[The effect of phospholipid transfer protein on cigarette smoke extract induced epithelial-mesenchymal transition of rat alveolar type Ⅱ cells]

OBJECTIVE

To investigate the effect of phospholipid transfer protein(PLTP) on cigarette smoke extract(CSE) induced epithelial-mesenchymal transition(EMT) in rat alveolar Type Ⅱ cells (RLE-6TN).

METHODS

CSE of different concentrations (0%, 0.25%, 0.5% and 1%) was co-cultured for 2 or 3 days with RLE-6TN, either pre-treated or not pre-treated with siRNA-PLTP for 6 h. Expression levels of E-cadherin mRNA and Vimentin mRNA were examined by RT-PCR, while expression levels of PLTP, E-cadherin, N-cadherin and Vimentin were examined by Western blot.

RESULTS

Our results showed that the expression of E-cadherin mRNA decreased in CSE-treated groups: 1.01±0.05, 0.74±0.05, 0.65±0.03, 0.30±0.08 respectively at different concentrations of CSE (0 %, 0.25%, 0.5 %, and 1.0%); while the level of Vimentin mRNA increased significantly in 1% CSE treated cells(1.88±0.49), compared with control cells (1.01±0.20). Treatment with CSE at different concentrations (0%, 0.25%, 0.5% and 1%) showed that the protein levels of PLTP were 0.42±0.02, 0.89±0.25, 1.08±0.18, 1.61±0.06 respectively; those of E-cadherin were 1.61±0.04, 1.08±0.10, 0.62±0.08, 0.68±0.17, respectively; those of N-cadherin were 0.60±0.14, 0.57±0.26, 0.88±0.30, 1.94±0.54, respectively; and those of Vimentin were 0.61±0.05, 0.98±0.16, 1.07±0.14, 1.34±0.19, respectively; all P<0.05 when the 1% CSE group was compared with the control group. EMT induced by CSE was significantly inhibited by siRNA-PLTP.

CONCLUSION

PLTP may be involved in CSE induced EMT of rat alveolar cells.

A Novel Approach for Ovine Primary Alveolar Epithelial Type II Cell Isolation and Culture from Fresh and Cryopreserved Tissue Obtained from Premature and Juvenile Animals

The in vivo ovine model provides a clinically relevant platform to study cardiopulmonary mechanisms and treatments of disease; however, a robust ovine primary alveolar epithelial type II (ATII) cell culture model is lacking. The objective of this study was to develop and optimize ovine lung tissue cryopreservation and primary ATII cell culture methodologies for the purposes of dissecting mechanisms at the cellular level to elucidate responses observed in vivo. To address this, we established in vitro submerged and air-liquid interface cultures of primary ovine ATII cells isolated from fresh or cryopreserved lung tissues obtained from mechanically ventilated sheep (128 days gestation-6 months of age). Presence, abundance, and mRNA expression of surfactant proteins was assessed by immunocytochemistry, Western Blot, and quantitative PCR respectively on the day of isolation, and throughout the 7 day cell culture study period. All biomarkers were significantly greater from cells isolated from fresh than cryopreserved tissue, and those cultured in air-liquid interface as compared to submerged culture conditions at all time points. Surfactant protein expression remained in the air-liquid interface culture system while that of cells cultured in the submerged system dissipated over time. Despite differences in biomarker magnitude between cells isolated from fresh and cryopreserved tissue, cells isolated from cryopreserved tissue remained metabolically active and demonstrated a similar response as cells from fresh tissue through 72 hr period of hyperoxia. These data demonstrate a cell culture methodology using fresh or cryopreserved tissue to support study of ovine primary ATII cell function and responses, to support expanded use of biobanked tissues, and to further understanding of mechanisms that contribute to in vivo function of the lung.

[Effects of Tetrandrine Prenatal Intervention on Alveolar Epithelial Cells Type I Differentiation in Rat Model of Nitrofen-induced Congenital Diaphragmatic Hernia]

OBJECTIVE

To investigate the effects of Tetrandrine (TET) prenatal intervention on the differentiation of alveolar epithelial cells type I (AEC I) in rat model of Nitrofen-induced congenital diaphragmatic hernia (CDH).

METHODS

Timed-pregnant Sprague-Dawley rats were divided into three groups, namely control, CDH and TET group on day 9.5 of gestation. The rats in TET group and CDH group were given 125 mg of Nitrofen by gavage one time, while the rats in control group were given the same dose of seed fat. After that, the rats in TET group was given 30 mg/kg of TET by gavage once a day for three days from day 18.5 of gestation, while the rats in CDH and control group were given the same dose of normal saline. On day 21.5 of gestation, all fetuses were delivered by cesarean, the lungs of fetuses were histologically evaluated by microscope and electron microscope. The expressions of type I cell-specific protein (RT140) and thyroid transcription factor 1 (TTF1) in alveolar fluid content were analyzed by RT-PCR and immunohistochemistry staining. To detect the number of AEC I and AEC II of each group by transmission electron microscopy and calculate the percentage of AEC I and AEC II (I/II%).

RESULTS

The microscope and electron microscope study found the lungs of fetuses in CDH group showed marked hypoplasia, in contrast to the improvement of hypoplasia in TET fetuses. The pulmonary alveolar area had significant difference statistically (P < 0.01) in each group, which present as control > TET > CDH. I/II% had significant difference statistically (P < 0.01) in each group, which present as control > TET > CDH. The expression level of TTF1 was up-regulated in both CDH and TET groups, and it was higher in CDH group (P < 0.01). The expression level of RT140 were down-regulated in CDH and TET groups, which was lower in CDH group (P < 0.01).

CONCLUSION

The development of AEC I was interfered in CDH rat model, TET prenatal treatment could improve the lung development of CDH.

