• The Korean Journal of Physiology and Pharmacology
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• v.1 no.1
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• pp.65-70
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• 1997

In order to investigate the effect of ANP on surfactant secretion from alveolar type II cell(AT II cell) during circulatory derangement in adult respiratory distress syndrome (ARDS), the secretion of surfactant from AT II cells was evaluated in purely isolated AT II cultures from rat lungs. For the simulation of sympathetic stimulation during circulatory derangement, primary AT II cultures were incubatedwith isoproterenol and IBMX. In this isoproterenol stimulated AT II cells, ANP were added in the media for the investigation of effect of ANP on surfactant secretion from AT II cells. For the evaluation of surfactant secretion, $[^3H]-methylcholine$ was incorporated and the level of radiolabelled choline chloride secreted from the cells was determined. As previously reported, isoproterenol and IBMX stimulated surfactant secretion from AT II cells. Isoproterenol showed synergistic increase of surfactant secretion with IBMX in AT II cells. In isoproterenol stimulated AT II cells, physiological level of ANP inhibited the secretion of surfactant in primary cultures of AT II cells. On the basis of these experimental it is suggested that, in association with ciculatory change during ARDS, increased secretion of ANP by the pulmonary edema, hypoxia and congestive heart heart failure might aggravate the symptoms of ARDS by reduction of surfactant secretion from AT II cells.

• The Korean Journal of Physiology
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• v.28 no.1
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• pp.71-77
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• 1994

In the animal model of acute respiratory distress syndrome (ARDS) induced by N-nitroso-N-methylurethane (NNNMU) the secretory activity of alveolar type H cells during acute alveolar injury was investigated by determining phospholipid and pulmonary surfactant associated proteins in crude surfactant. The mechanism of the secretory change was studied by determination of DNA and RNA levels in the lung tissue. After induction of acute alveolar injury with NNNMU, pulmonary hemorrhage, atelectasis and gross hypertrophy were observed. Seven days after NNNMU treatment the level of total DNA in lung homogenate was increased markedly indicating that a hypertrophy was induced by cellular proliferation. Although the total DNA level increased, the RNA/DNA ratio was gradually decreased after NNNMU treatment. Seven days after NNNMU treatment the RNA/DNA ratio returned to the normal control level. During the acute alveolar injury, phospholipid and surfactant associated proteins were reduced significantly as compared with the control, implying that the secretory activity of alveolar type II cells was altered during acute alveolar injury induced by NNNMU. The protein content in crude surfactant during peak injury(7 days after NNNMU) was decreased significantly but phospholipid/protein ratios were identical in both control and NNNMU treatment groups. SDS-PAGE of proteins in crude pulmonary surfactant showed a decrease in major surfactant associated protein(M.W. 38,000) during acute alveolar injury. The present study may suggest that while alveolar type H cells proliferate markedly, transcription of alveolar type ll cell gene was inhibited by an unknown mechanism such as DNA methylation induced by NNNMU. Such an inhibition of transcriptional activity is thought to be associated with the decreased secretory activity of alveolar type ll cells, which may lead to pulmonary atelectasis and edema during the acute alveolar injury.

• Genomics & Informatics
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• v.17 no.1
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• pp.8.1-8.10
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• 2019

Alveolar type II cells constitute a small fraction of the total lung cell mass. However, they play an important role in many cellular processes including trans-differentiation into type I cells as well as repair of lung injury in response to toxic chemicals and respiratory pathogens. Transcription factors are the regulatory proteins dynamically modulating DNA structure and gene expression. Transcription factor profiling in microarray datasets revealed that several members of AP1, ATF, $NF-{\kappa}B$, and C/EBP families involved in diverse responses were expressed in mouse lung type II cells. A transcriptional factor signature consisting of Cebpa, Srebf1, Stat3, Klf5, and Elf3 was identified in lung type II cells, Sox9+ pluripotent lung stem cells as well as in mouse lung development. Identification of the transcription factor profile in mouse lung type II cells will serve as a useful resource and facilitate the integrated analysis of signal transduction pathways and specific gene targets in a variety of physiological conditions.

