scholarly journals Stretch induces cytokine release by alveolar epithelial cells in vitro

1999 ◽  
Vol 277 (1) ◽  
pp. L167-L173 ◽  
Author(s):  
Nicholas E. Vlahakis ◽  
Mark A. Schroeder ◽  
Andrew H. Limper ◽  
Rolf D. Hubmayr
Keyword(s):  
Epithelial Cells ◽  
Cell Damage ◽  
A549 Cells ◽  
Alveolar Epithelium ◽  
Alveolar Epithelial Cells ◽  
Structural Cell ◽  
Alveolar Epithelial ◽  
Macrophage Colony ◽  
Factor Α

Mechanical ventilation can injure the lung, causing edema and alveolar inflammation. Interleukin-8 (IL-8) plays an important role in this inflammatory response. We postulated that cyclic cell stretch upregulates the production and release of IL-8 by human alveolar epithelium in the absence of structural cell damage or paracrine stimulation. To test this hypothesis, alveolar epithelial cells (A549 cells) were cultured on a deformable silicoelastic membrane. When stretched by 30% for up to 48 h, the cells released 49 ± 34% more IL-8 ( P < 0.001) than static controls. Smaller deformations (20% stretch) produced no consistent increase in IL-8. Stretch of 4 h duration increased IL-8 gene transcription fourfold above baseline. Stretch had no effect on cell proliferation, cell viability as assessed by51Cr release assay, or the release of granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-α. We conclude that deformation per se can trigger inflammatory signaling and that alveolar epithelial cells may be active participants in the alveolitis associated with ventilator-induced lung injury.

Silica directly increases permeability of alveolar epithelial cells

1990 ◽  
Vol 68 (4) ◽  
pp. 1354-1359 ◽  
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.

Impairment of cation transport in A549 cells and rat alveolar epithelial cells by hypoxia

1997 ◽  
Vol 273 (4) ◽  
pp. L797-L806 ◽  
Author(s):  
Heimo Mairbäurl ◽  
Ralf Wodopia ◽  
Sigrid Eckes ◽  
Susanne Schulz ◽  
Peter Bärtsch
Keyword(s):  
Epithelial Cells ◽  
A549 Cells ◽  
Alveolar Epithelium ◽  
Cell Types ◽  
Cation Transport ◽  
Alveolar Epithelial Cells ◽  
Alveolar Type ◽  
Water Reabsorption ◽  
Alveolar Epithelial

A reduced cation reabsorption across the alveolar epithelium decreases water reabsorption from the alveoli and could diminish clearing accumulated fluid. To test whether hypoxia restricts cation transport in alveolar epithelial cells, cation uptake was measured in rat lung alveolar type II pneumocytes (AII cells) in primary culture and in A549 cells exposed to normoxia and hypoxia. In AII and A549 cells, hypoxia caused a[Formula: see text]-dependent inhibition of the Na-K pump, of Na-K-2Cl cotransport, and of total and amiloride-sensitive22Na uptake. Nifedipine failed to prevent hypoxia-induced transport inhibition in both cell types. In A549 cells, the inhibition of the Na-K pump and Na-K-2Cl cotransport occurred within ∼30 min of hypoxia, was stable >20 h, and was reversed by 2 h of reoxygenation. There was also a reduction in cell membrane-associated Na-K-ATPase and a decrease in Na-K-2Cl cotransport flux after full activation with calyculin A, indicating a decreased transport capacity. [14C]serine incorporation into cell proteins was reduced in hypoxic A549 cells, but inhibition of protein synthesis with cycloheximide did not reduce ion transport. In AII and A549 cells, ATP levels decreased slightly, and ADP and the ATP-to-ADP ratio were unchanged after 4 h of hypoxia. In A549 cells, lactate, intracellular Na, and intracellular K were unchanged. These results indicate that hypoxia inhibits apical Na entry pathways and the basolateral Na-K pump in A549 cells and rat AII pneumocytes in culture, indicating a hypoxia-induced reduction of transepithelial Na transport and water reabsorption by alveolar epithelium. If similar changes occur in vivo, the impaired cation transport across alveolar epithelial cells might contribute to the formation of hypoxic pulmonary edema.

