Interleukin-10 protects cultured fetal rat type II epithelial cells from injury induced by mechanical stretch

Mechanical ventilation plays a central role in the pathogenesis of bronchopulmonary dysplasia. However, the mechanisms by which excessive stretch of fetal or neonatal type II epithelial cells contributes to lung injury are not well defined. In these investigations, isolated embryonic day 19 fetal rat type II epithelial cells were cultured on substrates coated with fibronectin and exposed to 5% or 20% cyclic stretch to simulate mechanical forces during lung development or lung injury, respectively. Twenty percent stretch of fetal type II epithelial cells increased necrosis, apoptosis, and proliferation compared with control, unstretched samples. By ELISA and real-time PCR (qRT-PCR), 20% stretch increased secretion of IL-8 into the media and IL-8 gene expression and inhibited IL-10 release. Interestingly, administration of recombinant IL-10 before 20% stretch did not affect cell lysis but significantly reduced apoptosis and IL-8 release compared with stretched samples without IL-10. Collectively, our studies suggest that IL-10 may play an important role in protection of fetal type II epithelial cells from injury secondary to stretch.

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A role for caveolin-1 in mechanotransduction of fetal type II epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00327.2009 ◽

2010 ◽

Vol 298 (6) ◽

pp. L775-L783 ◽

Cited By ~ 19

Author(s):

Yulian Wang ◽

Benjamin S. Maciejewski ◽

Diana Drouillard ◽

Melissa Santos ◽

Michael A. Hokenson ◽

...

Keyword(s):

Plasma Membrane ◽

Epithelial Cells ◽

Lung Development ◽

Fetal Lung ◽

Mechanical Stretch ◽

Erk Pathway ◽

Type Ii ◽

Caveolin 1 ◽

Fetal Lung Development ◽

Type Ii Cell

Mechanical forces are critical for fetal lung development. Using surfactant protein C (SP-C) as a marker, we previously showed that stretch-induced fetal type II cell differentiation is mediated via the ERK pathway. Caveolin-1, a major component of the plasma membrane microdomains, is important as a signaling protein in blood vessels exposed to shear stress. Its potential role in mechanotransduction during fetal lung development is unknown. Caveolin-1 is a marker of type I epithelial cell phenotype. In this study, using immunocytochemistry, Western blotting, and immunogold electron microscopy, we first demonstrated the presence of caveolin-1 in embryonic day 19 (E19) rat fetal type II epithelial cells. By detergent-free purification of lipid raft-rich membrane fractions and fluorescence immunocytochemistry, we found that mechanical stretch translocates caveolin-1 from the plasma membrane to the cytoplasm. Disruption of the lipid rafts with cholesterol-chelating agents further increased stretch-induced ERK activation and SP-C gene expression compared with stretch samples without disruptors. Similar results were obtained when caveolin-1 gene was knocked down by small interference RNA. In contrast, adenovirus overexpression of the wild-type caveolin-1 or delivery of caveolin-1 scaffolding domain peptide inside the cells decreased stretch-induced ERK phosphorylation and SP-C mRNA expression. In conclusion, our data suggest that caveolin-1 is present in E19 fetal type II epithelial cells. Caveolin-1 is translocated from the plasma membrane to the cytoplasm by mechanical stretch and functions as an inhibitory protein in stretch-induced type II cell differentiation via the ERK pathway.

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ROLES OF RhoA AND Rac1 ON ACTIN REMODELING AND CELL ALIGNMENT AND DIFFERENTIATION IN FETAL TYPE II EPITHELIAL CELLS EXPOSED TO CYCLIC MECHANICAL STRETCH

Experimental Lung Research ◽

10.1080/01902140802339615 ◽

2008 ◽

Vol 34 (10) ◽

pp. 663-680 ◽

Cited By ~ 17

Author(s):

Ophira Silbert ◽

Yulian Wang ◽

Benjamin S. Maciejewski ◽

Hyeon–Soo Lee ◽

Sunil K. Shaw ◽

...

Keyword(s):

Epithelial Cells ◽

Mechanical Stretch ◽

Type Ii ◽

Cell Alignment ◽

Actin Remodeling

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Mechanotransduction of stretch-induced prostanoid release by fetal lung epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00510.2005 ◽

2006 ◽

Vol 291 (3) ◽

pp. L487-L495 ◽

Cited By ~ 42

Author(s):

Ian B. Copland ◽

Denis Reynaud ◽

Cecil Pace-Asciak ◽

Martin Post

Keyword(s):