• Tuberculosis and Respiratory Diseases
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• v.70 no.6
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• pp.462-473
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• 2011

Background: Smoking is a risk factor for idiopathic pulmonary fibrosis (IPF), but the mechanism of the association remains obscure. There is evidence demonstrating that plasminogen activator inhibitor-1 (PAI-1) is involved in the progression of pulmonary fibrosis. This study was to determine whether the administration of small interfering RNA (siRNA) targeting PAI-1 or PAI-1 inhibitor to the cigarette smoking extract (CSE)-exposed rat alveolar type II epithelial cells (ATII cells) limits the epithelial-mesenchymal transition (EMT). Methods: ATII cells were isolated from lung of SD-rat using percoll gradient method and cultured with 5% CSE. The EMT was determined from the ATII cells by measuring the real-time RT PCR and western blotting after the PAI-1 siRNA transfection to the cells and after administration of tiplaxtinin, an inhibitor of PAI-1. The effect of PAI-1 inhibitor was also evaluated in the bleomycin-induced rats. Results: PAI-1 was overexpressed in the smoking exposed ATII cells and was directly associated with EMT. The EMT from the ATII cells was suppressed by PAI-1 siRNA transfection or administration of tiplaxtinin. Signaling pathways for EMT by smoking extract were through the phosphorylation of SMAD2 and ERK1/2, and finally Snail expression. Tiplaxtinin also suppressed the pulmonary fibrosis and PAI-1 expression in the bleomycin-induced rats. Conclusion: Our data shows that CSE induces rat ATII cells to undergo EMT by PAI-1 via SMAD2-ERK1/2-Snail activation. This suppression of EMT by PAI-1 siRNA transfection or PAI-1 inhibitor in primary type II alveolar epithelial cells might be involved in the attenuation of bleomycin-induced pulmonary fibrosis in rats.

• Advances in pediatric surgery
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• v.15 no.1
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• pp.1-10
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• 2009

Recently, amniotic fluid has gained attention as one of the potential sources for cell therapy and tissue engineering because it has characteristics of multipotent stem cells. However, current knowledge about what types of cells are naturally found in amniotic fluid is still limited. In this study, we aimed to investigate whether human amniotic fluid contains cells that have characteristics of respiratory cells. Samples of human amniotic fluid (5 mL per sample) obtained from amniocenteses were cultured with small airway growth medium (SAGM). Cells were grown until the third passage and the presence of type II alveolar cells were characterized by inverted microscopy, immunofluorescence, and reverse transcription polymerase chain reaction (RT-PCR). On inverted microscopy, cultured cells showed typical polygonal and cobblestone-like epithelial morphology. The morphology of cells was not changed after selection and passing. Immunofluorescence analysis demonstrated that the isolated cells stained positive for surfactant protein C (SPC), specific marker for type II alveolar cells. Cells also stained positive for TTF-1 protein but negative for CD 31 and vimentin. RT-PCR analysis of cells showed expression of SPC mRNA. This study has demonstrated that respiratory cells can be isolated and identified from human amniotic fluid cultured in SAGM medium. Our results may provide the basis for further investigations of amniotic fluid.

• Tuberculosis and Respiratory Diseases
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• v.82 no.2
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• pp.133-142
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• 2019

Background: Idiopathic pulmonary fibrosis involves irreversible alveolar destruction. Although alveolar epithelial type II cells are key functional participants within the lung parenchyma, how epithelial cells are affected upon bleomycin (BLM) exposure remains unknown. In this study, we determined whether BLM could induce cell cycle arrest via regulation of Schlafen (SLFN) family genes, a group of cell cycle regulators known to mediate growth-inhibitory responses and apoptosis in alveolar epithelial type II cells. Methods: Mouse AE II cell line MLE-12 were exposed to $1-10{\mu}g/mL$ BLM and $0.01-100{\mu}M$ baicalein (Bai), a G1/G2 cell cycle inhibitor, for 24 hours. Cell viability and levels of pro-inflammatory cytokines were analyzed by MTT and enzyme-linked immunosorbent assay, respectively. Apoptosis-related gene expression was evaluated by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Cellular morphology was determined after DAPI and Hoechst 33258 staining. To verify cell cycle arrest, propidium iodide (PI) staining was performed for MLE-12 after exposure to BLM. Results: BLM decreased the proliferation of MLE-12 cells. However, it significantly increased expression levels of interleukin 6, tumor necrosis factor ${\alpha}$, and transforming growth factor ${\beta}1$. Based on Hoechst 33258 staining, BLM induced condensation of nuclear and fragmentation. Based on DAPI and PI staining, BLM significantly increased the size of nuclei and induced G2/M phase cell cycle arrest. Results of qRT-PCR analysis revealed that BLM increased mRNA levels of BAX but decreased those of Bcl2. In addition, BLM/Bai increased mRNA levels of p53, p21, SLFN1, 2, 4 of Schlafen family. Conclusion: BLM exposure affects pulmonary epithelial type II cells, resulting in decreased proliferation possibly through apoptotic and cell cycle arrest associated signaling.

