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Pybus HJ, O'Dea RD, Brook BS. A dynamical model of TGF-β activation in asthmatic airways. MATHEMATICAL MEDICINE AND BIOLOGY : A JOURNAL OF THE IMA 2023; 40:238-265. [PMID: 37285178 DOI: 10.1093/imammb/dqad004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 06/08/2023]
Abstract
Excessive activation of the regulatory cytokine transforming growth factor $\beta $ (TGF-$\beta $) via contraction of airway smooth muscle (ASM) is associated with the development of asthma. In this study, we develop an ordinary differential equation model that describes the change in density of the key airway wall constituents, ASM and extracellular matrix (ECM), and their interplay with subcellular signalling pathways leading to the activation of TGF-$\beta $. We identify bistable parameter regimes where there are two positive steady states, corresponding to either reduced or elevated TGF-$\beta $ concentration, with the latter leading additionally to increased ASM and ECM density. We associate the former with a healthy homeostatic state and the latter with a diseased (asthmatic) state. We demonstrate that external stimuli, inducing TGF-$\beta $ activation via ASM contraction (mimicking an asthmatic exacerbation), can perturb the system irreversibly from the healthy state to the diseased one. We show that the properties of the stimuli, such as their frequency or strength, and the clearance of surplus active TGF-$\beta $, are important in determining the long-term dynamics and the development of disease. Finally, we demonstrate the utility of this model in investigating temporal responses to bronchial thermoplasty, a therapeutic intervention in which ASM is ablated by applying thermal energy to the airway wall. The model predicts the parameter-dependent threshold damage required to obtain irreversible reduction in ASM content, suggesting that certain asthma phenotypes are more likely to benefit from this intervention.
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Affiliation(s)
- Hannah J Pybus
- Department of Bioengineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Reuben D O'Dea
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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Li N, Cheng Y, Wang S, Liao H, Liu S. Inhibition of airway smooth muscle contraction and proliferation by LIM kinase inhibitor, LIMKi3. Adv Med Sci 2023; 68:186-194. [PMID: 37148787 DOI: 10.1016/j.advms.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/08/2023]
Abstract
PURPOSE Current medical treatment for asthma aims to inhibit airway smooth muscle (ASM) contraction and proliferation, however, the efficacy of available treatment options is unsatisfactory. Therefore, we explored the effect of LIM domain kinase (LIMK) inhibitor - LIMKi3, on ASM to improve the understanding of ASM contraction and proliferation mechanisms, and to investigate new therapeutic targets. MATERIALS AND METHODS Asthma model was induced in rats by intraperitoneal injection of ovalbumin. Using phospho-specific antibodies, we examined LIMK, phosphorylated LIMK, cofilin and phosphorylated cofilin. ASM contraction was studied in organ bath experiments. ASM cells proliferation was studied with cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assays. RESULTS Immunofluorescence indicated that LIMKs are expressed in ASM tissues. Western blot revealed that LIMK1 and phospho-cofilin were significantly elevated in asthma ASM tissues. The LIMK inhibitor, LIMKi3 (1 μM) could reduce cofilin phosphorylation and therefore inhibit contraction of ASM tissues, and induce actin filament breakdown as well as cell proliferation reduction in cultured human ASM cells. CONCLUSIONS ASM contraction and proliferation in asthma may underlie the effects of LIMKs. Small molecule LIMK inhibitor, LIMKi3, might be a potential therapeutic strategy for asthma.
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Affiliation(s)
- Ning Li
- Department of Neurosurgery, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China
| | - Yuanxiong Cheng
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong, China
| | - Shiyong Wang
- Department of Neurosurgery, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China
| | - Hua Liao
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China
| | - Shengming Liu
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China.
