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Mallek NM, Martin EM, Dailey LA, McCullough SD. Liquid application dosing alters the physiology of air-liquid interface (ALI) primary human bronchial epithelial cell/lung fibroblast co-cultures and in vitro testing relevant endpoints. FRONTIERS IN TOXICOLOGY 2024; 5:1264331. [PMID: 38464699 PMCID: PMC10922929 DOI: 10.3389/ftox.2023.1264331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 12/14/2023] [Indexed: 03/12/2024] Open
Abstract
Differentiated primary human bronchial epithelial cell (dpHBEC) cultures grown under air-liquid interface (ALI) conditions exhibit key features of the human respiratory tract and are thus critical for respiratory research as well as efficacy and toxicity testing of inhaled substances (e.g., consumer products, industrial chemicals, and pharmaceuticals). Many inhalable substances (e.g., particles, aerosols, hydrophobic substances, reactive substances) have physiochemical properties that challenge their evaluation under ALI conditions in vitro. Evaluation of the effects of these methodologically challenging chemicals (MCCs) in vitro is typically conducted by "liquid application," involving the direct application of a solution containing the test substance to the apical, air-exposed surface of dpHBEC-ALI cultures. We report that the application of liquid to the apical surface of a dpHBEC-ALI co-culture model results in significant reprogramming of the dpHBEC transcriptome and biological pathway activity, alternative regulation of cellular signaling pathways, increased secretion of pro-inflammatory cytokines and growth factors, and decreased epithelial barrier integrity. Given the prevalence of liquid application in the delivery of test substances to ALI systems, understanding its effects provides critical infrastructure for the use of in vitro systems in respiratory research as well as in the safety and efficacy testing of inhalable substances.
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Affiliation(s)
- Nicholas M. Mallek
- Curriculum in Toxicology and Environmental Medicine, University of North Carolina, Chapel Hill, NC, United States
| | - Elizabeth M. Martin
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, NC, United States
| | - Lisa A. Dailey
- Public Health and Integrated Toxicology Division, Center for Public Health and Environmental Assessment, United States Environmental Protection Agency, Chapel Hill, NC, United States
| | - Shaun D. McCullough
- Public Health and Integrated Toxicology Division, Center for Public Health and Environmental Assessment, United States Environmental Protection Agency, Chapel Hill, NC, United States
- Exposure and Protection, RTI International, Durham, NC, United States
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2
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Mallek NM, Martin EM, Dailey LA, McCullough SD. Liquid Application Dosing Alters the Physiology of Air-Liquid Interface Primary Bronchial Epithelial Cultures and In vitro Testing Relevant Endpoints. RESEARCH SQUARE 2023:rs.3.rs-2570280. [PMID: 36865279 PMCID: PMC9980280 DOI: 10.21203/rs.3.rs-2570280/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Differentiated Primary human bronchial epithelial cell (dpHBEC) cultures grown under air-liquid interface (ALI) conditions exhibit key features of the human respiratory tract and are thus critical for respiratory research as well as efficacy and toxicity testing of inhaled substances (e.g., consumer products, industrial chemicals, and pharmaceuticals). Many inhalable substances (e.g., particles, aerosols, hydrophobic substances, reactive substances) have physiochemical properties that challenge their evaluation under ALI conditions in vitro. Evaluation of the effects of these methodologically challenging chemicals (MCCs) in vitro is typically conducted by "liquid application," involving the direct application of a solution containing the test substance to the apical, air-exposed surface of dpHBEC-ALI cultures. We report that the application of liquid to the apical surface of a dpHBEC-ALI co-culture model results in significant reprogramming of the dpHBEC transcriptome and biological pathway activity, alternative regulation of cellular signaling pathways, increased secretion of pro-inflammatory cytokines and growth factors, and decreased epithelial barrier integrity. Given the prevalence of liquid application in the delivery of test substances to ALI systems, understanding its effects provides critical infrastructure for the use of in vitro systems in respiratory research as well as in the safety and efficacy testing of inhalable substances.
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Abstract
Ozone (O3), a criterion air pollutant produced as a product of internal combustion, generates increased inflammation, lung permeability, and airway hyperreactivity when exposed to rodents in laboratory settings. Airway hyperreactivity is defined as an exaggerated acute obstructive response of the airways to one or more nonspecific stimuli. Lung permeability is a measure of barrier functions that separate internal and external environments to limit access of pathogens and other noxious material. By modeling in vivo O3 exposure in rodents, this allows investigators to explore pulmonary and nonpulmonary O3 effects as a means of understanding its impact on human health and lung function. Furthermore, direct effects of O3 on epithelial permeability can be defined using in vitro exposures to airway epithelial cells. This chapter will focus on methods of generating O3 and then exposing rodents and cultured epithelial cells in laboratory settings.
