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Yasuda Y, Wang L, Chitano P, Seow CY. Critical roles of airway smooth muscle in mediating deep-inspiration-induced bronchodilation: a big stretch? Respir Res 2023; 24:250. [PMID: 37853472 PMCID: PMC10585885 DOI: 10.1186/s12931-023-02538-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 09/14/2023] [Indexed: 10/20/2023] Open
Abstract
BACKGROUND Deep inspiration (DI) has been shown to induce bronchodilation and bronchoprotection in bronchochallenged healthy subjects, but not in asthmatics. Strain-induced relaxation of airway smooth muscle (ASM) is considered one of the factors responsible for these effects. Other factors include the release or redistribution of pulmonary surfactant, alteration in mucus plugs, and changes in airway heterogeneity. MAIN BODY The present review is focused on the DI effect on ASM function, based on recent findings from ex vivo sheep lung experiments showing a large change in airway diameter during a DI. The amount of stretch on the airways, when applied to isolated airway rings in vitro, caused a substantial decrease in ASM contractility that takes many minutes to recover. When challenged with a bronchoconstrictor, the increase in pulmonary resistance in the ex vivo ovine lungs is mostly due to the increase in airway resistance. CONCLUSIONS Although non-ASM related factors cannot be excluded, the large strain on the airways associated with a DI substantially reduces ASM contractility and thus can account for most of the bronchodilatory and bronchoprotective effects of DI.
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Affiliation(s)
- Yuto Yasuda
- Centre for Heart Lung Innovation, St. Paul's Hospital, Providence Health Care, University of British Columbia, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada.
| | - Lu Wang
- Centre for Heart Lung Innovation, St. Paul's Hospital, Providence Health Care, University of British Columbia, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada
| | - Pasquale Chitano
- Centre for Heart Lung Innovation, St. Paul's Hospital, Providence Health Care, University of British Columbia, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada
| | - Chun Y Seow
- Centre for Heart Lung Innovation, St. Paul's Hospital, Providence Health Care, University of British Columbia, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
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2
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Dong SJ, Wang L, Chitano P, Coxson HO, Paré PD, Seow CY. Airway diameter at different transpulmonary pressures in ex vivo sheep lungs: Implications for deep-inspiration-induced bronchodilation and bronchoprotection. Am J Physiol Lung Cell Mol Physiol 2021; 321:L663-L674. [PMID: 34287071 DOI: 10.1152/ajplung.00208.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Deep inspiration (DI)-induced bronchodilation is the first line of defense against bronchoconstriction in healthy subjects. A hallmark of asthma is the lack of this beneficial effect of DI. The mechanism underlying the bronchodilatory effect of DI is not clear. Understanding the mechanism will help us unravel the mystery of asthma pathophysiology. It has been postulated that straining airway smooth muscle (ASM) during a DI could lead to bronchodilation and bronchoprotection. The hypothesis is currently under debate, and a central question is whether ASM is sufficiently stretched during a DI for its contractility to be compromised. Besides bronchoconstriction, another contributor to lung resistance is airway heterogeneity. The present study examines changes in airway diameter and heterogeneity at different lung volumes. Freshly explanted sheep lungs were used in plethysmographic measurements of lung resistance and elastance at different lung volumes while the airway dimensions were measured by computed tomography (CT). The change in airway diameter informed by CT measurements was applied to isolated airway ring preparations to determine the strain-induced loss of ASM contractility. We found that changing the transpulmonary pressure from 5 to 30 cmH2O led to a 51%-increase in lung volume, accompanied by a 46%-increase in the airway diameter with no change in airway heterogeneity. When comparable airway strains measured in the whole lung were applied to isolated airway rings in either relaxed or contracted state, a significant loss of ASM contractility was observed, suggesting that DI-induced bronchodilation and bronchoprotection can result from strain-induced loss of ASM contractility.