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Tatler AL. Asthmatic airway remodeling: long overlooked but too important to ignore. ANNALS OF TRANSLATIONAL MEDICINE 2023; 11:29. [PMID: 36819573 PMCID: PMC9929740 DOI: 10.21037/atm-22-5733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022]
Affiliation(s)
- Amanda L Tatler
- Biodiscovery Institute, School of Medicine, University of Nottingham, Nottingham, UK
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Winkler T. Mechanisms of airway remodeling converge at the critical point of bronchoconstriction in asthma. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:1188. [PMID: 36544670 PMCID: PMC9761168 DOI: 10.21037/atm-22-5095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 10/21/2022] [Indexed: 11/09/2022]
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Neelakantan S, Xin Y, Gaver DP, Cereda M, Rizi R, Smith BJ, Avazmohammadi R. Computational lung modelling in respiratory medicine. J R Soc Interface 2022; 19:20220062. [PMID: 35673857 PMCID: PMC9174712 DOI: 10.1098/rsif.2022.0062] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Computational modelling of the lungs is an active field of study that integrates computational advances with lung biophysics, biomechanics, physiology and medical imaging to promote individualized diagnosis, prognosis and therapy evaluation in lung diseases. The complex and hierarchical architecture of the lung offers a rich, but also challenging, research area demanding a cross-scale understanding of lung mechanics and advanced computational tools to effectively model lung biomechanics in both health and disease. Various approaches have been proposed to study different aspects of respiration, ranging from compartmental to discrete micromechanical and continuum representations of the lungs. This article reviews several developments in computational lung modelling and how they are integrated with preclinical and clinical data. We begin with a description of lung anatomy and how different tissue components across multiple length scales affect lung mechanics at the organ level. We then review common physiological and imaging data acquisition methods used to inform modelling efforts. Building on these reviews, we next present a selection of model-based paradigms that integrate data acquisitions with modelling to understand, simulate and predict lung dynamics in health and disease. Finally, we highlight possible future directions where computational modelling can improve our understanding of the structure–function relationship in the lung.
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Affiliation(s)
- Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Yi Xin
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahim Rizi
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver
- Anschutz Medical Campus, Aurora, CO, USA
- Department of Pediatric Pulmonary and Sleep Medicine, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA
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Joseph C, Tatler AL. Pathobiology of Airway Remodeling in Asthma: The Emerging Role of Integrins. J Asthma Allergy 2022; 15:595-610. [PMID: 35592385 PMCID: PMC9112045 DOI: 10.2147/jaa.s267222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/25/2022] [Indexed: 12/19/2022] Open
Abstract
Airway remodeling is a complex clinical feature of asthma that involves long-term disruption and modification of airway architecture, which contributes significantly to airway hyperresponsiveness (AHR) and lung function decline. It is characterized by thickening of the airway smooth muscle layer, deposition of a matrix below the airway epithelium, resulting in subepithelial fibrosis, changes within the airway epithelium, leading to disruption of the barrier, and excessive mucous production and angiogenesis within the airway wall. Airway remodeling contributes to stiffer and less compliant airways in asthma and leads to persistent, irreversible airflow obstruction. Current asthma treatments aim to reduce airway inflammation and exacerbations but none are targeted towards airway remodeling. Inhibiting the development of airway remodeling or reversing established remodeling has the potential to dramatically improve symptoms and disease burden in asthmatic patients. Integrins are a family of transmembrane heterodimeric proteins that serve as the primary receptors for extracellular matrix (ECM) components, mediating cell-cell and cell-ECM interactions to initiate intracellular signaling cascades. Cells present within the lungs, including structural and inflammatory cells, express a wide and varying range of integrin heterodimer combinations and permutations. Integrins are emerging as an important regulator of inflammation, repair, remodeling, and fibrosis in the lung, particularly in chronic lung diseases such as asthma. Here, we provide a comprehensive summary of the current state of knowledge on integrins in the asthmatic airway and how these integrins promote the remodeling process, and emphasize their potential involvement in airway disease.
