S48 NGAL inhibits cytoskeletal re-organisation, MMP-2 production and invasion in alveolar epithelial cells in an in vitro model of acute lung injury

Acute lung injury (ALI) induced by sepsis is characterized by disruption of the epithelial barrier and activation of alveolar macrophages (AMs), which leads to uncontrolled pulmonary inflammation. However, effective treatments for ALI are unavailable. The exact mechanism by which the initial mediator of alveolar epithelial cells (AECs) induces inflammation remains elusive. Here we investigated the roles of AEC-derived exosomes in AM activation and sepsis-induced ALI in vivo and in vitro. Cecal ligation and puncture (CLP) was utilized to establish septic lung injury model in rats. The effect of exosomal inhibition by intratracheal GW4869 administration on lung injury was investigated. To assess the effects of AEC-derived exosomes on ALI, we treated the rat alveolar epithelial cell line RLE-6TN with LPS to induce cell damage. Exosomes from conditioned medium of LPS-treated AECs (LPS-Exos) were isolated by ultracentrifugation. The miRNAs in LPS-Exos were screened by miRNA expression profile analysis. The effects of miR-92a-3p on the function of AMs were studied. We found that intratracheal GW4869 administration ameliorated lung injury following CLP-induced ALI. LPS-Exos were taken up by AMs and activated these cells. Consistently, administration of LPS-Exos in rats significantly aggravated pulmonary inflammation and alveolar permeability. Moreover, miR-92a-3p was enriched in LPS-Exos and could be delivered to AMs. Inhibition of miR-92a-3p in AECs diminished the proinflammatory effects of LPS-Exos in vivo and in vitro. Mechanistically, miR-92a-3p activates AMs along with pulmonary inflammation. This process results in activation of the NF-κB pathway and downregulation of PTEN expression, which was confirmed by a luciferase reporter assay. In conclusion, AEC-derived exosomes activate AMs and induce pulmonary inflammation mediated by miR-92a-3p in ALI. The present findings revealed a previously unidentified role of exosomal miR-92a-3p in mediating the crosstalk between injured AEC and AMs. miR-92a-3p in AEC exosomes might represent a novel diagnostic biomarker for ALI, which may lead to a new therapeutic approach.

Download Full-text

In vivo mitogenic action of HGF on lung epithelial cells: pulmotrophic role in lung regeneration

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1996.270.6.l1031 ◽

1996 ◽

Vol 270 (6) ◽

pp. L1031-L1039 ◽

Cited By ~ 17

Author(s):

H. Ohmichi ◽

K. Matsumoto ◽

T. Nakamura

Keyword(s):

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Dna Synthesis ◽

Airway Epithelial Cells ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Lung Regeneration

Hepatocyte growth factor (HGF) has mitogenic, morphogenic, and motogenic activities on epithelial cells and plays important roles in regeneration of the liver and the kidney. We previously found that the expression of HGF gene is rapidly induced in the lung after acute lung injury in experimental animals and that HGF levels are elevated in blood of patients with lung diseases. To search for a possible pulmotrophic function of HGF in lung regeneration, we examined the mitogenic activity of HGF on tracheal epithelial cells in vitro and evaluated the efficacy of HGF-administration on lung regeneration after acute lung injury in mice. HGF markedly stimulated proliferation and DNA synthesis of rat tracheal epithelial cells in primary culture in a dose-dependent manner. The intravenous injection of human recombinant HGF (10 micrograms.mouse-1.day-1) into mice with acute lung injury induced by the intratracheal infusion of 10 mM HCI stimulated DNA synthesis of airway epithelial cells to levels threefold higher than those in mice with no HGF-injections, but it did not stimulate DNA synthesis of alveolar epithelial cells. However, HGF injection at higher dose (100 micrograms.mouse-1.day-1) stimulated DNA synthesis of alveolar epithelial cells in vivo. These results indicate that HGF is a potent mitogen for airway epithelial cells and alveolar epithelial cells in vivo as well as in vitro. HGF may act as pulmotrophic factor responsible for airway and alveolar regeneration during lung regeneration after acute lung injury.

Download Full-text

Negative Effects of SIGIRR on TRAF6 Ubiquitination in Acute Lung Injury In Vitro

Journal of Immunology Research ◽

10.1155/2020/5097920 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Feng Tian ◽

Qiang Lu ◽

Jie Lei ◽

Yunfeng Ni ◽

Nianlin Xie ◽

...