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4
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Croft DP, Burton DS, Nagel DJ, Bhattacharya S, Falsey AR, Georas SN, Hopke PK, Johnston CJ, Kottmann RM, Litonjua AA, Mariani TJ, Rich DQ, Thevenet-Morrison K, Thurston SW, Utell MJ, McCall MN. The effect of air pollution on the transcriptomics of the immune response to respiratory infection. Sci Rep 2021; 11:19436. [PMID: 34593881 PMCID: PMC8484285 DOI: 10.1038/s41598-021-98729-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 09/13/2021] [Indexed: 12/24/2022] Open
Abstract
Combustion related particulate matter air pollution (PM) is associated with an increased risk of respiratory infections in adults. The exact mechanism underlying this association has not been determined. We hypothesized that increased concentrations of combustion related PM would result in dysregulation of the innate immune system. This epidemiological study includes 111 adult patients hospitalized with respiratory infections who underwent transcriptional analysis of their peripheral blood. We examined the association between gene expression at the time of hospitalization and ambient measurements of particulate air pollutants in the 28 days prior to hospitalization. For each pollutant and time lag, gene-specific linear models adjusting for infection type were fit using LIMMA (Linear Models For Microarray Data), and pathway/gene set analyses were performed using the CAMERA (Correlation Adjusted Mean Rank) program. Comparing patients with viral and/or bacterial infection, the expression patterns associated with air pollution exposure differed. Adjusting for the type of infection, increased concentrations of Delta-C (a marker of biomass smoke) and other PM were associated with upregulation of iron homeostasis and protein folding. Increased concentrations of black carbon (BC) were associated with upregulation of viral related gene pathways and downregulation of pathways related to antigen presentation. The pollutant/pathway associations differed by lag time and by type of infection. This study suggests that the effect of air pollution on the pathogenesis of respiratory infection may be pollutant, timing, and infection specific.
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Affiliation(s)
- Daniel P Croft
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA.
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA.
| | - David S Burton
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, NY, USA
| | - David J Nagel
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
| | - Soumyaroop Bhattacharya
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Ann R Falsey
- Department of Medicine, Infectious Diseases Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Steve N Georas
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
| | - Philip K Hopke
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA
- Institute for a Sustainable Environment, and Center for Air Resources Engineering and Science, Clarkson University, Potsdam, NY, USA
| | - Carl J Johnston
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - R Matthew Kottmann
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
| | - Augusto A Litonjua
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
| | - Thomas J Mariani
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA
| | - David Q Rich
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
- Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA
| | - Kelly Thevenet-Morrison
- Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA
| | - Sally W Thurston
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, NY, USA
| | - Mark J Utell
- Department of Medicine, Pulmonary and Critical Care Medicine Division, University of Rochester Medical Center, 601 Elmwood Avenue Box 692, Rochester, NY, 14642, USA
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
| | - Matthew N McCall
- Environmental Health Science Center, University of Rochester Medical Center, Rochester, NY, USA
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, NY, USA
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5
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Smyth T, Georas SN. Effects of ozone and particulate matter on airway epithelial barrier structure and function: a review of in vitro and in vivo studies. Inhal Toxicol 2021; 33:177-192. [PMID: 34346824 DOI: 10.1080/08958378.2021.1956021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The airway epithelium represents a crucial line of defense against the spread of inhaled pathogens. As the epithelium is the first part of the body to be exposed to the inhaled environment, it must act as both a barrier to and sentinel against any inhaled agents. Despite its vital role in limiting the spread of inhaled pathogens, the airway epithelium is also regularly exposed to air pollutants which disrupt its normal function. Here we review the current understanding of the structure and composition of the airway epithelial barrier, as well as the impact of inhaled pollutants, including the reactive gas ozone and particulate matter, on epithelial function. We discuss the current in vitro, rodent model, and human exposure findings surrounding the impact of various inhaled pollutants on epithelial barrier function, mucus production, and mucociliary clearance. Detailed information on how inhaled pollutants impact epithelial structure and function will further our understanding of the adverse health effects of air pollution exposure.