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Affiliation(s)
- Chitra Joseph
- Centre for Respiratory Research, National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Amanda L Tatler
- Centre for Respiratory Research, National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
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Humphrey JD. Constrained Mixture Models of Soft Tissue Growth and Remodeling - Twenty Years After. JOURNAL OF ELASTICITY 2021; 145:49-75. [PMID: 34483462 PMCID: PMC8415366 DOI: 10.1007/s10659-020-09809-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/29/2020] [Indexed: 05/06/2023]
Abstract
Soft biological tissues compromise diverse cell types and extracellular matrix constituents, each of which can possess individual natural configurations, material properties, and rates of turnover. For this reason, mixture-based models of growth (changes in mass) and remodeling (change in microstructure) are well-suited for studying tissue adaptations, disease progression, and responses to injury or clinical intervention. Such approaches also can be used to design improved tissue engineered constructs to repair, replace, or regenerate tissues. Focusing on blood vessels as archetypes of soft tissues, this paper reviews a constrained mixture theory introduced twenty years ago and explores its usage since by contrasting simulations of diverse vascular conditions. The discussion is framed within the concept of mechanical homeostasis, with consideration of solid-fluid interactions, inflammation, and cell signaling highlighting both past accomplishments and future opportunities as we seek to understand better the evolving composition, geometry, and material behaviors of soft tissues under complex conditions.
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Affiliation(s)
- J D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520 USA
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Rampadarath AK, Donovan GM. Mathematical modelling of lung function — what have we learnt and where to next? CURRENT OPINION IN PHYSIOLOGY 2021. [DOI: 10.1016/j.cophys.2021.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Pybus HJ, Tatler AL, Edgar LT, O'Dea RD, Brook BS. Reduced biomechanical models for precision-cut lung-slice stretching experiments. J Math Biol 2021; 82:35. [PMID: 33721103 PMCID: PMC7960642 DOI: 10.1007/s00285-021-01578-2] [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: 01/25/2020] [Revised: 08/25/2020] [Accepted: 02/14/2021] [Indexed: 01/25/2023]
Abstract
Precision-cut lung-slices (PCLS), in which viable airways embedded within lung parenchyma are stretched or induced to contract, are a widely used ex vivo assay to investigate bronchoconstriction and, more recently, mechanical activation of pro-remodelling cytokines in asthmatic airways. We develop a nonlinear fibre-reinforced biomechanical model accounting for smooth muscle contraction and extracellular matrix strain-stiffening. Through numerical simulation, we describe the stresses and contractile responses of an airway within a PCLS of finite thickness, exposing the importance of smooth muscle contraction on the local stress state within the airway. We then consider two simplifying limits of the model (a membrane representation and an asymptotic reduction in the thin-PCLS-limit), that permit analytical progress. Comparison against numerical solution of the full problem shows that the asymptotic reduction successfully captures the key elements of the full model behaviour. The more tractable reduced model that we develop is suitable to be employed in investigations to elucidate the time-dependent feedback mechanisms linking airway mechanics and cytokine activation in asthma.
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Affiliation(s)
- Hannah J Pybus
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
| | - Amanda L Tatler
- Respiratory Medicine, NIHR Biomedical Research Centre, University of Nottingham, Nottingham, UK
| | - Lowell T Edgar
- Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
| | - Reuben D O'Dea
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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Latorre M, Spronck B, Humphrey JD. Complementary roles of mechanotransduction and inflammation in vascular homeostasis. Proc Math Phys Eng Sci 2021; 477:20200622. [PMID: 33642928 PMCID: PMC7897647 DOI: 10.1098/rspa.2020.0622] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022] Open
Abstract
Arteries are exposed to relentless pulsatile haemodynamic loads, but via mechanical homeostasis they tend to maintain near optimal structure, properties and function over long periods in maturity in health. Numerous insults can compromise such homeostatic tendencies, however, resulting in maladaptations or disease. Chronic inflammation can be counted among the detrimental insults experienced by arteries, yet inflammation can also play important homeostatic roles. In this paper, we present a new theoretical model of complementary mechanobiological and immunobiological control of vascular geometry and composition, and thus properties and function. We motivate and illustrate the model using data for aortic remodelling in a common mouse model of induced hypertension. Predictions match the available data well, noting a need for increased data for further parameter refinement. The overall approach and conclusions are general, however, and help to unify two previously disparate literatures, thus leading to deeper insight into the separate and overlapping roles of mechanobiology and immunobiology in vascular health and disease.
