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Ma L, He Y, Xie H, Wang J, Chen J, Song S, Zhang L, Li L, Lai H, Liu Y, Chen H, Zhang X, Liu X, Zou Z, Zhang Q, Yan J, Tao A. Ferroptotic alveolar epithelial type II cells drive T H2 and T H17 mixed asthma triggered by birch pollen allergen Bet v 1. Cell Death Discov 2024; 10:96. [PMID: 38395974 PMCID: PMC10891108 DOI: 10.1038/s41420-024-01861-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 02/08/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Asthma is a common allergic disease characterized by airway hypersensitivity and airway remodeling. Ferroptosis is a regulated death marked by iron accumulation and lipid peroxidation. Several environmental pollutants and allergens have been shown to cause ferroptosis in epithelial cells, but the relationship between birch pollinosis and ferroptosis in asthma is poorly defined. Here, for the first time, we have identified ferroptosis of type II alveolar epithelial cells in mice with Bet v 1-induced asthma. Further analysis revealed that treatment with ferrostatin-1 reduced TH2/TH17-related inflammation and alleviated epithelial damage in mice with Bet v 1-induced asthma. In addition, ACSL4-knocked-down A549 cells are more resistant to Bet v 1-induced ferroptosis. Analysis of clinical samples verified higher serum MDA and 4-HNE concentrations compared to healthy individuals. We demonstrate that birch pollen allergen Bet v 1 induces ferroptosis underlaid TH2 and TH17 hybrid asthma. Lipid peroxidation levels can be considered as a biomarker of asthma severity, and treatment with a specific ferroptosis inhibitor could be a novel therapeutic strategy.
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Affiliation(s)
- Linyi Ma
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
- Department of Clinical Laboratory, General Hospital of the Yangtze River Shipping, Wuhan, 430005, China
| | - Ying He
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Huancheng Xie
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Jing Wang
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Jiaqian Chen
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Shijie Song
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Le Zhang
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Linmei Li
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - He Lai
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Yongping Liu
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Huifang Chen
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Xueyan Zhang
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Xueting Liu
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Zehong Zou
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China
| | - Qingling Zhang
- Guangdong Provincial Key Laboratory of Allergy & Immunology, Guangzhou Institute of Respiratory Health, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
| | - Jie Yan
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China.
| | - Ailin Tao
- The Second Affiliated Hospital, Guangdong Provincial Key Laboratory of Allergy & Immunology, The State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 250 Changgang Road East, Guangzhou, 510260, China.
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Zhang X, Su L, Pan P. Advances and Applications of Lung Organoids in the Research on Acute Respiratory Distress Syndrome (ARDS). J Clin Med 2024; 13:346. [PMID: 38256480 PMCID: PMC10816077 DOI: 10.3390/jcm13020346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/21/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024] Open
Abstract
Acute Respiratory Distress Syndrome (ARDS) is a sudden onset of lung injury characterized by bilateral pulmonary edema, diffuse inflammation, hypoxemia, and a low P/F ratio. Epithelial injury and endothelial injury are notable in the development of ARDS, which is more severe under mechanical stress. This review explains the role of alveolar epithelial cells and endothelial cells under physiological and pathological conditions during the progression of ARDS. Mechanical injury not only causes ARDS but is also a side effect of ventilator-supporting treatment, which is difficult to model both in vitro and in vivo. The development of lung organoids has seen rapid progress in recent years, with numerous promising achievements made. Multiple types of cells and construction strategies are emerging in the lung organoid culture system. Additionally, the lung-on-a-chip system presents a new idea for simulating lung diseases. This review summarizes the basic features and critical problems in the research on ARDS, as well as the progress in lung organoids, particularly in the rapidly developing microfluidic system-based organoids. Overall, this review provides valuable insights into the three major factors that promote the progression of ARDS and how advances in lung organoid technology can be used to further understand ARDS.
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Affiliation(s)
- Xingwu Zhang
- College of Pulmonary & Critical Care Medicine, 8th Medical Center, Chinese PLA General Hospital, Beijing 100091, China;
- School of Medicine, Tsinghua University, Beijing 100084, China
| | - Longxiang Su
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing 100730, China
| | - Pan Pan
- College of Pulmonary & Critical Care Medicine, 8th Medical Center, Chinese PLA General Hospital, Beijing 100091, China;
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Tang S, De Jesus AC, Chavez D, Suthakaran S, Moore SK, Suthakaran K, Homami S, Rathnasinghe R, May AJ, Schotsaert M, Britto CJ, Bhattacharya J, Hook JL. Rescue of alveolar wall liquid secretion blocks fatal lung injury due to influenza-staphylococcal coinfection. J Clin Invest 2023; 133:e163402. [PMID: 37581936 PMCID: PMC10541650 DOI: 10.1172/jci163402] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/10/2023] [Indexed: 08/17/2023] Open
Abstract
Secondary lung infection by inhaled Staphylococcus aureus (SA) is a common and lethal event for individuals infected with influenza A virus (IAV). How IAV disrupts host defense to promote SA infection in lung alveoli, where fatal lung injury occurs, is not known. We addressed this issue using real-time determinations of alveolar responses to IAV in live, intact, perfused lungs. Our findings show that IAV infection blocked defensive alveolar wall liquid (AWL) secretion and induced airspace liquid absorption, thereby reversing normal alveolar liquid dynamics and inhibiting alveolar clearance of inhaled SA. Loss of AWL secretion resulted from inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel in the alveolar epithelium, and airspace liquid absorption was caused by stimulation of the alveolar epithelial Na+ channel (ENaC). Loss of AWL secretion promoted alveolar stabilization of inhaled SA, but rescue of AWL secretion protected against alveolar SA stabilization and fatal SA-induced lung injury in IAV-infected mice. These findings reveal a central role for AWL secretion in alveolar defense against inhaled SA and identify AWL inhibition as a critical mechanism of IAV lung pathogenesis. AWL rescue may represent a new therapeutic approach for IAV-SA coinfection.
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Affiliation(s)
- Stephanie Tang
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
- Graduate School of Biomedical Sciences
| | - Ana Cassandra De Jesus
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
| | - Deebly Chavez
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
| | - Sayahi Suthakaran
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
- Graduate School of Biomedical Sciences
| | - Sarah K.L. Moore
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
| | - Keshon Suthakaran
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
| | - Sonya Homami
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
- Graduate School of Biomedical Sciences
| | - Raveen Rathnasinghe
- Graduate School of Biomedical Sciences
- Global Health and Emerging Pathogens Institute, Department of Microbiology
| | - Alison J. May
- Department of Cell, Developmental and Regenerative Biology
- Department of Otolaryngology, and
- Institute of Regenerative Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Michael Schotsaert
- Global Health and Emerging Pathogens Institute, Department of Microbiology
| | - Clemente J. Britto
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jahar Bhattacharya
- Departments of Medicine and Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York, USA
| | - Jaime L. Hook
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine
- Global Health and Emerging Pathogens Institute, Department of Microbiology
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Sanches Santos Rizzo Zuttion M, Moore SKL, Chen P, Beppu AK, Hook JL. New Insights into the Alveolar Epithelium as a Driver of Acute Respiratory Distress Syndrome. Biomolecules 2022; 12:biom12091273. [PMID: 36139112 PMCID: PMC9496395 DOI: 10.3390/biom12091273] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/02/2022] [Accepted: 09/08/2022] [Indexed: 11/29/2022] Open
Abstract
The alveolar epithelium serves as a barrier between the body and the external environment. To maintain efficient gas exchange, the alveolar epithelium has evolved to withstand and rapidly respond to an assortment of inhaled, injury-inducing stimuli. However, alveolar damage can lead to loss of alveolar fluid barrier function and exuberant, non-resolving inflammation that manifests clinically as acute respiratory distress syndrome (ARDS). This review discusses recent discoveries related to mechanisms of alveolar homeostasis, injury, repair, and regeneration, with a contemporary emphasis on virus-induced lung injury. In addition, we address new insights into how the alveolar epithelium coordinates injury-induced lung inflammation and review maladaptive lung responses to alveolar damage that drive ARDS and pathologic lung remodeling.
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Affiliation(s)
- Marilia Sanches Santos Rizzo Zuttion
- Women’s Guild Lung Institute, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Sarah Kathryn Littlehale Moore
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Peter Chen
- Women’s Guild Lung Institute, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Andrew Kota Beppu
- Women’s Guild Lung Institute, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
- Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Jaime Lynn Hook
- Lung Imaging Laboratory, Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Global Health and Emerging Pathogens Institute, Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Correspondence:
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Munis AM, Wright B, Jackson F, Lockstone H, Hyde SC, Green CM, Gill DR. RNA-seq analysis of the human surfactant air-liquid interface culture reveals alveolar type II cell-like transcriptome. Mol Ther Methods Clin Dev 2022; 24:62-70. [PMID: 34977273 PMCID: PMC8688965 DOI: 10.1016/j.omtm.2021.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 11/19/2021] [Indexed: 12/13/2022]
Abstract
Understanding pulmonary diseases requires robust culture models that are reproducible, sustainable in long-term culture, physiologically relevant, and suitable for assessment of therapeutic interventions. Primary human lung cells are physiologically relevant but cannot be cultured in vitro long term and, although engineered organoids are an attractive choice, they do not phenotypically recapitulate the lung parenchyma; overall, these models do not allow for the generation of reliable disease models. Recently, we described a new cell culture platform based on H441 cells that are grown at the air-liquid interface to produce the SALI culture model, for studying and correcting the rare interstitial lung disease surfactant protein B (SPB) deficiency. Here, we report the characterization of the effects of SALI culture conditions on the transcriptional profile of the constituent H441 cells. We further analyze the transcriptomics of the model in the context of surfactant metabolism and the disease phenotype through SFTPB knockout SALI cultures. By comparing the gene expression profile of SALI cultures with that of human lung parenchyma obtained via single-cell RNA sequencing, we found that SALI cultures are remarkably similar to human alveolar type II cells, implying clinical relevance of the SALI culture platform as a non-diseased human lung alveolar cell model.
