scholarly journals Comparative Analysis of Six IRF Family Members in Alveolar Epithelial Cell-Intrinsic Antiviral Responses

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2600
Author(s):  
Sandra Wüst ◽  
Paulina Schad ◽  
Sandy Burkart ◽  
Marco Binder
Keyword(s):  
Alveolar Epithelial Cell ◽  
A549 Cells ◽  
Experimental System ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Antiviral State ◽  
Alveolar Epithelial ◽  
Antiviral Responses ◽  
Relative Contribution ◽  
The Impact

Host cell-intrinsic antiviral responses are largely mediated by pattern-recognition receptor (PRR) signaling and the interferon (IFN) system. The IFN regulatory factor (IRF) family of transcription factors takes up a central role in transcriptional regulation of antiviral innate immunity. IRF3 and IRF7 are known to be key players downstream of PRRs mediating the induction of type I and III IFNs. IFN signaling then requires IRF9 for the expression of the full array of interferon stimulated genes (ISGs) ultimately defining the antiviral state of the cell. Other members of the IRF family clearly play a role in mediating or modulating IFN responses, such as IRF1, IRF2 or IRF5, however their relative contribution to mounting a functional antiviral response is much less understood. In this study, we systematically and comparatively assessed the impact of six members of the IRF family on antiviral signaling in alveolar epithelial cells. We generated functional knockouts of IRF1, -2, -3, -5, -7, and -9 in A549 cells, and measured their impact on the expression of IFNs and further cytokines, ISGs and other IRFs, as well as on viral replication. Our results confirmed the vital importance of IRF3 and IRF9 in establishing an antiviral state, whereas IRF1, 5 and 7 were largely dispensable. The previously described inhibitory activity of IRF2 could not be observed in our experimental system.

scholarly journals Characteristics of Passive Solute Transport across Primary Rat Alveolar Epithelial Cell Monolayers

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 331
Author(s):  
Yong Ho Kim ◽  
Kwang-Jin Kim ◽  
David Z. D’Argenio ◽  
Edward D. Crandall
Keyword(s):  
Epithelial Cell ◽  
Tight Junctions ◽  
Pore Radius ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Cell Monolayers ◽  
Alveolar Epithelial ◽  
Epithelial Cell Monolayers ◽  
Hydrophilic Solutes

Primary rat alveolar epithelial cell monolayers (RAECM) were grown without (type I cell-like phenotype, RAECM-I) or with (type II cell-like phenotype, RAECM-II) keratinocyte growth factor to assess passive transport of 11 hydrophilic solutes. We estimated apparent permeability (Papp) in the absence/presence of calcium chelator EGTA to determine the effects of perturbing tight junctions on “equivalent” pores. Papp across RAECM-I and -II in the absence of EGTA are similar and decrease as solute size increases. We modeled Papp of the hydrophilic solutes across RAECM-I/-II as taking place via heterogeneous populations of equivalent pores comprised of small (0.41/0.32 nm radius) and large (9.88/11.56 nm radius) pores, respectively. Total equivalent pore area is dominated by small equivalent pores (99.92–99.97%). The number of small and large equivalent pores in RAECM-I was 8.55 and 1.29 times greater, respectively, than those in RAECM-II. With EGTA, the large pore radius in RAECM-I/-II increased by 1.58/4.34 times and the small equivalent pore radius increased by 1.84/1.90 times, respectively. These results indicate that passive diffusion of hydrophilic solutes across an alveolar epithelium occurs via small and large equivalent pores, reflecting interactions of transmembrane proteins expressed in intercellular tight junctions of alveolar epithelial cells.

scholarly journals Transport of AOPP-Albumin into Human Alveolar Epithelial A549 Cell

2018 ◽  
Vol 21 ◽  
pp. 247-255 ◽  
Author(s):  
Masashi Kawami ◽  
Tadashi Shimonakamura ◽  
Ryoko Yumoto ◽  
Mikihisa Takano
Keyword(s):  
Alveolar Epithelial Cell ◽  
A549 Cells ◽  
Alveolar Epithelial Cells ◽  
Epithelial Cell Line ◽  
Ros Generation ◽  
Alveolar Epithelial ◽  
Lung Injuries ◽  
Km Value ◽  
Human Alveolar Epithelial Cell ◽  
Fluorescence Spectrometer

