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Nadeem SA, Zhang X, Nagpal P, Hoffman EA, Chan KS, Comellas AP, Saha PK. Automated CT-based decoupling of the effects of airway narrowing and wall thinning on airway counts in chronic obstructive pulmonary disease. Br J Radiol 2025; 98:150-159. [PMID: 39447037 DOI: 10.1093/bjr/tqae211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 09/09/2024] [Accepted: 10/13/2024] [Indexed: 10/26/2024] Open
Abstract
OBJECTIVE We examine pathways of airway alteration due to wall thinning, narrowing, and obliteration in chronic obstructive pulmonary disease (COPD) using CT-derived airway metrics. METHODS Ex-smokers (N = 649; age mean ± std: 69 ± 6 years; 52% male) from the COPDGene Iowa cohort (September 2013-July 2017) were studied. Total airway count (TAC), peripheral TAC beyond 7th generation (TACp), and airway wall thickness (WT) were computed from chest CT scans using previously validated automated methods. Causal relationships among demographic, smoking, spirometry, COPD severity, airway counts, WT, and scanner variables were analysed using causal inference techniques including direct acyclic graphs to assess multi-pathway alterations of airways in COPD. RESULTS TAC, TACp, and WT were significantly lower (P < .0001) in mild, moderate, and severe COPD compared to the preserved lung function group. TAC (TACp) losses attributed to narrowing and obliteration of small airways were 4.59%, 13.29%, and 32.58% (4.64%, 17.82%, and 45.51%) in mild, moderate, and severe COPD, while the losses attributed to wall thinning were 8.24%, 17.01%, and 22.95% (12.79%, 25.66%, and 33.95%) in respective groups. CONCLUSIONS Different pathways of airway alteration in COPD are observed using CT-derived automated airway metrics. Wall thinning is a dominant contributor to both TAC and TACp loss in mild and moderate COPD while narrowing and obliteration of small airways is dominant in severe COPD. ADVANCES IN KNOWLEDGE This automated CT-based study shows that wall thinning dominates airway alteration in mild and moderate COPD while narrowing and obliteration of small airways leads the alteration process in severe COPD.
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Affiliation(s)
- Syed Ahmed Nadeem
- Department of Radiology, University of Iowa, Iowa City, IA 52242, United States
| | - Xinyu Zhang
- Department of Statistics and Actuarial Science, University of Iowa, Iowa City, IA 52242, United States
| | - Prashant Nagpal
- Department of Radiology, University of Wisconsin, Madison, WI 53792, United States
| | - Eric A Hoffman
- Department of Radiology, University of Iowa, Iowa City, IA 52242, United States
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, United States
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Kung-Sik Chan
- Department of Statistics and Actuarial Science, University of Iowa, Iowa City, IA 52242, United States
| | - Alejandro P Comellas
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Punam K Saha
- Department of Radiology, University of Iowa, Iowa City, IA 52242, United States
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA 52242, United States
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2
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He W, Chao J, Gu A, Wang D. Evaluation of 6-PPD quinone toxicity on lung of male BALB/c mice by quantitative proteomics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 922:171220. [PMID: 38412880 DOI: 10.1016/j.scitotenv.2024.171220] [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: 10/24/2023] [Revised: 01/28/2024] [Accepted: 02/21/2024] [Indexed: 02/29/2024]
Abstract
N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ), a transformation product of tyre-derived 6-PPD, has been frequently detected in different environments. After 6-PPDQ exposure, we here aimed to examine dynamic lung bioaccumulation, lung injury, and the underlying molecular basis in male BALB/c mice. After single injection at concentration of 4 mg/kg, 6-PPDQ remained in lung up to day 28, and higher level of 6-PPDQ bioaccumulation in lung was observed after repeated injection. Severe inflammation was observed in lung after both single and repeated 6-PPDQ injection as indicated by changes of inflammatory cytokines (TNF-α, IL-6 and IL-10). Sirius red staining and hydroxyproline content analysis indicated that repeated rather than single 6-PPDQ injection induced fibrosis in lung. Repeated 6-PPDQ injection also severely impaired lung function in mice by influencing chord compliance (Cchord) and enhanced pause (Penh). Proteomes analysis was further carried out to identify molecular targets of 6-PPDQ after repeated injection, which was confirmed by transcriptional expression analysis and immunohistochemistry staining. Alterations in Ripk1, Fadd, Il-6st, and Il-16 expressions were identified to be associated with inflammation induction of lung after repeated 6-PPDQ injection. Alteration in Smad2 expression was identified to be associated with fibrosis formation in lung of 6-PPDQ exposed mice. Therefore, long-term and repeated 6-PPDQ exposure potentially resulted in inflammation and fibrosis in lung by affecting certain molecular signals in mammals. Our results suggested several aspects of lung injury caused by 6-PPDQ and provide the underlying molecular basis. These observations implied the possible risks of long-term 6-PPDQ exposure to human health.