Recellularization of decellularized lung scaffolds is enhanced by dynamic suspension culture

Strategies are needed to improve repopulation of decellularized lung scaffolds with stromal and functional epithelial cells. We demonstrate that decellularized mouse lungs recellularized in a dynamic low fluid shear suspension bioreactor, termed the rotating wall vessel (RWV), contained more cells with decreased apoptosis, increased proliferation and enhanced levels of total RNA compared to static recellularization conditions. These results were observed with two relevant mouse cell types: bone marrow-derived mesenchymal stromal (stem) cells (MSCs) and alveolar type II cells (C10). In addition, MSCs cultured in decellularized lungs under static but not bioreactor conditions formed multilayered aggregates. Gene expression and immunohistochemical analyses suggested differentiation of MSCs into collagen I-producing fibroblast-like cells in the bioreactor, indicating enhanced potential for remodeling of the decellularized scaffold matrix. In conclusion, dynamic suspension culture is promising for enhancing repopulation of decellularized lungs, and could contribute to remodeling the extracellular matrix of the scaffolds with subsequent effects on differentiation and functionality of inoculated cells.

[Protective Effect of Activated Nrf2 against Hyperoxia-induced Lung Injury in Neonatal Rats]

OBJECTIVE

To observe the effect of nuclear factor erythroid 2-related factor 2 (Nrf2) agonist on the apoptosis of alveolar cell induced by hyperoxia and to explore whether Nrf2 activation could protect neonatal rats from hyperoxia induced lung injury.

METHODS

90 neonatal Sprague-Dawley rats were randomized into room air group (FiO2 =21%, N group), hyperoxia group (0 group) and Nrf2 group (n=30 each). Neonatal rats in the 0 group and Nrf2 group received saline 0. 2 mL and Nrf2 agonist 30 mg/kg respectively at the first and second day after birth, and were exposed in high concentration oxygen (95%) for 4 d. N group rats were fed in room air. The apoptotic index (AI) and Nrf2 expression of lung tissue were detected by TUNEL and immunohistochemistry staining respectively.

RESULTS

Compared with 0 group (28. 8% ± 3. 0%), the AI of alveolar. cell was lower in N group (0. 7%±0. 6%) and Nrf2 group (7. 2% ± 0. 8%) (P<0. 01). The expression of Nrf2 was significantly higher in 0 group (926. 80 ± 130. 51) and Nrf2 group (1038. 40±151. 12) than that in N group (30. 03±9. 99) (P<0. 01).

CONCLUSION

Nrf2 activation could reduce the alveolar cellular apoptosis and protect neonatal rats from hyperoxia induced lung injury.

[Ischemic postconditioning attenuates pneumocyte apoptosis after lung ischemia/reperfusion injury via inactivation of p38 MAPK]

OBJECTIVE

To investigate the role of p38 MAPK on ischemic postconditioning (IPO) attenuating pneumocyte apoptosis after lung ischemia/reperfusion injury (LIRI).

METHODS

Forty adult male SD rats were randomly divided into 5 groups based upon the intervention (n = 8): control group (C), LIR group (I/R), LIR + IPO group (IPO), IPO + solution control group (D), IPO + SB203580 group (SB). Left lung tissue was isolated after the 2 hours of reperfusion, the ratio of wet lung weight to dry lung weight (W/D), and total lung water content (TLW) were measured. The histological structure of the left lung was observed under light and electron transmission microscopes, and scored by alveolar damage index of quantitative assessment (IQA). Apoptosis index (AI) of lung tissue was determined by terminal deoxynuleotidyl transferase mediated dUTP nick end and labeling (TUNEL) method. The mRNA expression and protein levels of and Bax were measured by RT-PCR and quantitative immunohistochemistry (IHC).

RESULTS

Compared with C group, W/D, TLW, IQA, AI and the expression of Bax of I/R were significantly increased, the expression of Bcl-2 and Bcl-2/Bax were significantly decreased (P < 0.05, P < 0.01), and was obviously morphological abnormality in lung tissue. Compared with I/R group, all the indexes of IPO except for the expression of Bcl-2 and Bcl-2/ Bax were obviously reduced, the expression of Bcl-2 and Bcl-2/Bax were increased (P < 0.05, P < 0.01). All the indexes between D and IPO were little or not significant( P > 0.05). The expression of Bcl-2 and Bcl-2/Bax of SB were significantly increased and other indexes were reduced than those of IPO (P < 0.05, P < 0.01).

CONCLUSION

IPO may attenuate pneumocyte apoptosis in LIRI by inactivation of p38 MAPK, up-regulating expression of Bcl-2/Bax ratio.

Whole-genome analysis of temporal gene expression during early transdifferentiation of human lung alveolar epithelial type 2 cells in vitro

It is generally accepted that the surfactant-producing pulmonary alveolar epithelial type II (AT2) cell acts as the progenitor of the type I (AT1) cell, but the regulatory mechanisms involved in this relationship remain the subject of active investigation. While previous studies have established a number of specific markers that are expressed during transdifferentiation from AT2 to AT1 cells, we hypothesized that additional, previously unrecognized, signaling pathways and relevant cellular functions are transcriptionally regulated at early stages of AT2 transition. In this study, a discovery-based gene expression profile analysis was undertaken of freshly isolated human AT2 (hAT2) cells grown on extracellular matrix (ECM) substrata known to either support (type I collagen) or retard (Matrigel) the early transdifferentiation process into hAT1-like cells over the first three days. Cell type-specific expression patterns analyzed by Illumina Human HT-12 BeadChip yielded over 300 genes that were up- or down-regulated. Candidate genes significantly induced or down-regulated during hAT2 transition to hAT1-like cells compared to non-transitioning hAT2 cells were identified. Major functional groups were also recognized, including those of signaling and cytoskeletal proteins as well as genes of unknown function. Expression of established signatures of hAT2 and hAT1 cells, such as surfactant proteins, caveolin-1, and channels and transporters, was confirmed. Selected novel genes further validated by qRT-PCR, protein expression analysis, and/or cellular localization included SPOCK2, PLEKHO1, SPRED1, RAB11FIP1, PTRF/CAVIN-1 and RAP1GAP. These results further demonstrate the utility of genome-wide analysis to identify relevant, novel cell type-specific signatures of early ECM-regulated alveolar epithelial transdifferentiation processes in vitro.