Purpose. Alveolar clearance of proteins, such as albumin, plays an essential role in recovery from lung injuries. Albumin is known to be oxidized by reactive oxygen species (ROS), leading to generation of advanced oxidation protein products (AOPP)-albumin in the alveolar lining fluid. In this study, we aimed to characterize the uptake of FITC-labeled AOPP-albumin (FITC-AOPP-albumin) into human alveolar epithelial cell line, A549. Methods. FITC-AOPP-albumin uptake into A549 cells and its effect of ROS generation was evaluated using fluorescence spectrometer and flow cytometry, respectively. Results. FITC-AOPP-albumin was taken up by A549 cells in a time- and temperature-dependent fashion, and showed saturation kinetics with a Km value of 0.37 mg/mL. The uptake of FITC-AOPP-albumin was suppressed by phenylarsine oxide, a clathrin-mediated endocytosis inhibitor, but not by indomethacin and nystatin, caveolae-mediated endocytosis inhibitors, or 5-(N-ethyl-N-isopropyl) amiloride, a macropinocytosis inhibitor. AOPP-albumin induced ROS generation in A549 cells, suggesting that alveolar clearance of AOPP-albumin should be important to prevent further ROS generation. Conclusion. AOPP-albumin is transported into alveolar epithelial cells through clathrin-mediated endocytosis, which may be important to prevent further ROS generation. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Injury of rat pulmonary alveolar epithelial cells by H2O2: dependence on phenotype and catalase

1991 ◽  
Vol 260 (4) ◽  
pp. L318-L325 ◽  
Author(s):  
R. H. Simon ◽  
J. A. Edwards ◽  
M. M. Reza ◽  
R. G. Kunkel
Keyword(s):  
Epithelial Cells ◽  
Catalase Activity ◽  
Lung Diseases ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Epithelial

In a variety of inflammatory lung diseases, type I alveolar epithelial cells are more likely to be injured than are type II cells. Because oxidants have been implicated as a cause of injury in various inflammatory lung diseases, we evaluated the effects of differentiation on alveolar epithelial cell susceptibility to H2O2-induced injury. With the use of isolated rat type II cells in culture, we found that the cytotoxic effect of H2O2 increased between days 2 and 7, when type II cells are known to lose their distinctive type II properties and assume a more type I-like appearance. We previously reported that type II cells utilized both intracellular catalase and glutathione-dependent reactions to protect against H2O2. We therefore examined whether alterations in either of these protective mechanisms were responsible for the differentiation-dependent changes in sensitivity to H2O2. We found that catalase activity within alveolar epithelial cells decreased between 2 and 7 days in culture, whereas no changes were detected in glutathione-dependent systems. We then used a histochemical technique that detects catalase activity and found that type II cells within rat lungs possessed numerous catalase-containing peroxisomes, whereas very few were detected in type I cells. These findings demonstrate that as type II cells assume a type I-like phenotype, they become more susceptible to H2O2-induced injury. This increased susceptibility is associated with reductions in intracellular catalase activity, both in vitro and in vivo.

scholarly journals β-Peltoboykinolic Acid from Astilbe rubra Attenuates TGF-β1-Induced Epithelial-to-Mesenchymal Transitions in Lung Alveolar Epithelial Cells

Molecules ◽  
2019 ◽  
Vol 24 (14) ◽  
pp. 2573 ◽  
Author(s):  
In Jae Bang ◽  
Ha Ryong Kim ◽  
Yukyoung Jeon ◽  
Mi Ho Jeong ◽  
Yong Joo Park ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Type I Collagen ◽  
A549 Cells ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Inhibitory Effects ◽  
Mesenchymal Transition ◽  
Alveolar Epithelial ◽  
Extracellular Matrix Components ◽  
Tgf Β1

Epithelial-to-mesenchymal transition (EMT) is increasingly recognized as contributing to the pathogenesis of idiopathic pulmonary fibrosis. Therefore, novel plant-based natural, active compounds have been sought for the treatment of fibrotic EMT. The aim of the present study was to investigate the inhibitory effects of Astilbe rubra on TGF-β1-induced EMT in lung alveolar epithelial cells (A549). A. rubra was subjected to extraction using 70% ethanol (ARE), and ethanol extracts of the aerial part and that of the rhizome were further partitioned using various solvents. Protein expression and cell motility were investigated to evaluate the inhibitory effects of ARE on EMT. EMT occurred in A549 cells treated with TGF-β1, but was prevented by co-treatment with ARE. The dichloromethane fractions showed the strongest inhibitory effect on TGF-β1-induced EMT. β-Peltoboykinolic acid was isolated from the dichloromethane fractions of A. rubra by activity-oriented isolation. β-Peltoboykinolic acid not only attenuated TGF-β1-induced EMT, but also the overproduction of extracellular matrix components including type I collagen and fibronectin. The Smad pathway activated by TGF-β1 was inhibited by co-treatment with β-peltoboykinolic acid. Taken together, these results indicate that β-peltoboykinolic acid from A. rubra and dichloromethane fractions shows potential as an antifibrotic agent in A549 cells treated with TGF-β1.