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Affiliation(s)
- Wenmiao He
- Key Laboratory of Environmental Medicine Engineering of Ministry of Education, Medical School, Southeast University, Nanjing, China; School of Public Health, Nanjing Medical University, Nanjing, China
| | - Jie Chao
- Key Laboratory of Environmental Medicine Engineering of Ministry of Education, Medical School, Southeast University, Nanjing, China
| | - Aihua Gu
- School of Public Health, Nanjing Medical University, Nanjing, China.
| | - Dayong Wang
- Key Laboratory of Environmental Medicine Engineering of Ministry of Education, Medical School, Southeast University, Nanjing, China.
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3
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Zhang K, Yao E, Aung T, Chuang PT. The alveolus: Our current knowledge of how the gas exchange unit of the lung is constructed and repaired. Curr Top Dev Biol 2024; 159:59-129. [PMID: 38729684 DOI: 10.1016/bs.ctdb.2024.01.002] [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] [Indexed: 05/12/2024]
Abstract
The mammalian lung completes its last step of development, alveologenesis, to generate sufficient surface area for gas exchange. In this process, multiple cell types that include alveolar epithelial cells, endothelial cells, and fibroblasts undergo coordinated cell proliferation, cell migration and/or contraction, cell shape changes, and cell-cell and cell-matrix interactions to produce the gas exchange unit: the alveolus. Full functioning of alveoli also involves immune cells and the lymphatic and autonomic nervous system. With the advent of lineage tracing, conditional gene inactivation, transcriptome analysis, live imaging, and lung organoids, our molecular understanding of alveologenesis has advanced significantly. In this review, we summarize the current knowledge of the constituents of the alveolus and the molecular pathways that control alveolar formation. We also discuss how insight into alveolar formation may inform us of alveolar repair/regeneration mechanisms following lung injury and the pathogenic processes that lead to loss of alveoli or tissue fibrosis.
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Affiliation(s)
- Kuan Zhang
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States
| | - Erica Yao
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States
| | - Thin Aung
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States
| | - Pao-Tien Chuang
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States.