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Affiliation(s)
- Altar M. Munis
- Gene Medicine Group, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Benjamin Wright
- Bioinformatics and Statistical Genetics Core, Wellcome Trust Center for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Frederic Jackson
- Clinical BioManufacturing Facility, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7JT, UK
| | - Helen Lockstone
- Bioinformatics and Statistical Genetics Core, Wellcome Trust Center for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Stephen C. Hyde
- Gene Medicine Group, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Catherine M. Green
- Clinical BioManufacturing Facility, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7JT, UK
- Chromosome Dynamics, The Wellcome Center for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Deborah R. Gill
- Gene Medicine Group, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
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Tung YC, Wang CK, Huang YK, Huang CK, Peng CC, Patra B, Chen HK, Tsao PN, Ling TY. Identifying distinct oxygen diffusivity through type I pneumocyte-like cell layers using microfluidic device. Talanta 2022; 236:122882. [PMID: 34635262 DOI: 10.1016/j.talanta.2021.122882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/07/2021] [Accepted: 09/11/2021] [Indexed: 12/22/2022]
Abstract
Oxygen is necessary for cellular respiration in aerobic organisms. In animals, such as human, inhaled oxygen moves from the alveoli to the blood through alveolar epithelium into pulmonary capillaries. Up to now, different studies have been reported to examine experimental oxygen diffusivity for simple membrane or single-celled organisms; however, devices capable of precisely characterizing oxygen transportation through cell layers with dimensions similar to their physiological ones have not been developed. In this study, we establish an integrated approach exploiting a multi-layer microfluidic device and relative fluorescence lifetime detection apparatus to reliably measure oxygen diffusivity through a cell layer. In the experiments, different types of cells, including A549 and 3T3 cell lines, lung stem/progenitor cells, and the differentiated type I pneumocyte-like cells, are used to form cell layers within the devices for their oxygen diffusivity evaluation. A distinct facilitated oxygen transportation behavior of the differentiated type I pneumocyte-like cells that has never been discussed before is identified using the approach. The study offered a new in vitro approach to evaluate the oxygen diffusivity across cell layers in a microfluidic device and open a door to construct more physiologically meaningful in vitro model system to study respiratory systems.
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Affiliation(s)
- Yi-Chung Tung
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Chien-Kai Wang
- Department of Mechanical Engineering, National Taiwan University, Taipei, 10617, Taiwan
| | - Yung-Kang Huang
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan
| | - Cheng-Kai Huang
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan
| | - Chien-Chung Peng
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Bishnubrata Patra
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Hung-Kuan Chen
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Division of Neonatology, Department of Pediatrics, National Taiwan University Hospital, Taipei, 10041, Taiwan
| | - Po-Nien Tsao
- Division of Neonatology, Department of Pediatrics, National Taiwan University Hospital, Taipei, 10041, Taiwan; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, 10051, Taiwan.
| | - Thai-Yen Ling
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, 10051, Taiwan.
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Hayek H, Kosmider B, Bahmed K. The role of miRNAs in alveolar epithelial cells in emphysema. Biomed Pharmacother 2021; 143:112216. [PMID: 34649347 PMCID: PMC9275516 DOI: 10.1016/j.biopha.2021.112216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 02/07/2023] Open
Abstract
Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease becoming one of the leading causes of mortality and morbidity globally. The significant risk factors for COPD are exposure to harmful particles such as cigarette smoke, biomass smoke, and air pollution. Pulmonary emphysema belongs to COPD and is characterized by a unique alveolar destruction pattern resulting in marked airspace enlargement. Alveolar type II (ATII) cells have stem cell potential; they proliferate and differentiate to alveolar type I cells to restore the epithelium after damage. Oxidative stress causes premature cell senescence that can contribute to emphysema development. MiRNAs regulate gene expression, are essential for maintaining ATII cell homeostasis, and their dysregulation contributes to this disease development. They also serve as biomarkers of lung diseases and potential therapeutics. In this review, we summarize recent findings on miRNAs’ role in alveolar epithelial cells in emphysema.
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Affiliation(s)
- Hassan Hayek
- Department of Microbiology, Immunology, and Inflammation, Temple University, Philadelphia, PA 19140, USA; Center for Inflammation and Lung Research, Temple University, Philadelphia, PA 19140, USA
| | - Beata Kosmider
- Department of Microbiology, Immunology, and Inflammation, Temple University, Philadelphia, PA 19140, USA; Center for Inflammation and Lung Research, Temple University, Philadelphia, PA 19140, USA; Department of Biomedical Education and Data Science, Temple University, Philadelphia, PA 19140, USA
| | - Karim Bahmed
- Center for Inflammation and Lung Research, Temple University, Philadelphia, PA 19140, USA; Department of Thoracic Medicine and Surgery, Temple University, Philadelphia, PA 19140, USA.
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Laube M, Pietsch S, Pannicke T, Thome UH, Fabian C. Development and Functional Characterization of Fetal Lung Organoids. Front Med (Lausanne) 2021; 8:678438. [PMID: 34552939 PMCID: PMC8450364 DOI: 10.3389/fmed.2021.678438] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 08/16/2021] [Indexed: 11/21/2022] Open
Abstract
Preterm infants frequently suffer from pulmonary complications due to a physiological and structural lung immaturity resulting in significant morbidity and mortality. Novel in vitro and in vivo models are required to study the underlying mechanisms of late lung maturation and to facilitate the development of new therapeutic strategies. Organoids recapitulate essential aspects of structural organization and possibly organ function, and can be used to model developmental and disease processes. We aimed at generating fetal lung organoids (LOs) and to functionally characterize this in vitro model in comparison to primary lung epithelial cells and lung explants ex vivo. LOs were generated with alveolar and endothelial cells from fetal rat lung tissue, using a Matrigel-gradient and air-liquid-interface culture conditions. Immunocytochemical analysis showed that the LOs consisted of polarized epithelial cell adhesion molecule (EpCAM)-positive cells with the apical membrane compartment facing the organoid lumen. Expression of the alveolar type 2 cell marker, RT2-70, and the Club cell marker, CC-10, were observed. Na+ transporter and surfactant protein mRNA expression were detected in the LOs. First time patch clamp analyses demonstrated the presence of several ion channels with specific electrophysiological properties, comparable to vital lung slices. Furthermore, the responsiveness of LOs to glucocorticoids was demonstrated. Finally, maturation of LOs induced by mesenchymal stem cells confirmed the convenience of the model to test and establish novel therapeutic strategies. The results showed that fetal LOs replicate key biological lung functions essential for lung maturation and therefore constitute a suitable in vitro model system to study lung development and related diseases.
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Affiliation(s)
- Mandy Laube
- Division of Neonatology, Department of Paediatrics, Center for Paediatric Research Leipzig, University of Leipzig, Leipzig, Germany
| | - Soeren Pietsch
- Division of Neonatology, Department of Paediatrics, Center for Paediatric Research Leipzig, University of Leipzig, Leipzig, Germany
| | - Thomas Pannicke
- Division of Neonatology, Department of Paediatrics, Center for Paediatric Research Leipzig, University of Leipzig, Leipzig, Germany
| | - Ulrich H Thome
- Division of Neonatology, Department of Paediatrics, Center for Paediatric Research Leipzig, University of Leipzig, Leipzig, Germany
| | - Claire Fabian
- Department of Vaccines and Infection Models, Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany
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Munis AM, Hyde SC, Gill DR. A human surfactant B deficiency air-liquid interface cell culture model suitable for gene therapy applications. Mol Ther Methods Clin Dev 2021; 20:237-246. [PMID: 33426150 PMCID: PMC7782204 DOI: 10.1016/j.omtm.2020.11.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/17/2020] [Indexed: 01/02/2023]
Abstract
Surfactant protein B (SPB) deficiency is a severe monogenic interstitial lung disorder that leads to loss of life in infants as a result of alveolar collapse and respiratory distress syndrome. The development and assessment of curative therapies for the deficiency are limited by the general lack of well-characterized and physiologically relevant in vitro models of human lung parenchyma. Here, we describe a new human surfactant air-liquid interface (SALI) culture model based on H441 cells, which successfully recapitulates the key characteristics of human alveolar cells in primary culture as evidenced by RNA and protein expression of alveolar cell markers. SALI cultures were able to develop stratified cellular layers with functional barrier properties that are stable for at least 28 days after air-lift. A SFTPB knockout model of SPB deficiency was generated via gene editing of SALI cultures. The SFTPB-edited SALI cultures lost expression of SPB completely and showed weaker functional barrier properties. We were able to correct this phenotype via delivery of a lentiviral vector pseudotyped with Sendai virus glycoproteins F/HN expressing SPB. We believe that SALI cultures can serve as an important in vitro research tool to study human alveolar epithelium, especially for the development of advanced therapy medicinal products targeting monogenic disorders.