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Affiliation(s)
- Shou-Jin Dong
- The UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada.,Respiratory Department, Chengdu First People's Hospital, Chengdu, China
| | - Lu Wang
- The UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
| | - Pasquale Chitano
- The UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
| | - Harvey O Coxson
- The UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
| | - Peter D Paré
- The UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada.,Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Chun Y Seow
- The UBC Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada.,Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
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3
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Xue Y, Bao W, Zhou Y, Fu Q, Hao H, Han L, Yin D, Zhang Y, Zhang X, Zhang M. Small-Airway Dysfunction is Involved in the Pathogenesis of Asthma: Evidence from Two Mouse Models. J Asthma Allergy 2021; 14:883-896. [PMID: 34285515 PMCID: PMC8286250 DOI: 10.2147/jaa.s312361] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 06/22/2021] [Indexed: 12/21/2022] Open
Abstract
Background There has been growing evidence of small-airway dysfunction in patients with asthma. Few studies have evaluated the mechanism of small-airway dysfunction in mouse models of asthma. Purpose We explored the correlation between small-airway spirometric variables and large-airway function or inflammation in different endotypes of asthma. Methods Ovalbumin (OVA) sensitization/challenge was used to produce a type 2 (T2)-high asthma model, and OVA combined with ozone exposure (OVA + ozone) was used for the T2-low asthma model with increased neutrophils. Spirometry, airway responsiveness, cytokine levels in bronchoalveolar lavage fluid (BALF), and pathological analyses of lung slices stained with hematoxylin-eosin, periodic acid–Schiff, and Masson’s trichrome stain were all determined. Muc5ac expression in lung tissue was evaluated by the reverse transcription-polymerase chain reaction (RT-PCR), and alpha-smooth muscle actin was measured by immunohistochemistry. Results Inflammatory cells infiltrated the lung tissue and inflammatory cytokines were increased in the BALF of both the OVA and OVA + ozone groups, compared with the control group. Peribronchial hypersecretion and collagen deposition were evident in the models. The OVA + ozone group showed greater neutrophilic infiltration and peribronchial smooth muscle proliferation than the OVA group. Large-airway obstruction, small-airway dysfunction, and airway hyperresponsiveness were confirmed in both models. Small-airway functional variables, such as MMEF (mean midexpiratory flow, average flow from 25 to 75% forced vital capacity [FVC]) and FEF50 (forced expiratory flow at 50% of FVC), were positively correlated with large-airway function and had a stronger negative correlation with airway inflammation, mucus secretion, and responsiveness than large-airway function. Conclusion Small-airway dysfunction was evident in the two endotypes of asthma and was correlated with severe airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. The small airways may be an important target in asthma treatment, and further research in the role of small-airway variables in the pathogenesis of asthma is warranted.
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Affiliation(s)
- Yishu Xue
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Wuping Bao
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Yan Zhou
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Qiang Fu
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Huijuan Hao
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Lei Han
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Dongning Yin
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Yingying Zhang
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Xue Zhang
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
| | - Min Zhang
- Department of Respiratory and Critical Care Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, People's Republic of China
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4
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Robichaud A, Fereydoonzad L, Collins SL, Loube JM, Ishii Y, Horton MR, Martin JG, Mitzner W. Airway compliance measurements in mouse models of respiratory diseases. Am J Physiol Lung Cell Mol Physiol 2021; 321:L204-L212. [PMID: 34009049 DOI: 10.1152/ajplung.00470.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The quantification of airway compliance (Caw) is essential to the study of airway alterations in disease models. However, the required measurements of airway pressure and volume are difficult to acquire in mice. We hypothesized that the inflation limb of full-range pressure-volume (PV) curves could be used to quantify Caw, as it contains a segment where only the airway tree is distended. The study objective was to assess the feasibility of the approach by analysis of full-range PV curves previously collected in three mouse models: an elastase model of emphysema, a genetic model spontaneously developing emphysema (leukotriene C4 synthase knockout; LTC4S-KO), and a bleomycin model of lung fibrosis. Attempts to validate results included Caw change relative to respiratory system compliance (ΔCaw/ΔC), the minute work of breathing (mWOB), and the elastance at 20.5 Hz (Ers_20.5) from prior respiratory mechanics measurements in the same subjects. Caw was estimated at 3% of total compliance in healthy mice or 2.3 ± 1 μL/cmH2O (n = 17). The technique detected changes in models of respiratory obstructive and restrictive diseases relative to control mice as well as differences in the two emphysema models studied. The changes in Caw were consistent with those seen in ΔCaw/ΔC, mWOB, or Ers_20.5, with some variations according to the model, as well as with results reported in the literature in humans and mice. Direct Caw measurements in subjects as small as mice could prove useful to further characterize other respiratory disease models associated with airway remodeling or to assess treatment effects.
