1
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Wang CJ, Noble PB, Elliot JG, James AL, Wang KCW. From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity. Compr Physiol 2023; 13:4321-4353. [PMID: 36715283 DOI: 10.1002/cphy.c220011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.
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Affiliation(s)
- Carolyn J Wang
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Peter B Noble
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - John G Elliot
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia.,Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
| | - Alan L James
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.,Medical School, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Kimberley C W Wang
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia.,Telethon Kids Institute, The University of Western Australia, Nedlands, Western Australia, Australia
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2
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Xiong D(JP, Martin JG, Lauzon AM. Airway smooth muscle function in asthma. Front Physiol 2022; 13:993406. [PMID: 36277199 PMCID: PMC9581182 DOI: 10.3389/fphys.2022.993406] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/14/2022] [Indexed: 11/27/2022] Open
Abstract
Known to have affected around 340 million people across the world in 2018, asthma is a prevalent chronic inflammatory disease of the airways. The symptoms such as wheezing, dyspnea, chest tightness, and cough reflect episodes of reversible airway obstruction. Asthma is a heterogeneous disease that varies in clinical presentation, severity, and pathobiology, but consistently features airway hyperresponsiveness (AHR)—excessive airway narrowing due to an exaggerated response of the airways to various stimuli. Airway smooth muscle (ASM) is the major effector of exaggerated airway narrowing and AHR and many factors may contribute to its altered function in asthma. These include genetic predispositions, early life exposure to viruses, pollutants and allergens that lead to chronic exposure to inflammatory cells and mediators, altered innervation, airway structural cell remodeling, and airway mechanical stress. Early studies aiming to address the dysfunctional nature of ASM in the etiology and pathogenesis of asthma have been inconclusive due to the methodological limitations in assessing the intrapulmonary airways, the site of asthma. The study of the trachealis, although convenient, has been misleading as it has shown no alterations in asthma and it is not as exposed to inflammatory cells as intrapulmonary ASM. Furthermore, the cartilage rings offer protection against stress and strain of repeated contractions. More recent strategies that allow for the isolation of viable intrapulmonary ASM tissue reveal significant mechanical differences between asthmatic and non-asthmatic tissues. This review will thus summarize the latest techniques used to study ASM mechanics within its environment and in isolation, identify the potential causes of the discrepancy between the ASM of the extra- and intrapulmonary airways, and address future directions that may lead to an improved understanding of ASM hypercontractility in asthma.
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Affiliation(s)
- Dora (Jun Ping) Xiong
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
| | - James G. Martin
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
| | - Anne-Marie Lauzon
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
- *Correspondence: Anne-Marie Lauzon,
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3
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Hackmann MJ, Elliot JG, Green FHY, Cairncross A, Cense B, McLaughlin RA, Langton D, James AL, Noble PB, Donovan GM. Requirements and limitations of imaging airway smooth muscle throughout the lung in vivo. Respir Physiol Neurobiol 2022; 301:103884. [PMID: 35301143 DOI: 10.1016/j.resp.2022.103884] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/08/2022] [Accepted: 03/05/2022] [Indexed: 11/18/2022]
Abstract
Clinical visualization and quantification of the amount and distribution of airway smooth muscle (ASM) in the lungs of individuals with asthma has major implications for our understanding of airway wall remodeling as well as treatments targeted at the ASM. This paper theoretically investigates the feasibility of quantifying airway wall thickness (focusing on the ASM) throughout the lung in vivo by means of bronchoscopic polarization-sensitive optical coherence tomography (PS-OCT). Using extensive human biobank data from subjects with and without asthma in conjunction with a mathematical model of airway compliance, we define constraints that airways of various sizes pose to any endoscopic imaging technique and how this is impacted by physiologically relevant processes such as constriction, inflation and deflation. We identify critical PS-OCT system parameters and pinpoint parts of the airway tree that are conducive to successful quantification of ASM. We further quantify the impact of breathing and ASM contraction on the measurement error and recommend strategies for standardization and normalization.
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Affiliation(s)
- Michael J Hackmann
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia; School of Engineering, University of Western Australia, Perth, Western Australia, Australia.
| | - John G Elliot
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia; West Australian Sleep Disorders Research Institute, Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
| | - Francis H Y Green
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Alvenia Cairncross
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Barry Cense
- School of Engineering, University of Western Australia, Perth, Western Australia, Australia; Department of Mechanical Engineering, Yonsei University, Seoul, South-Korea
| | - Robert A McLaughlin
- School of Engineering, University of Western Australia, Perth, Western Australia, Australia; Australian Research Council Centre of Excellence for Nanoscale Biophotonics, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, South Australia, Australia; Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, South Australia, Australia
| | - David Langton
- Faculty of Medicine, Nursing and Allied Health, Monash University, Melbourne, Victoria, Australia
| | - Alan L James
- West Australian Sleep Disorders Research Institute, Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; Medical School, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Peter B Noble
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, New Zealand
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4
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Raj SS, Mathew RM, Nair Y, S. T. A, T. P. V. Fabrication and Applications of Wrinkled Soft Substrates: An Overview. ChemistrySelect 2022. [DOI: 10.1002/slct.202200714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Soorya S. Raj
- Department of Chemistry CHRIST (Deemed to be University) Hosur Road Bangalore 560029 India
| | - Romina Marie Mathew
- Department of Chemistry CHRIST (Deemed to be University) Hosur Road Bangalore 560029 India
| | - Yamuna Nair
- Department of Chemistry CHRIST (Deemed to be University) Hosur Road Bangalore 560029 India
| | - Aruna S. T.
- Surface Engineering Division CSIR – National Aerospace Laboratories HAL Airport Road Bangalore 560017 India
| | - Vinod T. P.