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Affiliation(s)
- Marcos Latorre
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Bart Spronck
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA,Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA,Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA,e-mail:
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12
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Airway remodelling with spatial correlations: Implications for asthma pathogenesis. Respir Physiol Neurobiol 2020; 279:103469. [PMID: 32473215 DOI: 10.1016/j.resp.2020.103469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/30/2020] [Accepted: 05/21/2020] [Indexed: 12/11/2022]
Abstract
Airway remodelling is a cardinal feature of asthma in which airways undergo structural changes - in particular, increased airway smooth muscle mass and total airway wall area. Remodelling has long been thought to have functional consequences in asthma due to geometric effects that can increase airway narrowing and luminal occlusion. Prior studies have examined the distribution of remodelling between and within patients, but none have yet considered the possibility for spatial correlations in airway remodelling. That is, is remodelling clustered locally, or interrelated along proximal and distal locations of the bronchial tree? In view of recent interest regarding airway remodelling produced by mechanical stimuli, we developed a mathematical model to examine whether spatial correlations in airway remodelling could arise due to cycles of bronchoconstriction and mechanotransduction. Further, we compared modelling predictions to the spatial distribution of airway remodelling in lungs from subjects with and without asthma. Results indicate that spatial correlations in airway remodelling do exist in vivo, and cycles of bronchoconstriction and mechanotransduction are one plausible mechanism for their origin. These findings offer insights into the evolution of airway remodelling in asthma, which may inform strategies for treatment and prevention.
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Ambrosi D, Ben Amar M, Cyron CJ, DeSimone A, Goriely A, Humphrey JD, Kuhl E. Growth and remodelling of living tissues: perspectives, challenges and opportunities. J R Soc Interface 2019; 16:20190233. [PMID: 31431183 PMCID: PMC6731508 DOI: 10.1098/rsif.2019.0233] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/26/2019] [Indexed: 12/29/2022] Open
Abstract
One of the most remarkable differences between classical engineering materials and living matter is the ability of the latter to grow and remodel in response to diverse stimuli. The mechanical behaviour of living matter is governed not only by an elastic or viscoelastic response to loading on short time scales up to several minutes, but also by often crucial growth and remodelling responses on time scales from hours to months. Phenomena of growth and remodelling play important roles, for example during morphogenesis in early life as well as in homeostasis and pathogenesis in adult tissues, which often adapt to changes in their chemo-mechanical environment as a result of ageing, diseases, injury or surgical intervention. Mechano-regulated growth and remodelling are observed in various soft tissues, ranging from tendons and arteries to the eye and brain, but also in bone, lower organisms and plants. Understanding and predicting growth and remodelling of living systems is one of the most important challenges in biomechanics and mechanobiology. This article reviews the current state of growth and remodelling as it applies primarily to soft tissues, and provides a perspective on critical challenges and future directions.
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Affiliation(s)
- Davide Ambrosi
- Dipartimento di Matematica, Politecnico di Milano, Milan, Italy
| | - Martine Ben Amar
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris, France
| | - Christian J. Cyron
- Institute of Continuum Mechanics and Materials, Hamburg University of Technology, Hamburg, Germany
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
| | - Antonio DeSimone
- Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Oxford, UK
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
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Ito JT, Lourenço JD, Righetti RF, Tibério IFLC, Prado CM, Lopes FDTQS. Extracellular Matrix Component Remodeling in Respiratory Diseases: What Has Been Found in Clinical and Experimental Studies? Cells 2019; 8:cells8040342. [PMID: 30979017 PMCID: PMC6523091 DOI: 10.3390/cells8040342] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/03/2019] [Accepted: 04/09/2019] [Indexed: 01/09/2023] Open
Abstract
Changes in extracellular matrix (ECM) components in the lungs are associated with the progression of respiratory diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). Experimental and clinical studies have revealed that structural changes in ECM components occur under chronic inflammatory conditions, and these changes are associated with impaired lung function. In bronchial asthma, elastic and collagen fiber remodeling, mostly in the airway walls, is associated with an increase in mucus secretion, leading to airway hyperreactivity. In COPD, changes in collagen subtypes I and III and elastin, interfere with the mechanical properties of the lungs, and are believed to play a pivotal role in decreased lung elasticity, during emphysema progression. In ARDS, interstitial edema is often accompanied by excessive deposition of fibronectin and collagen subtypes I and III, which can lead to respiratory failure in the intensive care unit. This review uses experimental models and human studies to describe how inflammatory conditions and ECM remodeling contribute to the loss of lung function in these respiratory diseases.