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Affiliation(s)
- Altar M. Munis
- Gene Medicine Group, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Stephen C. Hyde
- Gene Medicine Group, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Deborah R. Gill
- Gene Medicine Group, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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Wirsching E, Fauler M, Fois G, Frick M. P2 Purinergic Signaling in the Distal Lung in Health and Disease. Int J Mol Sci 2020; 21:E4973. [PMID: 32674494 PMCID: PMC7404078 DOI: 10.3390/ijms21144973] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022] Open
Abstract
The distal lung provides an intricate structure for gas exchange in mammalian lungs. Efficient gas exchange depends on the functional integrity of lung alveoli. The cells in the alveolar tissue serve various functions to maintain alveolar structure, integrity and homeostasis. Alveolar epithelial cells secrete pulmonary surfactant, regulate the alveolar surface liquid (ASL) volume and, together with resident and infiltrating immune cells, provide a powerful host-defense system against a multitude of particles, microbes and toxicants. It is well established that all of these cells express purinergic P2 receptors and that purinergic signaling plays important roles in maintaining alveolar homeostasis. Therefore, it is not surprising that purinergic signaling also contributes to development and progression of severe pathological conditions like pulmonary inflammation, acute lung injury/acute respiratory distress syndrome (ALI/ARDS) and pulmonary fibrosis. Within this review we focus on the role of P2 purinergic signaling in the distal lung in health and disease. We recapitulate the expression of P2 receptors within the cells in the alveoli, the possible sources of ATP (adenosine triphosphate) within alveoli and the contribution of purinergic signaling to regulation of surfactant secretion, ASL volume and composition, as well as immune homeostasis. Finally, we summarize current knowledge of the role for P2 signaling in infectious pneumonia, ALI/ARDS and idiopathic pulmonary fibrosis (IPF).
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Affiliation(s)
| | | | | | - Manfred Frick
- Institute of General Physiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany; (E.W.); (M.F.); (G.F.)
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11
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Coulombe P, Paliouras GN, Clayton A, Hussainkhel A, Fuller M, Jovanovic V, Dauphinee S, Umlandt P, Xiang P, Kyle AH, Minchinton AI, Humphries RK, Hoodless PA, Parker JDK, Wright JL, Karsan A. Endothelial Sash1 Is Required for Lung Maturation through Nitric Oxide Signaling. Cell Rep 2020; 27:1769-1780.e4. [PMID: 31067462 DOI: 10.1016/j.celrep.2019.04.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 03/07/2019] [Accepted: 04/05/2019] [Indexed: 12/19/2022] Open
Abstract
The sterile alpha motif (SAM) and SRC homology 3 (SH3) domain containing protein 1 (Sash1) acts as a scaffold in TLR4 signaling. We generated Sash1-/- mice, which die in the perinatal period due to respiratory distress. Constitutive or endothelial-restricted Sash1 loss leads to a delay in maturation of alveolar epithelial cells causing reduced surfactant-associated protein synthesis. We show that Sash1 interacts with β-arrestin 1 downstream of the TLR4 pathway to activate Akt and endothelial nitric oxide synthase (eNOS) in microvascular endothelial cells. Generation of nitric oxide downstream of Sash1 in endothelial cells affects alveolar epithelial cells in a cGMP-dependent manner, inducing maturation of alveolar type 1 and 2 cells. Thus, we identify a critical cell nonautonomous function for Sash1 in embryonic development in which endothelial Sash1 regulates alveolar epithelial cell maturation and promotes pulmonary surfactant production through nitric oxide signaling. Lung immaturity is a major cause of respiratory distress and mortality in preterm infants, and these findings identify the endothelium as a potential target for therapy.
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Affiliation(s)
- Patrick Coulombe
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada; Department of Experimental Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Grigorios N Paliouras
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Ashley Clayton
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada; Department of Experimental Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Angela Hussainkhel
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada; Program of Interdisciplinary Oncology, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Megan Fuller
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Vida Jovanovic
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Shauna Dauphinee
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada; Department of Experimental Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Patricia Umlandt
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Ping Xiang
- Terry Fox Laboratory, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Alistair H Kyle
- Department of Integrative Oncology, BC Cancer Research Centre, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Andrew I Minchinton
- Department of Integrative Oncology, BC Cancer Research Centre, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - R Keith Humphries
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 2B5, Canada; Terry Fox Laboratory, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Pamela A Hoodless
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 2B5, Canada; Terry Fox Laboratory, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Jeremy D K Parker
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada
| | - Joanne L Wright
- Department of Pathology, University of British Colombia, Vancouver, BC V6T 2B5, Canada
| | - Aly Karsan
- Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10(th) Avenue, Vancouver, BC V5Z 1L3, Canada; Department of Experimental Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada; Program of Interdisciplinary Oncology, University of British Columbia, Vancouver, BC V6T 2B5, Canada; Department of Pathology, University of British Colombia, Vancouver, BC V6T 2B5, Canada.
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12
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Gonzalez R, Leaffer D, Chapin C, Gillespie AM, Eckalbar W, Dobbs L. Cell fate analysis in fetal mouse lung reveals distinct pathways for TI and TII cell development. Am J Physiol Lung Cell Mol Physiol 2019; 317:L653-L666. [PMID: 31432712 DOI: 10.1152/ajplung.00503.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Alveolar type I (TI) cells are large squamous cells that cover >95% of the internal surface area of the lung; type II (TII) cells are small cuboidal cells with distinctive intracellular surfactant storage organelles. Based on autoradiographic studies in the 1970s, the long-held paradigm of alveolar epithelial development has been a linear progression from undifferentiated progenitor cells through TII cells to TI cells. Subsequent data support the existence of more complex pathways. Recently, a bipotent TI/TII progenitor cell at embryonic day E18 has been inferred both from marker expression in developing airways and from statistical analyses of gene expression data obtained from single-lung embryonic cells. To study cell lineage directly by fate mapping, we developed new transgenic mouse models in which rtTA is driven either by the rat podoplanin or the mouse Sftpc gene to mark cells irreversibly in development. Using these models, we found two distinct lineage pathways. One pathway, evident as early as E12-15, is devoted almost exclusively to TI cell development; a second pathway gives rise predominantly to TII cells but also a subpopulation of TI cells. We have defined the molecular phenotypes of these distinct progenitor populations and have identified potential regulatory factors in TI and TII cell differentiation. By analyzing gene pathways in mature TI and TII cells, we identified potential novel functions of each cell type. These results provide novel insights into lung development and suggest a basis for testing strategies to promote alveolar differentiation and repair, including potential transplantation of lineage-specific progenitor cells.
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Affiliation(s)
- Robert Gonzalez
- Cardiovascular Research Institute, University of California, San Francisco, California
| | - David Leaffer
- Cardiovascular Research Institute, University of California, San Francisco, California
| | - Cheryl Chapin
- Department of Pediatrics, University of California, San Francisco, California
| | - Anne Marie Gillespie
- Cardiovascular Research Institute, University of California, San Francisco, California
| | - Walter Eckalbar
- Department of Medicine, University of California, San Francisco, California
| | - Leland Dobbs
- Cardiovascular Research Institute, University of California, San Francisco, California.,Department of Pediatrics, University of California, San Francisco, California.,Department of Medicine, University of California, San Francisco, California
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13
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Scheiber IF, Alarcon NO, Zhao N. Manganese Uptake by A549 Cells is Mediated by Both ZIP8 and ZIP14. Nutrients 2019; 11:nu11071473. [PMID: 31261654 PMCID: PMC6682971 DOI: 10.3390/nu11071473] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 06/20/2019] [Accepted: 06/26/2019] [Indexed: 12/16/2022] Open
Abstract
The alveolar epithelia of the lungs require manganese (Mn) as an essential nutrient, but also provide an entry route for airborne Mn that can cause neurotoxicity. Transporters involved in Mn uptake by alveolar epithelial cells are unknown. Recently, two members of the Zrt- and Irt-like protein (ZIP) family of metal transporters, ZIP8 and ZIP14, have been identified as crucial Mn importers in vivo. ZIP8 is by far most abundantly expressed in the lungs, whereas ZIP14 expression in the lungs is low compared to other tissues. We hypothesized that Mn uptake by alveolar epithelial cells is primarily mediated by ZIP8. To test our hypothesis, we used A549 cells, a type II alveolar cell line. Mirroring the in vivo situation, A549 cells expressed higher levels of ZIP8 than cell models for the liver, intestines, and kidney. Quantification of ZIP8 and ZIP14 revealed a strong enrichment of ZIP8 over ZIP14 in A549 cells. Using siRNA technology, we identified ZIP8 and ZIP14 as the major transporters mediating Mn uptake by A549 cells. To our surprise, knockdown of either ZIP8 or ZIP14 impaired Mn accumulation to a similar extent, which we traced back to similar amounts of ZIP8 and ZIP14 at the plasma membrane. Our study highlights the importance of both ZIP8 and ZIP14 in Mn metabolism of alveolar epithelial cells.
