scholarly journals Inhibition Mir-92a Alleviates Oxidative Stress and Apoptosis of Alveolar Epithelial Cells Induced by Lipopolysaccharide Exposure through TLR2/AP-1 Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Jian Cui ◽  
Huanhuan Ding ◽  
Yongyuan Yao ◽  
Wei Liu
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Inflammatory Response ◽  
Lung Tissue ◽  
Cell Apoptosis ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Rat Lung ◽  
Alveolar Epithelial

Objective. To probe into the role of miR-92a in alleviating oxidative stress and apoptosis of alveolar epithelial cell (AEC) injury induced by lipopolysaccharide (LPS) exposure through the Toll-like receptor (TLR) 2/activator protein-1 (AP-1) pathway. Methods. Acute lung injury (ALI) rat model and ALI alveolar epithelial cell model were constructed to inhibit the expression of miR-92a/TLR2/AP-1 in rat and alveolar epithelial cells (AECs), to detect the changes of oxidative stress, inflammatory response, and cell apoptosis in rat lung tissues and AECs, and to measure the changes of wet-dry weight (W/D) ratio in rat lung tissues. Results. Both inhibition of miR-92a expression and knockout of TLR2 and AP-1 gene could reduce LPS-induced rat ALI, alleviate pulmonary edema, inhibit oxidative stress and inflammatory response, and reduce apoptosis of lung tissue cells. In addition, the TLR2 and AP-1 levels in the lung tissues of ALI rats were noticed to be suppressed when inhibiting the expression of miR-92a, and the AP-1 level was also decreased after the knockout of TLR2 gene. Further, we verified this relationship in AECs and found that inhibition of miR-92a/TLR2/AP-1 also alleviated LPS-induced AEC injury, reduced cell apoptosis, and inhibited oxidative stress and inflammatory response. What is more, like that in rat lung tissue, the phenomenon also existed in AECs, that is, when the expression of miR-92a was inhibited, the expression of TLR2 and AP-1 was inhibited, and silencing TLR2 can reduce the expression level of AP-1. Conclusion. MiR-92a/TLR2/AP-1 is highly expressed in ALI, and its inhibition can improve oxidative stress and inflammatory response and reduce apoptosis of AECs.

scholarly journals Long non-coding RNA MALAT1 protects epithelial cells from LPS-induced acute lung injury by regulating miRNA-181a-3p /B

2020 ◽  
Author(s):  
Yaling Liu ◽  
Xiaodong Wang ◽  
Liqun Yang ◽  
Hong Xie
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Apoptosis ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Non Coding Rna ◽  
Tnf Α ◽  
Epithelial Cell Apoptosis ◽  
Long Non Coding Rna

Abstract Background Long non-coding RNA metastasis-associated lung adenocarcinoma transcript-1 (MALAT1) plays an important role in the pathophysiological process of inflammation. We aimed to investigate MALAT1 and its function in modulating miRNA-181a-3p and Bcl-2 in lipopolysaccharide (LPS)-induced acute lung injury (ALI). Methods We analysed MALAT1 in ALI patients, as well as the alveolar epithelial cell models of LPS-induced injury. The expression of MALAT1 and miRNA-181a-3p were evaluated by qRT-PCR, and Bcl-2 was measured by western blot. Inflammatory factors tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 mRNA levels were also quantified by qRT-PCR. Luciferase reporter assay was used to verify direct interaction between MALAT1 and miRNA-181a-3p, or miRNA-181a-3p and Bcl-2. Transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) assay was performed to detect alveolar epithelial cell apoptosis. Results Serum MALAT1 and Bcl-2 levels decreased in ALI patients, whereas miRNA-181a-3p, TNF-α, IL-1β and IL-6 levels increased (P<0.01). MALAT1 was inversely correlated to miRNA-181a-3p (R=-0.508, P=0.0031) in ALI patients. SiMALAT1 transfection upregulated miRNA-181a-3p level and downregulated Bcl-2 expression, aggravating alveolar epithelial cell apoptosis. MiRNA-181a-3p downregulated the Bcl-2 expression both in LPS-induced ALI rats and alveolar epithelial cells, as well as promoted apoptosis. TNF-α, IL-1β and IL-6 levels increased after LPS stimulation and siMALAT1 transfection. Conclusions The results demonstrate that LPS-induced ALI decreases lncRNA MALAT1, increases miRNA-181a-3p and inflammatory factor expression, downregulates the Bcl-2 level and promotes alveolar epithelial cell apoptosis. Down-regulation of MALAT1 may erase the protection of alveolar epithelial cells from LPS-induced ALI via up-regulating of miRNA-181a-3p.

