TRIM72 is required for effective repair of alveolar epithelial cell wounding

The molecular mechanisms for lung cell repair are largely unknown. Previous studies identified tripartite motif protein 72 (TRIM72) from striated muscle and linked its function to tissue repair. In this study, we characterized TRIM72 expression in lung tissues and investigated the role of TRIM72 in repair of alveolar epithelial cells. In vivo injury of lung cells was introduced by high tidal volume ventilation, and repair-defective cells were labeled with postinjury administration of propidium iodide. Primary alveolar epithelial cells were isolated and membrane wounding and repair were labeled separately. Our results show that absence of TRIM72 increases susceptibility to deformation-induced lung injury whereas TRIM72 overexpression is protective. In vitro cell wounding assay revealed that TRIM72 protects alveolar epithelial cells through promoting repair rather than increasing resistance to injury. The repair function of TRIM72 in lung cells is further linked to caveolin 1. These data suggest an essential role for TRIM72 in repair of alveolar epithelial cells under plasma membrane stress failure.

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Cross-talk between LAM cells and fibroblasts may influence alveolar epithelial cell behavior in Lymphangioleiomyomatosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00351.2021 ◽

2021 ◽

Author(s):

Debbie Clements ◽

Suzanne Miller ◽

Roya Babaei-Jadidi ◽

Mike Adam ◽

S. Steven Potter ◽

...

Keyword(s):

Epithelial Cells ◽

Cross Talk ◽

Ex Vivo ◽

Alveolar Epithelial Cell ◽

Alveolar Epithelial Cells ◽

Dependent Manner ◽

Epithelial Migration ◽

Alveolar Epithelial

Lymphangioleiomyomatosis (LAM) is a female specific cystic lung disease in which TSC2 deficient LAM cells, LAM-Associated Fibroblasts (LAFs) and other cell types infiltrate the lungs. LAM lesions can be associated with type II alveolar epithelial cells (AT2 cells). We hypothesised that the behaviour of AT2 cells in LAM is influenced locally by LAFs. We tested this hypothesis in patient samples and in vitro. In human LAM lung, nodular AT2 cells show enhanced proliferation when compared to parenchymal AT2 cells, demonstrated by increased Ki67 expression. Further, nodular AT2 cells express proteins associated with epithelial activation in other disease states including Matrix Metalloproteinase 7, and Fibroblast Growth Factor 7 (FGF7). In vitro, LAF conditioned medium is mitogenic and positively chemotactic for epithelial cells, increases the rate of epithelial repair and protects against apoptosis. In vitro, LAM patient-derived TSC2 null cells cocultured with LAFs upregulate LAF expression of the epithelial chemokine and mitogen FGF7, which is a potential mediator of fibroblast-epithelial crosstalk, in an mTOR dependent manner. In a novel in vitro model of LAM, ex vivo cultured LAM lung-derived microtissues promote both epithelial migration and adhesion. Our findings suggest that AT2 cells in LAM display a proliferative, activated phenotype and that fibroblast accumulation following LAM cell infiltration into the parenchyma contributes to this change in AT2 cell behaviour. Fibroblast-derived FGF7 may contribute to the cross-talk between LAFs and hyperplastic epithelium in vivo, but does not appear to be the main driver of the effects of LAFs on epithelial cells in vitro.

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C3 Promotes Clearance of Klebsiella pneumoniae by A549 Epithelial Cells

Infection and Immunity ◽

10.1128/iai.72.3.1767-1774.2004 ◽

2004 ◽

Vol 72 (3) ◽

pp. 1767-1774 ◽

Cited By ~ 26

Author(s):

Beatriz de Astorza ◽

Guadalupe Cortés ◽

Catalina Crespí ◽

Carles Saus ◽

José María Rojo ◽

...

Keyword(s):

Epithelial Cells ◽

Klebsiella Pneumoniae ◽

Alveolar Epithelial Cells ◽

Clinical Isolates ◽

Complement Components ◽

Innate Defense ◽

Alveolar Epithelial

ABSTRACT The airway epithelium represents a primary site for contact between microbes and their hosts. To assess the role of complement in this event, we studied the interaction between the A549 cell line derived from human alveolar epithelial cells and a major nosocomial pathogen, Klebsiella pneumoniae, in the presence of serum. In vitro, we found that C3 opsonization of poorly encapsulated K. pneumoniae clinical isolates and an unencapsulated mutant enhanced dramatically bacterial internalization by A549 epithelial cells compared to highly encapsulated clinical isolates. Local complement components (either present in the human bronchoalveolar lavage or produced by A549 epithelial cells) were sufficient to opsonize K. pneumoniae. CD46 could competitively inhibit the internalization of K. pneumoniae by the epithelial cells, suggesting that CD46 is a receptor for the binding of complement-opsonized K. pneumoniae to these cells. We observed that poorly encapsulated strains appeared into the alveolar epithelial cells in vivo but that (by contrast) they were completely avirulent in a mouse model of pneumonia compared to the highly encapsulated strains. Our results show that bacterial opsonization by complement enhances the internalization of the avirulent microorganisms by nonphagocytic cells such as A549 epithelial cells and allows an efficient innate defense.