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4
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Knudsen L, Hummel B, Wrede C, Zimmermann R, Perlman CE, Smith BJ. Acinar micromechanics in health and lung injury: what we have learned from quantitative morphology. Front Physiol 2023; 14:1142221. [PMID: 37025383 PMCID: PMC10070844 DOI: 10.3389/fphys.2023.1142221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/09/2023] [Indexed: 04/08/2023] Open
Abstract
Within the pulmonary acini ventilation and blood perfusion are brought together on a huge surface area separated by a very thin blood-gas barrier of tissue components to allow efficient gas exchange. During ventilation pulmonary acini are cyclically subjected to deformations which become manifest in changes of the dimensions of both alveolar and ductal airspaces as well as the interalveolar septa, composed of a dense capillary network and the delicate tissue layer forming the blood-gas barrier. These ventilation-related changes are referred to as micromechanics. In lung diseases, abnormalities in acinar micromechanics can be linked with injurious stresses and strains acting on the blood-gas barrier. The mechanisms by which interalveolar septa and the blood-gas barrier adapt to an increase in alveolar volume have been suggested to include unfolding, stretching, or changes in shape other than stretching and unfolding. Folding results in the formation of pleats in which alveolar epithelium is not exposed to air and parts of the blood-gas barrier are folded on each other. The opening of a collapsed alveolus (recruitment) can be considered as an extreme variant of septal wall unfolding. Alveolar recruitment can be detected with imaging techniques which achieve light microscopic resolution. Unfolding of pleats and stretching of the blood-gas barrier, however, require electron microscopic resolution to identify the basement membrane. While stretching results in an increase of the area of the basement membrane, unfolding of pleats and shape changes do not. Real time visualization of these processes, however, is currently not possible. In this review we provide an overview of septal wall micromechanics with focus on unfolding/folding as well as stretching. At the same time we provide a state-of-the-art design-based stereology methodology to quantify microarchitecture of alveoli and interalveolar septa based on different imaging techniques and design-based stereology.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Centre for Lung Research (DZL), Hannover, Germany
| | - Benjamin Hummel
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Christoph Wrede
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
- Research Core Unit Electron Microscopy, Hannover Medical School, Hannover, Germany
| | - Richard Zimmermann
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Carrie E Perlman
- Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, United States
| | - Bradford J Smith
- Department of Bioengineering, College of Engineering Design and Computing, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
- Department of Pediatric Pulmonary and Sleep Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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5
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Reimelt AM, Vasilescu DM, Beare R, Labode J, Knudsen L, Grothausmann R. Analysis of the alveolar shape in 3-D. Am J Physiol Lung Cell Mol Physiol 2023; 324:L358-L372. [PMID: 36719077 DOI: 10.1152/ajplung.00069.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Mechanical forces affect the alveolar shape, depending on location and tissue composition, and vary during the respiratory cycle. This study performs alveolar morphomics in different lobes of human lungs using models generated from three-dimensional (3-D) micro-computed tomography (microCT) images. Cylindrical tissue samples (1.6 cm × 2 cm) were extracted from two nontransplantable donor lungs (one ex-smoker and one smoker, 3 samples per subject) that were air-inflated and frozen solid in liquid nitrogen vapor. Samples were scanned with microCT (11 µm/voxel). Within representative cubic regions of interest (5.5 mm edge length), alveoli were segmented to produce corresponding 3-D models from which quantitative data were obtained. The surface of segmented alveoli (n_alv_total = 23,587) was divided into individual planar surfaces (facets) and angles between facet normals were calculated. Moreover, the number of neighboring alveoli was estimated for every alveolus. In this study, we examined intraindividual differences in alveolar morphology, which were reproducible in the lungs of two subjects. The main aspects are higher mean alveolar volumes (v_alv: 6.64 × 106 and 6.63 × 106 µm3 vs. 5.78 × 106 and 6.29 × 106 µm3) and surface sizes (s_alv: 0.19 and 0.18 mm2 vs. 0.17 mm2 in both lower lobes) in both upper lung lobes compared with the lower lobes. An increasing number of facets (f_alv) from top to bottom (12 and 14 in the upper lobes; 14 and 15 in the lower lobes), as well as a decreasing number of alveolar neighbors (nei_alv: 9 and 8 in the upper lobes; 8 and 7 in the lower lobes) from the upper lobes to the lower lobes were observed. We could observe an increasing ratio of alveolar entrance size to the surface size of the alveoli from top to bottom (S_ratio_alv: 0.71 and 0.64 in the upper lobes, 0.73 and 0.70 in the lower lobes). The angles between facet normals (ang_alv) were larger in the upper lobes (67.72° and 62.44°) of both lungs than in the lower lobes (66.19° and 61.30°). By using this new approach of analyzing alveolar 3-D data, which enables the estimation of facet, neighbor, and shape characteristics, we aimed to establish the baseline measures for in-depth studies of mechanical conditions and morphology.