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Affiliation(s)
- Timothy Smyth
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Steve N Georas
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, USA.,Department of Medicine, University of Rochester Medical Center, Rochester, NY, USA
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Contreras LM, Gonzalez-Rivera JC, Baldridge KC, Wang DS, Chuvalo-Abraham J, Ruiz LH. Understanding the Functional Impact of VOC-Ozone Mixtures on the Chemistry of RNA in Epithelial Lung Cells. Res Rep Health Eff Inst 2020; 2020:Res Rep Health Eff Inst. 2020 Jul;(201):3-43.. [PMID: 32845096 PMCID: PMC7448316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023] Open
Abstract
Introduction Ambient air pollution is associated with premature death caused by heart disease, stroke, chronic obstructive pulmonary disease (COPD), and lung cancer. Recent studies have suggested that ribonucleic acid (RNA) oxidation is a sensitive environment-related biomarker that is implicated in pathogenesis. Aims and Methods We used a novel approach that integrated RNA-Seq analysis with detection by immunoprecipitation techniques of the prominent RNA oxidative modification 8-oxo-7,8-dihydroguanine (8-oxoG). Our goal was to uncover specific messenger RNA (mRNA) oxidation induced by mixtures of volatile organic compounds (VOCs) and ozone in healthy human epithelial lung cells. To this end, we exposed the BEAS-2B human epithelial lung cell line to the gas- and particle-phase products formed from reactions of 790 ppb acrolein (ACR) and 670 ppb methacrolein (MACR) with 4 ppm ozone. Results Using this approach, we identified 222 potential direct targets of oxidation belonging to previously described pathways, as well as uncharacterized pathways, after air pollution exposures. We demonstrated the effect of our VOC-ozone mixtures on the morphology and actin cytoskeleton of lung cells, suggesting the influence of selective mRNA oxidation in members of pathways regulating physical components of the cells. In addition, we observed the influence of the VOC-ozone mixtures on metabolic cholesterol synthesis, likely implicated as a result of the incidence of mRNA oxidation and the deregulation of protein levels of squalene synthase (farnesyl-diphosphate farnesyltransferase 1 [FDFT1]), a key enzyme in endogenous cholesterol biosynthesis. Conclusions Overall, our findings indicate that air pollution influences the accumulation of 8-oxoG in transcripts of epithelial lung cells that largely belong to stress-induced signaling and metabolic and structural pathways. A strength of the study was that it combined traditional transcriptome analysis with transcriptome-wide 8-oxoG mapping to facilitate the discovery of underlying processes not characterized by earlier approaches. Investigation of the processes mediated by air pollution oxidation of RNA molecules in primary cells and animal models needs to be explored in future studies. Our research has thus opened new avenues to further inform the relationship between atmospheric agents on the one hand and cellular responses on the other that are implicated in diseases.
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Affiliation(s)
- L M Contreras
- McKetta Department of Chemical Engineering, University of Texas, Austin
| | | | - K C Baldridge
- McKetta Department of Chemical Engineering, University of Texas, Austin
| | - D S Wang
- McKetta Department of Chemical Engineering, University of Texas, Austin
| | | | - L H Ruiz
- McKetta Department of Chemical Engineering, University of Texas, Austin
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7
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Crouse DL, Erickson AC, Christidis T, Pinault L, van Donkelaar A, Li C, Meng J, Martin RV, Tjepkema M, Hystad P, Burnett R, Pappin A, Brauer M, Weichenthal S. Evaluating the Sensitivity of PM2.5–Mortality Associations to the Spatial and Temporal Scale of Exposure Assessment. Epidemiology 2020; 31:168-176. [DOI: 10.1097/ede.0000000000001136] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Rezaee F, Georas SN. Breaking barriers. New insights into airway epithelial barrier function in health and disease. Am J Respir Cell Mol Biol 2014; 50:857-69. [PMID: 24467704 DOI: 10.1165/rcmb.2013-0541rt] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Epithelial permeability is a hallmark of mucosal inflammation, but the molecular mechanisms involved remain poorly understood. A key component of the epithelial barrier is the apical junctional complex that forms between neighboring cells. Apical junctional complexes are made of tight junctions and adherens junctions and link to the cellular cytoskeleton via numerous adaptor proteins. Although the existence of tight and adherens junctions between epithelial cells has long been recognized, in recent years there have been significant advances in our understanding of the molecular regulation of junctional complex assembly and disassembly. Here we review the current thinking about the structure and function of the apical junctional complex in airway epithelial cells, emphasizing the translational aspects of relevance to cystic fibrosis and asthma. Most work to date has been conducted using cell culture models, but technical advancements in imaging techniques suggest that we are on the verge of important new breakthroughs in this area in physiological models of airway diseases.