• Korean Journal of Veterinary Service
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• v.20 no.1
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• pp.55-67
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• 1997

The morphological development of lungs in fetuses of 60, 90 and 120 days of gestation and neonates of Korean native goats was investigated by light, scanning and transmission electron mictroscope. The results were summarized as follows ; 1. Gross findings ; In the 60-days-old fetus, the lung was developed and differentiated into six lobes. 2. Light microscopic findings : The gland-like bronchioles were formed in loose mesenchyme at 60 days of gestation and the bronchial wall contained smooth muscles. The loose mesenchyme had been replaced by compact parenchymal tissue at 90 days of gestation and the cartilage plates appeared in bronchial wall which contained blood vessels, submucosal glands and smooth muscles. The lung parenchyma consisted of a fine network of alveoli at 120 days of gestation and the bronchial wall contained well-developed blood vessels, submucosal glands, cartilage plates and smooth muscles. In neonates, the lung tissue was similar to the mature lung tissue and the bronchial wall contained well developed cartilage plates. 3. Scanning electron microscopic findings : The epithelial cells lining the tubules were composed of cuboidal or columnar at 60 days of gestation and the epithelial cells lining the large airways were often ciliated : some were covered with stubby microvilli. The epithelial cells lining the canals were cuboidal at 90 days of gestation and the epithelial cells lining the bronchioles were ciliated cells or nonciliated(clara) cells, The clara cells contained row microvilli. The alvealor development of this stage was rapidly progressed ; the subdivision of canals by alveolar crests and assosiated wall attenuation resulted alveoli at 120 days of gestation and the respiratory bronchioles were lined by ciliated or nonciliated epithelial cells. In neonates, the epithelial cells lining the alveolar walls were mainly covered with pneumocyte type I ; Some were covered with pneu-mocyte type II. 4. Transmission electron microscopic findings : The epithelial cells lining the tubules were adhered with tight junction at apical borders of the adjacent cells at 60 days of gestation, which contained few organells and glycogen. The epithelial cells lining the canals were composed mostly of cuboidal cell at 90 days of gestation and the epithelial cells lining of the bronchioles were ciliated of nonciliated cell, which contained few organelles and abundant glycogen. The epithelial cells lining the alveolar walls were composed of pneumocyte type I and a few pneumocyte type II at 120 days of gestation. The epithelial cells lining of the bronchioles were ciliated or nonciliated cells. In neonates, pneumocyte type I was observed as flat and thin cytoplasmic extension in shape. Otherwise, pneumocyte type II was observed as cuboidal type with apical microvilli and contained osmiophillic lamellar inclusion bodies. Putting these various experiment results together, the lung development was slowly progressed at early stage, which was rapidly progressed in the late stage of gestation.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.51-82
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• 2005

To compare the pulmonary toxicity between ultrafine colloidal silica particles (UFCSs) and fine colloidal silica particles (FCSs), mice were intratracheally instilled with 3 mg of 14-nm UFCSs and 230-nm FCSs and pathologically examined from 30 mill to 24 hr post-exposure. Histopathologically, lungs exposed to both sizes of particles showed bronchiolar degeneration and necrosis, neutrophilic inflammation in alveoli with alveolar type II cell proliferation and particle-laden alveolar macrophage accumulation. UFCSs, however, induced extensive alveolar hemorrhage compared to FCSs from 30 min onwards. UFCSs also caused more severe bronchiolar epithelial cell necrosis and neutrophil influx in alveoli than FCSs at 12 and 24 hr post-exposure. Laminin positive immunolabellings in basement membranes of bronchioles and alveoli of UFCSs treated animals was weaker than those of FCSs treated animals in all observation times. Electron microscopy demonstrated UFCSs and FCSs on bronchiolar and alveolar wall surface as well as in the cytoplasm of alveolar epithelial cells, alveolar macrophages and neutrophils. Type I alveolar epithelial cell erosion with basement membrane damage in UFCSs treated animals was more severe than those in FCSs treated animals. At 12 and 24 hr post-exposure, bronchiolar epithelia cells in UFCSs treated animals showed more intense vacuolation and necrosis compared to FCSs treated animals. These findings suggest that UFCSs has greater ability to induce lung inflammation and tissue damages than FCSs.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.5
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• pp.617-628
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• 1998