- Department of Chemistry CHRIST (Deemed to be University) Hosur Road Bangalore 560029 India
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5
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Wang KCW, Donovan GM, James AL, Noble PB. Asthma: Pharmacological degradation of the airway smooth muscle layer. Int J Biochem Cell Biol 2020; 126:105818. [PMID: 32707120 DOI: 10.1016/j.biocel.2020.105818] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 07/15/2020] [Accepted: 07/20/2020] [Indexed: 12/23/2022]
Abstract
Asthma: A disease characterised by excessive and variable airway narrowing, and pathologies of inflammation and remodelling, particularly thickening of the airway smooth muscle (ASM). Treatment approaches dilate narrowed airways and reduce inflammation; however, remodelling seems largely neglected. This review considers the evolution of remodelling in asthma and whether conventional hypotheses that inflammation causes ASM thickening has mislead the medical community into thinking that anti-inflammatories will remedy this ASM defect. There is instead reasonable evidence that ASM thickening occurs independently of inflammation, such that therapies should employ strategies to directly modify ASM growth. Lessons have been learned from the use of untargeted bronchial thermoplasty and there should also be consideration of pharmacological therapies to ablate ASM. We discuss several new approaches to target ASM remodelling in asthma. A major current obstacle is our inability to image the ASM layer and assess treatment response. In this regard, polarisation-sensitive optical coherence tomography offers future promise.
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Affiliation(s)
- Kimberley C W Wang
- School of Human Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia; Telethon Kids Institute, The University of Western Australia, Nedlands, 6009, Western Australia, Australia.
| | - Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, 1142, New Zealand
| | - Alan L James
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, 6009, Western Australia, Australia; Medical School, The University of Western Australia, Nedlands, 6009, Western Australia, Australia
| | - Peter B Noble
- School of Human Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia
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6
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Zhao W, Zhao L, Zhao Y, Guo Z, Guo J, Lin C, Chiang RPY. Technology on sleep surgery. Sleep Biol Rhythms 2020. [DOI: 10.1007/s41105-020-00261-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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7
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Thiboutot J, Yuan W, Park HC, Lerner AD, Mitzner W, Yarmus LB, Li X, Brown RH. Current Advances in COPD Imaging. Acad Radiol 2019; 26:335-343. [PMID: 30093217 PMCID: PMC11247962 DOI: 10.1016/j.acra.2018.05.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 05/29/2018] [Accepted: 05/29/2018] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To review the recent advances in available technologies for imaging COPD and present the novel optical coherence tomography (OCT) airway imaging technology. MATERIALS AND METHODS This is an unstructured review of published evidence of available pulmonary imaging technologies along with a demonstration of state-of-the-art OCT imaging technology of in vivo human and animal airways. RESULTS Advanced imaging techniques such as Magnetic Resonance (MR) imaging using hyperoloarized noble gases, micro-Computed Tomography (micro-CT), and OCT aim to further our understanding of COPD. Lung densitometry can aid in identifying an exacerbation prone phenotype which may have implications for targeting specific therapies to these individuals. MR ventilation scans have the ability to provide a functional and regional distribution of airflow obstruction offering insight into the airway and parenchymal changes induced by COPD. Micro-CT gives a near microscopic view of the terminal bronchioles and alveoli permitting study of the microarchitecture of the lung ex vivo. Optical coherence tomography can visualize the microstructure of the airway walls (epithelium, smooth muscle, blood vessels, cartilage) permitting real time in vivo as well as longitudinal evaluation of airway changes in patients with COPD. CONCLUSION Advanced imaging techniques play a vital role in expanding our current understanding of COPD.
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Affiliation(s)
- Jeffrey Thiboutot
- Johns Hopkins University, Department of Medicine, Division of Pulmonary and Critical Care Medicine, 1830 E. Monument St. 5th Floor, Baltimore, MD 21205.
| | - Wu Yuan
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland
| | - Hyeon-Cheol Park
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland
| | - Andrew D Lerner
- Johns Hopkins University, Department of Medicine, Division of Pulmonary and Critical Care Medicine, 1830 E. Monument St. 5th Floor, Baltimore, MD 21205
| | - Wayne Mitzner
- Johns Hopkins University, Department of Environmental Health and Engineering, Baltimore, Maryland
| | - Lonny B Yarmus
- Johns Hopkins University, Department of Medicine, Division of Pulmonary and Critical Care Medicine, 1830 E. Monument St. 5th Floor, Baltimore, MD 21205
| | - Xingde Li
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland
| | - Robert H Brown
- Johns Hopkins University, Department of Anesthesiology and Critical Care Medicine, Medicine, Department of Medicine, Division of Pulmonary Medicine, Department of Environmental Health and Engineering, and Department of Radiology, Baltimore, Maryland
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9
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Miao Y, Jing JC, Desai V, Mahon SB, Brenner M, Veress LA, White CW, Chen Z. Automated 3D segmentation of methyl isocyanate-exposed rat trachea using an ultra-thin, fully fiber optic optical coherence endoscopic probe. Sci Rep 2018; 8:8713. [PMID: 29880863 PMCID: PMC5992171 DOI: 10.1038/s41598-018-26389-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/03/2018] [Indexed: 02/06/2023] Open
Abstract
Development of effective rescue countermeasures for toxic inhalational industrial chemicals, such as methyl isocyanate (MIC), has been an emerging interest. Nonetheless, current methods for studying toxin-induced airway injuries are limited by cost, labor time, or accuracy, and only provide indirect or localized information. Optical Coherence Tomography (OCT) endoscopic probes have previously been used to visualize the 3-D airway structure. However, gathering such information in small animal models, such as rat airways after toxic gas exposure, remains a challenge due to the required probe size necessary for accessing the small, narrow, and partially obstructed tracheas. In this study, we have designed a 0.4 mm miniature endoscopic probe and investigated the structural changes in rat trachea after MIC inhalation. An automated 3D segmentation algorithm was implemented so that anatomical changes, such as tracheal lumen volume and cross-sectional areas, could be quantified. The tracheal region of rats exposed to MIC by inhalation showed significant airway narrowing, especially within the upper trachea, as a result of epithelial detachment and extravascular coagulation within the airway. This imaging and automated reconstruction technique is capable of rapid and minimally-invasive identification of airway obstruction. This method can be applied to large-scale quantitative analysis of in vivo animal models.
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Affiliation(s)
- Yusi Miao
- Beckman Laser Institute, University of California Irvine, Irvine, 92612, California, USA.,Department of Biomedical Engineering, University of California Irvine, Irvine, 92697, California, USA
| | - Joseph C Jing
- Beckman Laser Institute, University of California Irvine, Irvine, 92612, California, USA.,Department of Biomedical Engineering, University of California Irvine, Irvine, 92697, California, USA
| | - Vineet Desai
- Beckman Laser Institute, University of California Irvine, Irvine, 92612, California, USA
| | - Sari B Mahon
- Beckman Laser Institute, University of California Irvine, Irvine, 92612, California, USA
| | - Matthew Brenner
- Beckman Laser Institute, University of California Irvine, Irvine, 92612, California, USA
| | - Livia A Veress
- Department of Pediatrics, University of Colorado Denver, Denver, 80204, Colorado, USA
| | - Carl W White
- Department of Pediatrics, University of Colorado Denver, Denver, 80204, Colorado, USA
| | - Zhongping Chen
- Beckman Laser Institute, University of California Irvine, Irvine, 92612, California, USA. .,Department of Biomedical Engineering, University of California Irvine, Irvine, 92697, California, USA.
