care. Perhaps new directions in personalized medicine including a systems biology approach, along with improved health care access and communication will lead to better methods to alleviate the burden of asthma. This review will discuss the benefits and limitations of the current approach to asthma management, new studies that could impact new directions in asthma management, and new insights related to mechanisms of asthma and allergic airways inflammation that could eventually lead to improved asthma control.
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Affiliation(s)
- Stanley J Szefler
- Helen Wohlberg & Herman Lambert Chair in Pharmacokinetics, Divisions of Pediatric Clinical Pharmacology and Allergy and Immunology, Department of Pediatrics, National Jewish Health, University of Colorado School of Medicine, Denver, CO 80206, USA.
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Hernandez JM, Janssen LJ. Thromboxane Prostanoid Receptor Activation Amplifies Airway Stretch-Activated Contractions Assessed in Perfused Intact Bovine Bronchial Segments. J Pharmacol Exp Ther 2011; 339:248-56. [DOI: 10.1124/jpet.111.182246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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Connolly SC, Smith PG, Fairbank NJ, Lall CA, Cole DJ, Mackinnon JD, Maksym GN. Chronic oscillatory strain induces MLCK associated rapid recovery from acute stretch in airway smooth muscle cells. J Appl Physiol (1985) 2011; 111:955-63. [PMID: 21737821 DOI: 10.1152/japplphysiol.00812.2009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A deep inspiration (DI) temporarily relaxes agonist-constricted airways in normal subjects, but in asthma airways are refractory and may rapidly renarrow, possibly due to changes in the structure and function of airway smooth muscle (ASM). Chronic largely uniaxial cyclic strain of ASM cells in culture causes several structural and functional changes in ASM similar to that in asthma, including increases in contractility, MLCK content, shortening velocity, and shortening capacity. However, changes in recovery from acute stretch similar to a DI have not been measured. We have therefore measured the response and recovery to large stretches of cells modified by chronic stretching and investigated the role of MLCK. Chronic, 10% uniaxial cyclic stretch, with or without a strain gradient, was administered for up to 11 days to cultured cells grown on Silastic membranes. Single cells were then removed from the membrane and subjected to 1 Hz oscillatory stretches up to 10% of the in situ cell length. These oscillations reduced stiffness by 66% in all groups (P < 0.05). Chronically strained cells recovered stiffness three times more rapidly than unstrained cells, while the strain gradient had no effect. The stiffness recovery in unstrained cells was completely inhibited by the MLCK inhibitor ML-7, but recovery in strained cells exhibiting increased MLCK was slightly inhibited. These data suggest that chronic strain leads to enhanced recovery from acute stretch, which may be attributable to the strain-induced increases in MLCK. This may also explain in part the more rapid renarrowing of activated airways following DI in asthma.
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Affiliation(s)
- Sarah C Connolly
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
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Molecular expression and functional role of canonical transient receptor potential channels in airway smooth muscle cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:731-47. [PMID: 21290324 DOI: 10.1007/978-94-007-0265-3_38] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Multiple canonical or classic transient receptor potential (TRPC) molecules are expressed in animal and human airway smooth muscle cells (SMCs). TRPC3, but not TRPC1, is a major molecular component of native non-selective cation channels (NSCCs) to contribute to the resting [Ca(2+)](i) and muscarinic increase in [Ca(2+)](i) in freshly isolated airway SMCs. TRPC3-encoded NSCCs are significantly increased in expression and activity in airway SMCs from ovalbumin-sensitized/challenged "asthmatic" mice, whereas TRPC1-encoded channel activity, but not its expression, is largely augmented. The upregulated TRPC3- and TRPC1-encoded NSCC activity both mediate "asthmatic" membrane depolarization in airway SMCs. Supportively, tumor necrosis factor-α (TNFα), an important asthma mediator, increases TRPC3 expression, and TRPC3 gene silencing inhibits TNFα-mediated augmentation of acetylcholine-evoked increase in [Ca(2+)](i) in passaged airway SMCs. In contrast, TRPC6 gene silencing has no effect on 1-oleoyl-2-acetyl-sn-glycerol (OAG)-evoked increase in [Ca(2+)](i) in primary isolated cells. These findings provide compelling information indicating that TRPC3-encoded NSCCs are important for physiological and pathological cellular responses in airway SMCs. However, continual studies are necessary to further determine whether, which, and how TRPC-encoded channels are involved in cellular responses in normal and diseased (e.g., asthmatic) airway SMCs.