Human decidua-derived mesenchymal stem cells differentiate into functional alveolar type II-like cells that synthesize and secrete pulmonary surfactant complexes

Lung alveolar type II (ATII) cells are specialized in the synthesis and secretion of pulmonary surfactant, a lipid-protein complex that reduces surface tension to minimize the work of breathing. Surfactant synthesis, assembly and secretion are closely regulated and its impairment is associated with severe respiratory disorders. At present, well-established ATII cell culture models are not available. In this work, Decidua-derived Mesenchymal Stem Cells (DMSCs) have been differentiated into Alveolar Type II- Like Cells (ATII-LCs), which display membranous cytoplasmic organelles resembling lamellar bodies, the organelles involved in surfactant storage and secretion by native ATII cells, and accumulate disaturated phospholipid species, a surfactant hallmark. Expression of characteristic ATII cells markers was demonstrated in ATII-LCs at gene and protein level. Mimicking the response of ATII cells to secretagogues, ATII-LCs were able to exocytose lipid-rich assemblies, which displayed highly surface active capabilities, including faster interfacial adsorption kinetics than standard native surfactant, even in the presence of inhibitory agents. ATII-LCs could constitute a highly useful ex vivo model for the study of surfactant biogenesis and the mechanisms involved in protein processing and lipid trafficking, as well as the packing and storage of surfactant complexes.

[Effects of ischemic postconditioning on pneumocyte apoptosis after lung ischemia/reperfusion injury in rats]

OBJECTIVE

To investigate the effects of ischemic postconditioning (IPostC) on pneumocyte apoptosis after lung ischemia/reperfusion injury in rats.

METHODS

Adult male SD rats were randomly divided into 3 groups based upon the intervention (n = 8): control group (C), lung ischemic reperfusion group (LIR), LIR+ IPostC group (IPostC). At the end of the experiment, blood specimens drawn from the arteria carotis were tested for the content of malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and myeloperoxidase (MPO); the pneumocyte apoptosis index (AI) was achieved by tennrminal deoxynucleotidyl transferase mediated dUTP nick end abeling (TUNEL); the expression of Bcl-2, Bax protein in lung tissue was accessed by quantitative immunohistochemistry (MHC) and Bcl-2, Bax mRNA by RT-PCR.

RESULTS

IPostC could significantly attenuate the MDA level, MPO activity and improve SOD activity in blood serum which was comparable to I/R and significantly reduced the number of TUNEL-positive cells compared with I/R group, expressed as Al (% total nuclei) from (39.0 +/- 3.46) to (8.0 +/- 0.88) (P < 0.01). The protein and mRNA expression of Bcl-2 and Bax showed that IPO significantly attenuated the ischemia/reperfusion-upregulated expression of Bax protein but improved the expression of Bcl-2 that improved the Bcl-2/Bax ratio (P < 0.01) .

CONCLUSION

IPostC may attenuate pneumocyte apoptosis in LIRI by up-regulating expression of Bcl-2/Bax ratio and by inhibiting oxidant generation and neutrophils filtration.

Human iPS cell-derived alveolar epithelium repopulates lung extracellular matrix

The use of induced pluripotent stem cells (iPSCs) has been postulated to be the most effective strategy for developing patient-specific respiratory epithelial cells, which may be valuable for lung-related cell therapy and lung tissue engineering. We generated a relatively homogeneous population of alveolar epithelial type II (AETII) and type I (AETI) cells from human iPSCs that had phenotypic properties similar to those of mature human AETII and AETI cells. We used these cells to explore whether lung tissue can be regenerated in vitro. Consistent with an AETII phenotype, we found that up to 97% of cells were positive for surfactant protein C, 95% for mucin-1, 93% for surfactant protein B, and 89% for the epithelial marker CD54. Additionally, exposing induced AETII to a Wnt/β-catenin inhibitor (IWR-1) changed the iPSC-AETII-like phenotype to a predominantly AETI-like phenotype. We found that of induced AET1 cells, more than 90% were positive for type I markers, T1α, and caveolin-1. Acellular lung matrices were prepared from whole rat or human adult lungs treated with decellularization reagents, followed by seeding these matrices with alveolar cells derived from human iPSCs. Under appropriate culture conditions, these progenitor cells adhered to and proliferated within the 3D lung tissue scaffold and displayed markers of differentiated pulmonary epithelium.

Trolox contributes to Nrf2-mediated protection of human and murine primary alveolar type II cells from injury by cigarette smoke

Cigarette smoke (CS) is a main risk factor for chronic obstructive pulmonary disease (COPD). Oxidative stress induced by CS causes DNA and lung damage. Oxidant/antioxidant imbalance occurs in the distal air spaces of smokers and in patients with COPD. We studied the effect of oxidative stress generated by CS both in vivo and in vitro on murine primary alveolar type II (ATII) cells isolated from nuclear erythroid 2-related factor-2 (Nrf2)(-/-) mice. We determined human primary ATII cell injury by CS in vitro and analyzed ATII cells isolated from smoker and non-smoker lung donors ex vivo. We also studied whether trolox (water-soluble derivative of vitamin E) could protect murine and human ATII cells against CS-induced DNA damage and/or decrease injury. We analyzed oxidative stress by 4-hydroxynonenal expression, reactive oxygen species (ROS) generation by Amplex Red Hydrogen Peroxide Assay, Nrf2, heme oxygenase 1, p53 and P53-binding protein 1 (53BP1) expression by immonoblotting, Nrf2 nuclear translocation, Nrf2 and p53 DNA-binding activities, apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay and cytokine production by ELISA. We found that ATII cells isolated from Nrf2(-/-) mice are more susceptible to CS-induced oxidative DNA damage mediated by p53/53BP1 both in vivo and in vitro compared with wild-type mice. Therefore, Nrf2 activation is a key factor to protect ATII cells against injury by CS. Moreover, trolox abolished human ATII cell injury and decreased DNA damage induced by CS in vitro. Furthermore, we found higher inflammation and p53 mRNA expression by RT-PCR in ATII cells isolated from smoker lung donors in comparison with non-smokers ex vivo. Our results indicate that the Nrf2 and p53 cross talk in ATII cells affect the susceptibility of these cells to injury by CS. Trolox can protect against oxidative stress, genotoxicity and inflammation induced by CS through ROS scavenging mechanism, and serve as a potential antioxidant prevention strategy against oxidative injury of ATII cells in CS-related lung diseases.