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Affiliation(s)
- Alex M Reimelt
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Dragoș M Vasilescu
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Richard Beare
- Academic Unit, Medicine, Peninsula Clinical School, Monash University, Melbourne, Victoria, Australia.,Developmental Imaging, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Jonas Labode
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Roman Grothausmann
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany.,Faculty of Engineering and Health, HAWK University of Applied Sciences and Arts, Göttingen, Germany
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6
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Chukowry PS, Spittle DA, Turner AM. Small Airways Disease, Biomarkers and COPD: Where are We? Int J Chron Obstruct Pulmon Dis 2021; 16:351-365. [PMID: 33628018 PMCID: PMC7899307 DOI: 10.2147/copd.s280157] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/11/2020] [Indexed: 11/23/2022] Open
Abstract
The response to treatment and progression of Chronic Obstructive Pulmonary Disease (COPD) varies significantly. Small airways disease (SAD) is being increasingly recognized as a key pathological feature of COPD. Studies have brought forward pathological evidence of small airway damage preceding the development of emphysema and the detection of obstruction using traditional spirometry. In recent years, there has been a renewed interest in the early detection of SAD and this has brought along an increased demand for physiological tests able to identify and quantify SAD. Early detection of SAD allows early targeted therapy and this suggests the potential for altering the course of disease. The aim of this article is to review the evidence available on the physiological testing of small airways. The first half will focus on the role of lung function tests such as maximum mid-expiratory flow, impulse oscillometry and lung clearance index in detecting and quantifying SAD. The role of Computed Tomography (CT) as a radiological biomarker will be discussed as well as the potential of recent CT analysis software to differentiate normal aging of the lungs to pathology. The evidence behind SAD biomarkers sourced from blood as well as biomarkers sourced from sputum and broncho-alveolar lavage (BAL) will be reviewed. This paper focuses on CC-16, sRAGE, PAI-1, MMP-9 and MMP-12.
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Affiliation(s)
- Priyamvada S Chukowry
- Respiratory Research Department, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Daniella A Spittle
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, B15 2TT, UK
| | - Alice M Turner
- Institute for Applied Health Research, University of Birmingham, Birmingham, B15 2TT, UK
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7
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Clark AR, Burrowes KS, Tawhai MH. Integrative Computational Models of Lung Structure-Function Interactions. Compr Physiol 2021; 11:1501-1530. [PMID: 33577123 DOI: 10.1002/cphy.c200011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Anatomically based integrative models of the lung and their interaction with other key components of the respiratory system provide unique capabilities for investigating both normal and abnormal lung function. There is substantial regional variability in both structure and function within the normal lung, yet it remains capable of relatively efficient gas exchange by providing close matching of air delivery (ventilation) and blood delivery (perfusion) to regions of gas exchange tissue from the scale of the whole organ to the smallest continuous gas exchange units. This is despite remarkably different mechanisms of air and blood delivery, different fluid properties, and unique scale-dependent anatomical structures through which the blood and air are transported. This inherent heterogeneity can be exacerbated in the presence of disease or when the body is under stress. Current computational power and data availability allow for the construction of sophisticated data-driven integrative models that can mimic respiratory system structure, function, and response to intervention. Computational models do not have the same technical and ethical issues that can limit experimental studies and biomedical imaging, and if they are solidly grounded in physiology and physics they facilitate investigation of the underlying interaction between mechanisms that determine respiratory function and dysfunction, and to estimate otherwise difficult-to-access measures. © 2021 American Physiological Society. Compr Physiol 11:1501-1530, 2021.
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Affiliation(s)
- Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Kelly S Burrowes
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Merryn H Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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8
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Cloonan SM, Kim K, Esteves P, Trian T, Barnes PJ. Mitochondrial dysfunction in lung ageing and disease. Eur Respir Rev 2020; 29:29/157/200165. [PMID: 33060165 DOI: 10.1183/16000617.0165-2020] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/25/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial biology has seen a surge in popularity in the past 5 years, with the emergence of numerous new avenues of exciting mitochondria-related research including immunometabolism, mitochondrial transplantation and mitochondria-microbe biology. Since the early 1960s mitochondrial dysfunction has been observed in cells of the lung in individuals and in experimental models of chronic and acute respiratory diseases. However, it is only in the past decade with the emergence of more sophisticated tools and methodologies that we are beginning to understand how this enigmatic organelle regulates cellular homeostasis and contributes to disease processes in the lung. In this review, we highlight the diverse role of mitochondria in individual lung cell populations and what happens when these essential organelles become dysfunctional with ageing and in acute and chronic lung disease. Although much remains to be uncovered, we also discuss potential targeted therapeutics for mitochondrial dysfunction in the ageing and diseased lung.