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Affiliation(s)
- Fariba Rezaee
- 1 Division of Pediatric Pulmonary Medicine, Department of Pediatrics, and
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9
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Epithelial barrier function: at the front line of asthma immunology and allergic airway inflammation. J Allergy Clin Immunol 2014; 134:509-20. [PMID: 25085341 DOI: 10.1016/j.jaci.2014.05.049] [Citation(s) in RCA: 325] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/30/2014] [Accepted: 05/30/2014] [Indexed: 02/08/2023]
Abstract
Airway epithelial cells form a barrier to the outside world and are at the front line of mucosal immunity. Epithelial apical junctional complexes are multiprotein subunits that promote cell-cell adhesion and barrier integrity. Recent studies in the skin and gastrointestinal tract suggest that disruption of cell-cell junctions is required to initiate epithelial immune responses, but how this applies to mucosal immunity in the lung is not clear. Increasing evidence indicates that defective epithelial barrier function is a feature of airway inflammation in asthmatic patients. One challenge in this area is that barrier function and junctional integrity are difficult to study in the intact lung, but innovative approaches should provide new knowledge in this area in the near future. In this article we review the structure and function of epithelial apical junctional complexes, emphasizing how regulation of the epithelial barrier affects innate and adaptive immunity. We discuss why defective epithelial barrier function might be linked to TH2 polarization in asthmatic patients and propose a rheostat model of barrier dysfunction that implicates the size of inhaled allergen particles as an important factor influencing adaptive immunity.
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10
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Chau E, Galloway JF, Nelson A, Breysse PN, Wirtz D, Searson PC, Sidhaye VK. Effect of modifying quantum dot surface charge on airway epithelial cell uptake in vitro. Nanotoxicology 2012; 7:1143-51. [PMID: 22783847 PMCID: PMC3737271 DOI: 10.3109/17435390.2012.711862] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The respiratory system is one of the portals of entry into the body, and hence inhalation of engineered nanomaterials is an important route of exposure. The broad range of physicochemical properties that influence biological responses necessitate the systematic study to contribute to understanding occupational exposure. Here, we report on the influence of nanoparticle charge and dose on human airway epithelial cells, and show that this platform can be used to evaluate consequences of exposure to engineered nanomaterials.
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Affiliation(s)
- Eric Chau
- Departments of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
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11
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Davidovich NET, Kloog Y, Wolf M, Elad D. Mechanophysical stimulations of mucin secretion in cultures of nasal epithelial cells. Biophys J 2011; 100:2855-64. [PMID: 21689518 DOI: 10.1016/j.bpj.2011.04.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 03/20/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022] Open
Abstract
Nasal epithelial cells secret mucins and are exposed in vivo to airflow-induced mechanophysical stresses, including wall shear stress (WSS), temperature, and humidity. In this work, human nasal epithelial cells cultured under air-liquid interface conditions were subjected to fields of airflow-induced oscillatory WSS at different temperature and humidity conditions. Changes in mucin secretion due to WSS were measured and the role of the cytoskeleton in mucin secretion was explored. Mucin secretion significantly increased in response to WSS in a magnitude-dependent manner with respect to static cultures and independently of the airflow temperature and humidity. In static cultures, mucin secretion decreased at high humidity with or without elevation of the temperature with respect to cultures at a comfortable climate. In cultures exposed to WSS, mucin secretion increased at high temperature with respect to cultures at comfortable climate conditions. The polymerization of actin microfilaments was shown to increase mucin secretion under WSS, whereas the dynamics of microtubule polymerization did not affect secretion. In conclusion, the data in this study show that mucin secretion is sensitive to oscillatory WSS as well as high temperature and humidity conditions.
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12
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Sidhaye VK, Chau E, Breysse PN, King LS. Septin-2 mediates airway epithelial barrier function in physiologic and pathologic conditions. Am J Respir Cell Mol Biol 2010; 45:120-6. [PMID: 20870893 DOI: 10.1165/rcmb.2010-0235oc] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Epithelial cells have the ability to regulate paracellular permeability dynamically in response to extracellular stimuli. With every respiratory effort, airway epithelial cells are exposed to both physiologic as well as pathologic stimuli, and regulation of the epithelial barrier in response to these stimuli is crucial to respiratory function. We report that increased membrane septin-2 localization mediates decreases in paracellular permeability by altering cortical actin arrangement in human airway epithelial cells. This phenomenon occurs in response to both physiologic levels of shear stress and a pathologic stimulus, particular matter exposure. The resulting changes in barrier function in response to septin-2 redistribution have a significant impact on the ability of the apical ligand, epidermal growth factor, to interact with its receptor, epidermal growth factor receptor, which is segregated to the basolateral side in airway epithelial cells. This suggests that the dynamic regulation of the epithelial barrier function is essential in regulating signaling responses to extracellular stimuli. These findings indicate that septin-2 plays a fundamental role in regulating barrier function by altering cortical actin expression.