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Affiliation(s)
- Ivo F Scheiber
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA
| | | | - Ningning Zhao
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA.
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Wosen JE, Mukhopadhyay D, Macaubas C, Mellins ED. Epithelial MHC Class II Expression and Its Role in Antigen Presentation in the Gastrointestinal and Respiratory Tracts. Front Immunol 2018; 9:2144. [PMID: 30319613 PMCID: PMC6167424 DOI: 10.3389/fimmu.2018.02144] [Citation(s) in RCA: 153] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/30/2018] [Indexed: 12/13/2022] Open
Abstract
As the primary barrier between an organism and its environment, epithelial cells are well-positioned to regulate tolerance while preserving immunity against pathogens. Class II major histocompatibility complex molecules (MHC class II) are highly expressed on the surface of epithelial cells (ECs) in both the lung and intestine, although the functional consequences of this expression are not fully understood. Here, we summarize current information regarding the interactions that regulate the expression of EC MHC class II in health and disease. We then evaluate the potential role of EC as non-professional antigen presenting cells. Finally, we explore future areas of study and the potential contribution of epithelial surfaces to gut-lung crosstalk.
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Affiliation(s)
- Jonathan E Wosen
- Program in Immunology, Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - Dhriti Mukhopadhyay
- Program in Immunology, Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - Claudia Macaubas
- Program in Immunology, Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - Elizabeth D Mellins
- Program in Immunology, Department of Pediatrics, Stanford University, Stanford, CA, United States
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15
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Hagiwara T, Yoshida S, Hidaka Y. Gene expression of the concentration-sensitive sodium channel is suppressed in lipopolysaccharide-induced acute lung injury in mice. Exp Lung Res 2017; 43:150-157. [PMID: 28557567 DOI: 10.1080/01902148.2017.1321064] [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] [Indexed: 12/25/2022]
Abstract
PURPOSE The concentration-sensitive sodium channel (NaC) is expressed in alveolar type II epithelial cells and pulmonary microvascular endothelial cells in mouse lungs. We recently reported that NaC contributes to amiloride-insensitive sodium transport in mouse lungs (Respiratory Physiology & Neurobiology, 2016). However, details regarding its physiological role in the lung remain unknown. To examine whether NaC is involved in alveolar fluid clearance during an acute lung injury (ALI), we analyzed the relationship between NaC gene expression in the lung and the development of pulmonary edema in lipopolysaccharide (LPS)-induced ALI mice. METHODS LPS-induced ALI mice were prepared by the intratracheal administration of LPS. Bronchoalveolar lavage (BAL) neutrophils and lung water content (LWCs) were used as a marker of ALI and pulmonary edema, respectively. NaC protein production in the lung was detected by immunoblotting and immunofluorescence. The gene expressions of NaC and the epithelial sodium channel (ENaC) of LPS-induced ALI mice were examined by quantitative RT-PCR over a time course of 14 days. RESULTS The BAL neutrophil count increased until day 2 after LPS administration and had nearly recovered by day 6. LWCs in LPS-induced mice gradually increased until day 8 and had recovered by day 14. The expression of the NaC protein in the lungs of LPS-induced mice dramatically decreased from day 2 to day 6, but recovered by day 8. The mRNA expression of NaC decreased in the lung, as well as those for α-, β-, and γ-ENaC during ALI. Thus, NaC expression is suppressed during the development stage of pulmonary edema and then recovers in the convalescent phase. CONCLUSION Our results suggest that suppression of the gene expression of NaC is involved in the development of pulmonary edema in ALI.
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Affiliation(s)
- Teruki Hagiwara
- a Department of Life Science, Faculty of Science and Engineering , Kindai University , Higashi-Osaka , Osaka , Japan
| | - Shigeru Yoshida
- a Department of Life Science, Faculty of Science and Engineering , Kindai University , Higashi-Osaka , Osaka , Japan
| | - Yuji Hidaka
- a Department of Life Science, Faculty of Science and Engineering , Kindai University , Higashi-Osaka , Osaka , Japan
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16
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A critical role for IRF5 in regulating allergic airway inflammation. Mucosal Immunol 2017; 10:716-726. [PMID: 27759022 PMCID: PMC5266556 DOI: 10.1038/mi.2016.92] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 08/14/2016] [Indexed: 02/04/2023]
Abstract
Interferon regulatory factor 5 (IRF5) is a key transcription factor involved in the control of the expression of proinflammatory cytokine and responses to infection, but its role in regulating pulmonary immune responses to allergen is unknown. We used genetic ablation, adenoviral vector-driven overexpression, and adoptive transfer approaches to interrogate the role of IRF5 in pulmonary immunity and during challenge with the aeroallergen, house dust mite. Global IRF5 deficiency resulted in impaired lung function and extracellular matrix (ECM) deposition. IRF5 was also essential for effective responses to inhaled allergen, controlling airway hyperresponsiveness, mucus secretion, and eosinophilic inflammation. Adoptive transfer of IRF5-deficient alveolar macrophages into the wild-type pulmonary milieu was sufficient to drive airway hyperreactivity, at baseline or following antigen challenge. These data identify IRF5-expressing macrophages as a key component of the immune defense of the airways. Manipulation of IRF5 activity in the lung could therefore be a viable strategy for the redirection of pulmonary immune responses and, thus, the treatment of lung disorders.
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18
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Ren H, Birch NP, Suresh V. An Optimised Human Cell Culture Model for Alveolar Epithelial Transport. PLoS One 2016; 11:e0165225. [PMID: 27780255 PMCID: PMC5079558 DOI: 10.1371/journal.pone.0165225] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 10/07/2016] [Indexed: 12/31/2022] Open
Abstract
Robust and reproducible in vitro models are required for investigating the pathways involved in fluid homeostasis in the human alveolar epithelium. We performed functional and phenotypic characterisation of ion transport in the human pulmonary epithelial cell lines NCI-H441 and A549 to determine their similarity to primary human alveolar type II cells. NCI-H441 cells exhibited high expression of junctional proteins ZO-1, and E-cadherin, seal-forming claudin-3, -4, -5 and Na+-K+-ATPase while A549 cells exhibited high expression of pore-forming claudin-2. Consistent with this phenotype NCI-H441, but not A549, cells formed a functional barrier with active ion transport characterised by higher electrical resistance (529 ± 178 Ω cm2 vs 28 ± 4 Ω cm2), lower paracellular permeability ((176 ± 42) ×10−8 cm/s vs (738 ± 190) ×10−8 cm/s) and higher transepithelial potential difference (11.9 ± 4 mV vs 0 mV). Phenotypic and functional properties of NCI-H441 cells were tuned by varying cell seeding density and supplement concentrations. The cells formed a polarised monolayer typical of in vivo epithelium at seeding densities of 100,000 cells per 12-well insert while higher densities resulted in multiple cell layers. Dexamethasone and insulin-transferrin-selenium supplements were required for the development of high levels of electrical resistance, potential difference and expression of claudin-3 and Na+-K+-ATPase. Treatment of NCI-H441 cells with inhibitors and agonists of sodium and chloride channels indicated sodium absorption through ENaC under baseline and forskolin-stimulated conditions. Chloride transport was not sensitive to inhibitors of the cystic fibrosis transmembrane conductance regulator (CFTR) under either condition. Channels inhibited by 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB) contributed to chloride secretion following forskolin stimulation, but not at baseline. These data precisely define experimental conditions for the application of NCI-H441 cells as a model for investigating ion and water transport in the human alveolar epithelium and also identify the pathways of sodium and chloride transport.
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Affiliation(s)
- Hui Ren
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- * E-mail:
| | - Nigel P. Birch
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
- Brain Research New Zealand, Rangahau Roro Aotearoa, New Zealand
| | - Vinod Suresh
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Department of Engineering Science, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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19
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Contribution of concentration-sensitive sodium channels to the absorption of alveolar fluid in mice. Respir Physiol Neurobiol 2016; 231:45-54. [PMID: 27259686 DOI: 10.1016/j.resp.2016.05.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 04/29/2016] [Accepted: 05/29/2016] [Indexed: 01/11/2023]
Abstract
The concentration-sensitive sodium channel (Nac) is activated by an increase in the extracellular sodium concentration. Although the expression of Nac in alveolar type II epithelial cells (AEC II) has been reported previously, the physiological role of Nac in the lung has not been established. We characterized Nac expression and examined amiloride-insensitive sodium transport mediated by Nac in mouse lung. Immunofluorescence studies revealed that Nac did not colocalize with either aquaporin 5 or cystic fibrosis transmembrane conductance regulator, but partially colocalized with the epithelial sodium channel γ-subunit. Immunoelectron microscopy studies showed that Nac localized at the basolateral membrane of pulmonary microvascular endothelial cells (PMVECs). Nac mRNA and protein were expressed in PMVECs isolated from the lungs of mice. Image analysis indicated that sodium influx into the alveolar wall was dependent on increases in extracellular sodium concentration. We conclude that Nac expressed in PMVECs and AEC II contributes to the reabsorption of sodium via an amiloride-insensitive pathway during alveolar fluid clearance.