Tenascin in rat lung development: in situ localization and cellular sources

1995 ◽  
Vol 269 (4) ◽  
pp. L482-L491 ◽  
Author(s):  
Y. Zhao ◽  
S. L. Young
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Epithelial Cells ◽  
Lung Tissue ◽  
Lung Development ◽  
Alveolar Epithelial Cells ◽  
Lung Fibroblasts ◽  
Rat Lung ◽  
Alveolar Epithelial

Tenascin (TN) is a hexameric extracellular matrix glycoprotein that may play an important role during lung development. TN protein is temporally and spatially restricted during lung organogenesis. The temporo-spatial and cellular expression of TN mRNA in lung remains unclear. Localization of message expression of TN in rat lung tissue was first investigated by using in situ hybridization performed with an antisense RNA probe. TN mRNA was present primarily within the mesenchyme of day 16 gestational age fetal rat lung tissue, whereas immunoreactive TN protein was found along the basement membrane. In postnatal day 3 rat lung tissue, TN mRNA was detected along alveolar septal walls and was concentrated at secondary septal tips. Expression of TN message was consistent with localization of immunoreactive TN protein. Accumulation of TN mRNA in alveolar septal tips suggests that mesenchyme may be the major source of TN mRNA. To investigate the cellular source of TN in rat lung, we studied the expression of TN in cultured rat lung fibroblasts, endothelial cells, and alveolar epithelial cells. Two TN isoforms having molecular mass of 230 and 180 kDa were in conditioned medium and in cellular extracts of lung fibroblasts and endothelial cells. TN was secreted and deposited in the extracellular matrix closely associated with the surface of lung fibroblasts and endothelial cells. Lung alveolar epithelial cells showed undetectable or barely detectable amounts of TN. These studies demonstrated that TN isoforms are expressed not only by lung fibroblasts but also by lung endothelial cells. The unique spatial localization of TN mRNA during lung development and expression of TN by different lung cell types suggested TN may be involved in matrix organization and cell-cell interactions during lung development.

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

2005 ◽  
Vol 288 (2) ◽  
pp. L342-L349 ◽  
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.

Effect of cigarette smoke and its condensates on alveolar epithelial cell injury in vitro

1994 ◽  
Vol 266 (1) ◽  
pp. L92-L100 ◽  
Author(s):  
S. Lannan ◽  
K. Donaldson ◽  
D. Brown ◽  
W. MacNee
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cigarette Smoke ◽  
Cell Injury ◽  
Cell Attachment ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Type Ii ◽  
Alveolar Epithelial

The oxidant-antioxidant balance in the airspaces of the lungs may be critical in protecting the lungs from the effects of cigarette smoke. We studied the effect of cigarette smoke and its condensates on the detachment, attachment, and proliferation of the A549 human alveolar epithelial cell line, in an in vitro model of cell injury and regeneration and the protective effects of antioxidants. Whole and vapor phase cigarette smoke decreased 51Cr-labeled A549 cell attachment, increased cell detachment, and decreased cell proliferation, as assessed by [3H]thymidine uptake. Freshly isolated rat type II alveolar epithelial cells showed an enhanced susceptibility to smoke-induced cell lysis when compared with the A549 cell line. Reduced glutathione (GSH) (400 microM) protected against the effects of cigarette smoke exposure on cell attachment, proliferation, and detachment. Depletion of intracellular GSH with buthionine sulfoxamine enhanced the epithelial cell detachment injury produced by smoke condensates. We conclude that cigarette smoke and its condensates cause an oxidant-induced injury to A549 human type II alveolar epithelial cells. Both intra- and extracellular GSH have important roles in protecting epithelial cells from the injurious effects of cigarette smoke.

scholarly journals Critical Roles of Inflammation and Apoptosis in Improved Survival in a Model of Hyperoxia-Induced Acute Lung Injury in Pneumocystis murina-Infected Mice

2009 ◽  
Vol 77 (3) ◽  
pp. 1053-1060 ◽  
Author(s):  
James M. Beck ◽  
Angela M. Preston ◽  
Steven E. Wilcoxen ◽  
Susan B. Morris ◽  
Anne Sturrock ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Lung Injury ◽  
Cell Apoptosis ◽  
Fas Ligand ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Gm Csf ◽  
Epithelial Cell Apoptosis ◽  
Ligand Expression