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Affiliation(s)
- Venkataramana K Sidhaye
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins Asthma and Allergy Center 4B.64, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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Humlicek AL, Manzel LJ, Chin CL, Shi L, Excoffon KJDA, Winter MC, Shasby DM, Look DC. Paracellular permeability restricts airway epithelial responses to selectively allow activation by mediators at the basolateral surface. THE JOURNAL OF IMMUNOLOGY 2007; 178:6395-403. [PMID: 17475869 DOI: 10.4049/jimmunol.178.10.6395] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Respiratory pathogens and toxins often assault the lung from the airway lumen. Airway epithelia may initiate and amplify inflammation in response to these attacks, but under certain conditions confinement of inflammation to the airway lumen may be beneficial to the host. Accordingly, we hypothesized that airway epithelial polarity allows different responses to basolateral vs apical stimuli that may modulate inflammation. Using primary human airway epithelial cells differentiated at an air-liquid interface in culture, we found that responses to several cytokines required basolateral mediator application. In contrast, responses to Haemophilus influenzae occurred after either basolateral or apical interaction with airway epithelia. Experiments focused on IFN-gamma receptor polarity confirmed its predominant basolateral location in cultured airway epithelia as well as in normal human airway tissue. Furthermore, physical and pharmacologic disruption of barrier function in airway epithelia allowed responses to apical application of IFN-gamma and other cytokines. These in vitro studies directly correlated with experiments in mice in which an airway epithelial response to IFN-gamma injected into the airway lumen was seen only after disruption of barrier function. The results indicate that airway epithelia with intact barrier function restrict inflammatory responses by limitation of cell activation through requiring interaction of selected mediators with the basolateral surface. However, loss of barrier integrity allows epithelial responses to these mediators if located in the airway lumen to amplify airway defenses.
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Affiliation(s)
- Alicia L Humlicek
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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14
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Morrison D, Rahman I, MacNee W. Permeability, inflammation and oxidant status in airspace epithelium exposed to ozone. Respir Med 2006; 100:2227-34. [PMID: 17023150 DOI: 10.1016/j.rmed.2005.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 10/02/2005] [Accepted: 10/07/2005] [Indexed: 12/22/2022]
Abstract
The aim of the study was to investigate possible mechanisms of epithelial injury in normal subjects exposed to environmentally relevant concentrations of ozone. Fifteen healthy non-smoking subjects (M:F 12:3) were studied. Five of the 15 subjects were exposed to filtered air, six were exposed to ozone 100 parts per billion (ppb) and seven were exposed to ozone 400 ppb with 99mtechnetium labelled diethylene-triamine-penta-acetate (99mTc-DTPA) or bronchoalveolar lavage (BAL) performed 1 or 6 h after exposure as indicated above. All the above studies were performed on different occasions at least 5 days apart. The subjects were exposed on each occasion for 1h during intermittent exercise at a ventilation of 40l min-1. 99mTc-DTPA lung clearance did not change after either level of ozone exposure, but neutrophils increased in BAL 6 h after exposure to 400 ppb. Superoxide anion release from mixed BAL leucocytes decreased 1 h after 100 ppb and 6 h after 400 ppb. Products of lipid peroxidation in epithelial lining fluid decreased both 1 and 6 h after 400 ppb. There was no change in anti-oxidant capacity or glutathione concentrations. Ozone exposure did not increase epithelial permeability, but was associated with neutrophil influx into the airspaces, without evidence of increased oxidative stress.