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21
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Wujak ŁA, Blume A, Baloğlu E, Wygrecka M, Wygowski J, Herold S, Mayer K, Vadász I, Besuch P, Mairbäurl H, Seeger W, Morty RE. FXYD1 negatively regulates Na(+)/K(+)-ATPase activity in lung alveolar epithelial cells. Respir Physiol Neurobiol 2015; 220:54-61. [PMID: 26410457 DOI: 10.1016/j.resp.2015.09.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 09/17/2015] [Accepted: 09/20/2015] [Indexed: 01/10/2023]
Abstract
Acute respiratory distress syndrome (ARDS) is clinical syndrome characterized by decreased lung fluid reabsorption, causing alveolar edema. Defective alveolar ion transport undertaken in part by the Na(+)/K(+)-ATPase underlies this compromised fluid balance, although the molecular mechanisms at play are not understood. We describe here increased expression of FXYD1, FXYD3 and FXYD5, three regulatory subunits of the Na(+)/K(+)-ATPase, in the lungs of ARDS patients. Transforming growth factor (TGF)-β, a pathogenic mediator of ARDS, drove increased FXYD1 expression in A549 human lung alveolar epithelial cells, suggesting that pathogenic TGF-β signaling altered Na(+)/K(+)-ATPase activity in affected lungs. Lentivirus-mediated delivery of FXYD1 and FXYD3 allowed for overexpression of both regulatory subunits in polarized H441 cell monolayers on an air/liquid interface. FXYD1 but not FXYD3 overexpression inhibited amphotericin B-sensitive equivalent short-circuit current in Ussing chamber studies. Thus, we speculate that FXYD1 overexpression in ARDS patient lungs may limit Na(+)/K(+)-ATPase activity, and contribute to edema persistence.
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Affiliation(s)
- Łukasz A Wujak
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany; Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; Department of Biochemistry, University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Anna Blume
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Emel Baloğlu
- Department of Sports Medicine, Medical Clinic VII, University Hospital Heidelberg, University of Heidelberg, Translational Lung Research Center (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Medical Pharmacology, Acibadem University, İstanbul, Turkey
| | - Małgorzata Wygrecka
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany; Department of Biochemistry, University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Jegor Wygowski
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Susanne Herold
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Konstantin Mayer
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - István Vadász
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Petra Besuch
- Department of Pathology, Klinikum Frankfurt (Oder) GmbH, Frankfurt (Oder), Germany
| | - Heimo Mairbäurl
- Department of Biochemistry, University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Werner Seeger
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany; Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Rory E Morty
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany; Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
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22
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Lin S, Racz J, Tai MF, Brooks KM, Rzeczycki P, Heath LJ, Newstead MW, Standiford TJ, Rosania GR, Stringer KA. A Role for Low Density Lipoprotein Receptor-Related Protein 1 in the Cellular Uptake of Tissue Plasminogen Activator in the Lungs. Pharm Res 2015; 33:72-82. [PMID: 26231141 DOI: 10.1007/s11095-015-1763-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/21/2015] [Indexed: 01/10/2023]
Abstract
PURPOSE To gain knowledge of lung clearance mechanisms of inhaled tissue plasminogen activator (tPA). METHODS Using an in vivo mouse model and ex vivo murine whole organ cell suspensions, we examined the capability of the lungs to utilize LRP1 receptor-mediated endocytosis (RME) for the uptake of exogenous tPA with and without an LRP1 inhibitor, receptor associated protein (RAP), and quantitatively compared it to the liver. We also used a novel imaging technique to assess the amount LRP1 in sections of mouse liver and lung. RESULTS Following intratracheal administration, tPA concentrations in the bronchoalveolar lavage fluid (BALF) declined over time following two-compartment pharmacokinetics suggestive of a RME clearance mechanism. Ex vivo studies showed that lung and liver cells are similarly capable of tPA uptake via LRP1 RME which was reduced by ~50% by RAP. The comparable lung and liver uptake of tPA is likely due to equivalent amounts of LRP1 of which there was an abundance in the alveolar epithelium. CONCLUSIONS Our findings indicate that LRP1 RME is a candidate clearance mechanism for inhaled tPA which has implications for the development of safe and effective dosing regimens of inhaled tPA for the treatment of plastic bronchitis and other fibrin-inflammatory airway diseases in which inhaled tPA may have utility.
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Affiliation(s)
- Swan Lin
- Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Jennifer Racz
- Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Melissa F Tai
- Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Kristina M Brooks
- Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Phillip Rzeczycki
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Lauren J Heath
- Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael W Newstead
- Division of Pulmonary and Critical Care Medicine, School of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Theodore J Standiford
- Division of Pulmonary and Critical Care Medicine, School of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Gus R Rosania
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
| | - Kathleen A Stringer
- Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
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Xu J, Zong Y, Li X, Zhang Y, Li J. Divergent expression of α-ENaC in middle ear mucosa in the course of otitis media with effusion induced by barotrauma. Acta Otolaryngol 2015; 135:651-4. [PMID: 25873260 DOI: 10.3109/00016489.2015.1017888] [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: 11/13/2022]
Abstract
CONCLUSION Gene transcription and protein expression of α-ENaC showed a divergent expression in association with the development of OME induced by barotrauma. OBJECTIVES ENaC was identified to mediate the fluid absorption through epithelia of the middle ear. This study was designed to investigate the involvement of ENaC in otitis media with effusion (OME) induced by barotrauma. METHODS A rat model of otitis media with effusion was established using a pressure cabin. The dynamic expression of α-ENaC was detected by Real time-PCR and western blot in the course of otitis media. RESULTS Compared with the control, the volume of α-ENaC mRNA and protein increased significantly by 3.18-fold and 2.8-fold on the 3(rd) day, respectively, while decreased by 0.54-fold and 0.32-fold on the 7(th) day, respectively.
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Affiliation(s)
- Ji Xu
- Department of Otorhinolaryngology Head and Neck Surgery, Ren Ji Hospital, School of Medicine , Shanghai , PR China
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The Contribution of the Airway Epithelial Cell to Host Defense. Mediators Inflamm 2015; 2015:463016. [PMID: 26185361 PMCID: PMC4491388 DOI: 10.1155/2015/463016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 12/11/2014] [Indexed: 12/19/2022] Open
Abstract
In the context of cystic fibrosis, the epithelial cell has been characterized in terms of its ion transport capabilities. The ability of an epithelial cell to initiate CFTR-mediated chloride and bicarbonate transport has been recognized early as a means to regulate the thickness of the epithelial lining fluid and recently as a means to regulate the pH, thereby determining critically whether or not host defense proteins such as mucins are able to fold appropriately. This review describes how the epithelial cell senses the presence of pathogens and inflammatory conditions, which, in turn, facilitates the activation of CFTR and thus directly promotes pathogens clearance and innate immune defense on the surface of the epithelial cell. This paper summarizes functional data that describes the effect of cytokines, chemokines, infectious agents, and inflammatory conditions on the ion transport properties of the epithelial cell and relates these key properties to the molecular pathology of cystic fibrosis. Recent findings on the role of cystic fibrosis modifier genes that underscore the role of the epithelial ion transport in host defense and inflammation are discussed.
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Schwagerus E, Sladek S, Buckley ST, Armas-Capote N, de la Rosa DA, Harvey BJ, Fischer H, Illek B, Huwer H, Schneider-Daum N, Lehr CM, Ehrhardt C. Expression and function of the epithelial sodium channel δ-subunit in human respiratory epithelial cells in vitro. Pflugers Arch 2015; 467:2257-73. [DOI: 10.1007/s00424-015-1693-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 11/24/2022]
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Brune K, Frank J, Schwingshackl A, Finigan J, Sidhaye VK. Pulmonary epithelial barrier function: some new players and mechanisms. Am J Physiol Lung Cell Mol Physiol 2015; 308:L731-45. [PMID: 25637609 DOI: 10.1152/ajplung.00309.2014] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/27/2015] [Indexed: 12/20/2022] Open
Abstract
The pulmonary epithelium serves as a barrier to prevent access of the inspired luminal contents to the subepithelium. In addition, the epithelium dictates the initial responses of the lung to both infectious and noninfectious stimuli. One mechanism by which the epithelium does this is by coordinating transport of diffusible molecules across the epithelial barrier, both through the cell and between cells. In this review, we will discuss a few emerging paradigms of permeability changes through altered ion transport and paracellular regulation by which the epithelium gates its response to potentially detrimental luminal stimuli. This review is a summary of talks presented during a symposium in Experimental Biology geared toward novel and less recognized methods of epithelial barrier regulation. First, we will discuss mechanisms of dynamic regulation of cell-cell contacts in the context of repetitive exposure to inhaled infectious and noninfectious insults. In the second section, we will briefly discuss mechanisms of transcellular ion homeostasis specifically focused on the role of claudins and paracellular ion-channel regulation in chronic barrier dysfunction. In the next section, we will address transcellular ion transport and highlight the role of Trek-1 in epithelial responses to lung injury. In the final section, we will outline the role of epithelial growth receptor in barrier regulation in baseline, acute lung injury, and airway disease. We will then end with a summary of mechanisms of epithelial control as well as discuss emerging paradigms of the epithelium role in shifting between a structural element that maintains tight cell-cell adhesion to a cell that initiates and participates in immune responses.