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Al-Muhsen S, Johnson JR, Hamid Q. Remodeling in asthma. J Allergy Clin Immunol 2011; 128:451-62; quiz 463-4. [PMID: 21636119 DOI: 10.1016/j.jaci.2011.04.047] [Citation(s) in RCA: 311] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 04/22/2011] [Accepted: 04/26/2011] [Indexed: 01/26/2023]
Abstract
Airway remodeling encompasses the structural alterations in asthmatic compared with normal airways. Airway remodeling in asthmatic patients involves a wide array of pathophysiologic features, including epithelial changes, increased smooth muscle mass, increased numbers of activated fibroblasts/myofibroblasts, subepithelial fibrosis, and vascular changes. Multiple cytokines, chemokines, and growth factors released from both inflammatory and structural cells in the airway tissue create a complex signaling environment that drives these structural changes. However, recent investigations have changed our understanding of asthma from a purely inflammatory disease to a disease in which both inflammatory and structural components are equally involved. Several reports have suggested that asthma primarily develops because of serious defects in the epithelial layer that allow environmental allergens, microorganisms, and toxins greater access to the airway tissue and that can also stimulate the release of mediators from the epithelium, thus contributing to tissue remodeling. Lung-resident fibroblasts and smooth muscle cells have also been implicated in the pathogenesis of airway remodeling. Remodeling is assumed to result in persistent airflow limitation, a decrease in lung function, and airway hyperresponsiveness. Asthmatic subjects experience an accelerated decrease in lung function compared with healthy subjects, which is proportionally related to the duration and severity of their disease.
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Affiliation(s)
- Saleh Al-Muhsen
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
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197
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Mast cells reside in myometrium and cervix, but are dispensable in mice for successful pregnancy and labor. Immunol Cell Biol 2011; 90:321-9. [DOI: 10.1038/icb.2011.40] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
PURPOSE OF REVIEW the present article will address the potential for bronchial thermoplasty to be used in addition to conventional medications to help us treat our patients with severe asthma. RECENT FINDINGS two recently published studies report on the use of bronchial thermoplasty in patients with severe asthma. Now that patients with a range of asthma severity have been treated with bronchial thermoplasty, we are better able to comment on the appropriate selection of patients for this therapy that should optimize benefits and limit complications. In addition, studies reporting longer term follow-up are now available indicating the persistence of benefit and the absence of late developing adverse events. SUMMARY bronchial thermoplasty represents a novel approach to asthma treatment that is complementary to anti-inflammatory and bronchodilating therapies. Criteria for selecting appropriate patients are established and experience with bronchial thermoplasty is expanding since US Food and Drug Administration approval was obtained in April 2010.
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Laprad AS, Lutchen KR. The dissolution of intact airway responsiveness from breathing fluctuations: what went wrong? J Appl Physiol (1985) 2011; 110:1506-7. [PMID: 21454749 DOI: 10.1152/japplphysiol.00356.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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200
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The CHI3L1 rs4950928 polymorphism is associated with asthma-related hospital admissions in children and young adults. Ann Allergy Asthma Immunol 2011; 106:381-6. [PMID: 21530869 DOI: 10.1016/j.anai.2011.01.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 12/29/2010] [Accepted: 01/26/2011] [Indexed: 11/20/2022]
Abstract
BACKGROUND Asthma exacerbations are the commonest cause of medical admissions in childhood. These have a significant effect on quality of life and are a major financial burden on worldwide healthcare services. A range of gene-environment interactions may influence the course and severity of asthma in children and their response to medication. The Chitinase 3-like 1 (CHI3L1)-131C>G genotype (rs4950928) is associated with increased asthma susceptibility and severity in adults. OBJECTIVES To study the interactions of the Chitinase 3-Like-1 functional promoter SNP rs4950928 and its role on asthma exacerbations in a population of children and young adults with asthma. METHODS A cross-sectional survey was undertaken using medical records and direct interviews of 1,071 children and young adults with asthma, aged 3 to 22 years, from Scotland. Saliva samples were collected for genotyping. Binary logistic regression was used to calculate odds ratios (ORs) and P-values for measures of asthma exacerbations. RESULTS The minor -131G allele confers protection against asthma-related hospital admissions (OR = 0.62; 95% CI 0.41-0.92; P = .018) in children and young adults with asthma. CONCLUSIONS Our study shows that rs4950928 is significantly associated with hospital admissions in children and young adults; screening for rs4950928 may predict asthma-related hospital admissions, and through individually defined treatment management plans, potentially reduce health care costs.
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