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Affiliation(s)
- Douglas Morrison
- Respiratory Medicine Unit, Department of Medicine, University of Edinburgh, Medical School, Teviot Place, Edinburgh EH3 9YW, Scotland, UK
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15
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Lawrence DW, Comerford KM, Colgan SP. Role of VASP in reestablishment of epithelial tight junction assembly after Ca2+ switch. Am J Physiol Cell Physiol 2002; 282:C1235-45. [PMID: 11997237 DOI: 10.1152/ajpcell.00288.2001] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epithelial permeability is tightly regulated by intracellular messengers. Critical to maintaining barrier integrity is the formation of tight junction complexes. A number of signaling pathways have been implicated in tight junction biogenesis; however, the precise molecular mechanisms are not fully understood. A growing body of evidence suggests a role for intracellular cAMP in tight junction assembly. Using an epithelial model, we investigated the role of cAMP signal transduction in barrier recovery after Ca2+ switch. Our data demonstrate that elevation of intracellular cAMP levels significantly enhanced barrier recovery after Ca2+ switch. Parallel experiments revealed that epithelial barrier recovery is diminished by H-89, a specific and potent inhibitor of cAMP-dependent protein kinase (protein kinase A) activity. Of the possible PKA effector proteins, the vasodilator-stimulated phosphoprotein (VASP) is an attractive candidate, since it has been implicated in actin-binding and cross-linking functions. We therefore hypothesized that VASP may play a role in the cAMP-mediated regulation of epithelial junctional reassembly after Ca2+ switch. We demonstrate here that VASP is phosphorylated via a PKA-dependent process under conditions that enhance barrier recovery. Confocal laser scanning microscopy studies revealed that VASP localizes with ZO-1 at the tight junction and at cell-cell borders and that phospho-VASP appears at the junction after Ca2+ switch. Subsequent transfection studies utilizing epithelial cells expressing truncated forms of VASP abnormal in oligomerization or actin-binding activity revealed a functional diminution of barrier recovery after Ca2+ chelation. Our present studies suggest that VASP may provide a link between cAMP signal transduction and epithelial permeability.
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Affiliation(s)
- Donald W Lawrence
- Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts 02115, USA
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16
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Banan A, Smith GS, Kokoska ER, Miller TA. Role of actin cytoskeleton in prostaglandin-induced protection against ethanol in an intestinal epithelial cell line. J Surg Res 2000; 88:104-13. [PMID: 10644474 DOI: 10.1006/jsre.1999.5786] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Prostaglandins (PGs) protect a variety of gastrointestinal cells against injury induced by ethanol and other noxious agents. This investigation attempted to discern the mechanism of cytoprotection as it relates to the relationship between actin and PGs in IEC-6 cells (a rat intestinal epithelial cell line). IEC-6 cells were incubated in Dulbecco's modified Eagle's medium +/- 16,16-dimethyl prostaglandin E(2) (dmPG, 2.6 microM) for 15 min and subsequently incubated in medium containing 1, 2.5, 5, 7.5, and 10% ethanol (EtOH). Cells were then processed for immunocytochemistry using FITC-phalloidin in order to stain the actin cytoskeleton, and cell viability was determined by trypan blue exclusion. Quantitative Western immunoblotting of fractioned G-actin (nonpolymerized; S1) and F-actin (polymerized; S2) was also carried out. EtOH concentrations equal to and greater than 5% led to the collapse of the actin cytoskeleton as depicted by extensive disorganization and fragmentation. In addition, these same EtOH concentrations significantly decreased the S2 fraction and increased the S1 pool of actin. Preincubation with dmPG prevented collapse of the actin cytoskeleton, significantly increased the S2 polymerized fraction as determined by quantitative immunoblotting, and increased cell viability in EtOH-treated cultures. Prior incubation with cytochalasin D, an actin disruptive agent, not only reduced cell viability but also prevented the cytoprotective effects of dmPG. Phalloidin, an actin stabilizing agent, had effects similar to that of dmPG as demonstrated by stability of the actin cytoskeleton and increased cellular viability. Such findings indicate that PGs are important in the organization and stability of actin under in vitro conditions. These effects on actin may play an essential role in the mechanism of PG-induced cytoprotection.