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Affiliation(s)
- Suzanne M Cloonan
- Division of Pulmonary and Critical Care Medicine, Joan and Sanford I. Weill Dept of Medicine, New York, NY, USA.,School of Medicine, Trinity College Dublin and Tallaght University Hospital, Dublin, Ireland
| | - Kihwan Kim
- Division of Pulmonary and Critical Care Medicine, Joan and Sanford I. Weill Dept of Medicine, New York, NY, USA
| | - Pauline Esteves
- Univ-Bordeaux, Centre de Recherche Cardio-thoracique de Bordeaux, U1045, Dépt de Pharmacologie, CIC 1401, Bordeaux, France.,INSERM, Centre de Recherche Cardio-thoracique de Bordeaux, U1045, CIC 1401, Bordeaux, France
| | - Thomas Trian
- Univ-Bordeaux, Centre de Recherche Cardio-thoracique de Bordeaux, U1045, Dépt de Pharmacologie, CIC 1401, Bordeaux, France.,INSERM, Centre de Recherche Cardio-thoracique de Bordeaux, U1045, CIC 1401, Bordeaux, France
| | - Peter J Barnes
- National Heart and Lung Institute, Imperial College, London, UK
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9
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Uddin MA, Barabutis N. P53 in the impaired lungs. DNA Repair (Amst) 2020; 95:102952. [PMID: 32846356 PMCID: PMC7437512 DOI: 10.1016/j.dnarep.2020.102952] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 08/13/2020] [Indexed: 12/12/2022]
Abstract
Our laboratory is focused on investigating the supportive role of P53 towards the maintenance of lung homeostasis. Acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, pulmonary fibrosis, bronchial asthma, pulmonary arterial hypertension, pneumonia and tuberculosis are respiratory pathologies, associated with dysfunctions of this endothelium defender (P53). Herein we review the evolving role of P53 towards the aforementioned inflammatory disorders, to potentially reveal new therapeutic possibilities in pulmonary disease.
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Affiliation(s)
- Mohammad A Uddin
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana 71201, USA
| | - Nektarios Barabutis
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana 71201, USA.
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10
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Merkt W, Bueno M, Mora AL, Lagares D. Senotherapeutics: Targeting senescence in idiopathic pulmonary fibrosis. Semin Cell Dev Biol 2019; 101:104-110. [PMID: 31879264 DOI: 10.1016/j.semcdb.2019.12.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/13/2019] [Accepted: 12/13/2019] [Indexed: 12/17/2022]
Abstract
Idiopathic pulmonary fibrosis (IPF) is a fatal chronic lung disease characterized by progressive scarring of the lung tissue, leading to respiratory failure. There is no cure for IPF, and current anti-fibrotic treatments modestly arrest its further progression. IPF prevalence and incidence increase with age, which is a recognized risk factor. Intense clinical and basic research over the last fifteen years has shown that hallmarks of accelerated aging are present in the lungs of patients with IPF. Different cell types in IPF lungs exhibit premature hallmarks of aging, including telomere attrition and cellular senescence. In this Review, we discuss recent insights into the mechanisms behind these age-related alterations and their contribution to the development of lung fibrosis. We focus on the genetic and molecular basis of telomere attrition in alveolar type II epithelial cells, which promote cellular senescence and lung fibrosis. Mechanistically, senescent cells secrete pro-fibrotic factors that activate scar-forming myofibroblasts. Ultimately, senescent alveolar epithelial cells lose their regenerative capacity, impeding fibrosis resolution. In addition, mitochondrial dysfunction is strongly associated with the appearance of senescent epithelial cells and senescent myofibroblasts in IPF, which persist in the fibrotic tissue by adapting their metabolic pathways and becoming resistant to apoptosis. We discuss emerging novel therapeutic strategies to treat IPF by targeting cellular senescence with the so-called senotherapeutics.