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Affiliation(s)
| | | | - Samuel L Collins
- Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Jeffrey Martin Loube
- Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Yumiko Ishii
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Maureen R Horton
- Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - James G Martin
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Wayne Mitzner
- Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
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5
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Tartaglione G, Spaziano G, Sgambato M, Russo TP, Liparulo A, Esposito R, Mirra S, Filosa R, Roviezzo F, Polverino F, D'Agostino B. Nociceptin/Orphanin Fq in inflammation and remodeling of the small airways in experimental model of airway hyperresponsiveness. Physiol Rep 2018; 6:e13906. [PMID: 30370666 PMCID: PMC6204362 DOI: 10.14814/phy2.13906] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 09/28/2018] [Accepted: 09/28/2018] [Indexed: 12/20/2022] Open
Abstract
It is widely recognized that airway inflammation and remodeling play a key role not only in the central airway but also small airway pathology during asthma. Nociceptin/Orphanin FQ (N/OFQ), an endogenous peptide, and its receptor N/OFQ peptide (NOP) are involved in airway hyperresponsiveness (AHR). We studied a murine model of AHR in order to understand the role of N/OFQ in the inflammation and remodeling of the small airways. Balb/c mice were sensitized to ovalbumin (OVA). At days 0 and 7 (pre-OVA sensitization) or from day 21 to 23 (post-OVA sensitization), the mice were treated intraperitoneally with N/OFQ or saline solution. After the last OVA challenge, all OVA-sensitized mice were aerosol-challenged with 1% OVA in PBS for 48 h, and then euthanized. Small airway compliance (sCaw ) was measured and lung samples were collected for histological and molecular evaluations such as perimeter and diameter of small airway, total wall area, airway smooth muscle (ASM) thickness and number of alveolar attachments. Both pre- and post-OVA sensitization N/OFQ treatments induced: (1) increases in sCaw ; (2) reduction of the bronchial wall thickness; (3) attenuation of the hyperplastic phase of airway smooth muscle mass; and (4) protection against loss of alveolar attachments compared with saline solution treatments. These results suggest that N/OFQ protects against inflammation, and mechanical damage and remodeling of small airways caused by OVA sensitization, suggesting a new potential therapeutic target for asthma.
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Affiliation(s)
- Gioia Tartaglione
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Giuseppe Spaziano
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Manuela Sgambato
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Teresa Palmira Russo
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Angela Liparulo
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Renata Esposito
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Salvatore Mirra
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | - Rosanna Filosa
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
| | | | | | - Bruno D'Agostino
- Department of Experimental MedicineSchool of MedicineSection of PharmacologyUniversity of Campania “L. Vanvitelli”NaplesItaly
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6
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Kathiriya JJ, Nakra N, Nixon J, Patel PS, Vaghasiya V, Alhassani A, Tian Z, Allen-Gipson D, Davé V. Galectin-1 inhibition attenuates profibrotic signaling in hypoxia-induced pulmonary fibrosis. Cell Death Discov 2017; 3:17010. [PMID: 28417017 PMCID: PMC5385413 DOI: 10.1038/cddiscovery.2017.10] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 01/10/2017] [Indexed: 12/18/2022] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is characterized by lung remodeling arising from epithelial injury, aberrant fibroblast growth, and excessive deposition of extracellular matrix. Repeated epithelial injury elicits abnormal wound repair and lung remodeling, often associated with alveolar collapse and edema, leading to focal hypoxia. Here, we demonstrate that hypoxia is a physiological insult that contributes to pulmonary fibrosis (PF) and define its molecular roles in profibrotic activation of lung epithelial cells. Hypoxia increased transcription of profibrotic genes and altered the proteomic signatures of lung epithelial cells. Network analysis of the hypoxic epithelial proteome revealed a crosstalk between transforming growth factor-β1 and FAK1 (focal adhesion kinase-1) signaling, which regulated transcription of galectin-1, a profibrotic molecule. Galectin-1 physically interacted with and activated FAK1 in lung epithelial cells. We developed a novel model of exacerbated PF wherein hypoxia, as a secondary insult, caused PF in mice injured with subclinical levels of bleomycin. Hypoxia elevated expression of phosphorylated FAK1, galectin-1, and α-smooth muscle actin and reduced caspase-3 activation, suggesting aberrant injury repair. Galectin-1 inhibition caused apoptosis in the lung parenchyma and reduced FAK1 activation, preventing the development of hypoxia-induced PF. Galectin-1 inhibition also attenuated fibrosis-associated lung function decline. Further, galectin-1 transcript levels were increased in the lungs of IPF patients. In summary, we have identified a profibrotic role of galectin-1 in hypoxia signaling driving PF.