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Flagellin/TLR5 Stimulate Myeloid Progenitors to Enter Lung Tissue and to Locally Differentiate Into Macrophages

Frontiers in Immunology ◽

10.3389/fimmu.2021.621665 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xin Lei ◽

Jara Palomero ◽

Iris de Rink ◽

Tom de Wit ◽

Martijn van Baalen ◽

...

Keyword(s):

Epithelial Cells ◽

Low Frequency ◽

Lavage Fluid ◽

Lung Lavage ◽

Alveolar Epithelial Cells ◽

Mouse Bone Marrow ◽

Alveolar Epithelial ◽

Toll Like Receptor 5

Toll-like receptor 5 (TLR5) is the receptor of bacterial Flagellin. Reportedly, TLR5 engagement helps to combat infections, especially at mucosal sites, by evoking responses from epithelial cells and immune cells. Here we report that TLR5 is expressed on a previously defined bipotent progenitor of macrophages (MΦs) and osteoclasts (OCs) that resides in the mouse bone marrow (BM) and circulates at low frequency in the blood. In vitro, Flagellin promoted the generation of MΦs, but not OCs from this progenitor. In vivo, MΦ/OC progenitors were recruited from the blood into the lung upon intranasal inoculation of Flagellin, where they rapidly differentiated into MΦs. Recruitment of the MΦ/OC progenitors into the lung was likely promoted by the CCL2/CCR2 axis, since the progenitors expressed CCR2 and type 2 alveolar epithelial cells (AECs) produced CCL2 upon stimulation by Flagellin. Moreover, CCR2 blockade reduced migration of the MΦ/OC progenitors toward lung lavage fluid (LLF) from Flagellin-inoculated mice. Our study points to a novel role of the Flagellin/TLR5 axis in recruiting circulating MΦ/OC progenitors into infected tissue and stimulating these progenitors to locally differentiate into MΦs. The progenitor pathway to produce MΦs may act, next to monocyte recruitment, to fortify host protection against bacterial infection at mucosal sites.

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Silica directly increases permeability of alveolar epithelial cells

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.4.1354 ◽

1990 ◽

Vol 68 (4) ◽

pp. 1354-1359 ◽

Cited By ~ 11

Author(s):

R. K. Merchant ◽

M. W. Peterson ◽

G. W. Hunninghake

Keyword(s):

Epithelial Cells ◽

Cell Injury ◽

Alveolar Epithelial Cell ◽

Alveolar Epithelium ◽

Alveolar Epithelial Cells ◽

Dependent Manner ◽

Alveolar Epithelial ◽

Lactate Dehydrogenase Release ◽

Capillary Membrane

Alveolar epithelial cell injury and increased alveolar-capillary membrane permeability are important features of acute silicosis. To determine whether silica particles contribute directly to this increased permeability, we measured paracellular permeability of rat alveolar epithelium after exposure to silica, in vitro, using markers of the extracellular space. Silica (Minusil) markedly increased permeability in a dose- and time-dependent manner. This was not the result of cytolytic injury, because lactate dehydrogenase release from monolayers exposed to silica was not increased. Pretreatment of the silica with serum, charged dextrans, or aluminum sulfate blocked the increase in permeability. Scanning electron microscopy demonstrated adherence of the silica to the surface of the alveolar epithelial cells. Thus silica can directly increase permeability of alveolar epithelium.

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Pulmonary surfactant inhibition of nanoparticle uptake by alveolar epithelial cells

Scientific Reports ◽

10.1038/s41598-020-76332-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

M. Radiom ◽

M. Sarkis ◽

O. Brookes ◽

E. K. Oikonomou ◽

A. Baeza-Squiban ◽

...