Keyword(s):

Immune Response ◽

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Alveolar Macrophage ◽

Signaling Pathway ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Macrophage Cells

In this study, the effects of single immunoglobin IL-1 receptor-related protein (SIGIRR) on tumor necrosis factor- (TNF-) receptor-associated factor 6 (TRAF6) ubiquitination in acute lung injury (ALI) were evaluated in both alveolar epithelial cells and alveolar macrophage cells in vitro. Our results found that SIGIRR negatively regulated TRAF6 ubiquitination and such SIGIRR inhibition could enhance the TRAF6 expression in both alveolar epithelial cells (AECs) and alveolar macrophage cells (AMCs). SIGIRR knockdown may increase NF-κB activity via TRAF6 regulation by the classical but not the nonclassical NF-κB signaling pathway. Such modulation between TRAF6 and SIGIRR could affect cytokine secretion and exacerbate the immune response; the IL-8, NFKB1, and NFKBIA mRNA levels were reduced after SIGIRR overexpression. The current study reveals the molecular mechanisms of the negative regulatory roles of SIGIRR on the innate immune response related to the LPS/TLR-4 signaling pathway and provides evidence for strategies to clinically treat inflammatory diseases.

Download Full-text

Oxypaeoniflorin Prevents Acute Lung Injury Induced by Lipopolysaccharide through the PTEN/AKT Pathway in a Sirt1-Dependent Manner

Oxidative Medicine and Cellular Longevity ◽

10.1155/2021/6878026 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Fan Guohua ◽

Zhu Tieyuan ◽

Wang Rui ◽

Xiong Juan

Keyword(s):

Oxidative Stress ◽

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Inflammatory Response ◽

Alveolar Epithelial Cells ◽

Dependent Manner ◽

Alveolar Epithelial ◽

And Oxidative Stress

Acute lung injury (ALI) is featured by pulmonary edema, alveolar barrier injury, inflammatory response, and oxidative stress. The activation of Sirt1 could relieve lipopolysaccharide- (LPS-) induced murine ALI by maintaining pulmonary epithelial barrier function. Oxypaeoniflorin (Oxy) serves as a major component of Paeonia lactiflora Pall., exerting cardioprotection by activating Sirt1. However, the role of Oxy in ALI induced by LPS remains unclear. The aim of the present study is to illustrate the modulatory effects and molecular mechanisms by which Oxy operates in ALI induced by LPS. The intraperitoneal injection of LPS was performed to establish the murine ALI model while LPS-treated alveolar epithelial cells were used to mimic the in vitro ALI model. Levels of lung injury, oxidative stress, and inflammatory response were detected to observe the potential effects of Oxy on ALI. Oxy treatment mitigated lung edema, inflammatory response, and oxidative stress in mouse response to LPS, apart from improving 7-day survival. Meanwhile, Oxy also increased the expression and activity of Sirt1. Intriguingly, Sirt1 deficiency or inhibition counteracted the protective effects of Oxy treatment in LPS-treated mice or LPS-treated alveolar epithelial cells by regulating the PTEN/AKT signaling pathway. These results demonstrated that Oxy could combat ALI in vivo and in vitro through inhibiting inflammatory response and oxidative stress in a Sirt1-dependent manner. Oxy owns the potential to be a promising candidate against ALI.

Download Full-text

The PI3K/AKT/mTOR pathway regulates autophagy to induce apoptosis of alveolar epithelial cells in chronic obstructive pulmonary disease caused by PM2.5 particulate matter

Journal of International Medical Research ◽

10.1177/0300060520927919 ◽

2020 ◽

Vol 48 (7) ◽

pp. 030006052092791 ◽

Cited By ~ 1

Author(s):

Fang Zhang ◽

Hui Ma ◽

Zhong Lan Wang ◽

Wei Hua Li ◽

Hua Liu ◽

...

Keyword(s):

Chronic Obstructive Pulmonary Disease ◽

Epithelial Cells ◽

In Vitro Model ◽

Mtor Pathway ◽

Alveolar Epithelial Cells ◽

Chronic Obstructive ◽

Obstructive Pulmonary Disease ◽

Alveolar Epithelial ◽

Vitro Model

Objective Many lung diseases are associated with changes in autophagic activity. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway plays a key regulatory role in autophagy. Our aim was to explore the function of PI3K/AKT/mTOR pathway on autophagy in chronic obstructive pulmonary disease (COPD) caused by particulate matter with a diameter <2.5 µm (PM2.5). Methods Male C57BL/6 mice were randomly divided into sham, model, and PI3K inhibitor groups. Mice were exposed to PM2.5 for 4 weeks to establish an in vivo COPD model. Alveolar epithelial cells were stimulated with PM2.5 to establish an in vitro COPD model. Results In mice with COPD induced by PM2.5, the PI3K inhibitor PF-04979064 suppressed protein expression of PI3K, p-AKT, and p-mTOR to increase apoptosis of alveolar epithelial cells and reduce autophagy. Short interfering PI3K suppressed the PI3K/AKT/mTOR pathway to induce apoptosis and reduce autophagy of alveolar epithelial cells in an in vitro model of COPD. Activation of PI3K induced the PI3K/AKT/mTOR pathway to reduce apoptosis of alveolar epithelial cells in the in vitro model of COPD by promoting autophagy. Conclusions These data demonstrate that PI3K/AKT/mTOR pathway regulates autophagy to induce apoptosis of alveolar epithelial cells in COPD.