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Affiliation(s)
- Jaymin J Kathiriya
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Niyati Nakra
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Jenna Nixon
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Puja S Patel
- University of Miami, Coral Gables, FL 33124, USA
| | - Vijay Vaghasiya
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Ahmed Alhassani
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Zhi Tian
- University of Miami, Coral Gables, FL 33124, USA
| | - Diane Allen-Gipson
- Department of Pharmaceutical Science, College of Pharmacy, University of South Florida, Tampa, FL 33612, USA
| | - Vrushank Davé
- Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.,Department of Cancer Biology and Evolution, H Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
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7
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Sera T, Yokota H, Tanaka G, Uesugi K, Yagi N, Schroter RC. Murine pulmonary acinar mechanics during quasi-static inflation using synchrotron refraction-enhanced computed tomography. J Appl Physiol (1985) 2013; 115:219-28. [PMID: 23661619 DOI: 10.1152/japplphysiol.01105.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We visualized pulmonary acini in the core regions of the mouse lung in situ using synchrotron refraction-enhanced computed tomography (CT) and evaluated their kinematics during quasi-static inflation. This CT system (with a cube voxel of 2.8 μm) allows excellent visualization of not just the conducting airways, but also the alveolar ducts and sacs, and tracking of the acinar shape and its deformation during inflation. The kinematics of individual alveoli and alveolar clusters with a group of terminal alveoli is influenced not only by the connecting alveolar duct and alveoli, but also by the neighboring structures. Acinar volume was not a linear function of lung volume. The alveolar duct diameter changed dramatically during inflation at low pressures and remained relatively constant above an airway pressure of ∼8 cmH2O during inflation. The ratio of acinar surface area to acinar volume indicates that acinar distension during low-pressure inflation differed from that during inflation over a higher pressure range; in particular, acinar deformation was accordion-like during low-pressure inflation. These results indicated that the alveoli and duct expand differently as total acinar volume increases and that the alveolar duct may expand predominantly during low-pressure inflation. Our findings suggest that acinar deformation in the core regions of the lung is complex and heterogeneous.
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Affiliation(s)
- Toshihiro Sera
- Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, Japan.
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8
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Airway distension during lung inflation in healthy and allergic-sensitised mice in vivo. Respir Physiol Neurobiol 2012; 185:639-46. [PMID: 23253555 DOI: 10.1016/j.resp.2012.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 11/14/2012] [Accepted: 12/06/2012] [Indexed: 11/22/2022]
Abstract
We evaluated the airway distention during lung inflation of varying size in healthy and allergic-sensitised mice in vivo. Computed tomography (CT) images of healthy and ovalbumin-treated mice were acquired using a synchrotron in vivo CT system when lung pressures was 0 and 20 cmH(2)O, and the morphometric distension (diameter, length, and volume) and the compliance of airway segments (to as small as ~150 μm internal diameter) were calculated. With respect to airway size, in healthy mice, the changes in airway diameter and compliance were larger in the small-airway group. In contrast, in allergic-sensitised mice, there were no significant differences in the changes in airway distension or compliance. Airway wall thickness in allergic-sensitised mice increased significantly in all airway groups, but the change was much larger in the small than in the large-airway group. Compared with healthy airways, the changes in diameter and airway compliance of the allergic-sensitised mice were significantly smaller in the small-airway group.