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Affiliation(s)
- Wolfgang Merkt
- Department of Hematology, Oncology and Rheumatology, Internal Medicine V, University Hospital of Heidelberg, Heidelberg, Germany; Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Fibrosis Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Marta Bueno
- Aging Institute. School of Medicine. University of Pittsburgh, Pittsburgh, PA, USA; Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ana L Mora
- Aging Institute. School of Medicine. University of Pittsburgh, Pittsburgh, PA, USA; Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - David Lagares
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Fibrosis Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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11
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Schulte H, Mühlfeld C, Brandenberger C. Age-Related Structural and Functional Changes in the Mouse Lung. Front Physiol 2019; 10:1466. [PMID: 31866873 PMCID: PMC6904284 DOI: 10.3389/fphys.2019.01466] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/14/2019] [Indexed: 01/01/2023] Open
Abstract
Lung function declines with advancing age. To improve our understanding of the structure-function relationships leading to this decline, we investigated structural alterations in the lung and their impact on micromechanics and lung function in the aging mouse. Lung function analysis was performed in 3, 6, 12, 18, and 24 months old C57BL/6 mice (n = 7-8/age), followed by lung fixation and stereological sample preparation. Lung parenchymal volume, total, ductal and alveolar airspace volume, alveolar volume and number, septal volume, septal surface area and thickness were quantified by stereology as well as surfactant producing alveolar epithelial type II (ATII) cell volume and number. Parenchymal volume, total and ductal airspace volume increased in old (18 and 24 months) compared with middle-aged (6 and 12 months) and young (3 months) mice. While the alveolar number decreased from young (7.5 × 106) to middle-aged (6 × 106) and increased again in old (9 × 106) mice, the mean alveolar volume and mean septal surface area per alveolus conversely first increased in middle-aged and then declined in old mice. The ATII cell number increased from middle-aged (8.8 × 106) to old (11.8 × 106) mice, along with the alveolar number, resulting in a constant ratio of ATII cells per alveolus in all age groups (1.4 ATII cells per alveolus). Lung compliance and inspiratory capacity increased, whereas tissue elastance and tissue resistance decreased with age, showing greatest changes between young and middle-aged mice. In conclusion, alveolar size declined significantly in old mice concomitant with a widening of alveolar ducts and late alveolarization. These changes may partly explain the functional alterations during aging. Interestingly, despite age-related lung remodeling, the number of ATII cells per alveolus showed a tightly controlled relation in all age groups.
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Affiliation(s)
- Henri Schulte
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany
| | - Christian Mühlfeld
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany.,Cluster of Excellence REBIRTH (From Regenerative Biology to Reconstructive Therapy), Hanover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hanover, Germany
| | - Christina Brandenberger
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany.,Cluster of Excellence REBIRTH (From Regenerative Biology to Reconstructive Therapy), Hanover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hanover, Germany
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12
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Tawhai MH, Clark AR, Chase JG. The Lung Physiome and virtual patient models: From morphometry to clinical translation. Morphologie 2019; 103:131-138. [PMID: 31570307 DOI: 10.1016/j.morpho.2019.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 06/10/2023]
Abstract
The understanding or prediction of specific functions of the lung can be made using compact models that have identifiable parameters and that are custom designed to the problem of interest. However, when structure contributes to function - as is the case with most lung pathologies - structure-based, biophysical models become essential. Here we describe the application of structure-based models within the lung Physiome framework to identifying and explaining patient risk in 12patients diagnosed with acute pulmonary embolism. The model integrates perfusion, ventilation, and gas exchange to predict arterial blood gases and pulmonary artery pressure in individual patient models in response to patient-specific blood clot distribution, with full or partial arterial occlusion. The necessity for a patient-specific approach with biophysical models that account for scale-specific structure and function is demonstrated.
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Affiliation(s)
- M H Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
| | - A R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - J G Chase
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
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Lignelli E, Palumbo F, Myti D, Morty RE. Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia. Am J Physiol Lung Cell Mol Physiol 2019; 317:L832-L887. [PMID: 31596603 DOI: 10.1152/ajplung.00369.2019] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.