Effects of transdifferentiation and EGF on claudin isoform expression in alveolar epithelial cells

2005 ◽  
Vol 98 (1) ◽  
pp. 322-328 ◽  
Author(s):  
Stephen P. Chen ◽  
Beiyun Zhou ◽  
Brigham C. Willis ◽  
Argelia J. Sandoval ◽  
Janice M. Liebler ◽  
...  
Keyword(s):  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Transepithelial Resistance ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Phenotypic Properties ◽  
Alveolar Epithelial ◽  
I Cells ◽  
Over Time

Rat alveolar epithelial type II cells grown on polycarbonate filters form high-resistance monolayers and concurrently acquire many phenotypic properties of type I cells. Treatment with EGF has previously been shown to increase transepithelial resistance across alveolar epithelial cell (AEC) monolayers. We investigated changes in claudin expression in primary cultured AEC during transdifferentiation to the type I cell-like phenotype ( days 0, 1, and 8), and on day 5 in culture ± EGF (10 ng/ml) from day 0 or day 4. Claudins 4 and 7 were increased, whereas claudins 3 and 5 were decreased, on later compared with earlier days in culture. Exposure to EGF led to increases in claudins 4 and 7 and decreases in claudins 3 and 5. Claudin 1 was only faintly detectable in freshly isolated type II cells and remained unchanged over time in culture and after exposure to EGF. These results suggest that increases in transepithelial resistance accompanying AEC transdifferentiation and/or EGF exposure are mediated, at least in part, by changes in the pattern of expression of specific claudin isoforms.

Modulation of α-ENaC and α1-Na+-K+-ATPase by cAMP and dexamethasone in alveolar epithelial cells

2001 ◽  
Vol 281 (1) ◽  
pp. L217-L230 ◽  
Author(s):  
André Dagenais ◽  
Christine Denis ◽  
Marie-France Vives ◽  
Sonia Girouard ◽  
Chantal Massé ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Mrna Expression ◽  
Time Course ◽  
A549 Cells ◽  
State Level ◽  
Fold Increase ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Atpase Gene ◽  
The Impact

cAMP and dexamethasone are known to modulate Na+ transport in epithelial cells. We investigated whether dibutyryl cAMP (DBcAMP) and dexamethasone modulate the mRNA expression of two key elements of the Na+ transport system in isolated rat alveolar epithelial cells: α-, β-, and γ-subunits of the epithelial Na+channel (ENaC) and the α1- and β1-subunits of Na+-K+-ATPase. The cells were treated for up to 48 h with DBcAMP or dexamethasone to assess their long-term impact on the steady-state level of ENaC and Na+-K+-ATPase mRNA. DBcAMP induced a twofold transient increase of α-ENaC and α1-Na+-K+-ATPase mRNA that peaked after 8 h of treatment. It also upregulated β- and γ-ENaC mRNA but not β1-Na+-K+-ATPase mRNA. Dexamethasone augmented α-ENaC mRNA expression 4.4-fold in cells treated for 24 h and also upregulated β- and γ-ENaC mRNA. There was a 1.6-fold increase at 8 h of β1-Na+-K+-ATPase mRNA but no significant modulation of α1-Na+-K+-ATPase mRNA expression. Because DBcAMP and dexamethasone did not increase the stability of α-ENaC mRNA, we cloned 3.2 kb of the 5′ sequences flanking the mouse α-ENaC gene to study the impact of DBcAMP and dexamethasone on α-ENaC promoter activity. The promoter was able to drive basal expression of the chloramphenicol acetyltransferase (CAT) reporter gene in A549 cells. Dexamethasone increased the activity of the promoter by a factor of 5.9. To complete the study, the physiological effects of DBcAMP and dexamethasone were investigated by measuring transepithelial current in treated and control cells. DBcAMP and dexamethasone modulated transepithelial current with a time course reminiscent of the profile observed for α-ENaC mRNA expression. DBcAMP had a greater impact on transepithelial current (2.5-fold increase at 8 h) than dexamethasone (1.8-fold increase at 24 h). These results suggest that modulation of α-ENaC and Na+-K+-ATPase gene expression is one of the mechanisms that regulates Na+ transport in alveolar epithelial cells.