Reticulocalbin 3 deficiency in alveolar epithelium attenuated LPS-induced ALI via NF-κB signaling

2021 ◽  
Vol 320 (4) ◽  
pp. L627-L639
Author(s):  
Xiaoqian Shi ◽  
Xiaojie An ◽  
Liu Yang ◽  
Zhipeng Wu ◽  
Danni Zan ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Lung Injury ◽  
Inflammatory Response ◽  
Secretory Pathway ◽  
Alveolar Epithelium ◽  
Repair Process ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial

Acute respiratory distress syndrome (ARDS) is characterized by acute lung injury (ALI) secondary to an excessive alveolar inflammatory response. Reticulocalbin 3 (Rcn3) is an endoplasmic reticulum (ER) lumen protein in the secretory pathway. We previously reported the indispensable role of Rcn3 in type II alveolar epithelial cells (AECIIs) during lung development and the lung injury repair process. In the present study, we further observed a marked induction of Rcn3 in the alveolar epithelium during LPS-induced ALI. In vitro alveolar epithelial (MLE-12) cells consistently exhibited a significant induction of Rcn3 accompanied with NF-κB activation in response to LPS exposure. We examined the role of Rcn3 in the alveolar inflammatory response by using mice with a selective deletion of Rcn3 in alveolar epithelial cells upon doxycycline administration. The Rcn3 deficiency significantly blunted the ALI and alveolar inflammation induced by intratracheal LPS instillation but not that induced by an intraperitoneal LPS injection (secondary insult); the alleviated ALI was accompanied by decreases in NF-κB activation and NLRP3 levels but not in GRP78 and cleaved caspase-3 levels. The studies conducted in MLE-12 cells consistently showed that Rcn3 knockdown blunted the activations of NF-κB signaling and NLRP3-dependent inflammasome upon LPS exposure. Collectively, these findings suggest a novel role for Rcn3 in regulating the alveolar inflammatory response to pulmonary infection via the NF-κB/NLRP3/inflammasome axis and shed additional light on the mechanism of ARDS/ALI.

Rat alveolar epithelial cells concomitantly express plasminogen activator inhibitor-1 and urokinase

1991 ◽  
Vol 260 (4) ◽  
pp. L286-L295 ◽  
Author(s):  
T. J. Gross ◽  
R. H. Simon ◽  
C. J. Kelly ◽  
R. G. Sitrin
Keyword(s):  
Epithelial Cells ◽  
Plasminogen Activator ◽  
Alveolar Epithelium ◽  
Plasminogen Activator Inhibitor ◽  
Alveolar Epithelial Cells ◽  
Plasminogen Activator Inhibitor 1 ◽  
Necrosis Factor Alpha ◽  
Alveolar Epithelial ◽  
Pai 1

There is considerable evidence to suggest that intra-alveolar plasminogen activation is instrumental in many aspects of inflammatory lung injury and subsequent tissue repair. Rat alveolar epithelial cells produce large quantities of urokinase-type plasminogen activator (uPA) in vitro, and uPA expression is modulated in association with cellular differentiation and exposure to inflammatory mediators. We now report that these cells also secrete heat-stable PA inhibitory activity having the characteristics of PA inhibitor type 1 (PAI-1). In particular, immunoreactive PAI-1 was demonstrable in conditioned media, cell lysates, and extracellular matrix from epithelial cell cultures. As alveolar epithelial cells differentiated in vitro, secreted PA inhibitor activity increased significantly from 104 +/- PAI U/ml (n = 5, mean +/- SE) on day 2 to 442 +/- 150 on day 7 in parallel with increases in secreted and matrix-associated immunoreactive PAI-1. PAI-1 mRNA expression decreased over this same period suggesting posttranscriptional regulation. The levels of both newly synthesized antigen and PAI-1 mRNA were increased by exposure to lipopolysaccharide and tumor necrosis factor-alpha. Thus, by the coexpression of uPA and PAI-1, the alveolar epithelium may actively regulate the generation of plasmin in both the normal and injured alveolus.

scholarly journals Human β-Defensin 2 Is Expressed and Associated with Mycobacterium tuberculosis during Infection of Human Alveolar Epithelial Cells