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Affiliation(s)
- Ettore Lignelli
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, member of the German Center for Lung Research, Giessen, Germany
| | - Francesco Palumbo
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, member of the German Center for Lung Research, Giessen, Germany
| | - Despoina Myti
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, member of the German Center for Lung Research, Giessen, Germany
| | - Rory E Morty
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, member of the German Center for Lung Research, Giessen, Germany
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Aghasafari P, Heise RL, Reynolds A, Pidaparti RM. Aging Effects on Alveolar Sacs Under Mechanical Ventilation. J Gerontol A Biol Sci Med Sci 2019; 74:139-146. [PMID: 29746613 PMCID: PMC6333941 DOI: 10.1093/gerona/gly097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 04/26/2018] [Indexed: 11/14/2022] Open
Abstract
Alveolar sacs are primarily responsible for gas exchange in the human respiratory system and lose their functionality with aging. Three-dimensional (3D) models of young and old human alveolar sacs were constructed and fluid-solid interaction was employed to investigate the contribution of age-related changes to decline in alveolar sacs function under mechanical ventilation (MV). Simulation results illustrated that compliance and pressure reduced in the alveolar sacs of the elderly adults, and they have to work harder to breathe. Morphological changes were found to be mainly responsible for the decline in alveolar sacs function. Influence of individual differences on the alveolar sacs function was negligible and 95% confidence intervals for compliance and work of breathing (WOB) using measures from different individuals also support this finding. Moreover, higher mortality risk was recorded for elderly adults who undergo MV. Specifically, ventilator devices setting has been identified as a potential parameter for compromising respiratory function in the elderly adults. Volume-controlled ventilation applied less pressure, whereas, pressure-controlled ventilation resulted in higher compliance in the alveolar sacs and decreased WOB. Sensitivity of alveolar sacs to ventilator setting under the volume-controlled mode illustrated that increasing breathing frequency and decreasing the ratio of inhalation to exhalation times and TV caused an increase in alveolar sacs expansion and compliance in older patients. Results from this study can help clinicians to develop individualized and effective ventilator protocols and to improve respiratory function in the elderly adults.
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Affiliation(s)
- Parya Aghasafari
- Department of Mechanical Engineering, University of Georgia, Athens
| | - Rebeca L Heise
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond
- VCU Johnson Center for Critical Care and Pulmonary Research, Virginia Commonwealth University, Richmond
| | - Angela Reynolds
- Department of Mathematics & Applied Mathematics, Virginia Commonwealth University, Richmond
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Knudsen L, Ochs M. The micromechanics of lung alveoli: structure and function of surfactant and tissue components. Histochem Cell Biol 2018; 150:661-676. [PMID: 30390118 PMCID: PMC6267411 DOI: 10.1007/s00418-018-1747-9] [Citation(s) in RCA: 206] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2018] [Indexed: 12/14/2022]
Abstract
The mammalian lung´s structural design is optimized to serve its main function: gas exchange. It takes place in the alveolar region (parenchyma) where air and blood are brought in close proximity over a large surface. Air reaches the alveolar lumen via a conducting airway tree. Blood flows in a capillary network embedded in inter-alveolar septa. The barrier between air and blood consists of a continuous alveolar epithelium (a mosaic of type I and type II alveolar epithelial cells), a continuous capillary endothelium and the connective tissue layer in-between. By virtue of its respiratory movements, the lung has to withstand mechanical challenges throughout life. Alveoli must be protected from over-distension as well as from collapse by inherent stabilizing factors. The mechanical stability of the parenchyma is ensured by two components: a connective tissue fiber network and the surfactant system. The connective tissue fibers form a continuous tensegrity (tension + integrity) backbone consisting of axial, peripheral and septal fibers. Surfactant (surface active agent) is the secretory product of type II alveolar epithelial cells and covers the alveolar epithelium as a biophysically active thin and continuous film. Here, we briefly review the structural components relevant for gas exchange. Then we describe our current understanding of how these components function under normal conditions and how lung injury results in dysfunction of alveolar micromechanics finally leading to lung fibrosis.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany. .,REBIRTH Cluster of Excellence, Hannover, Germany.
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