Association of ICAM-1 with the cytoskeleton in rat alveolar epithelial cells in primary culture

1996 ◽  
Vol 271 (5) ◽  
pp. L707-L718 ◽  
Author(s):  
W. W. Barton ◽  
S. E. Wilcoxen ◽  
P. J. Christensen ◽  
R. Paine
Keyword(s):  
Endothelial Cells ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Alveolar Epithelial Cell ◽  
Inflammatory Cells ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Epithelial

Intercellular adhesion molecule-1 ICAM-1) is a transmembrane adhesion protein that is expressed constitutively on the apical surface of type I cells in vivo and on type II cells in vitro as they spread in culture, assuming type I cell-like characteristics. To investigate the possible interaction of ICAM-1 with the alveolar epithelial cell cytoskeleton, rat type II cells in primary culture were extracted with nonionic detergent, and residual ICAM-1 associated with the cytoskeletal remnants was determined using immunofluorescence microscopy, immunoprecipitation, and cell-based enzyme-linked immunosorbent assay. A large fraction of alveolar epithelial cell ICAM-1 remained associated with the cytoskeleton after detergent extraction, whereas two other transmembrane molecules, transferrin receptor and class II major histocompatibility complex, were completely removed. ICAM-1 was redistributed on the cell surface after the disruption of actin filaments with cytochalasin B, suggesting interaction with the actin cytoskeleton. In contrast, ICAM-1 was completely detergent soluble in rat pulmonary artery endothelial cells, human umbilical vein endothelial cells, and rat alveolar macrophages. The association of ICAM-1 with the alveolar epithelial cell cytoskeleton was not altered after stimulation with inflammatory cytokines. However, detergent resistant ICAM-1 was significantly increased after crosslinking of ICAM-1 on the cell surface, suggesting that this cytoskeletal association may be modulated by interactions of alveolar epithelial cells with inflammatory cells. The association of ICAM-1 with the cytoskeleton in alveolar epithelial cells may provide a fixed intermediary between mobile inflammatory cells and the alveolar surface.

scholarly journals Alveolar Epithelial Inter-alpha-trypsin Inhibitor Heavy Chain 4 Deficiency Associated With Senescence-regulated Apoptosis by Particulate Air Pollution

2020 ◽  
Author(s):  
Xiao-Yue Chen ◽  
Po-Hao Feng ◽  
Yi-Ying Chen ◽  
Chih-Da Wu ◽  
Sheng-Ming Wu ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Trypsin Inhibitor ◽  
Alveolar Epithelial Cell ◽  
A549 Cells ◽  
Diesel Exhaust Particles ◽  
Alveolar Epithelial Cells ◽  
Sirtuin 1 ◽  
Dependent Manner ◽  
Alveolar Epithelial

Abstract Background: Inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4) is considered a type II acute-phase protein; however, the role of ITIH4 in the lungs after exposure to fine particulate matter (PM2.5) remains unclear. The objective of this study was to investigate the role of ITIH4 in the lungs in response to PM2.5 exposure.Results: ITIH4 expression in bronchoalveolar lavage fluid (BAL) of 47 healthy subjects and of SD rats exposed to PM2.5 was determined, and the underlying anti-apoptotic and matrix-stabilizing pathways in A549 cells by diesel exhaust particles (DEPs) were also investigated. First, we observed that an interquartile range (IQR) increase in PM2.5 accounted for a decrease of 2.673 ng/mL in ITIH4, an increase of 1.104 pg/mL in 8-isoprostane, and an increase of 6.918 pg/mL in interleukin (IL)-6 in human BAL. Increases in 8-isoprostane and IL-6 in the lungs and decreases in ITIH4 in the BAL, lungs, and serum were observed after PM2.5 exposure. ITIH4 was correlated with lung lysates and BAL samples (r=0.377, p<0.01), whereas ITIH4 was correlated with IL-6 in BAL (r=-0.420, p<0.01). ITIH4 expression was significantly reduced in alveolar epithelial cells by PM2.5. ITIH4 expression decreased after DEP exposure in a dose-dependent manner. A decrease in sirtuin 1 (Sirt1) and increases in phosphorylated extracellular signal-regulated kinase (p-ERK) and caspase-3 were observed after DEP exposure. Conclusions: In conclusion, PM2.5 decreased ITIH4 in the lungs, which was associated with alveolar epithelial cell senescence and apoptosis. ITIH4 could be a vital protein in regulating alveolar destruction, and its deficiency occurs due to PM2.5.