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Affiliation(s)
- Kieran Brune
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - James Frank
- The Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco VA Medical Center, and NCIRE/Veterans Health Research Institute, San Francisco, California
| | - Andreas Schwingshackl
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - James Finigan
- Division of Oncology, Cancer Center, National Jewish Health, Denver, Colorado
| | - Venkataramana K Sidhaye
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland;
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Thompson KE, Korbmacher JP, Hecht E, Hobi N, Wittekindt OH, Dietl P, Kranz C, Frick M. Fusion-activated cation entry (FACE) via P2X₄ couples surfactant secretion and alveolar fluid transport. FASEB J 2013; 27:1772-83. [PMID: 23307836 DOI: 10.1096/fj.12-220533] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Two fundamental mechanisms within alveoli are essential for lung function: regulated fluid transport and secretion of surfactant. Surfactant is secreted via exocytosis of lamellar bodies (LBs) in alveolar type II (ATII) cells. We recently reported that LB exocytosis results in fusion-activated cation entry (FACE) via P2X₄ receptors on LBs. We propose that FACE, in addition to facilitating surfactant secretion, modulates alveolar fluid transport. Correlative fluorescence and atomic force microscopy revealed that FACE-dependent water influx correlated with individual fusion events in rat primary ATII cells. Moreover, ATII cell monolayers grown at air-liquid interface exhibited increases in short-circuit current (Isc) on stimulation with ATP or UTP. Both are potent agonists for LB exocytosis, but only ATP activates FACE. ATP, not UTP, elicited additional fusion-dependent increases in Isc. Overexpressing dominant-negative P2X₄ abrogated this effect by ∼50%, whereas potentiating P2X4 lead to ∼80% increase in Isc. Finally, we monitored changes in alveolar surface liquid (ASL) on ATII monolayers by confocal microscopy. Only stimulation with ATP, not UTP, led to a significant, fusion-dependent, 20% decrease in ASL, indicating apical-to-basolateral fluid transport across ATII monolayers. Our data support the first direct link between LB exocytosis, regulation of surfactant secretion, and transalveolar fluid resorption via FACE.
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Hardman CS, Panova V, McKenzie ANJ. IL-33 citrine reporter mice reveal the temporal and spatial expression of IL-33 during allergic lung inflammation. Eur J Immunol 2012; 43:488-98. [PMID: 23169007 PMCID: PMC3734634 DOI: 10.1002/eji.201242863] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/28/2012] [Accepted: 11/15/2012] [Indexed: 12/13/2022]
Abstract
Interleukin-33 (IL-33) is an IL-1 family cytokine that signals via its receptor T1/ST2, and is a key regulator of inflammation, notably the type-2 response implicated in allergic asthma. Critical to our understanding of the role of IL-33 is the identification of the cellular sources of IL-33. Although progress has been made in this area, the development of a robust live cell reporter of expression would allow the localisation of IL-33 during ongoing immune responses. We have generated a fluorescent reporter mouse line, Il33Cit/+, to define the expression profile of IL-33 in vivo and demonstrate its temporal and spatial expression during experimental allergic asthma responses. We found that type-2 pneumocytes constitute the major source of IL-33 upon allergic lung inflammation following exposure to OVA, fungal extract or ragweed pollen. Using Il33Cit/Cit mice (IL-33-deficient), we establish a role for IL-33 early in the initiation of type-2 responses and the induction of nuocytes (ILC2). We also demonstrate a potential mechanism of action by which IL-33 rapidly initiates type-2 immune responses. Il33Cit/+ mice have enabled new insights into the initiation of type-2 responses and will provide an important tool for further dissection of this important inflammatory pathway in vivo.
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Affiliation(s)
- Clare S Hardman
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK
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Fronius M, Clauss WG, Althaus M. Why Do We have to Move Fluid to be Able to Breathe? Front Physiol 2012; 3:146. [PMID: 22661953 PMCID: PMC3357553 DOI: 10.3389/fphys.2012.00146] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 05/01/2012] [Indexed: 12/11/2022] Open
Abstract
The ability to breathe air represents a fundamental step in vertebrate evolution that was accompanied by several anatomical and physiological adaptations. The morphology of the air-blood barrier is highly conserved within air-breathing vertebrates. It is formed by three different plies, which are represented by the alveolar epithelium, the basal lamina, and the endothelial layer. Besides these conserved morphological elements, another common feature of vertebrate lungs is that they contain a certain amount of fluid that covers the alveolar epithelium. The volume and composition of the alveolar fluid is regulated by transepithelial ion transport mechanisms expressed in alveolar epithelial cells. These transport mechanisms have been reviewed extensively. Therefore, the present review focuses on the properties and functional significance of the alveolar fluid. How does the fluid enter the alveoli? What is the fate of the fluid in the alveoli? What is the function of the alveolar fluid in the lungs? The review highlights the importance of the alveolar fluid, its volume and its composition. Maintenance of the fluid volume and composition within certain limits is critical to facilitate gas exchange. We propose that the alveolar fluid is an essential element of the air-blood barrier. Therefore, it is appropriate to refer to this barrier as being formed by four plies, namely (1) the thin fluid layer covering the apical membrane of the epithelial cells, (2) the epithelial cell layer, (3) the basal membrane, and (4) the endothelial cells.
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Affiliation(s)
- Martin Fronius
- Molecular Cell Physiology, Institute of Animal Physiology, Justus-Liebig-University Giessen Giessen, Germany
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Paisley D, Gosling M, Danahay H. Regulation of airway mucosal hydration. Expert Rev Clin Pharmacol 2012; 3:361-9. [PMID: 22111616 DOI: 10.1586/ecp.10.19] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Ion channels control the hydration status of the airway epithelium through apical anion secretion and cation absorption, which is accompanied by osmotically obligated water. The key channels in this process are the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), which is principally responsible for Cl(-) secretion by airway epithelial cells, and the epithelial Na(+) channel (ENaC), which is responsible for the absorption of Na ions. In CF, defective CFTR-mediated Cl(-) secretion and an accompanying upregulation in ENaC-mediated Na absorption results in a reduction in airway surface liquid volume, leading to poorly hydrated mucus and impaired mucociliary clearance. Restoration of normal airway hydration by modulation of ion channel activity represents an important therapeutic strategy for CF. CFTR corrector and potentiator compounds are being developed with the aim of recovering normal Cl(-) secretion. Ca(2+)-activated Cl(-) channels (CaCCs) are expressed by the respiratory epithelia and are reported to be functionally upregulated in CF and offer a 'surrogate' pathway for Cl(-) secretion. TMEM16A has recently been described as a CaCC in the airway epithelium and, as such, represents an alternative target for restoring Cl(-) secretion in CF. An alternative therapeutic strategy for CF is to inhibit ENaC, thereby blocking excessive Na absorption. This can be achieved by direct blockade of ENaC or inhibition of the channel-activating proteases (CAPs), whose activity regulates ENaC function. This review will describe the regulation of airway mucosal hydration by ion channels and the efforts currently underway to restore normal mucosal hydration in disease patients by modulating the function of these channels.
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Affiliation(s)
- Derek Paisley
- Novartis Institutes for Biomedical Research, Wimblehurst Road, Horsham, West Sussex, UK
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Abstract
The pulmonary alveolar epithelium, comprised of alveolar Type I (TI) and Type II (TII) cells, covers more than 99% of the internal surface area of the lungs. The study of isolated and cultured alveolar epithelial TI and TII cells has provided a large amount of information about the functions of both cell types. This chapter provides information about methods for isolating and culturing both of these cell types from rat lungs.
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Kosmider B, Messier EM, Chu HW, Mason RJ. Human alveolar epithelial cell injury induced by cigarette smoke. PLoS One 2011; 6:e26059. [PMID: 22163265 PMCID: PMC3233536 DOI: 10.1371/journal.pone.0026059] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/13/2011] [Indexed: 12/19/2022] Open
Abstract
Background Cigarette smoke (CS) is a highly complex mixture and many of its components are known carcinogens, mutagens, and other toxic substances. CS induces oxidative stress and cell death, and this cell toxicity plays a key role in the pathogenesis of several pulmonary diseases. Methodology/Principal Findings We studied the effect of cigarette smoke extract (CSE) in human alveolar epithelial type I-like (ATI-like) cells. These are isolated type II cells that are differentiating toward the type I cell phenotype in vitro and have lost many type II cell markers and express type I cell markers. ATI-like cells were more sensitive to CSE than alveolar type II cells, which maintained their differentiated phenotype in vitro. We observed disruption of mitochondrial membrane potential, apoptosis and necrosis that were detected by double staining with acridine orange and ethidium bromide or Hoechst 33342 and propidium iodide and TUNEL assay after treatment with CSE. We also detected caspase 3 and caspase 7 activities and lipid peroxidation. CSE induced nuclear translocation of Nrf2 and increased expression of Nrf2, HO-1, Hsp70 and Fra1. Moreover, we found that Nrf2 knockdown sensitized ATI-like cells to CSE and Nrf2 overexpression provided protection against CSE-induced cell death. We also observed that two antioxidant compounds N-acetylcysteine and trolox protected ATI-like cells against injury by CSE. Conclusions Our study indicates that Nrf2 activation is a major factor in cellular defense of the human alveolar epithelium against CSE-induced toxicity and oxidative stress. Therefore, antioxidant agents that modulate Nrf2 would be expected to restore antioxidant and detoxifying enzymes and to prevent CS-related lung injury and perhaps lessen the development of emphysema.