Roles of p38 MAPK and JNK in TGF-β1-induced human alveolar epithelial to mesenchymal transition

BACKGROUND AND AIMS

Idiopathic pulmonary fibrosis (IPF) is associated with significant morbidity and mortality despite aggressive therapy. The aim of the present study is to investigate the roles of p38 MAPK and JNK in TGF-β1-induced human alveolar epithelial to mesenchymal transition (EMT), which could be a possible mechanism of IPF.

METHODS

A549 cells were treated with TGF-β1 (3 ng/mL) for 48 h to induce EMT. The expression of mesenchymal phenotypic markers including desmin, α-smooth muscle actin (α-SMA) and vimentin, and expression of epithelial phenotypic markers including E-cadherin, zonula occludens-1 (ZO-1) and aquaporin-5 (AQP5) were detected by Western blot. The roles of p38 MAPK and JNK in TGF-β1-mediated EMT were investigated using gene silencing and inhibitor SB-203580 and SP-600125.

RESULTS

The data showed that TGF-β1 induced A549 cells with an alveolar epithelial type II cell phenotype to undergo EMT. The process of EMT was accompanied by morphological alteration and expression of the myofibroblast marker desmin, α-SMA and vimentin, concomitant with a downregulation of the epithelial cell marker E-cadherin, ZO-1 and AQP5. TGF-β1-induced EMT occurred through phosphorylation of p38 MAPK and JNK and was inhibited by inhibitor SB-203580 and SP-600125 and gene silencing.

CONCLUSIONS

TGF-β1 induces A549 alveolar epithelial cells (AECs) to undergo EMT partially via p38 MAPK and JNK activation and supports the concept of EMT in lung epithelial cells.

Lung alterations following single or multiple low-dose carbon black nanoparticle aspirations in mice

Carbon black nanoparticle (CBNP) applications in high doses have been shown to be harmful to the lung. It is postulated that even small, environmentally relevant concentrations induce changes on lung homeostasis. The present study determined the impact of low-dose single and multiple CBNP (Printex 90) applications on mouse alveolar cell metabolism, especially inflammatory and oxidative stress parameters. Nanoparticles were administered to mice by a single or 8 oropharyngeal aspirations at wk 1, 2, 3, 5, 7, 9, 11, and 12 using 7 μg Printex 90, 7 μg DQ12 quartz (positive control), with water vehicle and saline as negative controls. After 2 d or 3 mo lung function was analyzed. Further lung histology, bronchoalveolar lavage fluid (BALF) parameters, and mRNA expression of cytokines and antioxidants enzymes in type II pneumocytes were measured on d 3 or after 3 mo. Single low-dose Printex 90 application induced no marked alterations in lung functions or BALF phospholipid levels but significant decrease in superoxide dismutase 2 and numerically elevated glutathione peroxidase 3 mRNA expression levels in type II pneumocytes. Multiple CBNP applications produced reduced lung function, collagen accumulation, elevated phospholipid levels in BALF, and a massive infiltration of macrophages. Type II pneumocyte mRNA expression of antioxidative enzymes remained unchanged throughout the subchronic experiment, but showed a significant decrease in interleukin (IL)-6Rα mRNA expression. This study demonstrates that an environmentally relevant CBNP concentration induced an acute inflammatory response, an effect that is exacerbated throughout the subchronic duration.

[Effects of simvastatin on lipopolysaccharide induced α-subunit epithelial sodium channel mRNA in rat lung alveolar type II epithelial cells]

OBJECTIVE

To study the impact of simvastatin on α-subunit epithelial sodium channel (α-ENaC) mRNA expression in primary culture alveolar typeII (ATII) epithelial cell of rats induced by lipopolysaccharide (LPS) in vitro.

METHODS

ATII of primary generation were isolated from adult Sprague-Dawley (SD) rats. The cells were randomly divided into five groups: blank control group, LPS injured group (final concentration of LPS 1 mg/L), simvastatin low and high concentration groups (final concentration of simvastatin 20 μmol/L, 30 μmol/L, respectively), solution control group. Then, after being intervened for 1, 12 and 24 hours, the level of human tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were monitored by enzyme-linked immunosorbent assay (ELISA), and α-ENaC mRNA expression was tested by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

After being intervened for 1, 12 and 24 hours, expressions of TNF-α and IL-1β in LPS injured group were obviously higher than those in blank control group. Expressions of TNF-α and IL-1β at 1, 12 and 24 hours in simvastatin low concentration group were significantly decreased compared with those in LPS injured group (TNF-α 1 hour: 1178.80±127.43 ng/L vs. 2336.00±170.04 ng/L, 12 hours: 1003.60±59.61 ng/L vs. 2479.80±210.41 ng/L, 24 hours: 695.80±25.24 ng/L vs. 1167.60±132.72 ng/L; IL-β 1 hour: 285.00±42.60 ng/L vs. 429.60±27.39 ng/L, 12 hours: 238.60±24.12 ng/L vs. 822.20±12.74 ng/L, 24 hours: 213.40±17.87 ng/L vs. 637.60±22.96 ng/L, all P<0.05). Expressions of TNF-α and IL-1β in high concentration group were decreased more obviously than those in low concentration group (TNF-α 1 hour: 965.60±24.45 ng/L vs. 1178.80±127.43 ng/L, 12 hours: 522.80±16.89 ng/L vs. 1003.60±59.61 ng/L, 24 hours: 252.40±17.64 ng/L vs. 695.80±25.24 ng/L; IL-1β 1 hour: 225.60±34.44 ng/L vs. 285.00±42.60 ng/L, 12 hours: 190.60±17.64 ng/L vs. 238.60±24.12 ng/L, 24 hours: 152.80±14.70 ng/L vs. 213.40±17.87 ng/L, all P<0.05), but increased compared with those in blank control group. After being intervened for 1 hour, no evident changes were observed in expression of α-ENaC mRNA in all groups. After being intervened for 12 hours and 24 hours, evident decrease in expression of α-ENaC mRNA (A value) was observed in LPS injured group compared with blank control group (12 hours: 0.211±0.021 vs. 0.496±0.027, 24 hours: 0.253±0.030 vs. 0.482±0.030, both P<0.05). Expressions of α-ENaC mRNA in simvastatin low concentration group evidently increased compared with those in LPS injured group (12 hours: 0.363±0.030 vs. 0.211±0.021, 24 hours: 0.309±0.024 vs. 0.253±0.030, both P<0.05). Expressions of α-ENaC mRNA in simvastatin high concentration group increased more obviously compared with those in low concentration group (12 hours: 0.413±0.034 vs. 0.363±0.030, 24 hours: 0.346±0.024 vs. 0.309±0.024, both P<0.05), but decreased compared with blank control group. No evident difference in expressions of all indexes in solution control group was observed compared with those in blank control group.