ABSTRACT Pneumocystis infections increase host susceptibility to additional insults that would be tolerated in the absence of infection, such as hyperoxia. In an in vivo model using CD4-depleted mice, we previously demonstrated that Pneumocystis murina pneumonia causes significant mortality following an otherwise nonlethal hyperoxic insult. Infected mice demonstrated increased pulmonary inflammation and alveolar epithelial cell apoptosis compared to controls. To test the mechanisms underlying these observations, we examined expression of components of the Fas-Fas ligand pathway in P. murina-infected mice exposed to hyperoxia. Hyperoxia alone increased expression of Fas on the surface of type II alveolar epithelial cells; conversely, infection with P. murina led to increased lung expression of Fas ligand. We hypothesized that inhibition of inflammatory responses or direct inhibition of alveolar epithelial cell apoptosis would improve survival in P. murina-infected mice exposed to hyperoxia. Mice were depleted of CD4+ T cells and infected with P. murina and then were exposed to >95% oxygen for 4 days, followed by return to normoxia. Experimental groups received vehicle, dexamethasone, or granulocyte-macrophage colony-stimulating factor (GM-CSF). Compared with the vehicle-treated group, treatment with dexamethasone reduced Fas ligand expression and significantly improved survival. Similarly, treatment with GM-CSF, an agent we have shown protects alveolar epithelial cells against apoptosis, decreased Fas ligand expression and also improved survival. Our results suggest that the dual stresses of P. murina infection and hyperoxia induce lung injury via activation of the Fas-Fas ligand pathway and that corticosteroids and GM-CSF reduce mortality in P. murina-infected mice exposed to hyperoxic stress by inhibition of inflammation and apoptosis.

scholarly journals VEGF in the lung: a role for novel isoforms

2010 ◽  
Vol 298 (6) ◽  
pp. L768-L774 ◽  
Author(s):  
Julia Varet ◽  
Samantha K. Douglas ◽  
Laura Gilmartin ◽  
Andrew R. L. Medford ◽  
David O. Bates ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Epithelial Cells ◽  
Lung Tissue ◽  
Alveolar Epithelial Cell ◽  
Vascular Endothelial Cell ◽  
Alveolar Epithelial Cells ◽  
Normal Lung ◽  
Alveolar Type ◽  
Thymidine Uptake ◽  
Alveolar Epithelial

Vascular endothelial cell growth factor (VEGF) is a potent mitogen and permogen that increases in the plasma and decreases in the alveolar space in respiratory diseases such as acute respiratory distress syndrome (ARDS). This observation has led to controversy over the role of this potent molecule in lung physiology and disease. We hypothesized that some of the VEGF previously detected in normal lung may be of the anti-angiogenic family (VEGFxxxb) with significant potential effects on VEGF bioactivity. VEGFxxxb protein expression was assessed by indirect immunohistochemistry in normal and ARDS tissue. Expression of VEGFxxxb was also detected by immunoblotting in normal lung tissue, primary human alveolar type II (ATII) cells, and bronchoalveolar lavage (BAL) fluid in normal subjects and by ELISA in normal, “at risk,” and ARDS subjects. The effect of VEGF165 and VEGF165b on both human primary endothelial cells and alveolar epithelial cell proliferation was assessed by [3H]thymidine uptake. We found that VEGF165b was widely expressed in normal healthy lung tissue but is reduced in ARDS lung. VEGF121b and VEGF165b were present in whole lung, BAL, and ATII lysate. The proliferative effect of VEGF165 on both human primary endothelial cells and human alveolar epithelial cells was significantly inhibited by VEGF165b ( P < 0.01). These data demonstrate that the novel VEGFxxxb family members are expressed in normal lung and are reduced in ARDS. A specific functional effect on primary human endothelial and alveolar epithelial cells has also been shown. These data suggest that the VEGFxxxb family may have a role in repair after lung injury.

scholarly journals Dexmedetomidine Attenuates Oxidative Stress Induced Lung Alveolar Epithelial Cell ApoptosisIn Vitro

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jian Cui ◽  
Hailin Zhao ◽  
Chunyan Wang ◽  
James J. Sun ◽  
Kaizhi Lu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Epithelial Cell ◽  
Cell Cycle Arrest ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Epithelial Cell Line ◽  
Alveolar Epithelial ◽  
Cycle Arrest ◽  
E Cadherin

Background. Oxidative stress plays a pivotal role in the lung injuries of critical ill patients. This study investigates the protection conferred byα2adrenoceptor agonist dexmedetomidine (Dex) from lung alveolar epithelial cell injury induced by hydrogen peroxide (H2O2) and the underlying mechanisms.Methods. The lung alveolar epithelial cell line, A549, was cultured and then treated with 500 μM H2O2with or without Dex (1 nM) or Dex in combination with atipamezole (10 nM), an antagonist ofα2receptors. Their effect on mitochondrial membrane potential (Δψm), reactive oxygen species (ROS), and the cell cycle was assessed by flow cytometry. Cleaved-caspases 3 and 9, BAX, Bcl-2, phospho-mTOR (p-mTOR), ERK1/2, and E-cadherin expression were also determined with immunocytochemistry.Results. Upregulation of cleaved-caspases 3 and 9 and BAX and downregulation of Bcl-2, p-mTOR, and E-cadherin were found following H2O2treatment, and all of these were reversed by Dex. Dex also prevented the ROS generation, cytochrome C release, and cell cycle arrest induced by H2O2. The effects of Dex were partially reversed by atipamezole.Conclusion. Our study demonstrated that Dex protected lung alveolar epithelial cells from apoptotic injury, cell cycle arrest, and loss of cell adhesion induced by H2O2through enhancing the cell survival and proliferation.