2005 ◽  
Vol 73 (8) ◽  
pp. 4505-4511 ◽  
Author(s):  
Bruno Rivas-Santiago ◽  
Stephan K. Schwander ◽  
Carmen Sarabia ◽  
Gill Diamond ◽  
Marcia E. Klein-Patel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Electron Microscopy ◽  
Mycobacterium Tuberculosis ◽  
Epithelial Cells ◽  
A549 Cells ◽  
Alveolar Epithelial Cells ◽  
Epithelial Cell Line ◽  
Blood Monocytes ◽  
Alveolar Epithelial

ABSTRACT To determine the role of human β-defensin 2 (HBD-2) in human tuberculosis, we studied the in vitro induction of HBD-2 gene expression by Mycobacterium tuberculosis H37Rv infection in the human lung epithelial cell line A549, in alveolar macrophages (AM), and in blood monocytes (MN) by reverse transcription-PCR. We also studied the induction of HBD-2 gene expression by mannose lipoarabinomannan (manLAM) from M. tuberculosis. Intracellular production of HBD-2 peptide was detected by immunocytochemistry and electron microscopy. Our results demonstrated that there was induction of HBD-2 mRNA in A549 cells after infection with M. tuberculosis at various multiplicities of infection (MOI) and that there was stimulation with manLAM. AM expressed the HBD-2 gene only at a high MOI with M. tuberculosis. MN did not express HBD-2 at any of the experimental M. tuberculosis MOI. Immunostaining revealed the presence of intracellular HBD-2 peptide in A549 cells following infection with M. tuberculosis, and the staining was more intense in areas where there were M. tuberculosis clusters. By using electron microscopy we also demonstrated production of HBD-2 after M. tuberculosis infection and adherence of HBD-2 to the membranes of M. tuberculosis. Alveolar epithelial cells are among the first cells to encounter M. tuberculosis following aerogenic infection. As HBD-2 has been shown to control growth of M. tuberculosis and has chemotactic activity, our results suggest that HBD-2 induction by M. tuberculosis may have a role in the pathogenesis of human tuberculosis.

Urokinase plasminogen activator released by alveolar epithelial cells modulates alveolar epithelial repair in vitro

2005 ◽  
Vol 94 (12) ◽  
pp. 1257-1264 ◽  
Author(s):  
Coretta Van Leer ◽  
Monika Stutz ◽  
André Haeberli ◽  
Thomas Geiser
Keyword(s):  
Epithelial Cells ◽  
Pulmonary Fibrosis ◽  
Wound Repair ◽  
Alveolar Epithelium ◽  
Alveolar Epithelial Cells ◽  
Alveolar Type ◽  
Epithelial Repair ◽  
Alveolar Epithelial ◽  
Fibrin Matrix

SummaryIntra-alveolar fibrin is formed following lung injury and inflammation and may contribute to the development of pulmonary fibrosis. Fibrin turnover is altered in patients with pulmonary fibrosis, resulting in intra-alveolar fibrin accumulation, mainly due to decreased fibrinolysis. Alveolar type II epithelial cells (AEC) repair the injured alveolar epithelium by migrating over the provisional fibrin matrix. We hypothesized that repairing alveolar epithelial cells modulate the underlying fibrin matrix by release of fibrinolytic activity, and that the degree of fibrinolysis modulates alveolar epithelial repair on fibrin. To test this hypothesis we studied alveolar epithelial wound repair in vitro using a modified epithelial wound repair model with human A549 alveolar epithelial cells cultured on a fibrin matrix. In presence of the inflammatory cytokine interleukin-1β, wounds increase by 800% in 24 hours mainly due to detachment of the cells, whereas in serum-free medium wound areas decreases by 22.4 ± 5.2 % (p<0.01). Increased levels of D-dimer, FDP and uPA in the cell supernatant of IL-1β-stimulated A549 epithelial cells indicate activation of fibrinolysis by activation of the plasmin system. In presence of low concentrations of fibrinolysis inhibitors, including specific blocking anti-uPA antibodies, alveolar epithelial repair in vitro was improved, whereas in presence of high concentrations of fibrinolysis inhibitors, a decrease was observed mainly due to decreased spreading and migration of cells. These findings suggest the existence of a fibrinolytic optimum at which alveolar epithelial repair in vitro is most efficient. In conclusion, uPA released by AEC alters alveolar epithelial repair in vitro by modulating the underlying fibrin matrix.