CONCLUSIONS

High dose simvastatin could improve α-ENaC mRNA expression in primary culture ATII epithelial cells of rats. This may act by modulation the level of TNF-α and IL-1β.

[Isolation and characterization of human alveolar type II cells and phenotypes maintaining study]

OBJECTIVE

To establish a method of isolate, purify, primary culture and identify human alveolar type II cells (AT II ) in vitro, as well as its possible maintaining phenotype characteristics.

METHODS

The marginal lung tissue was collected. AT II cells were isolated with trypsin and elastase, purified by a series of steps, such as, cell sieve filtration, differential adhesion, gradient separation and anti-CD14 beads separation. AT II cells were identified with immunofluorescence of human pro-surfactant-associated protein C (pro-SP-C), Green DND-26 probe and electron microscope. The purity of AT II cells was measured by immunofluorescence of human pro-SP-C and Green DND-26 probe. The viability of AT II cells was measured by trypan blue staining. The phenotypes (SP-A, SP-B,SP-C, SP-D) were monitored with reverse transcription-polymerase chain reaction (RT-PCR) at different time points.

RESULTS

The output of AT II cells from lung tissue was (5-10) x 105/g, and the cell viability was (93 ± 2)% with trypan blue staining, the cell purity was about 98% with pro-SP-C immunofluorescence and Green DND-26 fluorescent probe, the lamellar bodies were clearly observed with transmission electron microscope. In the aspect of phenotypes maintaining, the time of surfactant expression was about 24 days [SP-A: 0.52 + 0.03 (day 16), 0.35 + 0.02 (day 20),0.26 ± 0.01 (day 24), 0.10 + 0.08 (day 28); SP-C: 0.68 0.16 (day l6), 0.31 + 0.04 (day 20), 0.18 + 0.06 (day 24), 0.14 + 0.09 (day 28)], and the longest one was more than 28 days [SP-B: 1.05 + 0.17 (day 16), 0.76 + 0.35(day 20), 0.55 0.15 (day 24), 0.36 0.19 (day 28); SP-D: 0.52 0.19 (day 16), 0.33 + 0.12 (day 20), 0.31 +0.04 (day 24), 0.23 ± 0.02 (day 28)).

CONCLUSION

We successfully established a procedure to separate, purify,identify of AT II cells, which retain primary phenotypic characteristics over long period.

Ectopic ERK expression induces phenotypic conversion of C10 cells and alters DNA methyltransferase expression

BACKGROUND

Many lung carcinogens activate mitogen activated protein kinase (MAPK) pathways and DNA methyltransferases (DNMTs) are under investigation as therapeutic targets for lung cancer. Our goal is to determine whether C10 type II alveolar epithelial cells are a sensitive model to investigate ERK-dependent transformation and DNMT expression patterns in experimental lung cancer.

FINDINGS

Ectopic expression of an extracellular signal regulated kinase (ERK)-green fluorescent protein (ERK1-GFP) induces acquisition of growth in soft agar that is selectively associated with latent effects on the expression of DNA methyl transferases (DNMT1 and 3b), xeroderma pigmentosum complementation group A (XPA), DNA-dependent protein kinase catalytic subunit (DNA-PKcs), increased phosphatase activity and enhanced sensitivity to 5-azacytidine (5-azaC)-mediated toxicity, relative to controls.

CONCLUSIONS

Ectopic expression of ERK alone is sufficient to promote phenotypic conversion of C10 cells associated with altered DNMT expression patterns and sensitivity to DNMT inhibitor. This model may have applications for predicting sensitivity to DNMT inhibitors.

[Protective effect of N-acetylcysteine against pneumocyte apoptosis during ischemia/reperfusion injury of lung in rats]

OBJECTIVE

To investigate the effect of N-acetylcysteine (NAC) on apoptosis of pneumocytes and expression of caspase-3 during lung ischemia/reperfusion injury (LIRI) in rats, and to explore the possible role of NAC in pneumocyte apoptosis.

METHODS

Forty-two male Sprague-Dawley rats were randomly divided into three groups: sham operation group, LIRI group (LIRI was produced by 45 minutes of clamping of the pulmonary hilum followed by 3 hours or 6 hours of reperfusion), and NAC group (NAC 150 mg/kg was injected intraperitoneally before LIRI). Lung specimens were harvested 3 hours or 6 hours after LIRI. Apoptosis rate in lung tissue was determined with flow cytometer after Annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) staining. Malondialdehyde (MDA, thiobarbituric acid) and superoxide dismutase (SOD, xanthine oxidase) of lung tissue were measured. Expression of caspase-3 in lung was determined by reverse transcription-polymerase chain reaction (RT-PCR), and the changes in ultrastructure of lung tissue were observed by electron microscope.