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Affiliation(s)
- A Banan
- Theodore Cooper Surgical Research Institute, Saint Louis University Health Sciences Center, St. Louis, Missouri 63104, USA
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17
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Veronesi B, Carter JD, Devlin RB, Simon SA, Oortgiesen M. Neuropeptides and capsaicin stimulate the release of inflammatory cytokines in a human bronchial epithelial cell line. Neuropeptides 1999; 33:447-56. [PMID: 10657523 DOI: 10.1054/npep.1999.0761] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The role of neuropeptides in initiating and modulating airway inflammation was examined in a human bronchial epithelial cell line (i.e. BEAS-2B). At a range of concentrations, exposure of BEAS-2B cells to Substance P (SP) or calcitonin gene related protein resulted in immediate increases in intracellular calcium ([Ca(2+)](i)), the synthesis of the transcripts for the inflammatory cytokines, IL-6, IL-8 and TNFalpha after 2 h exposure, and the release of their proteins after 6 h exposure. Addition of thiorphan (100 nM), an inhibitor of neutral endopeptidase, enhanced the levels of SP-stimulated cytokine release. Stimulation of IL-6 by SP occurred in a conventional receptor-mediated manner as demonstrated by its differential release by fragments SP 4-11 and SP 1-4 and by the blockage of IL-6 release with the non-peptide, NK-1 receptor antagonist, CP-99 994. In addition to the direct stimulation of inflammatory cytokines, SP (0.5 microM), in combination with TNFalpha (25 units/ml), synergistically stimulated IL-6 release. BEAS-2B cells also responded to the botanical irritant, capsaicin (10 microM) with increases in [Ca(2+)](i) and IL-8 cytokine release after 4 h exposure. The IL-8 release was dependent on the presence of extracellular calcium. Capsaicin-stimulated increases of [Ca(2+)](i) and cytokine release could be reduced to control levels by pre-exposure to capsazepine, an antagonist of capsaicin (i.e. vanilloid) receptor(s) or by deletion of extracellular calcium from the exposure media. The present data indicate that the BEAS-2B human epithelial cell line expresses neuropeptide and capsaicin-sensitive pathways, whose activation results in immediate increases of [Ca(2+)](i) stimulation of inflammatory cytokine transcripts and the release of their cytokine proteins.
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Affiliation(s)
- B Veronesi
- National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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18
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Chang MM, Wu R, Plopper CG, Hyde DM. IL-8 is one of the major chemokines produced by monkey airway epithelium after ozone-induced injury. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:L524-32. [PMID: 9728047 DOI: 10.1152/ajplung.1998.275.3.l524] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A rhesus monkey interleukin (IL)-8 cDNA clone with >94% homology to the human IL-8 gene was isolated by differential hybridization from a cDNA library of distal airways after ozone inhalation. In situ hybridization and immunohistochemistry showed increased IL-8 mRNA and protein levels in epithelial cells at 1 h but not at 24 h after inhalation of ozone. The appearance of IL-8 in airway epithelial cells correlated well with neutrophil influx into airway epithelia and lumens. Air-liquid interface cultures of tracheobronchial epithelial cells were exposed to ozone in vitro. We observed a transient increase in IL-8 secretion in culture medium immediately after ozone exposure and a dose-dependent increase in IL-8 secretion and mRNA production. In vitro neutrophil chemotaxis showed a parallel dose and time profile to epithelial cell secretion of IL-8. Treatment with anti-IL-8 neutralizing antibody blocked >80% of the neutrophil chemotaxis in vitro. These results suggest that IL-8 is a key chemokine in acute ozone-induced airway inflammation in primates.
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Affiliation(s)
- M M Chang
- Center for Comparative Respiratory Biology and Medicine, University of California, Davis, California 95616, USA
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19
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Kafoury RM, Pryor WA, Squadrito GL, Salgo MG, Zou X, Friedman M. Lipid ozonation products activate phospholipases A2, C, and D. Toxicol Appl Pharmacol 1998; 150:338-49. [PMID: 9653065 DOI: 10.1006/taap.1998.8418] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ozone exposure, in vitro, has been shown to activate phospholipases A2 (PLA2), C (PLC), and D (PLD) in airway epithelial cells. However, because of its high reactivity, ozone cannot penetrate far into the air/lung tissue interface. It has been proposed that ozone reacts with unsaturated fatty acids (UFA) in the epithelial lining fluid (ELF) and cell membranes to generate a cascade of lipid ozonation products (LOP) that mediate ozone-induced toxicity. To test this hypothesis, we exposed cultured human bronchial epithelial cells (BEAS-2B) to LOP (1-100 microM) produced from the ozonation of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) and measured the activity of PLA2, PLC, and PLD. The PLA2 isoform responsible for arachidonic acid release (AA) in stimulated cultures was also characterized. Activation of PLA2, PLC, and PLD by three oxidants, hydrogen peroxide (H2O2), tert-butyl hydroperoxide (t-BOOH) and 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) also was measured and compared to that of LOP. The derivatives of ozonized POPC at the sn-2 residue, 9-oxononanoyl (PC-ALD), 9-hydroxy-9-hydroperoxynonanoyl (PC-HHP), and 8-(-5-octyl-1,2,4-trioxolan-3-yl-) octanoyl (POPC-OZ) selectively activated PLA2 in a dose-dependent fashion. Cytosolic PLA2 (cPLA2) measured in the cytosolic fraction of stimulated cell lysates was found to be the predominant isoform responsible for AA release. PLC activation was exclusively induced by the hydroxyhydroperoxide derivatives. PC-HHP and the 9-carbon hydroxyhydroperoxide (HHP-C9) increased PLC activity. PLD activity also was induced by LOP generated from POPC. Incubation of cultures with H2O2 alone did not stimulate PLC; however, in the presence of the aldehyde, nonanal, a 62 +/- 2% increase in PLC activity was found, suggesting that the increase in activity was due to the formation of the intermediate HHP-C9. t-BOOH, and AAPH also failed to induce PLA2 activation, but did activate PLC, under conditions of exposure identical to that of LOP. Only t-BOOH activated PLD. These results suggest that biologically relevant concentrations of LOP activate PLA2, PLC, and PLD in the airway epithelial cell, a primary target to ozone exposure. The activation of these phospholipases may play a role in the development of lung inflammation during ozone exposure.