Evidence for amiloride-sensitive sodium channels in alveolar epithelial cells

1992 ◽  
Vol 262 (4) ◽  
pp. L405-L411 ◽  
Author(s):  
R. M. Russo ◽  
R. L. Lubman ◽  
E. D. Crandall
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Chloride Transport ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial Cells ◽  
Sodium Uptake ◽  
Alveolar Epithelial ◽  
22Na Uptake

To maintain alveolar air spaces relatively fluid free, the alveolar epithelium appears capable of vectorial transport of water and solutes. Active transepithelial transport of sodium by alveolar epithelial cell monolayers has previously been demonstrated, indicating that alveolar pneumocytes must possess ion transport mechanisms by which sodium can enter the cells apically for subsequent extrusion via Na(+)-K(+)-adenosinetriphosphatase activity at the basolateral surface. In this study, sodium entry mechanisms were investigated by directly measuring 22Na uptake into rat alveolar epithelial cells grown in primary culture. Cells exhibited increasing 22Na uptake with time over a 30-min interval. Total sodium uptake was compared in the presence and absence of several sodium transport inhibitors. Uptake was inhibited by the sodium channel blockers amiloride and benzamil but was not affected by two amiloride analogues (bromohexamethylene amiloride and dimethylamiloride) with diminished specificity for blocking sodium channels and enhanced specificity for inhibiting the Na(+)-H+ antiporter. Uptake was also unaffected by the chloride transport inhibitor bumetanide or by the absence of glucose. These data suggest that sodium uptake occurs primarily via sodium channel and that Na(+)-H+ antiport, Na(+)-K(+)-2Cl- cotransport, and Na(+)-glucose cotransport do not contribute significantly to sodium uptake under these experimental conditions. The presence of sodium channels in the alveolar epithelial cell membrane may provide the major entry mechanism by which sodium enters these cells for subsequent active extrusion, thereby effecting net salt and water reabsorption from the alveolar spaces.

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.

GM-CSF provides autocrine protection for murine alveolar epithelial cells from oxidant-induced mitochondrial injury

2012 ◽  
Vol 302 (3) ◽  
pp. L343-L351 ◽  
Author(s):  
Anne Sturrock ◽  
Elfateh Seedahmed ◽  
Mustafa Mir-Kasimov ◽  
Jonathan Boltax ◽  
Michael L. McManus ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Lung Injury ◽  
Alveolar Epithelial Cells ◽  
Type Ii ◽  
Mitochondrial Injury ◽  
Akt Activation ◽  
Alveolar Epithelial ◽  
Gm Csf

Exposure of mice to hyperoxia induces alveolar epithelial cell (AEC) injury, acute lung injury and death. Overexpression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in the lung protects against these effects, although the mechanisms are not yet clear. Hyperoxia induces cellular injury via effects on mitochondrial integrity, associated with induction of proapoptotic members of the Bcl-2 family. We hypothesized that GM-CSF protects AEC through effects on mitochondrial integrity. MLE-12 cells (a murine type II cell line) and primary murine type II AEC were subjected to oxidative stress by exposure to 80% oxygen and by exposure to H2O2. Exposure to H2O2 induced cytochrome c release and decreased mitochondrial reductase activity in MLE-12 cells. Incubation with GM-CSF significantly attenuated these effects. Protection induced by GM-CSF was associated with Akt activation. GM-CSF treatment also resulted in increased expression of the antiapoptotic Bcl-2 family member, Mcl-1. Primary murine AEC were significantly more tolerant of oxidative stress than MLE-12 cells. In contrast to MLE-12 cells, primary AEC expressed significant GM-CSF at baseline and demonstrated constitutive activation of Akt and increased baseline expression of Mcl-1. Treatment with exogenous GM-CSF further increased Akt activation and Mcl-1 expression in primary AEC. Conversely, suppression of AEC GM-CSF expression by use of GM-CSF-specific small interfering RNA resulted in decreased tolerance of oxidative stress, Furthermore, silencing of Mcl-1 prevented GM-CSF-induced protection. We conclude that GM-CSF protects alveolar epithelial cells against oxidative stress-induced mitochondrial injury via the Akt pathway and its downstream components, including Mcl-1. Epithelial cell-derived GM-CSF may contribute to intrinsic defense mechanisms limiting lung injury.

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