RESULTS

Compared with that of the sham operation group, apoptosis rate of pulmonary cells was significantly increased at 3 hours and 6 hours in LIRI group [(25.60 ± 3.22)% vs. (2.19 ± 0.48)% , (26.01 ± 4.50)% vs. (2.55 ± 0.36)%], the content of MDA (nmol/mg) was significantly increased (3.26 ± 0.32 vs. 0.73 ± 0.23, 3.53 ± 0.46 vs. 1.08 ± 0.42), and the activity of SOD (U/mg) was significantly lowered (32.80 ± 3.82 vs. 60.51 ± 6.81, 33.44 ± 3.24 vs. 64.19 ± 6.60), and the expression of caspase-3 mRNA in lung tissue was significantly up-regulated (0.717 ± 0.037 vs. 0.216 ± 0.046, 0.744 ± 0.046 vs. 0.227 ± 0.037, all P < 0.01). Compared with that of the LIRI group, apoptosis rate of pulmonary cell was significantly decreased [(14.42 ± 1.61)% vs. (25.60 ± 3.22)%, (10.02 ± 1.64)% vs. (26.01 ± 4.50)%], content of MDA (nmol/mg) was lowered significantly (1.75 ± 0.33 vs. 3.26 ± 0.32, 2.15 ± 0.25 vs. 3.53 ± 0.46), and activity of SOD (U/mg) was significantly elevated (42.76 ± 2.06 vs. 32.80 ± 3.82, 44.94 ± 3.11 vs. 33.44 ± 3.24, all P < 0.01) in NAC group. The expression of caspase-3 in lung tissue was remarkably down-regulated compared with that of LIRI group (0.441 ± 0.038 vs. 0.717 ± 0.037, 0.410 ± 0.037 vs. 0.744 ± 0.046, both P < 0.01). The ultrastructure changes in lung tissue were milder in NAC group than in LIRI group. Positive correlation was found between the expression of caspase-3 and apoptosis rate and the content of MDA (3 hours: r = 0.9036, 0.9216; 6 hours: r = 0.9655, 0.9650, all P < 0.01), but negative correlation was found between apoptosis rate and activity of SOD (3 hours: r = -0.9511, 6 hours: r = - 0.9574, both P < 0.01) after LIRI 3 hours and 6 hours.

CONCLUSION

During early period of LIRI, caspase-3 was significantly deregulated by NAC, therefore the cellular apoptosis was inhibited, thus protecting lung tissue from LIRI.

Transcript profiling using ESTs from Paracoccidioides brasiliensis in models of infection

Transcript profiling is an invaluable strategy to study differential gene expression. Here we describe a detailed protocol for applying a subtractive hybridization technique, representational difference analysis (RDA), as a molecular strategy for the identification of differentially expressed genes in studies of host-fungus interaction. Bioinformatics tools that can be used in the analysis of expressed sequence tags (ESTs) are also detailed.

Isolation, cultivation, and application of human alveolar epithelial cells

The blood-air barrier formed by the alveolar epithelium of the peripheral lung is crucial for the pulmonary delivery of drugs. Most existing in vitro models mimicking the blood-air barrier are represented by tumor cells or immortalized cells and lack biological relevance due to their genetic alterations and underexpressed essential physiological functions. However, the increasing interest of aerosol administration of medicines to the respiratory system requires the development and use of representative in vitro models. Thereby, human alveolar epithelial cells (hAEpC) are a suitable test system allowing standardized toxicity and transport studies for newly developed compounds and delivery systems. The isolation, purification, and cultivation of hAEpC are described as well as their possible application in the so-called Pharmaceutical Aerosol Deposition Device On Cell Cultures (PADDOCC) mimicking the complete inhalation process of a powder aerosol in vitro.

[The role of heme oxygenase 1 in hydrogen peroxide induced apoptosis and mitochondrial trans membrane potential change in rat primary type II alveolar epithelium cells]

OBJECTIVE

To understand the role of heme oxygenase-1 (HO-1) in hydrogen peroxide [H(2)O(2)] induced apoptosis and mitochondrial trans-membrane potential (MTMP) change in primary alveolar epithelial cell type II(AEC II).

METHODS

Primary AEC II collected from healthy Sprague Dawley (SD) rats were cultured for 24 hours, then divided into four groups to be treated with: (1) saline; (2) H(2)O(2) (0.5 mmol/L); (3) H(2)O(2) +HO-1 (0.2 mmol/L); (4) H(2)O(2) +zinc original porphyrin IX (HO-1 inhibitor, 20 μmol/L). The morphology of cells in the cultures was examined by fluorescent microscopy 2.5 hours later, and the number of apoptotic cells / the MTMP determined by flow-cytometry 0.5, 1.0, 1.5, 2.0 and 2.5 hours later.

RESULTS

Large number of cells in with green (early apoptotic) or red (later apoptotic) fluorescence were observed by microscope in cultures treated with H(2)O(2) , and H(2)O(2) + HO-1 inhibitor, but such cells were obviously fewer in HO-1 treated cultures. Compared with saline treated cells, H(2)O(2) treated cells had significantly higher apoptosis rate, that increased with time, reaching peak value 2.5 hours into the treatment [0.5 hour: (30.27 ± 0.74)% vs. (3.76 ± 0.81)%, 2.5 hours: (40.46 ± 0.91)% vs. (22.74 ± 0.60)%, both P < 0.05], while the rate of MTMP depolarization was significantly lower (0.99 ± 0.21 vs. 1.91 ± 0.16, P < 0.05) in these cells. Compared with H(2)O(2) treated cells, the apoptosis rate in HO-1 treated cells was significantly lower [0.5 hour: (5.99 ± 0.60)% vs. (30.27 ± 0.74)%, 2.5 hours: (22.69 ± 1.69)% vs. (40.46 ± 0.91)%, both P < 0.05], and their rate of MTMP depolarization higher (2.02 ± 0.12 vs. 0.99 ± 0.21, P < 0.05). Compared with HO-1 treated cells, HO-1 inhibitor treated cells had significantly higher apoptosis rate which reached peak value 2.5 hours into the treatment [0.5 hour: (30.73 ± 1.08)% vs. (5.99 ± 0.60)%, 2.5 hours: (41.38 ± 0.57)% vs. (22.69 ± 1.69)%, both P < 0.05], while rate of MTMP depolarization in these cells was significantly lower (0.98 ± 0.09 vs. 2.02 ± 0.12, P < 0.05).

CONCLUSION

HO-1 could maintain the integrity of AEC II and stabilize their mitochondria membrane potential, protecting the cells from H(2)O(2) induced damage.

[Effect of sulfonic tanshinone sodium injection on the expression and activity of aquaporin-5 of human alveolar epithelial cells after seawater exposure]

OBJECTIVE

To explore the effects of tanshinone IIA on the activity of aquaporin-5 (AQP5) in human alveolar epithelial cells (A549) after seawater exposure and its possible mechanism.