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Affiliation(s)
- R M Kafoury
- Department of Environmental Health Sciences, Tulane University Medical Center, New Orleans, Louisiana 70112, USA
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Potter-Perigo S, Kaplan ED, Luchtel DL, Baker C, Altman LC, Wight TN. Ozone alters the expression of tenascin-C in cultured primate nasal epithelial cells. Am J Respir Cell Mol Biol 1998; 18:471-8. [PMID: 9533934 DOI: 10.1165/ajrcmb.18.4.2966] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Tenascin-C is an extracellular matrix component which is transiently expressed in association with epithelial cell detachment, proliferation, and migration. This molecule has been identified in respiratory tissue, but little is known about the cellular source of tenascin-C or the factors that regulate its production. Since air pollutants are known to disrupt epithelial integrity, we investigated the regulation of tenascin-C in response to 0.3 ppm ozone in differentiated primate nasal epithelial cells in culture at an air-medium interface. The expression of tenascin-C was upregulated in response to ozone, as determined by Northern blot analysis, Western blotting, and immunofluorescent staining. In contrast, there was no change in the mRNA levels for versican, biglycan, perlecan, or collagen type I. Reduced cellular attachment to the substrate was evident in ozone-treated cultures in association with tenascin-C deposition at the interfaces between cells and basal surfaces. The presence of tenascin-C on denuded areas of the matrix suggests that tenascin-C may have been instrumental in the loss of patches of cells. The modulation of tenascin-C synthesis and distribution may play a significant role in the response of respiratory epithelial cells to ozone exposure.
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Affiliation(s)
- S Potter-Perigo
- Department of Pathology, University of Washington, Seattle, Washington 98195-7470, USA
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Matsui H, Johnson LG, Randell SH, Boucher RC. Loss of binding and entry of liposome-DNA complexes decreases transfection efficiency in differentiated airway epithelial cells. J Biol Chem 1997; 272:1117-26. [PMID: 8995411 DOI: 10.1074/jbc.272.2.1117] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The target cells for gene therapy of cystic fibrosis lung disease are the well differentiated cells that line airway lumens. Employing cultures of airway epithelial cells that grow like "islands" and exhibit a continuum of cellular differentiation, we studied the mechanisms that render well differentiated cells more difficult to transfect with cationic liposomes than poorly differentiated cells. The poorly differentiated cells at the edge of the islands were transfectable with liposome-DNA complexes (pCMVbeta:LipofectACE = 1:5 (w/w)), whereas the more differentiated cells in the center of the islands were not. Evaluation of the steps leading to lipid-mediated transfection revealed that edge cells bound more liposome-DNA complexes, in part due to a more negative surface charge (as measured by cationized ferritin binding), and that edge cells internalized more liposome-DNA complexes than central cells. Edge cells exhibited receptor-mediated endocytosis of LDL, pinocytosis of 10-nm microspheres, and phagocytosis of 2-microm microspheres, whereas central cells were only capable of receptor-mediated endocytosis. Cytochalasin B, which inhibited pinocytosis by 65% and phagocytosis by 93%, decreased edge cell liposome-DNA complex entry by 50%. Potassium depletion, which decreased phagocytosis by >90% but had no effect on pinocytosis, inhibited edge cell liposome-DNA complex entry by 71%. These results indicate that liposome-DNA complexes enter edge cells via phagocytosis and that this pathway is not detectable in central cells. In conclusion, both reduced negative surface charge and absence of phagocytosis internalization pathways in relatively differentiated cells may explain differentiation-dependent decrements in cationic liposome-mediated gene transfer in airway epithelia.
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Affiliation(s)
- H Matsui
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill 27599-7248, USA.
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