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10
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Adams DC, Hariri LP, Miller AJ, Wang Y, Cho JL, Villiger M, Holz JA, Szabari MV, Hamilos DL, Scott Harris R, Griffith JW, Bouma BE, Luster AD, Medoff BD, Suter MJ. Birefringence microscopy platform for assessing airway smooth muscle structure and function in vivo. Sci Transl Med 2017; 8:359ra131. [PMID: 27708064 DOI: 10.1126/scitranslmed.aag1424] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 08/19/2016] [Indexed: 12/30/2022]
Abstract
The inability to visualize airway smooth muscle (ASM) cells in vivo is a major obstacle in understanding their role in normal physiology and diseases. At present, there is no imaging modality available to assess ASM in vivo. Confocal endomicroscopy lacks the penetration depth and field of view, and conventional optical coherence tomography (OCT) does not have sufficient contrast to differentiate ASM from surrounding tissues. We have developed a birefringence microscopy platform that leverages the micro-organization of tissue to add further dimension to traditional OCT. We have used this technology to validate ASM measurements in ex vivo swine and canine studies, visualize and characterize volumetric representations of ASM in vivo, and quantify and predict ASM contractile force as a function of optical retardation. We provide in vivo images and volumetric assessments of ASM in living humans and document structural disease variations in subjects with mild asthma. The opportunity to link inflammatory responses to ASM responses and to link ASM responses to clinical responses and outcomes could lead to an increased understanding of diseases of the airway and, ultimately, to improved patient outcomes.
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Affiliation(s)
- David C Adams
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Lida P Hariri
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Alyssa J Miller
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Yan Wang
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Josalyn L Cho
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Martin Villiger
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Jasmin A Holz
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Margit V Szabari
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Daniel L Hamilos
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - R Scott Harris
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Jason W Griffith
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Brett E Bouma
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Andrew D Luster
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Benjamin D Medoff
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Melissa J Suter
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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11
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Optical coherence tomography-based contact indentation for diaphragm mechanics in a mouse model of transforming growth factor alpha induced lung disease. Sci Rep 2017; 7:1517. [PMID: 28473708 PMCID: PMC5431417 DOI: 10.1038/s41598-017-01431-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/30/2017] [Indexed: 01/25/2023] Open
Abstract
This study tested the utility of optical coherence tomography (OCT)-based indentation to assess mechanical properties of respiratory tissues in disease. Using OCT-based indentation, the elastic modulus of mouse diaphragm was measured from changes in diaphragm thickness in response to an applied force provided by an indenter. We used a transgenic mouse model of chronic lung disease induced by the overexpression of transforming growth factor-alpha (TGF-α), established by the presence of pleural and peribronchial fibrosis and impaired lung mechanics determined by the forced oscillation technique and plethysmography. Diaphragm elastic modulus assessed by OCT-based indentation was reduced by TGF-α at both left and right lateral locations (p < 0.05). Diaphragm elastic modulus at left and right lateral locations were correlated within mice (r = 0.67, p < 0.01) suggesting that measurements were representative of tissue beyond the indenter field. Co-localised images of diaphragm after TGF-α overexpression revealed a layered fibrotic appearance. Maximum diaphragm force in conventional organ bath studies was also reduced by TGF-α overexpression (p < 0.01). Results show that OCT-based indentation provided clear delineation of diseased diaphragm, and together with organ bath assessment, provides new evidence suggesting that TGF-α overexpression produces impairment in diaphragm function and, therefore, an increase in the work of breathing in chronic lung disease.
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12
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Baldi S, Hartley R, Brightling C, Gupta S. Asthma. IMAGING 2016. [DOI: 10.1183/2312508x.10002815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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13
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Kirby M, Lane P, Coxson HO. Measurement of pulmonary structure and function. IMAGING 2016. [DOI: 10.1183/2312508x.10003415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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14
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Hartley R, Baldi S, Brightling C, Gupta S. Novel imaging approaches in adult asthma and their clinical potential. Expert Rev Clin Immunol 2015; 11:1147-62. [PMID: 26289375 DOI: 10.1586/1744666x.2015.1072049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Currently, imaging in asthma is confined to chest radiography and CT. The emergence of new imaging techniques and tremendous improvement of existing imaging methods, primarily due to technological advancement, has completely changed its research and clinical prospects. In research, imaging in asthma is now being employed to provide quantitative assessment of morphology, function and pathogenic processes at the molecular level. The unique ability of imaging for non-invasive, repeated, quantitative, and in vivo assessment of structure and function in asthma could lead to identification of 'imaging biomarkers' with potential as outcome measures in future clinical trials. Emerging imaging techniques and their utility in the research and clinical setting is discussed in this review.
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Affiliation(s)
- Ruth Hartley
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK
| | - Simonetta Baldi
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK
| | - Chris Brightling
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK
| | - Sumit Gupta
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK.,b 2 Radiology Department, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Leicester, LE3 9QP, UK
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15
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McLaughlin RA, Noble PB, Sampson DD. Optical coherence tomography in respiratory science and medicine: from airways to alveoli. Physiology (Bethesda) 2015; 29:369-80. [PMID: 25180266 DOI: 10.1152/physiol.00002.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Optical coherence tomography is a rapidly maturing optical imaging technology, enabling study of the in vivo structure of lung tissue at a scale of tens of micrometers. It has been used to assess the layered structure of airway walls, quantify both airway lumen caliber and compliance, and image individual alveoli. This article provides an overview of the technology and reviews its capability to provide new insights into respiratory disease.