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Affiliation(s)
- Juliana T Ito
- Department of Clinical Medicine, Laboratory of Experimental Therapeutics/LIM-20, School of Medicine of University of Sao Paulo, Sao Paulo 01246-903, Brazil.
| | - Juliana D Lourenço
- Department of Clinical Medicine, Laboratory of Experimental Therapeutics/LIM-20, School of Medicine of University of Sao Paulo, Sao Paulo 01246-903, Brazil.
| | - Renato F Righetti
- Department of Clinical Medicine, Laboratory of Experimental Therapeutics/LIM-20, School of Medicine of University of Sao Paulo, Sao Paulo 01246-903, Brazil.
- Rehabilitation service, Sírio-Libanês Hospital, Sao Paulo 01308-050, Brazil.
| | - Iolanda F L C Tibério
- Department of Clinical Medicine, Laboratory of Experimental Therapeutics/LIM-20, School of Medicine of University of Sao Paulo, Sao Paulo 01246-903, Brazil.
| | - Carla M Prado
- Department of Bioscience, Laboratory of Studies in Pulmonary Inflammation, Federal University of Sao Paulo, Santos 11015-020, Brazil.
| | - Fernanda D T Q S Lopes
- Department of Clinical Medicine, Laboratory of Experimental Therapeutics/LIM-20, School of Medicine of University of Sao Paulo, Sao Paulo 01246-903, Brazil.
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The anatomic substrate of irreversible airway obstruction and barotrauma in a case of hurricane-triggered fatal status asthmaticus during puerperium: Lessons from an autopsy. Respir Med Case Rep 2018; 26:136-141. [PMID: 30603604 PMCID: PMC6306954 DOI: 10.1016/j.rmcr.2018.12.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 12/19/2018] [Indexed: 01/27/2023] Open
Abstract
Non-fully reversible airway obstruction in fatal asthma is often seen in association with profound structural changes of the bronchial wall, termed airway remodeling. Evidence suggests that heavy precipitation events can trigger epidemics of severe asthma. We present a case of fatal asthma in a young woman with no prior near-fatal exacerbations and postulate that the patient's extensive airway remodeling and puerperal state (susceptibility factors), in combination with a massive allergen challenge during a hurricane landfall (triggering factor), played a central role in her death. The autopsy revealed diffuse obstruction of proximal and distal bronchi by mucous plugs together with transmural chronic inflammation, tissue eosinophilia, extensive goblet cell hyperplasia with MUC-5 expression and airway smooth muscle (ASM) thickening. The observed distribution of airway remodeling was heterogeneous with sparing of the lingula, which exhibited hyperinflation and expansion of perivascular spaces indicative of dissecting air. The massive stagnation of mucus and significant inter-airway structural heterogeneity created an anatomical substrate for unequal airflow distribution facilitating the development of barotrauma. Although not considered conventional risk factors for fatal asthma, we believe that in this case, the patient's puerperal state in conjunction with an extreme environmental event dispersing aeroallergens were major contributors to the development of a fatal asthma attack. Our autopsy findings suggest that effective strategies to evacuate stagnated mucus and induce relaxation of thickened ASM are crucial in the management of life-threatening asthma exacerbations.
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