Keyword(s):

Epithelial Cells ◽

Pulmonary Surfactant ◽

Fluid Layer ◽

Alveolar Epithelial Cell ◽

Cell System ◽

Engineered Nanoparticles ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Inhaled Nanoparticles

Abstract Pulmonary surfactant forms a sub-micrometer thick fluid layer that covers the surface of alveolar lumen and inhaled nanoparticles therefore come in to contact with surfactant prior to any interaction with epithelial cells. We investigate the role of the surfactant as a protective physical barrier by modeling the interactions using silica-Curosurf-alveolar epithelial cell system in vitro. Electron microscopy displays that the vesicles are preserved in the presence of nanoparticles while nanoparticle-lipid interaction leads to formation of mixed aggregates. Fluorescence microscopy reveals that the surfactant decreases the uptake of nanoparticles by up to two orders of magnitude in two models of alveolar epithelial cells, A549 and NCI-H441, irrespective of immersed culture on glass or air–liquid interface culture on transwell. Confocal microscopy corroborates the results by showing nanoparticle-lipid colocalization interacting with the cells. Our work thus supports the idea that pulmonary surfactant plays a protective role against inhaled nanoparticles. The effect of surfactant should therefore be considered in predictive assessment of nanoparticle toxicity or drug nanocarrier uptake. Models based on the one presented in this work may be used for preclinical tests with engineered nanoparticles.

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Pneumocystis Pneumonia Increases the Susceptibility of Mice to Sublethal Hyperoxia

Infection and Immunity ◽

10.1128/iai.71.10.5970-5978.2003 ◽

2003 ◽

Vol 71 (10) ◽

pp. 5970-5978 ◽

Cited By ~ 7

Author(s):

James M. Beck ◽

Angela M. Preston ◽

Steven E. Wilcoxen ◽

Susan B. Morris ◽

Eric S. White ◽

...

Keyword(s):

T Cells ◽

Epithelial Cell ◽

Cell Injury ◽

Alveolar Epithelial Cell ◽

Pulmonary Inflammation ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Epithelial Cell Injury

ABSTRACT Patients with Pneumocystis pneumonia often develop respiratory failure after entry into medical care, and one mechanism for this deterioration may be increased alveolar epithelial cell injury. In vitro, we previously demonstrated that Pneumocystis is not cytotoxic for alveolar epithelial cells. In vivo, however, infection with Pneumocystis could increase susceptibility to injury by stressors that, alone, would be sublethal. We examined transient exposure to hyperoxia as a prototypical stress that does cause mortality in normal mice. Mice were depleted of CD4+ T cells and inoculated intratracheally with Pneumocystis. Control mice were depleted of CD4+ T cells but did not receive Pneumocystis. After 4 weeks, mice were maintained in normoxia, were exposed to hyperoxia for 4 days, or were exposed to hyperoxia for 4 days followed by return to normoxia. CD4-depleted mice with Pneumocystis pneumonia demonstrated significant mortality after transient exposure to hyperoxia, while all uninfected control mice survived this stress. We determined that organism burdens were not different. However, infected mice exposed to hyperoxia and then returned to normoxia demonstrated significant increases in inflammatory cell accumulation and lung cell apoptosis. We conclude that Pneumocystis pneumonia leads to increased mortality following a normally sublethal hyperoxic insult, accompanied by alveolar epithelial cell injury and increased pulmonary inflammation.

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Nanomaterials induce different levels of oxidative stress, depending on the used model system: Comparison of in vitro and in vivo effects

10.21203/rs.3.rs-57664/v1 ◽

2020 ◽

Author(s):

Isabel Karkossa ◽

Anne Bannuscher ◽

Bryan Hellack ◽

Wendel Wohlleben ◽

Julie Laloy ◽

...

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Alveolar Macrophages ◽

Model System ◽

Alveolar Epithelial Cells ◽

Model Systems ◽

Alveolar Epithelial ◽

Different Levels

Abstract Background The immense variety and constant development of nanomaterials (NMs) raise the demand for a facilitated risk assessment, for which knowledge on NMs mode of actions (MoAs) is required. For this purpose, a comprehensive data basis is of paramountcy that can be obtained using omics. Furthermore, the establishment of suitable in vitro test systems is indispensable to follow the 3R concept and to master the high number of NMs. In the present study, we aimed at comparing NM effects in vitro and in vivo using a multi-omics approach. We applied an integrated data evaluation strategy based on proteomics and metabolomics to four silica NMs and one titanium dioxide-based NM. For in vitro investigations, alveolar epithelial cells and alveolar macrophages were treated with different doses of NMs, and the results were compared to effects on rat lungs after short-term inhalations and instillations at varying doses with and without a recovery period.Results Since the production of reactive oxygen species (ROS) is described to be a critical biological effect of NMs, and enrichment analyses confirmed oxidative stress as a significant effect upon NM treatment in vitro in the present study, we focused on different levels of oxidative stress. Thus, we found opposite changes for proteins and metabolites that are related to the production of reduced glutathione in alveolar epithelial cells and alveolar macrophages, illustrating that NMs MoAs depend on the used model system. Interestingly, in vivo, pathways related to inflammation were affected to a greater extent than oxidative stress responses. Hence, the assignment of the observed effects to the levels of oxidative stress was different in vitro and in vivo as well. However, the overall classification of “active” and “passive” NMs was consistent in vitro and in vivo.Conclusions The consistent classification indicates both tested cell lines to be suitable for NM toxicity assessment even though the induced levels of oxidative stress strongly depend on the used model systems. Thus, the here presented results highlight that model systems need to be carefully revised to decipher the extent to which they can replace in vivo testing.