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Affiliation(s)
- Robert A McLaughlin
- Optical & Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Perth, Australia;
| | - Peter B Noble
- School of Anatomy, Physiology & Human Biology, and Centre for Neonatal Research & Education, School of Paediatrics and Child Health, The University of Western Australia, Crawley, Australia; and
| | - David D Sampson
- Optical & Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Perth, Australia; Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, Perth, Australia
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16
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Patient-Specific Airway Wall Remodeling in Chronic Lung Disease. Ann Biomed Eng 2015; 43:2538-51. [PMID: 25821112 DOI: 10.1007/s10439-015-1306-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Accepted: 03/20/2015] [Indexed: 12/20/2022]
Abstract
Chronic lung disease affects more than a quarter of the adult population; yet, the mechanics of the airways are poorly understood. The pathophysiology of chronic lung disease is commonly characterized by mucosal growth and smooth muscle contraction of the airways, which initiate an inward folding of the mucosal layer and progressive airflow obstruction. Since the degree of obstruction is closely correlated with the number of folds, mucosal folding has been extensively studied in idealized circular cross sections. However, airflow obstruction has never been studied in real airway geometries; the behavior of imperfect, non-cylindrical, continuously branching airways remains unknown. Here we model the effects of chronic lung disease using the nonlinear field theories of mechanics supplemented by the theory of finite growth. We perform finite element analysis of patient-specific Y-branch segments created from magnetic resonance images. We demonstrate that the mucosal folding pattern is insensitive to the specific airway geometry, but that it critically depends on the mucosal and submucosal stiffness, thickness, and loading mechanism. Our results suggests that patient-specific airway models with inherent geometric imperfections are more sensitive to obstruction than idealized circular models. Our models help to explain the pathophysiology of airway obstruction in chronic lung disease and hold promise to improve the diagnostics and treatment of asthma, bronchitis, chronic obstructive pulmonary disease, and respiratory failure.
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17
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Le Tuan T, Nguyen NM, Demoulin B, Bonabel C, Nguyen-Thi PL, Ioan I, Schweitzer C, Nguyen HTT, Varechova S, Marchal F. Specific airway resistance in healthy young Vietnamese and Caucasian adults. Respir Physiol Neurobiol 2015; 211:17-21. [PMID: 25796614 DOI: 10.1016/j.resp.2015.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/25/2015] [Accepted: 03/02/2015] [Indexed: 11/28/2022]
Abstract
In healthy Vietnamese children the respiratory resistance has been suggested to be similar at 110 cm height but larger at 130 cm when compared with data in Caucasians from the literature, suggesting smaller airways in older Vietnamese children (Vu et al., 2008). The hypothesis tested here is whether the difference in airway resistance remains consistent throughout growth, and if it is larger in adult Vietnamese than in Caucasians. Airway resistance and Functional Residual Capacity were measured in healthy young Caucasian and Vietnamese adults in their respective native country using identical equipment and protocols. Ninety five subjects in Vietnam (60 males) and 101 in France (41 males) were recruited. Airway resistance was significantly larger in Vietnamese than in Caucasians and in females than in males, consistent with difference in body dimensions. Specific airway resistance however was not different by ethnicity or gender. The findings do not support the hypothesis that airway size at adult age - once normalized for lung volume - differs between Vietnamese and Caucasians.
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Affiliation(s)
- Thanh Le Tuan
- Department of Physiology, Hanoi Medical University , Hanoi, Vietnam
| | - Ngoc Minh Nguyen
- Department of Physiology, Hanoi Medical University , Hanoi, Vietnam
| | - Bruno Demoulin
- Department of Physiology, University of Lorraine, Vandoeuvre les Nancy, France
| | - Claude Bonabel
- Department of Paediatric Lung Function Testing, University Hospital of Nancy, Children's Hospital, Vandoeuvre les Nancy, France
| | - Phi Linh Nguyen-Thi
- Department of Epidemiology, University Hospital of Nancy, Vandoeuvre les Nancy, France
| | - Iulia Ioan
- Department of Paediatric Lung Function Testing, University Hospital of Nancy, Children's Hospital, Vandoeuvre les Nancy, France
| | - Cyril Schweitzer
- Department of Paediatric Lung Function Testing, University Hospital of Nancy, Children's Hospital, Vandoeuvre les Nancy, France; Department of Epidemiology, University Hospital of Nancy, Vandoeuvre les Nancy, France
| | - H T T Nguyen
- Department of Physiology, Hanoi Medical University , Hanoi, Vietnam
| | - Silvia Varechova
- Department of Paediatric Lung Function Testing, University Hospital of Nancy, Children's Hospital, Vandoeuvre les Nancy, France; Department of Epidemiology, University Hospital of Nancy, Vandoeuvre les Nancy, France
| | - Francois Marchal
- Department of Paediatric Lung Function Testing, University Hospital of Nancy, Children's Hospital, Vandoeuvre les Nancy, France; Department of Epidemiology, University Hospital of Nancy, Vandoeuvre les Nancy, France.
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18
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Ansell TK, McFawn PK, McLaughlin RA, Sampson DD, Eastwood PR, Hillman DR, Mitchell HW, Noble PB. Does smooth muscle in an intact airway undergo length adaptation during a sustained change in transmural pressure? J Appl Physiol (1985) 2015; 118:533-43. [DOI: 10.1152/japplphysiol.00724.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In isolated airway smooth muscle (ASM) strips, an increase or decrease in ASM length away from its current optimum length causes an immediate reduction in force production followed by a gradual time-dependent recovery in force, a phenomenon termed length adaptation. In situ, length adaptation may be initiated by a change in transmural pressure (Ptm), which is a primary physiological determinant of ASM length. The present study sought to determine the effect of sustained changes in Ptm and therefore, ASM perimeter, on airway function. We measured contractile responses in whole porcine bronchial segments in vitro before and after a sustained inflation from a baseline Ptm of 5 cmH2O to 25 cmH2O, or deflation to −5 cmH2O, for ∼50 min in each case. In one group of airways, lumen narrowing and stiffening in response to electrical field stimulation (EFS) were assessed from volume and pressure signals using a servo-controlled syringe pump with pressure feedback. In a second group of airways, lumen narrowing and the perimeter of the ASM in situ were determined by anatomical optical coherence tomography. In a third group of airways, active tension was determined under isovolumic conditions. Both inflation and deflation reduced the contractile response to EFS. Sustained Ptm change resulted in a further decrease in contractile response, which returned to baseline levels upon return to the baseline Ptm. These findings reaffirm the importance of Ptm in regulating airway narrowing. However, they do not support a role for ASM length adaptation in situ under physiological levels of ASM lengthening and shortening.