METHODS

Routinely cultured A549 cells were divided into different groups according to different content of seawater: blank control group, 15%, 25%, 50%, 75%, 100% seawater groups; they were divided into different groups according to the duration of exposure to 25% seawater: blank control group, 1, 4, 8 hours groups; they were also divided into different groups according to concentration of tanshinone IIA and exposed to seawater for 4 hours: blank control group, 25% seawater group, 25, 50, 75, 100 μg/ml tanshinone IIA intervention groups. The expressions of AQP5 were respectively assayed by Western blotting and immunohistochemistry.

RESULTS

The results of Western blotting showed that the expressions of AQP5 were remarkably higher at 8 hours of exposure to seawater in 25% and 50% seawater groups than those in blank control group (1.053±0.231, 1.116±0.316 vs. 0.101±0.081, both P<0.05); the expression of AQP5 in 1-hour group showed a slight increase compared with blank control group (0.306±0.125 vs. 0.288±0.098, P>0.05), that in 4-hour group was increased significantly (1.423±0.377, P<0.01), and in 8-hour group (1.507±0.461) it was slightly higher than that in 4-hour group without statistical significance. The AQP5 expression was significantly lower in tanshinone IIA 25 μg/ml and 50 μg/ml intervention groups than that in 25% seawater group (0.580±0.186, 0.499±0.172 vs. 1.013±0.287, both P<0.05). Immuno-histochemistry showed that the expression of AQP5 was markedly up-regulated after A549 cells were stimulated with 25% seawater for 4 hours as compared with blank control group (7.21±0.78 vs. 0.41±0.07, P<0.01), but intervention of tanshinone IIA significantly inhibited the up-regulation of AQP5 expression (3.02±0.23) induced by 25% seawater (P<0.05).

CONCLUSION

The experimental results showed that tanshinone IIA is innocuous to A549 at a dosage of 25 μg/ml, and it can decrease the overexpression of AQP5 induced by seawater.

[Effects of cyclosporine A on pneumocyte apoptosis with lung ischemia/reperfusion injury in rats]

OBJECTIVE

To investigate the effects of cyclosporine A (CsA), a powerful inhibitor of mitochondrial permeability transition pore (MPTP), on pneumocyte apoptosis, the release of cytochrome C and the activity of caspase-3 after lung ischemia/reperfusion, and explore the mechanisms.

METHODS

Single lung in situ ischemia/reperfusion animal model was used. 30 SD rats were randomly divided into three groups (n = 10): sham (S) group, ischemia/reperfusion (I/R) group and cyclosporine A (CsA) group. Apoptosis of pneumocyte was assessed by TUNEL method, cytochrome C (CytC) in cytoplasm was detected by immunohistochemistry techniques, and the activity of caspase-3 was measured with spectrophotometer.

RESULTS

The content of CytC in cytoplasm, the activity of caspase-3, and the value of apoptosis index (AI) in ischemia/reperfusion group were evidently higher than that in S group (P < 0.01). CsA suppressed apoptosis as well as CytC release and caspase-3 activity (P < 0.01).

CONCLUSION

CsA can prevent the release of cytochrome C, block the apoptosis of pneumocyte accordingly maybe by closing the MPTP.

Plasma membrane trafficking in alveolar type II cells

Alveolar type II (ATII) cells produce surfactant and release it into the alveolar space via exocytosis of lamellar bodies (LBs). On the other hand, various forms of endocytosis take place, enabling the recycling of surfactant as well as of integral membrane proteins to the LB. Here we investigated the trafficking of protein and lipid components of plasma membrane between the plasma and limiting LB membrane by over-expressing lysosomal associated membrane protein 3 fused to green fluorescence protein (LAMP-3-GFP) and farnesylated DsRed (DsRed-Farn). LAMP-3-GFP was homogenously distributed over the entire limiting LB membrane, whereas DsRed-Farn predominantly accumulated at the plasma membrane. However, in a minor LB fraction, DsRed-Farn was also found in discrete domains at its limiting membrane. Upon stimulation of ATII cells with secretagogues, the area of DsRed-Farn domains on LB surfaces increased 2 to 4 fold within 20 minutes of stimulation. This increase remained unaffected by phenylarsine oxide, an inhibitor of clathrin-dependent endocytosis, but was almost abolished by filipin and indomethacin, blockers of clathrin-independent endocytosis. It was also blocked by bafilomycin A1, wortmannin and LY294002, inhibitors of intra-cellular vesicular transport. We conclude that secretagogues facilitate the transport of plasma membrane components to LBs via a clathrin-independent vesicular transport pathway.

[Detection of SLC34A2 in patients with pulmonary alveolar microlithiasis and the effect of SLC34A2 on transportation of calcium and phosphate in human alveolar epithelial cells]

OBJECTIVE

To detect the mutation of SLC34A2 in patients with pulmonary alveolar microlithiasis and to study the effect of SLC34A2 on transportation of calcium and phosphate in human alveolar epithelial cell (A549) cells.

METHODS

The gene SLC34A2 was detected by segmentation-PCR and gene sequencing. RNA was obtained by Trizol from fresh lung tissues and the target gene was acquired by RT-PCR. Eukaryotic expression of recombinant pcDNA3.1(+)-SLC34A2 was constructed and SLC34A2 was transfected to A549 cells by liposome. The expression of SLC34A2 mRNA was detected by RT-PCR, and the content of calcium and phosphate of the extracellular fluid was measured by commercial kits. The cell experiments consisted of 3 groups including a control group (5 x 10(5)/well, one well), a blank group (5 x 10(5)/well, one well), a transfection group (5 x 10(5)/well, four wells). Every experiment was repeated 6 times.