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9
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Thomas AC, Kaushik SS, Nouls J, Potts EN, Slipetz DM, Foster WM, Driehuys B. Effects of corticosteroid treatment on airway inflammation, mechanics, and hyperpolarized ³He magnetic resonance imaging in an allergic mouse model. J Appl Physiol (1985) 2012; 112:1437-44. [PMID: 22241062 PMCID: PMC3362235 DOI: 10.1152/japplphysiol.01293.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 01/10/2012] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to assess the effects of corticosteroid therapy on a murine model of allergic asthma using hyperpolarized (3)He magnetic resonance imaging (MRI) and respiratory mechanics measurements before, during, and after methacholine (MCh) challenge. Three groups of mice were prepared, consisting of ovalbumin sensitized/ovalbumin challenged (Ova/Ova, n = 5), Ova/Ova challenged but treated with the corticosteroid dexamethasone (Ova/Ova+Dex, n = 3), and ovalbumin-sensitized/saline-challenged (Ova/PBS, n = 4) control animals. All mice underwent baseline 3D (3)He MRI, then received a MCh challenge while 10 2D (3)He MR images were acquired for 2 min, followed by post-MCh 3D (3)He MRI. Identically treated groups underwent respiratory mechanics evaluation (n = 4/group) and inflammatory cell counts (n = 4/group). Ova/Ova animals exhibited predominantly large whole lobar defects at baseline, with significantly higher ventilation defect percentage (VDP = 19 ± 4%) than Ova/PBS (+2 ± 1%, P = 0.01) animals. Such baseline defects were suppressed by dexamethasone (0%, P = 0.009). In the Ova/Ova group, MCh challenge increased VDP on both 2D (+30 ± 8%) and 3D MRI scans (+14 ± 2%). MCh-induced VDP changes were diminished in Ova/Ova+Dex animals on both 2D (+21 ± 9%, P = 0.63) and 3D scans (+7 ± 2%, P = 0.11) and also in Ova/PBS animals on 2D (+6 ± 3%, P = 0.07) and 3D (+4 ± 1%, P = 0.01) scans. Because MCh challenge caused near complete cessation of ventilation in four of five Ova/Ova animals, even as large airways remained patent, this implies that small airway (<188 μm) obstruction predominates in this model. This corresponds with respiratory mechanics observations that MCh challenge significantly increases elastance and tissue damping but only modestly affects Newtonian airway resistance.
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Affiliation(s)
- Abraham C Thomas
- Center for In Vivo Microscopy, Box 3302, Duke Univ. Medical Center, Durham, NC 27710, USA
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10
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Tatler AL, John AE, Jolly L, Habgood A, Porte J, Brightling C, Knox AJ, Pang L, Sheppard D, Huang X, Jenkins G. Integrin αvβ5-mediated TGF-β activation by airway smooth muscle cells in asthma. THE JOURNAL OF IMMUNOLOGY 2011; 187:6094-107. [PMID: 22025551 DOI: 10.4049/jimmunol.1003507] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Severe asthma is associated with airway remodeling, characterized by structural changes including increased smooth muscle mass and matrix deposition in the airway, leading to deteriorating lung function. TGF-β is a pleiotropic cytokine leading to increased synthesis of matrix molecules by human airway smooth muscle (HASM) cells and is implicated in asthmatic airway remodeling. TGF-β is synthesized as a latent complex, sequestered in the extracellular matrix, and requires activation for functionality. Activation of latent TGF-β is the rate-limiting step in its bioavailability. This study investigated the effect of the contraction agonists LPA and methacholine on TGF-β activation by HASM cells and its role in the development of asthmatic airway remodeling. The data presented show that LPA and methacholine induced TGF-β activation by HASM cells via the integrin αvβ5. Our findings highlight the importance of the β5 cytoplasmic domain because a polymorphism in the β5 subunit rendered the integrin unable to activate TGF-β. To our knowledge, this is the first description of a biologically relevant integrin that is unable to activate TGF-β. These data demonstrate that murine airway smooth muscle cells express αvβ5 integrins and activate TGF-β. Finally, these data show that inhibition, or genetic loss, of αvβ5 reduces allergen-induced increases in airway smooth muscle thickness in two models of asthma. These data highlight a mechanism of TGF-β activation in asthma and support the hypothesis that bronchoconstriction promotes airway remodeling via integrin mediated TGF-β activation.