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Affiliation(s)
- Thomas K. Ansell
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Peter K. McFawn
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Robert A. McLaughlin
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - David D. Sampson
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, Western Australia, Australia
| | - Peter R. Eastwood
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
- West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; and
| | - David R. Hillman
- West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; and
| | - Howard W. Mitchell
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Peter B. Noble
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
- Centre for Neonatal Research and Education, School of Paediatrics and Child Health, University of Western Australia, Crawley, Western Australia, Australia
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19
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Noble PB, Pascoe CD, Lan B, Ito S, Kistemaker LEM, Tatler AL, Pera T, Brook BS, Gosens R, West AR. Airway smooth muscle in asthma: linking contraction and mechanotransduction to disease pathogenesis and remodelling. Pulm Pharmacol Ther 2014; 29:96-107. [PMID: 25062835 DOI: 10.1016/j.pupt.2014.07.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 07/12/2014] [Accepted: 07/15/2014] [Indexed: 02/07/2023]
Abstract
Asthma is an obstructive airway disease, with a heterogeneous and multifactorial pathogenesis. Although generally considered to be a disease principally driven by chronic inflammation, it is becoming increasingly recognised that the immune component of the pathology poorly correlates with the clinical symptoms of asthma, thus highlighting a potentially central role for non-immune cells. In this context airway smooth muscle (ASM) may be a key player, as it comprises a significant proportion of the airway wall and is the ultimate effector of acute airway narrowing. Historically, the contribution of ASM to asthma pathogenesis has been contentious, yet emerging evidence suggests that ASM contractile activation imparts chronic effects that extend well beyond the temporary effects of bronchoconstriction. In this review article we describe the effects that ASM contraction, in combination with cellular mechanotransduction and novel contraction-inflammation synergies, contribute to asthma pathogenesis. Specific emphasis will be placed on the effects that ASM contraction exerts on the mechanical properties of the airway wall, as well as novel mechanisms by which ASM contraction may contribute to more established features of asthma such as airway wall remodelling.
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Affiliation(s)
- Peter B Noble
- School of Anatomy, Physiology and Human Biology, University of Western Australia, WA, Australia
| | - Chris D Pascoe
- Center for Heart Lung Innovation, University of British Columbia, BC, Canada
| | - Bo Lan
- Center for Heart Lung Innovation, University of British Columbia, BC, Canada; Bioengineering College, Chongqing University, Chongqing, China
| | - Satoru Ito
- Department of Respiratory Medicine, Nagoya University, Aichi, Japan
| | - Loes E M Kistemaker
- Department of Molecular Pharmacology, University of Groningen, The Netherlands
| | - Amanda L Tatler
- Division of Respiratory Medicine, University of Nottingham, United Kingdom
| | - Tonio Pera
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, United Kingdom
| | - Reinoud Gosens
- Department of Molecular Pharmacology, University of Groningen, The Netherlands
| | - Adrian R West
- Department of Physiology, University of Manitoba, MB, Canada; Biology of Breathing, Manitoba Institute of Child Health, MB, Canada.
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20
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Lee AMD, Kirby M, Ohtani K, Candido T, Shalansky R, MacAulay C, English J, Finley R, Lam S, Coxson HO, Lane P. Validation of airway wall measurements by optical coherence tomography in porcine airways. PLoS One 2014; 9:e100145. [PMID: 24949633 PMCID: PMC4064993 DOI: 10.1371/journal.pone.0100145] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 05/22/2014] [Indexed: 11/19/2022] Open
Abstract
Examining and quantifying changes in airway morphology is critical for studying longitudinal pathogenesis and interventions in diseases such as chronic obstructive pulmonary disease and asthma. Here we present fiber-optic optical coherence tomography (OCT) as a nondestructive technique to precisely and accurately measure the 2-dimensional cross-sectional areas of airway wall substructure divided into the mucosa (WAmuc), submucosa (WAsub), cartilage (WAcart), and the airway total wall area (WAt). Porcine lung airway specimens were dissected from freshly resected lung lobes (N = 10). Three-dimensional OCT imaging using a fiber-optic rotary-pullback probe was performed immediately on airways greater than 0.9 mm in diameter on the fresh airway specimens and subsequently on the same specimens post-formalin-fixation. The fixed specimens were serially sectioned and stained with H&E. OCT images carefully matched to selected sections stained with Movat's pentachrome demonstrated that OCT effectively identifies airway epithelium, lamina propria, and cartilage. Selected H&E sections were digitally scanned and airway total wall areas were measured. Traced measurements of WAmuc, WAsub, WAcart, and WAt from OCT images of fresh specimens by two independent observers found there were no significant differences (p>0.05) between the observer's measurements. The same wall area measurements from OCT images of formalin-fixed specimens found no significant differences for WAsub, WAcart and WAt, and a small but significant difference for WAmuc. Bland-Altman analysis indicated there were negligible biases between the observers for OCT wall area measurements in both fresh and formalin-fixed specimens. Bland-Altman analysis also indicated there was negligible bias between histology and OCT wall area measurements for both fresh and formalin-fixed specimens. We believe this study sets the groundwork for quantitatively monitoring pathogenesis and interventions in the airways using OCT.
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Affiliation(s)
- Anthony M. D. Lee
- Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada
- * E-mail:
| | - Miranda Kirby
- Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Keishi Ohtani
- Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada
| | - Tara Candido
- Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Rebecca Shalansky
- Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Calum MacAulay
- Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada
| | - John English
- Department of Pathology, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Richard Finley
- Department of Surgery, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Stephen Lam
- Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada
| | - Harvey O. Coxson
- Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Pierre Lane
- Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada
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21
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Jin L, Chen D, Hayward RC, Suo Z. Creases on the interface between two soft materials. SOFT MATTER 2014; 10:303-311. [PMID: 24651667 DOI: 10.1039/c3sm51512e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Theory and experiment are presented to show that an interface between two soft materials under compression can form creases, a type of bifurcation distinct from wrinkles. While creases bifurcate from a state of flat interface by a deformation localized in space and large in amplitude, wrinkles bifurcate from a state of flat interface by a deformation nonlocal in space and infinitesimal in amplitude. The interfacial creases set in at a lower critical compression than interfacial wrinkles, but higher than surface creases. The condition for the onset of interfacial creases is scale-free, and is calculated in terms of elastic moduli, pre-strains and applied strains.