Mechanical Ventilation ◽

Arachidonic Acid ◽

Epithelial Cells ◽

Fetal Lung ◽

Lung Epithelial Cells ◽

Cyclic Stretch ◽

Mitogen Activated Protein Kinase ◽

Lung Epithelial ◽

The Media ◽

Cox 2

Mechanical ventilation is the primary supportive treatment for infants and adults suffering from severe respiratory failure. Adverse mechanical ventilation (overdistension of the lung) triggers a proinflammatory response. Along with cytokines, inflammatory mediators such as bioactive lipids are involved in the regulation of the inflammatory response. The arachidonic acid pathway is a key source of bioactive lipid mediators, including prostanoids. Although ventilation has been shown to influence the production of prostanoids in the lung, the mechanotransduction pathways are unknown. Herein, we established that cyclic stretch of fetal lung epithelial cells, but not fibroblasts, can evoke an extremely sensitive, rapid alteration in eicosanoid metabolism through a cyclooxygenase (COX)-2 dependent mechanism. Cyclic stretch significantly increased PGI2, PGF2α, PGD2, PGE2, and thromboxane B2 levels in the media of epithelial cells, but did not alter leukotriene B4 or 12-hydroxyeicosatetraenoic acid levels. Inhibition of COX-2, but not COX-1, attenuated the cyclic stretch-induced PG increase in the media, suggesting that cyclic stretch primarily affected PG synthesis. Substrate (free arachidonic acid) availability for PG generation was increased because of a cyclic stretch-induced activation of cytosolic phospholipase A2 (cPLA2) via an influx of extracellular calcium and phosphorylation by mitogen-activated protein kinase, p44/42MAPK. The data are compatible with cPLA2 and COX-2 being intimately involved in regulating the injury response to adverse mechanical ventilation.

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An enhancer region determines hSP-B gene expression in bronchiolar and ATII epithelial cells in transgenic mice

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00280.2002 ◽

2003 ◽

Vol 284 (3) ◽

pp. L481-L488 ◽

Cited By ~ 10

Author(s):

Li Yang ◽

Angela Naltner ◽

Allison Kreiner ◽

Dong Yan ◽

Angelynn Cowen ◽

...

Keyword(s):

Gene Expression ◽

Epithelial Cells ◽

Transgenic Mice ◽

Transgenic Mouse ◽

Lung Development ◽

Alveolar Type ◽

Transcriptional Level ◽

Lacz Gene ◽

Type Ii ◽

Enhancer Region

Regulation of the surfactant protein B gene (SP-B) is developmentally controlled and highly tissue specific. To elucidate the SP-B gene temporal/spatial expression pattern in lung development at the transcriptional level, a transgenic mouse model line carrying the human SP-B (hSP-B) 1.5-kb 5′-flanking regulatory region and the lacZ gene was established. Expression of hSP-B 1.5-kb lacZ gene started at the onset of lung formation [embryonic day 9 (E9)] and was restricted to epithelial cells throughout prenatal and postnatal lung development. In the adult lung, hSP-B 1.5-kb lacZ gene expression was restricted to bronchiolar and alveolar type II epithelial cells. In lung explant culturing studies, the hSP-B 1.5-kb lacZ gene was highly expressed in newly formed epithelial tubules during the respiratory branching process. In a second transgenic mouse line, an enhancer region, which binds to thyroid transcription factor-1, retinoic acid receptor, signal transducers and activators of transcription 3, and nuclear receptor coactivators (SRC-1, ACTR, TIF2, and CBP/p300), was deleted from the hSP-B 1.5-kb lacZ gene. The deletion abolished hSP-B lacZ gene expression in bronchiolar epithelial cells and significantly reduced its expression level in alveolar type II epithelial cells in transgenic mice.

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STAT-3 regulates surfactant phospholipid homeostasis in normal lung and during endotoxin-mediated lung injury

Journal of Applied Physiology ◽

10.1152/japplphysiol.00875.2007 ◽

2008 ◽

Vol 104 (6) ◽

pp. 1753-1760 ◽

Cited By ~ 29

Author(s):

Machiko Ikegami ◽

Angelica Falcone ◽

Jeffrey A. Whitsett

Keyword(s):

Epithelial Cells ◽

Lung Injury ◽

Critical Role ◽

Lung Mechanics ◽

Normal Lung ◽

Type Ii Cells ◽

Type Ii ◽

Phospholipid Synthesis ◽

Respiratory Epithelial Cells ◽

Respiratory Epithelial

Acute lung injury associated with surfactant deficiency remains a major cause of pulmonary morbidity and mortality. Since signal transducer and activator of transcription-3 (STAT-3) plays an important role in protecting respiratory epithelial cells during injury, we hypothesized that STAT-3 may regulate gene expression in type II cells that mediate surfactant phospholipid synthesis. Conditional deletion of Stat-3 in respiratory epithelial cells in the lung of transgenic mice ( Stat-3Δ/Δ mice) decreased surfactant phospholipid synthesis and secretion. Deletion of Stat-3 was associated with decreased expression of Akt2, Srebf-1, and other genes expressed in type II cells that may influence surfactant phospholipid synthesis ( Glut-1, Slc34a2, Gpam, Acox2, and Cds2). Stat-3Δ/Δ mice were more susceptible to intratracheal lipopolysaccharide (LPS). Saturated phosphatidylcholine and surfactant protein B levels were significantly decreased in bronchoalveolar lavage fluid from LPS-treated Stat-3Δ/Δ mice. Alveolar capillary leak, proinflammatory cytokine expression, and perturbations of lung mechanics caused by LPS were exacerbated after deletion of STAT-3. STAT-3 plays a critical role in the regulation of surfactant lipid synthesis in the normal lung and during lung injury caused by LPS.