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Affiliation(s)
- Amanda L Tatler
- Nottingham Respiratory Biomedical Research Unit, University of Nottingham, Nottingham NG5 1PB, United Kingdom
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11
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Kelly VJ, Brown NJ, King GG, Thompson BR. The bronchodilator response of in vivo specific airway compliance in adults with asthma. Ann Biomed Eng 2010; 39:1125-35. [PMID: 21184178 DOI: 10.1007/s10439-010-0206-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 11/08/2010] [Indexed: 11/28/2022]
Abstract
A new technique has been developed to determine in vivo airway compliance in humans that is specific to airway size and transpulmonary pressure, and can be represented as a three-dimensional surface. As yet, the ability of this technique to detect changes in specific airway compliance with disease status has not been demonstrated. The aim of this study was to assess whether this technique could determine changes in airway compliance which are thought to occur with altered smooth muscle tone in adults with asthma. Airway compliance was measured and displayed as a surface in adults with asthma before and after a reduction in smooth muscle tone by bronchodilator administration. Compliance, with respect to airway size, was calculated at three specific lung volumes; functional residual capacity (FRC), total lung capacity (TLC), and midway between FRC and TLC (MID). After bronchodilator, airway compliance increased at FRC and MID in the smaller airways (<3 mm). Furthermore, airway compliance under both conditions was greater in the smaller airways compared to the larger airways. In conclusion, our method may have future utility in assessing changes in airway compliance in respiratory diseases such as asthma.
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Affiliation(s)
- Vanessa J Kelly
- The Department of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3004, Australia
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12
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Kelly VJ, Brown NJ, King GG, Thompson BR. A method to determine in vivo, specific airway compliance, in humans. Med Biol Eng Comput 2010; 48:489-96. [PMID: 20217265 DOI: 10.1007/s11517-010-0576-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Accepted: 01/09/2010] [Indexed: 10/19/2022]
Abstract
In order to understand the pathophysiology of diseases such as asthma and chronic obstructive pulmonary disease, it is essential to measure the mechanical properties of the airways. Currently, there are no methods to measure and quantify in vivo airway compliance in humans. In order to develop a method, we generated a curve-fitting algorithm that combines airway diameter measurements by high resolution computed tomography with pressure-volume curves obtained by the esophageal balloon technique. Our method allows the description of diameter-pressure curves for airways of varying size, presented as a 3D surface, from which specific airway compliance can be determined at any transpulmonary pressure. Applying this method to data from two healthy subjects, we found that small airways are more compliant than large airways and specific airway compliance was greatest at low transpulmonary pressures. In conclusion, our 3D surface is a useful tool to measure and quantify in vivo specific airway compliance in humans.
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Affiliation(s)
- Vanessa J Kelly
- Department of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
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Tsuda A, Filipovic N, Haberthür D, Dickie R, Matsui Y, Stampanoni M, Schittny JC. Finite element 3D reconstruction of the pulmonary acinus imaged by synchrotron X-ray tomography. J Appl Physiol (1985) 2008; 105:964-76. [PMID: 18583378 PMCID: PMC2536812 DOI: 10.1152/japplphysiol.90546.2008] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2008] [Accepted: 06/16/2008] [Indexed: 11/22/2022] Open
Abstract
The alveolated structure of the pulmonary acinus plays a vital role in gas exchange function. Three-dimensional (3D) analysis of the parenchymal region is fundamental to understanding this structure-function relationship, but only a limited number of attempts have been conducted in the past because of technical limitations. In this study, we developed a new image processing methodology based on finite element (FE) analysis for accurate 3D structural reconstruction of the gas exchange regions of the lung. Stereologically well characterized rat lung samples (Pediatr Res 53: 72-80, 2003) were imaged using high-resolution synchrotron radiation-based X-ray tomographic microscopy. A stack of 1,024 images (each slice: 1024 x 1024 pixels) with resolution of 1.4 mum(3) per voxel were generated. For the development of FE algorithm, regions of interest (ROI), containing approximately 7.5 million voxels, were further extracted as a working subunit. 3D FEs were created overlaying the voxel map using a grid-based hexahedral algorithm. A proper threshold value for appropriate segmentation was iteratively determined to match the calculated volume density of tissue to the stereologically determined value (Pediatr Res 53: 72-80, 2003). The resulting 3D FEs are ready to be used for 3D structural analysis as well as for subsequent FE computational analyses like fluid dynamics and skeletonization.
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Affiliation(s)
- A Tsuda
- Molecular and Integrative Physiological Sciences, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA.
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Sera T, Yokota H, Fujisaki K, Fukasaku K, Tachibana H, Uesugi K, Yagi N, Himeno R. Development of high-resolution 4Din vivo-CT for visualization of cardiac and respiratory deformations of small animals. Phys Med Biol 2008; 53:4285-301. [DOI: 10.1088/0031-9155/53/16/005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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