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Affiliation(s)
- Lihua Jin
- School of Engineering and Applied Sciences, Kavli Institute for Nanobio Science and Technology, Harvard University, Cambridge, Massachusetts 02138, USA.
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22
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Harvey BC, Parameswaran H, Lutchen KR. Can tidal breathing with deep inspirations of intact airways create sustained bronchoprotection or bronchodilation? J Appl Physiol (1985) 2013; 115:436-45. [PMID: 23722710 DOI: 10.1152/japplphysiol.00009.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fluctuating forces imposed on the airway smooth muscle due to breathing are believed to regulate hyperresponsiveness in vivo. However, recent animal and human isolated airway studies have shown that typical breathing-sized transmural pressure (Ptm) oscillations around a fixed mean are ineffective at mitigating airway constriction. To help understand this discrepancy, we hypothesized that Ptm oscillations capable of producing the same degree of bronchodilation as observed in airway smooth muscle strip studies requires imposition of strains larger than those expected to occur in vivo. First, we applied increasingly larger amplitude Ptm oscillations to a statically constricted airway from a Ptm simulating normal functional residual capacity of 5 cmH2O. Tidal-like oscillations (5-10 cmH2O) imposed 4.9 ± 2.0% strain and resulted in 11.6 ± 4.8% recovery, while Ptm oscillations simulating a deep inspiration at every breath (5-30 cmH2O) achieved 62.9 ± 12.1% recovery. These same Ptm oscillations were then applied starting from a Ptm = 1 cmH2O, resulting in approximately double the strain for each oscillation amplitude. When extreme strains were imposed, we observed full recovery. On combining the two data sets, we found a linear relationship between strain and resultant recovery. Finally, we compared the impact of Ptm oscillations before and after constriction to Ptm oscillations applied only after constriction and found that both loading conditions had a similar effect on narrowing. We conclude that, while sufficiently large strains applied to the airway wall are capable of producing substantial bronchodilation, the Ptm oscillations necessary to achieve those strains are not expected to occur in vivo.
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Affiliation(s)
- Brian C Harvey
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA.
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23
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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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24
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Walker C, Gupta S, Raj V, Siddiqui S, Brightling CE. Imaging advances in asthma. ACTA ACUST UNITED AC 2013; 5:453-65. [PMID: 23484630 DOI: 10.1517/17530059.2011.609886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Asthma is a global burden, affecting 5% of the general adult population, with approximately 5 - 10% suffering from severe asthma. Severe asthma is a complex heterogeneous disease entity, with high morbidity and mortality. Recent years have seen the introduction of a vast array of new imaging technologies, which have provided the ability to comprehensively, non-invasively and functionally assess the lungs. These advances have resulted in a better understanding of the pathophysiology in severe asthma and have the unprecedented potential to unravel the structure-function relationship of severe asthma in the future. AREAS COVERED This review article chronologically describes the technological advances currently used and to be used in the future. The article covers pitfalls in imaging of the airways and lung parenchyma in asthma from chest x-rays, CT scans, MRI, confocal florescence endomicroscopy to computational fluid dynamics. EXPERT OPINION Novel qualitative and quantitative imaging techniques have enabled us to study the large airway architecture in detail, assess the small airway structure and perform functional or novel physiological evaluations. Despite spectacular advances in imaging techniques and the birth of new modalities, there is an urgent need for both proof-of-concept studies, large cross-sectional and longitudinal clinical trials in severe asthma to validate and clinically correlate imaging-derived measures. This will extend our current understanding of the pathophysiology of severe asthma, and unravel the structure-function relationship, with the potential to discover novel severe asthma phenotypes, predict mortality, morbidity and response to existing and novel pharmacological and non-pharmacological therapies.
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Affiliation(s)
- Carolina Walker
- University of Leicester , Institute for Lung Health, Department of Infection , Inflammation and Immunity, Leicester , UK
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25
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Hariri LP, Applegate MB, Mino-Kenudson M, Mark EJ, Medoff BD, Luster AD, Bouma BE, Tearney GJ, Suter MJ. Volumetric optical frequency domain imaging of pulmonary pathology with precise correlation to histopathology. Chest 2013; 143:64-74. [PMID: 22459781 DOI: 10.1378/chest.11-2797] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Lung cancer is the leading cause of cancer-related mortality. Radiology and bronchoscopy techniques do not have the necessary resolution to evaluate lung lesions on the microscopic scale, which is critical for diagnosis. Bronchial biopsy specimens can be limited by sampling error and small size. Optical frequency domain imaging (OFDI) provides volumetric views of tissue microstructure at near-histologic resolution and may be useful for evaluating pulmonary lesions to increase diagnostic accuracy. Bronchoscopic OFDI has been evaluated in vivo, but a lack of correlated histopathology has limited the ability to develop accurate image interpretation criteria. METHODS We performed OFDI through two approaches (airway-centered and parenchymal imaging) in 22 ex vivo lung specimens, using tissue dye to precisely correlate imaging and histology. RESULTS OFDI of normal airway allowed visualization of epithelium, lamina propria, cartilage, and alveolar attachments. Carcinomas exhibited architectural disarray, loss of normal airway and alveolar structure, and rapid light attenuation. Squamous cell carcinomas showed nested architecture. Atypical glandular formation was appreciated in adenocarcinomas, and uniform trabecular gland formation was seen in salivary gland carcinomas. Mucinous adenocarcinomas showed alveolar wall thickening with intraalveolar mucin. Interstitial fibrosis was visualized as signal-dense tissue, with an interstitial distribution in mild interstitial fibrotic disease and a diffuse subpleural pattern with cystic space formation in usual interstitial pneumonitis. CONCLUSIONS To our knowledge, this study is the first demonstration of volumetric OFDI with precise correlation to histopathology in lung pathology. We anticipate that OFDI may play a role in assessing airway and parenchymal pathology, providing fresh insights into the volumetric features of pulmonary disease.