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Affiliation(s)
- Beata Kosmider
- Department of Medicine, National Jewish Health, Denver, Colorado, United States of America.
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Soukup B, Benjamin A, Orogo-Wenn M, Walters D. Physiological effect of protein kinase C on ENaC-mediated lung liquid regulation in the adult rat lung. Am J Physiol Lung Cell Mol Physiol 2011; 302:L133-9. [PMID: 21949158 DOI: 10.1152/ajplung.00031.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tight control of lung liquid (LL) regulation is vital for pulmonary function. The aim of this work was to determine whether PKC activation is involved in the physiological regulation of LL volume in a whole lung preparation. Rat lungs were perfused with a modified Ringer solution, and the lumen was filled with the same solution without glucose. LL volume was measured during a control period and after modulating drugs were administered, and net LL transepithelial movement (J(v)) was calculated. When the PKC activator PMA (10(-5) M) and the Ca(2+) ionophore ionomycin (10(-6) M) were instilled into the lung together, J(v) was significantly reduced (P = 0.03). This reduction was blocked by the PKC inhibitor chelerythrine chloride (10(-6) M; P = 0.56) and by a second PKC inhibitor GF109203X (10(-5) M; P = 0.98). When PMA and ionomycin were added with the β-adrenergic agonist terbutaline, the terbutaline-induced increase in J(v) was abolished. Addition of PMA and ionomycin with the epithelial Na(+) channel (ENaC) blocker amiloride had no additional inhibitory effect. Together, these results suggest that PKC is likely to be involved in LL absorption, and the ability of PMA/ionomycin to block the terbutaline-induced increase in J(v) suggests that the downstream target of PKC is ENaC.
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Affiliation(s)
- Benjamin Soukup
- Division of Biomedical Sciences, St. George's University of London, London, United Kingdom
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Tam A, Wadsworth S, Dorscheid D, Man SFP, Sin DD. The airway epithelium: more than just a structural barrier. Ther Adv Respir Dis 2011; 5:255-73. [PMID: 21372121 DOI: 10.1177/1753465810396539] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian airway is lined by a variety of specialized epithelial cells that not only serve as a physical barrier but also respond to environment-induced damage through the release of biologically active factors and constant cellular renewal. The lung epithelium responds to environmental insults such as pathogens, cigarette smoke and pollution by secreting inflammatory mediators and antimicrobial peptides, and by recruiting immune cells to the site of infection or damage. When the epithelium is severely damaged, basal cells and Clara cells that have stem-cell-like properties are capable of self-renewal and proliferation in the affected area, to repair the damage. In order to effectively fight off infections, the epithelium requires the assistance of neutrophils recruited from the peripheral circulation through transendothelial followed by transepithelial migration events. Activated neutrophils migrate across the epithelium through a series of ligand-receptor interactions to the site of injury, where they secrete proteolytic enzymes and oxidative radicals for pathogen destruction. However, chronic activation and recruitment of neutrophils in airway diseases such as chronic obstructive pulmonary disease and asthma has been associated with tissue damage and disease severity. In this paper, we review the current understanding of the airway epithelial response to injury and its interaction with inflammatory cells, in particular the neutrophil.
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Affiliation(s)
- Anthony Tam
- The UBC James Hogg Research Centre, Providence Heart and Lung Centre and Department of Medicine, University of British Columbia, UBC, Vancouver, BC, Canada
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Yurdakök M. Transient tachypnea of the newborn: what is new? J Matern Fetal Neonatal Med 2011; 23 Suppl 3:24-6. [PMID: 20807157 DOI: 10.3109/14767058.2010.507971] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
An infant born by cesarean delivery is at risk of having excessive pulmonary fluid which makes predisposition to transient tachypnea of the newborn (TTN), because fetal thorax compression during labor leads to the loss of large volumes liquid from the lungs. At birth, the pulmonary epithelium switches from predominantly facilitated Cl⁻ secretion to predominantly active Na+ reabsorption with the increase expression epithelial Na+ -channels (ENaC). Diminished activity or immaturity of this process may contribute to the development of TTN. Familial clustering of some TTN cases shows a genetic predisposition in the developing of this disorder. Antenatal glucocorticoids induce lung Na+ reabsorption by increasing the number and activity of channels even in hypoxia. Since a large release of fetal adrenaline occurs late in labor stimulating ENaC to start reabsorbing lung fluids, aerolized ß-agonists may be used in the treatment. Genetic predisposition for ß-adrenergic hyporesponsiveness may cause TTN in newborn period, and asthma/wheezing in older age groups. Although furosemide accelerates lung fluid resorption and cause pulmonary vasodilatation, oral or aerosolized furosemide cannot be recommended as treatment for TTN unless additional data become available.
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Affiliation(s)
- Murat Yurdakök
- Neonatal Intensive Care Unit, Hacettepe University Children's Hospital, Ankara, Turkey.
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Königshoff M. Lung Cancer in Pulmonary Fibrosis: Tales of Epithelial Cell Plasticity. Respiration 2011; 81:353-8. [DOI: 10.1159/000326299] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Niven RW. Toward managing chronic rejection after lung transplant: the fate and effects of inhaled cyclosporine in a complex environment. Adv Drug Deliv Rev 2011; 63:88-109. [PMID: 20950661 DOI: 10.1016/j.addr.2010.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 09/09/2010] [Accepted: 10/05/2010] [Indexed: 10/19/2022]
Abstract
The fate and effects of inhaled cyclosporine A (CsA) are considered after deposition on the lung surface. Special emphasis is given to a post-lung transplant environment and to the potential effects of the drug on the various cell types it is expected to encounter. The known stability, metabolism, pharmacokinetics and pharmacodynamics of the drug have been reviewed and discussed in the context of the lung microenvironment. Arguments support the contention that the immuno-inhibitory and anti-inflammatory effects of CsA are not restricted to T-cells. It is likely that pharmacologically effective concentrations of CsA can be sustained in the lungs but due to the complexity of uptake and action, the elucidation of effective posology must ultimately rely on clinical evidence.
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Mac Sweeney R, Fischer H, McAuley DF. Nasal potential difference to detect Na+ channel dysfunction in acute lung injury. Am J Physiol Lung Cell Mol Physiol 2010; 300:L305-18. [PMID: 21112943 DOI: 10.1152/ajplung.00223.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Pulmonary fluid clearance is regulated by the active transport of Na(+) and Cl(-) through respiratory epithelial ion channels. Ion channel dysfunction contributes to the pathogenesis of various pulmonary fluid disorders including high-altitude pulmonary edema (HAPE) and neonatal respiratory distress syndrome (RDS). Nasal potential difference (NPD) measurement allows an in vivo investigation of the functionality of these channels. This technique has been used for the diagnosis of cystic fibrosis, the archetypal respiratory ion channel disorder, for over a quarter of a century. NPD measurements in HAPE and RDS suggest constitutive and acquired dysfunction of respiratory epithelial Na(+) channels. Acute lung injury (ALI) is characterized by pulmonary edema due to alveolar epithelial-interstitial-endothelial injury. NPD measurement may enable identification of critically ill ALI patients with a susceptible phenotype of dysfunctional respiratory Na(+) channels and allow targeted therapy toward Na(+) channel function.
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Affiliation(s)
- R Mac Sweeney
- Respiratory Medicine Research Programme, Centre for Infection and Immunity, Queen’s University, Belfast, Northern Ireland
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Bove PF, Grubb BR, Okada SF, Ribeiro CMP, Rogers TD, Randell SH, O'Neal WK, Boucher RC. Human alveolar type II cells secrete and absorb liquid in response to local nucleotide signaling. J Biol Chem 2010; 285:34939-49. [PMID: 20801871 PMCID: PMC2966108 DOI: 10.1074/jbc.m110.162933] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 08/23/2010] [Indexed: 12/21/2022] Open
Abstract
A balance sheet describing the integrated homeostasis of secretion, absorption, and surface movement of liquids on pulmonary surfaces has remained elusive. It remains unclear whether the alveolus exhibits an intra-alveolar ion/liquid transport physiology or whether it secretes ions/liquid that may communicate with airway surfaces. Studies employing isolated human alveolar type II (AT2) cells were utilized to investigate this question. Human AT2 cells exhibited both epithelial Na(+) channel-mediated Na(+) absorption and cystic fibrosis transmembrane conductance regulator-mediated Cl(-) secretion, both significantly regulated by extracellular nucleotides. In addition, we observed in normal AT2 cells an absence of cystic fibrosis transmembrane conductance regulator regulation of epithelial Na(+) channel activity and an absence of expression/activity of reported calcium-activated chloride channels (TMEM16A, Bestrophin-1, ClC2, and SLC26A9), both features strikingly different from normal airway epithelial cells. Measurements of alveolar surface liquid volume revealed that normal AT2 cells: 1) achieved an extracellular nucleotide concentration-dependent steady state alveolar surface liquid height of ∼4 μm in vitro; 2) absorbed liquid when the lumen was flooded; and 3) secreted liquid when treated with UTP or forskolin or subjected to cyclic compressive stresses mimicking tidal breathing. Collectively, our studies suggest that human AT2 cells in vitro have the capacity to absorb or secrete liquid in response to local alveolar conditions.