Nuclear localization of leukotriene A4 hydrolase in type II alveolar epithelial cells in normal and fibrotic lung

2005 ◽  
Vol 289 (2) ◽  
pp. L224-L232 ◽  
Author(s):  
Thomas G. Brock ◽  
Young-Jik Lee ◽  
Elana Maydanski ◽  
Tessa L. Marburger ◽  
Ming Luo ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Nuclear Localization ◽  
A549 Cells ◽  
Alveolar Epithelial Cells ◽  
Nuclear Accumulation ◽  
Aminopeptidase Activity ◽  
Type I ◽  
Type Ii ◽  
Alveolar Epithelial ◽  
Leukotriene A4

Leukotriene A4 (LTA4) hydrolase catalyzes the final step in leukotriene B4 (LTB4) synthesis. In addition to its role in LTB4 synthesis, the enzyme possesses aminopeptidase activity. In this study, we sought to define the subcellular distribution of LTA4 hydrolase in alveolar epithelial cells, which lack 5-lipoxygenase and do not synthesize LTA4. Immunohistochemical staining localized LTA4 hydrolase in the nucleus of type II but not type I alveolar epithelial cells of normal mouse, human, and rat lungs. Nuclear localization of LTA4 hydrolase was also demonstrated in proliferating type II-like A549 cells. The apparent redistribution of LTA4 hydrolase from the nucleus to the cytoplasm during type II-to-type I cell differentiation in vivo was recapitulated in vitro. Surprisingly, this change in localization of LTA4 hydrolase did not affect the capacity of isolated cells to convert LTA4 to LTB4. However, proliferation of A549 cells was inhibited by the aminopeptidase inhibitor bestatin. Nuclear accumulation of LTA4 hydrolase was also conspicuous in epithelial cells during alveolar repair following bleomycin-induced acute lung injury in mice, as well as in hyperplastic type II cells associated with fibrotic lung tissues from patients with idiopathic pulmonary fibrosis. These results show for the first time that LTA4 hydrolase can be accumulated in the nucleus of type II alveolar epithelial cells and that redistribution of the enzyme to the cytoplasm occurs with differentiation to the type I phenotype. Furthermore, the aminopeptidase activity of LTA4 hydrolase within the nucleus may play a role in promoting epithelial cell growth.

Effect of alveolar epithelial cell plasticity on the regulation of GM-CSF expression

2012 ◽  
Vol 302 (6) ◽  
pp. L504-L511 ◽  
Author(s):  
Mustafa Mir-Kasimov ◽  
Anne Sturrock ◽  
Michael McManus ◽  
Robert Paine
Keyword(s):  
Lung Injury ◽  
Alveolar Epithelial Cell ◽  
Collagen Matrix ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Phenotypic Characteristics ◽  
Regulation Of Expression ◽  
Alveolar Epithelial ◽  
Gm Csf ◽  
Tnf Α

Local pulmonary expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) is critically important for defense of the pulmonary alveolar space. It is required for surfactant homeostasis and pulmonary innate immune responses and is protective against lung injury and aberrant repair. Alveolar epithelial cells (AEC) are a major source of GM-CSF; however, the control of homeostatic expression of GM-CSF is incompletely characterized. Increasing evidence suggests considerable plasticity of expression of AEC phenotypic characteristics. We tested the hypothesis that this plasticity extends to regulation of expression of GM-CSF using 1) MLE-12 cells (a commonly used murine cell line expressing some features of normal type II AEC, 2) primary murine AEC incubated under standard conditions [resulting in rapid spreading and loss of surfactant protein C (SP-C) expression with induction of the putative type I cell marker (T1α)], or 3) primary murine AEC on a hyaluronic acid/collagen matrix in defined medium, resulting in preservation of SP-C expression. AEC in standard cultures constitutively express abundant GM-CSF, with further induction in response to IL-1β but little response to TNF-α. In contrast, primary cells cultured to preserve SP-C expression and MLE-12 cells both express little GM-CSF constitutively, with significant induction in response to TNF-α and limited response to IL-1β. We conclude that constitutive and cytokine-induced expression of GM-CSF by AEC varies in concert with other cellular phenotypic characteristics. These changes may have important implications both for the maintenance of normal pulmonary homeostasis and for the process of repair following lung injury.

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