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Affiliation(s)
- Lida P Hariri
- Department of Pathology, Boston; Wellman Center for Photomedicine, Boston; Harvard Medical School, Cambridge
| | - Matthew B Applegate
- Pulmonary and Critical Care Unit, Boston; Wellman Center for Photomedicine, Boston
| | | | - Eugene J Mark
- Department of Pathology, Boston; Harvard Medical School, Cambridge
| | - Benjamin D Medoff
- Pulmonary and Critical Care Unit, Boston; Harvard Medical School, Cambridge
| | - Andrew D Luster
- Rheumatology, Allergy and Immunology Division, Massachusetts General Hospital, Boston; Harvard Medical School, Cambridge
| | - Brett E Bouma
- Wellman Center for Photomedicine, Boston; Harvard Medical School, Cambridge; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA
| | - Guillermo J Tearney
- Department of Pathology, Boston; Wellman Center for Photomedicine, Boston; Harvard Medical School, Cambridge; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA
| | - Melissa J Suter
- Pulmonary and Critical Care Unit, Boston; Wellman Center for Photomedicine, Boston; Harvard Medical School, Cambridge.
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26
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McLaughlin RA, Yang X, Quirk BC, Lorenser D, Kirk RW, Noble PB, Sampson DD. Static and dynamic imaging of alveoli using optical coherence tomography needle probes. J Appl Physiol (1985) 2012; 113:967-74. [DOI: 10.1152/japplphysiol.00051.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Imaging of alveoli in situ has for the most part been infeasible due to the high resolution required to discern individual alveoli and limited access to alveoli beneath the lung surface. In this study, we present a novel technique to image alveoli using optical coherence tomography (OCT). We propose the use of OCT needle probes, where the distal imaging probe has been miniaturized and encased within a hypodermic needle (as small as 30-gauge, outer diameter 310 μm), allowing insertion deep within the lung tissue with minimal tissue distortion. Such probes enable imaging at a resolution of ∼12 μm within a three-dimensional cylindrical field of view with diameter ∼1.5 mm centered on the needle tip. The imaging technique is demonstrated on excised lungs from three different species: adult rats, fetal sheep, and adult pigs. OCT needle probes were used to image alveoli, small bronchioles, and blood vessels, and results were matched to histological sections. We also present the first dynamic OCT images acquired with an OCT needle probe, allowing tracking of individual alveoli during simulated cyclical lung inflation and deflation.
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Affiliation(s)
- Robert A. McLaughlin
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Xiaojie Yang
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Bryden C. Quirk
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Dirk Lorenser
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Rodney W. Kirk
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Peter B. Noble
- Centre for Neonatal Research and Education, School of Women's and Infants' Health, University of Western Australia, Crawley, Western Australia, Australia; and
| | - David D. Sampson
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley Western Australia, Australia
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27
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Wright D, Sharma P, Ryu MH, Rissé PA, Ngo M, Maarsingh H, Koziol-White C, Jha A, Halayko AJ, West AR. Models to study airway smooth muscle contraction in vivo, ex vivo and in vitro: implications in understanding asthma. Pulm Pharmacol Ther 2012; 26:24-36. [PMID: 22967819 DOI: 10.1016/j.pupt.2012.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 08/14/2012] [Accepted: 08/17/2012] [Indexed: 11/16/2022]
Abstract
Asthma is a chronic obstructive airway disease characterised by airway hyperresponsiveness (AHR) and airway wall remodelling. The effector of airway narrowing is the contraction of airway smooth muscle (ASM), yet the question of whether an inherent or acquired dysfunction in ASM contractile function plays a significant role in the disease pathophysiology remains contentious. The difficulty in determining the role of ASM lies in limitations with the models used to assess contraction. In vivo models provide a fully integrated physiological response but ASM contraction cannot be directly measured. Ex vivo and in vitro models can provide more direct assessment of ASM contraction but the loss of factors that may modulate ASM responsiveness and AHR, including interaction between multiple cell types and disruption of the mechanical environment, precludes a complete understanding of the disease process. In this review we detail key advantages of common in vivo, ex vivo and in vitro models of ASM contraction, as well as emerging tissue engineered models of ASM and whole airways. We also highlight important findings from each model with respect to the pathophysiology of asthma.
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Affiliation(s)
- David Wright
- Medical Research Council and Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, United Kingdom
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28
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Abstract
Pulmonary function testing is part of routine clinical practice in respiratory medicine. It is based around spirometry, which will remain the central measurement of lung function given its prognostic significance and its integral role in defining severity of airways disease. However, there is an increasing body of evidence from studies using new methods of lung function measurement which are providing new insights into pathophysiology of disease. This body of data is forming a basis for their future clinical role, once the economics of producing the relevant devices becomes attractive. The forced oscillation technique and multiple breath nitrogen washout are currently the most commonly used of the newer lung function techniques, which are refinements of long-established techniques. Optical coherence tomography, optical reflection, electrical impedance and vibration response imaging have arisen by development of novel devices. The recent use of these techniques is reviewed.
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Affiliation(s)
- Gregory G King
- Woolcock Institute of Medical Research, The Northern Clinical School, Sydney Medical School, University of Sydney, New South Wales, Australia.
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29
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Models and approaches to understand the role of airway remodelling in disease. Pulm Pharmacol Ther 2011; 24:478-86. [PMID: 21824523 DOI: 10.1016/j.pupt.2011.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 07/19/2011] [Accepted: 07/21/2011] [Indexed: 11/23/2022]
Abstract
Airway remodelling is a collective term for changes in the amount or organisation of the cellular and molecular constituents of the airway wall. Remodelling occurs in and is associated with the pathophysiology of airways diseases including asthma and chronic obstructive pulmonary disease. The remodelling that occurs in these diseases exhibits both shared and distinct features. Remodelling is generally considered to be deleterious to airway function but recent studies also indicate potential protective effects. However, the true impact of different aspects of the remodelling process on lung function, both negative and positive, is poorly understood. In addition, the genetic susceptibility and processes by which environmental insults drive the cell and molecular events which result in airway remodelling and the potential for therapeutic reversibility are also incompletely understood. The last 10-15 years has seen the development of animal models of airway remodelling which have been refined and modified as new factors such as exacerbations and early life influences have been recognised as being of importance. In addition, invertebrate models have been put forward and complex in vitro culture systems and lung slice preparations developed. In parallel, imaging technology has developed to an extent where it is feasible using a combination of techniques to image structural components, cells and proteins in the airway wall as well as to analyse biological processes, cell and receptor activation non-invasively over time. The integration of data from in vivo and in vitro models together with use of imaging techniques in man and animals should allow validation of models, further our understanding of the pathophysiology of airway remodelling and potentially improve predictive accuracy for the translation of novel therapeutic agents into the clinic.