RESULTS

No mutation was found in patients with pulmonary alveolar microlithiasis. SLC34A2 cDNA was successfully amplified and the eukaryotic expression recombinant pcDNA3.1(+)-SLC34A2 was successfully constructed. The amount of SLC34A2 mRNA of the transfected cells was significantly higher (2.48 +/- 0.45), compared to the control cells (0.55 +/- 0.07) and the blank cells (0.60 +/- 0.06), q = 16.25, 15.78, all P < 0.01. The content of calcium and phosphate in the supernatant of the transfected cells was lower [(0.110 +/- 0.016) mmol/L, (3.8 +/- 0.4) mmol/L], compared with the control [(0.254 +/- 0.047) mmol/L, (7.3 +/- 0.8) mmol/L] and the blank (0.262 +/- 0.041) mmol/L, (7.1 +/- 0.4) mmol/L], q = 8.657 - 13.892, all P < 0.01.

CONCLUSIONS

In human lung alveolar epithelial cells, the content of calcium and phosphate in cell supernatant decreased with increased amount of SLC34A2 mRNA. Mutation of SLC34A2 may not be at the DNA level.

[Apoptosis of alveolar epithelial cells and pulmonary vascular endothelial cells in chronic obstructive pulmonary disease]

OBJECTIVE

To investigate the relationship between apoptosis of alveolar epithelial cells and pulmonary vascular endothelial cells in chronic obstructive pulmonary disease (COPD) and the relationship between apoptosis and lung function and emphysema.

METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into a smoke exposure group (COPD group) and a normal control group (NC group). The rat model of COPD was established by exposure to cigarette smoke for 80 days, and lung tissues were obtained. Lung tissue samples were also collected respectively from patients with COPD (n = 13) and without COPD (n = 12). Lung sections stained by HE were observed to study the morphological alteration, and mean linear intercept (MLI) and mean alveolar numbers (MAN) were measured to estimate the extent of emphysema in rats. Quantitative analysis of apoptosis of alveolar epithelial cells and pulmonary vascular endothelial cells was undertaken by TdT-mediated dUTP nick end labeling (TUNEL). The data distributed normally were expressed as (-x) +/- s, and the independent-samples t-test was used for comparison of means. Nonparametric data were expressed as median (quartile range), and Wilcoxon rank sum test was used for comparison. Correlation between apoptosis of the two kinds of cells in patients with COPD was estimated by Spearman rank correlation coefficients, and the correlations between the specific indexes, such as FEV(1)%Pre, FEV(1)/FVC(%), residual volume/total lung capacity(%) [RV/TLC(%)], MLI, MAN, and the cell apoptosis were also investigated. Statistical difference was accepted at P < 0.05.

RESULTS

Destruction of alveolar walls and enlargement of alveolar space were observed as pathological changes of lung tissues from patients and rats with COPD. The apoptotic index (AI) of alveolar epithelial cells and pulmonary vascular endothelial cells were (28.9 +/- 3.1)%, (13.2 +/- 2.6)% in patient COPD group; (10.0 +/- 1.0)%, (4.1 +/- 0.4)% in rat COPD group; the differences being significant (t = -23.946, -8.820, -24.273, -36.422, all P < 0.05), as compared with NC groups [(5.8 +/- 1.2)%, (5.6 +/- 1.5)%, (2.1 +/- 0.4)%, (0.2 +/- 0.1)% respectively]. In patient COPD group, the AI of alveolar epithelial cells was significantly higher than that of pulmonary vascular endothelial cells (t = -13.889, P < 0.05) and both were positively correlated with each other (r = 0.60, P < 0.05). In patient COPD group, both the apoptosis of alveolar epithelial cells and pulmonary vascular endothelial cells revealed negative correlations to FEV(1)(%)pre (r = -0.83, -0.69, all P < 0.05) and FEV(1)/FVC(%) (r = -0.95, -0.71, all P < 0.05), but positive correlations were demonstrated between them and RV/TLC(%) (r = 0.93, 0.70, all P < 0.05). In rat COPD group, MLI of lung tissue showed a positive correlation with the AI of alveolar epithelial cells (r = 0.59, P < 0.05) while MAN a negative correlation with the latter (r = -0.81, P < 0.05).

CONCLUSIONS

Abnormal apoptosis of alveolar epithelial cells and pulmonary vascular endothelial cells was present in patients and rats with COPD, which was related to the changes of lung function or pathological changes of lung tissues. The results suggest that the abnormal changes of apoptosis of pulmonary tissue in COPD may be involved in the pathogenesis of the disease.

The effect of TGF-β1 and Smad7 gene transfer on the phenotypic changes of rat alveolar epithelial cells

The aim of this study was to investigate whether transforming growth factor-β1 (TGF-β1) could induce alveolar epithelial-mesenchymal transition (EMT) in vitro, and whether Smad7 gene transfer could block this transition. We also aimed to elucidate the possible mechanisms of these processes. The Smad7 gene was transfected to the rat type II alveolar epithelial cell line (RLE-6TN). Expression of the EMT-associated markers was assayed by Western Blot and Real-time PCR. Morphological alterations were examined via phase-contrast microscope and fluorescence microscope, while ultrastructural changes were examined via electron microscope. TGF-β1 treatment induced a fibrotic phenotype of RLE-6TN with increased expression of fibronectin (FN), α-smooth muscle actin (α-SMA) and vimentin, and decreased expression of E-cadherin (E-cad) and cytokeratin19 (CK19). After transfecting the RLE-6TN with the Smad7 gene, the expression of the mesenchymal markers was downregulated while that of the epithelial markers was upregulated. TGF-β1 treatment for 48 h resulted in the separation of RLE-6TN from one another and a change into elongated, myofibroblast-like cells. After the RLE-6TN had been transfected with the Smad7 gene, TGF-β1 treatment had no effect on the morphology of the RLE-6TN. TGF-β1 treatment for 48 h resulted in an abundant expression of α-SMA in the RLE-6TN. If the RLE-6TN were transfected with the Smad7 gene, TGF-β1 treatment for 48 h could only induce a low level of α-SMA expression. Furthermore, TGF-β1 treatment for 12 h resulted in the degeneration and swelling of the osmiophilic multilamellar bodies, which were the markers of type II alveolar epithelial cells. TGF-β1 can induce alveolar epithelial-mesenchymal transition in vitro, which is dependent on the Smads signaling pathway to a certain extent. Overexpression of the Smad7 gene can partially block this process.