In order to understand the pathogenetic mechanism of adult respiratory distress syndrome (ARDS), the role of phospholipase A2 (PLA2) in association with oxidative stress was investigated in rats. $Interleukin-1{\alpha}\;(IL-1,\;50\;{\mu}g/rat)$ was used to induce acute lung injury by neutrophilic respiratory burst. Five hours after IL-1 insufflation into trachea, microvascular integrity was disrupted, and protein leakage into the alveolar lumen was followed. An infiltration of neutrophils was clearly observed after IL-1 treatment. It was the origin of the generation of oxygen radicals causing oxidative stress in the lung. IL-1 increased tumor necrosis factor (TNF) and cytokine-induced neutrophil chemoattractant (CINC) in the bronchoalveolar lavage fluid, but mepacrine, a PLA2 inhibitor, did not change the levels of these cytokines. Although IL-1 increased PLA2 activity time-dependently, mepacrine inhibited the activity almost completely. Activation of PLA2 elevated leukotriene C4 and B4 (LTC4 and LTB4), and 6-keto-prostaglandin $F2{\alpha}\;(6-keto-PGF2{\alpha})$ was consumed completely by respiratory burst induced by IL-1. Mepacrine did not alter these changes in the contents of lipid mediators. To estimate the functional changes of alveolar barrier during the oxidative stress, quantitative changes of pulmonary surfactant, activity of gamma glutamyltransferase (GGT), and ultrastructural changes were examined. IL-1 increased the level of phospholipid in the bronchoalveolar lavage (BAL) fluid, which seemed to be caused by abnormal, pathological release of lamellar bodies into the alveolar lumen. Mepacrine recovered the amount of surfactant up to control level. IL-1 decreased GGT activity, while mepacrine restored it. In ultrastructural study, when treated with IL-1, marked necroses of endothelial cells and type II pneumocytes were observed, while mepacrine inhibited these pathological changes. In histochemical electron microscopy, increased generation of oxidants was identified around neutrophils and in the cytoplasm of type II pneumocytes. Mepacrine reduced the generation of oxidants in the tissue produced by neutrophilic respiratory burst. In immunoelectron microscopic study, PLA2 was identified in the cytoplasm of the type II pneumocytes after IL-1 treatment, but mepacrine diminished PLA2 particles in the cytoplasm of the type II pneumocyte. Based on these experimental results, it is suggested that PLA2 plays a pivotal role in inducing acute lung injury mediated by IL-1 through the oxidative stress by neutrophils. By causing endothelial damage, functional changes of pulmonary surfactant and alveolar type I pneumocyte, oxidative stress disrupts microvascular integrity and alveolar barrier.

• Tuberculosis and Respiratory Diseases
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• v.43 no.6
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• pp.925-935
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• 1996

Background : In order to elucidate one of the pathogenic mechanisms of ARDS associated with pulmonary surfactant and oxidant injury, acute lung injury was induced by N-nitroso N-methylurethane (NNNMU). In this model, the role of phospholipase $A_2$ ($PLA_2$), surfactant, gamma glutamyl transferase (GGT) and morphology were investigated to delineate one of the pathogenic mechanisms of ARDS by inhibition of $PLA_2$ with high dose of dexamethasone. Method: Acute lung injury was induced in Sprague-Dawley rats by NNNMU which is known to induce acute lung injury in experimental animals. To know the function of the alveolar type II cells, GGT activity in the lung and bronchoalveolar lavage was measured. Surfactant phospholipid was measured also. $PLA_2$ activity was measured to know the role of $PLA_2$ in ARDS. Morphological study was performed to know the effect of $PLA_2$ inhibition on the ultrastructure of the lung by high dose of dexamethasone. Results : Six days after NNNMU treatment (4 mg/kg), conspicuous pulmonary edema was induced and the secretion of pulmonary surfactant was decreased significantly. In the acutely injured rats' lung massive infiltration of leukocytes was observed. At the same time rats given NNNMU had increased $PLA_2$ and GGT activity tremendously. Morphological study revealed bizarre shaped alveolar type II cells and hypertrophied lamellar bodies in the cytoplasm of the alveolar type II cells. But after dexamethasone treatment (20 mg/kg, for six days) in NNNMU-treated rats, these changes were diminished i.e. there were decrease of pulmonary edema and increase of surfactant secretion from alveolar type D cells. Rats given dexamethasone and NNNMU had decreased $PLA_2$ and GGT activity in comparison to NNNMU induced ARDS rats. Conclusion : Inhibition of $PLA_2$ by high dose of dexamethasone decreased pathological findings caused by infiltration of leukocytes and respiratory burst. Based on these experimental results, it is suggested that an activation of $PLA_2$ is the one of the major factors to evoke the acute lung injury in NNNMU-induced ARDS rats.