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Protective effect of IL-6 on alveolar epithelial cell death induced by hydrogen peroxide

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00016.2004 ◽

2005 ◽

Vol 288 (2) ◽

pp. L342-L349 ◽

Cited By ~ 32

Author(s):

Hiroshi Kida ◽

Mitsuhiro Yoshida ◽

Shigenori Hoshino ◽

Koji Inoue ◽

Yukihiro Yano ◽

...

Keyword(s):

Gene Expression ◽

Cell Death ◽

Epithelial Cell ◽

Epithelial Cells ◽

Alveolar Epithelial Cell ◽

Alveolar Epithelial Cells ◽

Lung Fibroblasts ◽

Alveolar Epithelial ◽

Epithelial Cell Death

The goal of this study was to examine whether IL-6 could directly protect lung resident cells, especially alveolar epithelial cells, from reactive oxygen species (ROS)-induced cell death. ROS induced IL-6 gene expression in organotypic lung slices of wild-type (WT) mice. ROS also induced IL-6 gene expression in mouse primary lung fibroblasts, dose dependently. The organotypic lung slices of WT were more resistant to ROS-induced DNA fragmentation than those of IL-6-deficient (IL-6−/−) mice. WT resistance against ROS was abrogated by treatment with anti-IL-6 antibody. TdT-mediated dUTP nick end labeling stain and electron microscopy revealed that DNA fragmented cells in the IL-6−/− slice included alveolar epithelial cells and endothelial cells. In vitro studies demonstrated that IL-6 reduced ROS-induced A549 alveolar epithelial cell death. Together, these data suggest that IL-6 played an antioxidant role in the lung by protecting lung resident cells, especially alveolar epithelial cells, from ROS-induced cell death.

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

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1991.260.4.l318 ◽

1991 ◽

Vol 260 (4) ◽

pp. L318-L325 ◽

Cited By ~ 4

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.

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ER Stress is Involved in Epithelial-To-Mesenchymal Transition of Alveolar Epithelial Cells Exposed to a Hypoxic Microenvironment

International Journal of Molecular Sciences ◽

10.3390/ijms20061299 ◽

2019 ◽

Vol 20 (6) ◽

pp. 1299 ◽

Cited By ~ 4

Author(s):

Eva Delbrel ◽

Yurdagül Uzunhan ◽

Abdoulaye Soumare ◽

Thomas Gille ◽

Dominique Marchant ◽

...

Keyword(s):

Epithelial Cells ◽

Er Stress ◽

Epithelial To Mesenchymal Transition ◽

Alveolar Epithelial Cells ◽

Mesenchymal Transition ◽

Alveolar Epithelial ◽

Rat Lungs ◽

Fibrotic Process

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and fatal interstitial lung disease of unknown origin. Alveolar epithelial cells (AECs) play an important role in the fibrotic process as they undergo sustained endoplasmic reticulum (ER) stress, and may acquire a mesenchymal phenotype through epithelial-to-mesenchymal transition (EMT), two phenomena that could be induced by localized alveolar hypoxia. Here we investigated the potential links between hypoxia, ER stress and EMT in AECs. Methods: ER stress and EMT markers were assessed by immunohistochemistry, western blot and qPCR analysis, both in vivo in rat lungs exposed to normoxia or hypoxia (equivalent to 8% O2) for 48 h, and in vitro in primary rat AECs exposed to normoxia or hypoxia (1.5% O2) for 2–6 days. Results: Hypoxia induced expression of mesenchymal markers, pro-EMT transcription factors, and the activation of ER stress markers both in vivo in rat lungs, and in vitro in AECs. In vitro, pharmacological inhibition of ER stress by 4-PBA limited hypoxia-induced EMT. Calcium chelation or hypoxia-inducible factor (HIF) inhibition also prevented EMT induction under hypoxic condition. Conclusions: Hypoxia and intracellular calcium are both involved in EMT induction of AECs, mainly through the activation of ER stress and HIF signaling pathways.

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