Download Full-text

Endocytosis in an in vitro model of the human alveolar epithelial barrier: Uptake of GM-1 by human alveolar epithelial cells in primary culture

10.1240/sav_gbm_2004_h_000616 ◽

2004 ◽

Vol 2004 (Fall) ◽

Author(s):

Sabine Fuchs ◽

Michael Laue ◽

Maria Iris Hermanns ◽

Charles James Kirkpatrick

Keyword(s):

Epithelial Cells ◽

Primary Culture ◽

In Vitro Model ◽

Alveolar Epithelial Cells ◽

Epithelial Barrier ◽

Alveolar Epithelial ◽

Vitro Model ◽

Human Alveolar Epithelial Cells

Download Full-text

Monolayers of porcine alveolar epithelial cells in primary culture as an in vitro model for drug absorption studies

European Journal of Pharmaceutics and Biopharmaceutics ◽

10.1016/j.ejpb.2006.11.006 ◽

2007 ◽

Vol 66 (3) ◽

pp. 372-382 ◽

Cited By ~ 19

Author(s):

Anne Steimer ◽

Helmut Franke ◽

Eleonore Haltner-Ukomado ◽

Michael Laue ◽

Carsten Ehrhardt ◽

...

Keyword(s):

Epithelial Cells ◽

Primary Culture ◽

Drug Absorption ◽

In Vitro Model ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Absorption Studies ◽

Vitro Model

Download Full-text

H2O2 inhibits alveolar epithelial wound repair in vitro by induction of apoptosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00177.2003 ◽

2004 ◽

Vol 287 (2) ◽

pp. L448-L453 ◽

Cited By ~ 55

Author(s):

Thomas Geiser ◽

Masanobu Ishigaki ◽

Coretta van Leer ◽

Michael A. Matthay ◽

V. Courtney Broaddus

Keyword(s):

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Cell Viability ◽

Wound Repair ◽

Wound Edge ◽

Alveolar Epithelial ◽

Induction Of Apoptosis

Reactive oxygen species (ROS) are released into the alveolar space and contribute to alveolar epithelial damage in patients with acute lung injury. However, the role of ROS in alveolar repair is not known. We studied the effect of ROS in our in vitro wound healing model using either human A549 alveolar epithelial cells or primary distal lung epithelial cells. We found that H2O2 inhibited alveolar epithelial repair in a concentration-dependent manner. At similar concentrations, H2O2 also induced apoptosis, an effect seen particularly at the edge of the wound, leading us to hypothesize that apoptosis contributes to H2O2-induced inhibition of wound repair. To learn the role of apoptosis, we blocked caspases with the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp (zVAD). In the presence of H2O2, zVAD inhibited apoptosis, particularly at the wound edge and, most importantly, maintained alveolar epithelial wound repair. In H2O2-exposed cells, zVAD also maintained cell viability as judged by improved cell spreading and/or migration at the wound edge and by a more normal mitochondrial potential difference compared with cells not treated with zVAD. In conclusion, H2O2 inhibits alveolar epithelial wound repair in large part by induction of apoptosis. Inhibition of apoptosis can maintain wound repair and cell viability in the face of ROS. Inhibiting apoptosis may be a promising new approach to improve repair of the alveolar epithelium in patients with acute lung injury.

Download Full-text

Adrenomedullin expression in a rat model of acute lung injury induced by hypoxia and LPS

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00314.2004 ◽

2005 ◽

Vol 288 (3) ◽

pp. L536-L545 ◽

Cited By ~ 19

Author(s):

Jackeline Agorreta ◽

Javier J. Zulueta ◽

Luis M. Montuenga ◽

Mercedes Garayoa

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Cell Lines ◽

Rat Model ◽

In Vitro Model ◽

Rat Lung ◽

Vitro Model

Adrenomedullin (ADM) is upregulated independently by hypoxia and LPS, two key factors in the pathogenesis of acute lung injury (ALI). This study evaluates the expression of ADM in ALI using experimental models combining both stimuli: an in vivo model of rats treated with LPS and acute normobaric hypoxia (9% O2) and an in vitro model of rat lung cell lines cultured with LPS and exposed to hypoxia (1% O2). ADM expression was analyzed by in situ hybridization, Northern blot, Western blot, and RIA analyses. In the rat lung, combination of hypoxia and LPS treatments overcomes ADM induction occurring after each treatment alone. With in situ techniques, the synergistic effect of both stimuli mainly correlates with ADM expression in inflammatory cells within blood vessels and, to a lesser extent, to cells in the lung parenchyma and bronchiolar epithelial cells. In the in vitro model, hypoxia and hypoxia + LPS treatments caused a similar strong induction of ADM expression and secretion in epithelial and endothelial cell lines. In alveolar macrophages, however, LPS-induced ADM expression and secretion were further increased by the concomitant exposure to hypoxia, thus paralleling the in vivo response. In conclusion, ADM expression is highly induced in a variety of key lung cell types in this rat model of ALI by combination of hypoxia and LPS, suggesting an essential role for this mediator in this syndrome.

Download Full-text