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Affiliation(s)
- Peter F. Bove
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Barbara R. Grubb
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Seiko F. Okada
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Carla M. P. Ribeiro
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Troy D. Rogers
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Scott H. Randell
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Wanda K. O'Neal
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Richard C. Boucher
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Evidence for Na+-glucose cotransporter in type I alveolar epithelium. Histochem Cell Biol 2010; 134:129-36. [PMID: 20625908 DOI: 10.1007/s00418-010-0725-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2010] [Indexed: 10/19/2022]
Abstract
Functional evidence of Na(+)-glucose cotransport in rat lung has been provided by Basset et al. (J. Physiol. 384:325-345, 1987). By autoradiography [(3)H]phloridzin binding has been found confined to alveolar epithelial type II cells in mouse and rabbit lungs (Boyd, J. Physiol. 422: 44P, 1990). In this research we checked by immunofluorescence whether Na(+)-glucose cotransporter (SGLT1) is also expressed in alveolar type I cells. Lungs of anesthetized rats and lambs were fixed by paraformaldehyde, perfused in pulmonary artery, or instilled into a bronchus, respectively. Tissue blocks embedded in paraffin or frozen were sectioned. Two specific anti-SGLT1 antibodies for rat recognizing aminoacid sequence 402-420, and 546-596 were used in both species. Bound primary antibody was detected by secondary antibody conjugated to fluorescein isothiocianate or Texas red, respectively. In some sections cellular nuclei were also stained. In rats alveolar type I cells were identified by fluorescent Erythrina cristagalli lectin. Sections were examined by confocal laser-scanning microscope. Both in rats and lambs alveolar epithelium was stained by either antibody; no labeling occurred in negative controls. Hence, SGLT1 appears to be also expressed in alveolar type I cells. This is functionally relevant because type I cells provide 95-97% of alveolar surface, and SGLT1, besides contributing to removal of lung liquid under some circumstances, keeps low glucose concentration in lining liquid, which is useful to prevent lung infection.
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Kosmider B, Loader JE, Murphy RC, Mason RJ. Apoptosis induced by ozone and oxysterols in human alveolar epithelial cells. Free Radic Biol Med 2010; 48:1513-24. [PMID: 20219673 PMCID: PMC2965594 DOI: 10.1016/j.freeradbiomed.2010.02.032] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 02/18/2010] [Accepted: 02/21/2010] [Indexed: 12/19/2022]
Abstract
The mechanism of ozone-induced lung cell injury is poorly understood. One hypothesis is that ozone induces lipid peroxidation and that these peroxidated lipids produce oxidative stress and DNA damage. Oxysterols are lipid peroxides formed by the direct effects of ozone on pulmonary surfactant and cell membranes. We studied the effects of ozone and the oxysterol 5beta,6beta-epoxycholesterol (beta-epoxide) and its metabolite cholestan-6-oxo-3,5-diol (6-oxo-3,5-diol) on human alveolar epithelial type I-like cells (ATI-like cells) and type II cells (ATII cells). Ozone and oxysterols induced apoptosis and cytotoxicity in ATI-like cells. They also generated reactive oxygen species and DNA damage. Ozone and beta-epoxide were strong inducers of nuclear factor erythroid 2-related factor 2, heat shock protein 70, and Fos-related antigen 1 protein expression. Furthermore, we found higher sensitivity of ATI-like cells compared to ATII cells exposed to ozone or treated with beta-epoxide or 6-oxo-3,5-diol. In general the response to the cholesterol epoxides was similar to the effect of ozone. Understanding the response of human ATI-like cells and ATII cells to oxysterols may be useful for further studies, because these compounds may represent useful biomarkers in other diseases.
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Affiliation(s)
- Beata Kosmider
- Department of Medicine, National Jewish Health, 1400 Jackson Street, Denver, Colorado 80206
| | - Joan E. Loader
- Department of Pediatrics, National Jewish Health, 1400 Jackson Street, Denver, Colorado 80206
| | - Robert C. Murphy
- Department of Pharmacology, University of Colorado Denver, 12801 East 17th Avenue, Aurora, Colorado 80045
| | - Robert J. Mason
- Department of Medicine, National Jewish Health, 1400 Jackson Street, Denver, Colorado 80206
- Address correspondence to Dr. Robert J. Mason, Department of Medicine, National Jewish Health, 1400 Jackson Street, Denver, CO 80206. Fax: +1 303 270 2353; phone: +1 303 398 1302;
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Königshoff M, Eickelberg O. WNT signaling in lung disease: a failure or a regeneration signal? Am J Respir Cell Mol Biol 2009; 42:21-31. [PMID: 19329555 DOI: 10.1165/rcmb.2008-0485tr] [Citation(s) in RCA: 210] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The WNT family of signaling proteins is essential to organ development in general and lung morphogenesis in particular. Originally identified as a developmentally active signaling pathway, the WNT pathway has recently been linked to the pathogenesis of important lung diseases, in particular lung cancer and pulmonary fibrosis. This review summarizes our current understanding about WNT signaling in lung development and disease, and is structured into three chapters. The first chapter presents an introduction to WNT signaling, outlining WNT proteins, their receptors and signaling intermediates, as well as the regulation of this complex pathway. The second chapter focuses on the role of WNT signaling in the normal embryonic and adult lung, and highlights recent findings of altered WNT signaling in lung diseases, such as lung cancer, pulmonary fibrosis, or pulmonary arterial hypertension. In the last chapter, we will discuss novel data and ideas about the biological effects of WNT signaling on the cellular level, highlighting pleiotropic effects induced by WNT ligands on distinct cell types, and how these cellular effects may be relevant to the pathogenesis of the aforementioned diseases.
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Affiliation(s)
- Melanie Königshoff
- Comprehensive Pneumology Center, Ludwig Maximilians University München and Helmholtz Zentrum München, Institute of Lung Biology and Disease, Ingolstädter Landstrasse 1, Munich, Germany.
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Pariselli F, Sacco MG, Rembges D. An optimized method for in vitro exposure of human derived lung cells to volatile chemicals. ACTA ACUST UNITED AC 2008; 61:33-9. [PMID: 18650076 DOI: 10.1016/j.etp.2008.05.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 05/29/2008] [Indexed: 11/18/2022]
Abstract
Volatile organic compounds (VOCs) such as benzene and toluene, and low molecular weight carbonyls like formaldehyde belong to the main air pollutants found in indoor environments. They are suspected to induce acute and chronic adverse health effects like asthma, allergic and cardiovascular diseases, and strongly affect well-being. Our aim was to further develop and optimize an in vitro method to study the exposure of epithelial tumour lung cells (A549) by using a commercial exposure chamber (CULTEX) to assess the biological effects of VOCs and carbonyl compounds at low concentration levels. Exposing the cells to toluene, benzene and formaldehyde at mixing ratios varying from 0.1 to 0.6ppmv in air resulted in reproducible direct effects with the induction of an inflammatory response and a modification of the glutathione redox status.
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Affiliation(s)
- F Pariselli
- Institute for Health and Consumer Protection, Ispra (VA), Italy.
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Shlyonsky V, Goolaerts A, Mies F, Naeije R. Electrophysiological characterization of rat type II pneumocytes in situ. Am J Respir Cell Mol Biol 2008; 39:36-44. [PMID: 18276797 DOI: 10.1165/rcmb.2007-0227oc] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Optimal aeration of the lungs is dependent on an alveolar fluid clearance, a process that is governed by Na+ and Cl- transport. However, the specific contribution of various ion channels in different alveolar cell types under basal or stimulated conditions is not exactly known. We established a novel functional model of rat lung slices suitable for nystatin-perforated whole-cell patch-clamp experiments. Lung slices retained a majority of live cells for up to 72 hours. Type II pneumocytes in situ had a mean capacitance of 8.8 +/- 2.5 pF and a resting membrane potential of -4.4 +/- 1.9 mV. Bath replacement of Na+ with NMDG+ decreased inward whole-cell currents by 70%, 21% and 52% of which were sensitive to 10 microM and 1 mM of amiloride, respectively. Exposure of slices to 0.5 microM dexamethasone for 1 hour did not affect ion currents, while chronic exposure (0.5 microM, 24-72 h) induced an increase in both total Na+-entry currents and amiloride-sensitive currents. Under acute exposure to 100 microM cpt-cAMP, Type II cells in situ rapidly hyperpolarized by 25-30 mV, due to activation of whole-cell Cl- currents sensitive to 0.1 mM of 5-Nitro-2-(3-phenylpropylamino)benzoic acid. In addition, in the presence of cpt-cAMP, total sodium currents and currents sensitive to 10 microM amiloride increased by 32% and 70%, respectively. Thus, in Type II pneumocytes in situ: (1) amiloride-sensitive sodium channels contribute to only half of total Na+-entry and are stimulated by chronic exposure to glucocorticoids; (2) acute increase in cellular cAMP content simultaneously stimulates the entry of Cl- and Na+ ions.
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Affiliation(s)
- Vadim Shlyonsky
- Université Libre de Bruxelles, Laboratoire de Physiologie et Physiopathologie, Campus Erasme, CP 604, 808 Route de Lennik, 1070 Bruxelles, Belgium.
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