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Noble PB, Jones RL, Needi ET, Cairncross A, Mitchell HW, James AL, McFawn PK. Responsiveness of the human airway in vitro during deep inspiration and tidal oscillation. J Appl Physiol (1985) 2011; 110:1510-8. [PMID: 21310892 DOI: 10.1152/japplphysiol.01226.2010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In healthy individuals, deep inspiration produces bronchodilation and reduced airway responsiveness, which may be a response of the airway wall to mechanical stretch. The aim of this study was to examine the in vitro response of isolated human airways to the dynamic mechanical stretch associated with normal breathing. Human bronchial segments (n = 6) were acquired from patients without airflow obstruction undergoing lung resection for pulmonary neoplasms. The side branches were ligated and the airways were mounted in an organ bath chamber. Airway narrowing to cumulative concentrations of acetylcholine (3 × 10(-6) M to 3 × 10(-3) M) was measured under static conditions and in the presence of "tidal" oscillations with intermittent "deep inspiration." Respiratory maneuvers were simulated by varying transmural pressure using a motor-controlled syringe pump (tidal 5 to 10 cmH(2)O at 0.25 Hz, deep inspiration 5 to 30 cmH(2)O). Airway narrowing was determined from decreases in lumen volume. Tidal oscillation had no effect on airway responses to acetylcholine which was similar to those under static conditions. Deep inspiration in tidally oscillating, acetylcholine-contracted airways produced potent, transient (<1 min) bronchodilation, ranging from full reversal in airway narrowing at low acetylcholine concentrations to ∼50% reversal at the highest concentration. This resulted in a temporary reduction in maximal airway response (P < 0.001), without a change in sensitivity to acetylcholine. Our findings are that the mechanical stretch of human airways produced by physiological transmural pressures generated during deep inspiration produces bronchodilation and a transient reduction in airway responsiveness, which can explain the beneficial effects of deep inspiration in bronchial provocation testing in vivo.
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Affiliation(s)
- Peter B Noble
- Div. of Clinical Sciences, Telethon Institute for Child Health Research, 100 Roberts Rd., Subiaco, Western Australia, Australia 6008.
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Li B, Cao YP, Feng XQ. Growth and surface folding of esophageal mucosa: a biomechanical model. J Biomech 2010; 44:182-8. [PMID: 20880530 DOI: 10.1016/j.jbiomech.2010.09.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Revised: 09/08/2010] [Accepted: 09/08/2010] [Indexed: 10/19/2022]
Abstract
Mucosal folding in such biological vessels as esophagus and airway is essential to their physiological functions and can be affected by some diseases, e.g., inflammation, edema, lymphoma, and asthma. A biomechanical model within the framework of finite deformation theory is proposed to address the mucosal folding induced by the growth and residual stresses in the tissue. A hyperelastic constitutive law is adopted for the mucosal layer, which grows in a cylindrical lumen. The fields of the engendered displacements and residual stresses are solved analytically. Furthermore, the instability analysis predicts the folding number, which agrees well with our experimental observations. This study not only sheds light on the biomechanical mechanisms underlying mucosal folding but also provides a promising approach for determining the residual stress level in living tissues under different physiological or pathological conditions according to their folding features.
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Affiliation(s)
- Bo Li
- Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
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Thiagarajah JR, Song Y, Derichs N, Verkman AS. Airway surface liquid depth imaged by surface laser reflectance microscopy. ACTA ACUST UNITED AC 2010; 136:353-62. [PMID: 20713545 PMCID: PMC2931148 DOI: 10.1085/jgp.201010490] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The thin layer of liquid at the surface of airway epithelium, the airway surface liquid (ASL), is important in normal airway physiology and in the pathophysiology of cystic fibrosis. At present, the best method to measure ASL depth involves scanning confocal microscopy after staining with an aqueous-phase fluorescent dye. We describe here a simple, noninvasive imaging method to measure ASL depth by reflectance imaging of an epithelial mucosa in which the surface is illuminated at a 45-degree angle by an elongated 13-µm wide rectangular beam produced by a 670-nm micro-focus laser. The principle of the method is that air–liquid, liquid–liquid, and liquid–cell interfaces produce distinct specular or diffuse reflections that can be imaged to give a micron-resolution replica of the mucosal surface. The method was validated using fluid layers of specified thicknesses and applied to measure ASL depth in cell cultures and ex vivo fragments of pig trachea. In addition, the method was adapted to measure transepithelial fluid transport from the dynamics of fluid layer depth. Compared with confocal imaging, ASL depth measurement by surface laser reflectance microscopy does not require dye staining or costly instrumentation, and can potentially be adapted for in vivo measurements using fiberoptics.
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Affiliation(s)
- Jay R Thiagarajah
- Department of Medicine, University of California, San Francisco, CA 94143, USA
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Distribution of airway narrowing responses across generations and at branching points, assessed in vitro by anatomical optical coherence tomography. Respir Res 2010; 11:9. [PMID: 20092657 PMCID: PMC2824705 DOI: 10.1186/1465-9921-11-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 01/22/2010] [Indexed: 11/20/2022] Open
Abstract
Background Previous histological and imaging studies have shown the presence of variability in the degree of bronchoconstriction of airways sampled at different locations in the lung (i.e., heterogeneity). Heterogeneity can occur at different airway generations and at branching points in the bronchial tree. Whilst heterogeneity has been detected by previous experimental approaches, its spatial relationship either within or between airways is unknown. Methods In this study, distribution of airway narrowing responses across a portion of the porcine bronchial tree was determined in vitro. The portion comprised contiguous airways spanning bronchial generations (#3-11), including the associated side branches. We used a recent optical imaging technique, anatomical optical coherence tomography, to image the bronchial tree in three dimensions. Bronchoconstriction was produced by carbachol administered to either the adventitial or luminal surface of the airway. Luminal cross sectional area was measured before and at different time points after constriction to carbachol and airway narrowing calculated from the percent decrease in luminal cross sectional area. Results When administered to the adventitial surface, the degree of airway narrowing was progressively increased from proximal to distal generations (r = 0.80 to 0.98, P < 0.05 to 0.001). This 'serial heterogeneity' was also apparent when carbachol was administered via the lumen, though it was less pronounced. In contrast, airway narrowing was not different at side branches, and was uniform both in the parent and daughter airways. Conclusions Our findings demonstrate that the bronchial tree expresses intrinsic serial heterogeneity, such that narrowing increases from proximal to distal airways, a relationship that is influenced by the route of drug administration but not by structural variations accompanying branching sites.
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