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Bcl-2 overexpression in type II epithelial cells does not prevent hyperoxia-induced acute lung injury in mice

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00212.2009 ◽

2010 ◽

Vol 299 (3) ◽

pp. L312-L322 ◽

Cited By ~ 8

Author(s):

Isabelle Métrailler-Ruchonnet ◽

Alessandra Pagano ◽

Stéphanie Carnesecchi ◽

Karim Khatib ◽

Pedro Herrera ◽

...

Keyword(s):

Cell Death ◽

Epithelial Cells ◽

Lung Injury ◽

Ex Vivo ◽

Lung Damage ◽

Type Ii Cells ◽

Type Ii ◽

Lung Weight

Bcl-2 is an anti-apoptotic molecule preventing oxidative stress damage and cell death. We have previously shown that Bcl-2 is able to prevent hyperoxia-induced cell death when overexpressed in a murine fibrosarcoma cell line L929. We hypothesized that its specific overexpression in pulmonary epithelial type II cells could prevent hyperoxia-induced lung injury by protecting the epithelial side of the alveolo-capillary barrier. In the present work, we first showed that in vitro Bcl-2 can rescue murine pulmonary epithelial cells (MLE12) from oxygen-induced cell apoptosis, as shown by analysis of LDH release, annexin V/propidium staining, and caspase-3 activity. We then generated transgenic mice overexpressing specifically Bcl-2 in lung epithelial type II cells under surfactant protein C (SP-C) promoter (Tg-Bcl-2) and exposed them to hyperoxia. Bcl-2 did not hinder hyperoxia-induced mitochondria and DNA oxidative damage of type II cell in vivo. Accordingly, lung damage was identical in both Tg-Bcl-2 and littermate mice strains, as measured by lung weight, bronchoalveolar lavage, and protein content. Nevertheless, we observed a significant lower number of TUNEL-positive cells in type II cells isolated from Tg-Bcl-2 mice exposed to hyperoxia compared with cells isolated from littermate mice. In summary, these results show that although Bcl-2 overexpression is able to prevent hyperoxia-induced cell death at single cell level in vitro and ex vivo, it is not sufficient to prevent cell death of parenchymal cells and to protect the lung from acute damage in mice.

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Cellular biomechanics in the lung

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00141.2002 ◽

2002 ◽

Vol 283 (3) ◽

pp. L503-L509 ◽

Cited By ~ 39

Author(s):

Christopher M. Waters ◽

Peter H. S. Sporn ◽

Mingyao Liu ◽

Jeffrey J. Fredberg

Keyword(s):

Wound Healing ◽

Epithelial Cells ◽

Airway Hyperresponsiveness ◽

Mechanical Stretch ◽

Mechanical Deformation ◽

Airway Epithelial Cells ◽

Lung Epithelial Cells ◽

Stable Cell Line ◽

Normal Lung ◽

Mechanical Forces

Mechanical forces affect both the function and phenotype of cells in the lung. In this symposium, recent studies were presented that examined several aspects of biomechanics in lung cells and their relationship to disease. Wound healing and recovery from injury in the airways involve epithelial cell spreading and migration on a substrate that undergoes cyclic mechanical deformation; enhanced green fluorescent protein-actin was used in a stable cell line to examine cytoskeletal changes in airway epithelial cells during wound healing. Eosinophils migrate into the airways during asthmatic attacks and can also be exposed to cyclic mechanical deformation; cyclic mechanical stretch caused a decrease in leukotriene C4 synthesis that may be dependent on mechanotransduction mechanisms involving the production of reactive oxygen species. Recent studies have suggested that proinflammatory cytokines are increased in ventilator-induced lung injury and may be elevated by overdistention of the lung tissue; microarray analysis of human lung epithelial cells demonstrated that cyclic mechanical stretch alone profoundly affects gene expression. Finally, airway hyperresponsiveness is a basic feature of asthma, but the relationship between airway hyperresponsiveness and changes in airway smooth muscle (ASM) function remain unclear. New analysis of the behavior of the ASM cytoskeleton (CSK) suggests, however, that the CSK may behave as a glassy material and that glassy behavior may account for the extensive ASM plasticity and remodeling that contribute to airway hyperresponsiveness. Together, the presentations at this symposium demonstrated the remarkable and varied roles that mechanical forces may play in both normal lung physiology as well as pathophysiology.

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