Glutathione homeostasis in alveolar epithelial cells in vitro and lung in vivo under oxidative stress

1995 ◽  
Vol 269 (3) ◽  
pp. L285-L292 ◽  
Author(s):  
I. Rahman ◽  
X. Y. Li ◽  
K. Donaldson ◽  
D. J. Harrison ◽  
W. MacNee
Keyword(s):  
Epithelial Cells ◽  
Enzyme Activities ◽  
A549 Cells ◽  
Intratracheal Instillation ◽  
Alveolar Epithelial Cells ◽  
Tnf Alpha ◽  
Epithelial Cell Line ◽  
Alveolar Epithelial

We studied the acute effects of cigarette smoke condensate (CSC), H2O2, and tumor necrosis factor (TNF)-alpha on the glutathione (GSH) redox system in a human type II epithelial cell line (A549) in vitro. CSC, in vitro and in vivo after intratracheal instillation of CSC in the rat, produced a depletion of intracellular soluble GSH, concomitant with GSH-conjugate formation, without significant elevation of oxidized GSH (GSSG), protein-GSH mixed disulfides (PrSSG), nor any GSH efflux from the cells. By contrast, H2O2 (500 microM) after 5-min exposure to A549 cells caused significant depletion of intracellular GSH associated with an efflux of GSSG and a significant increase in the formation of PrSSG. TNF-alpha, in concentrations of 100 U/ml and 1,000 U/ml, produced a significant depletion of GSH in A549 cells after 4- and 24-h exposure, with an associated elevation of GSSG. The activities of glutathione peroxidase, gamma-glutamylcysteine synthetase, and glucose-6-phosphate dehydrogenase were significantly decreased in epithelial cells and in rat lungs after CSC exposure, without change in glutathione S-transferase and glutathione reductase activities. By contrast, H2O2 and TNF-alpha did not alter these enzyme activities in epithelial cells. Thus GSH depletion and alteration in enzyme activities in alveolar epithelial cells by CSC, H2O2, and TNF-alpha occur by different mechanisms.

Nano-Curcumin Regulates p53 Phosphorylation and PAI-1 Expression during Bleomycin Induced Injury in Alveolar Basal Epithelial Cells

2020 ◽  
Vol 16 (1) ◽  
pp. 85-89
Author(s):  
Mahesh M. Gouda ◽  
Ashwini Prabhu ◽  
Varsha Reddy S.V. ◽  
Rafa Jahan ◽  
Yashodhar P. Bhandary
Keyword(s):  
Epithelial Cells ◽  
Lung Injury ◽  
Molecular Mechanisms ◽  
A549 Cells ◽  
Plasminogen Activator Inhibitor ◽  
Underlying Mechanism ◽  
Protective Role ◽  
Alveolar Epithelial Cells ◽  
Cellular Damage

Background: Bleomycin (BLM) is known to cause DNA damage in the Alveolar Epithelial Cells (AECs). It is reported that BLM is involved in the up-regulation of inflammatory molecules such as neutrophils, macrophages, chemokines and cytokines. The complex underlying mechanism for inflammation mediated progression of lung injury is still unclear. This investigation was designed to understand the molecular mechanisms associated with p53 mediated modulation of Plasminogen Activator Inhibitor-I (PAI-I) expression and its regulation by nano-curcumin formulation. Methods: A549 cells were treated with BLM to cause the cellular damage in vitro and commercially available nano-curcumin formulation was used as an intervention. Cytotoxic effect of nano-curcumin was analyzed using Methyl Thiazolyl Tetrazolium (MTT) assay. Protein expressions were analyzed using western blot to evaluate the p53 mediated changes in PAI-I expression. Results: Nano-curcumin showed cytotoxicity up to 88.5 % at a concentration of 20 μg/ml after 48 h of treatment. BLM exposure to the cells activated the phosphorylation of p53, which in turn increased PAII expression. Nano-curcumin treatment showed a protective role against phosphorylation of p53 and PAI-I expression, which in turn regulated the fibro-proliferative phase of injury induced by bleomycin. Conclusion: Nano-curcumin could be used as an effective intervention to regulate the severity of lung injury, apoptosis of AECs and fibro-proliferation during pulmonary injury.

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