Different Concentrations Of Cigarette Smoke Extract Research Articles

Angiopoietin-like 4 knockdown attenuates cigarette smoke extract-induced oxidative stress and apoptosis in lung bronchial epithelial cells by inhibiting NADPH oxidase.

It has been found that angiopoietin-like 4 (ANGPTL4) expression is increased in the serum of patients with chronic obstructive pulmonary disease (COPD). Herein, cigarette smoke extract (CSE) was used to stimulate oxidative stress in bronchial epithelial cells BEAS-2B, and the role and potential mechanism of ANGPTL4 in smoking-induced lung dysfunction were explored. The roles of different concentrations of CSE (0, 1, 2.5, 5, or 10%) in cell viability and ANGPTL4 levels were evaluated. Following ANGPTL4 being knocked down, the effects of ANGPTL4 knockdown on oxidative stress and apoptosis were determined. Moreover, the level of NADPH oxidase 2 (NOX2) was upregulated to assess the mediated role of NOX in the regulation of ANGPTL4, along with JNK/p38 MAPK signaling. CSE treatment elevated the level of ANGPTL4, and ANGPTL4 knockdown reduced CSE-induced oxidative stress, apoptosis, and NOX level in BEAS-2B cells. The greatest degree of alteration was found in NOX2, and additional NOX2 overexpression broke the inhibitory influences of ANGPTL4 knockdown on oxidative stress and apoptosis. Otherwise, ANGPTL4 knockdown hindered the activation of JNK/p38 MAPK signaling, whereas NOX2 overexpression activated this signaling pathway. Together, ANGPTL4 knockdown attenuated CSE-induced oxidative stress, apoptosis, and activation of JNK/MAPK signaling by inhibiting NOX.

Bufei Yishen formula attenuates cigarette smoke extract-induced airway mucus hypersecretion by regulating Notch signaling pathway

To explore the mechanism of Bufei Yishen formula (BYF) on attenuating cigarette smoke extract (CSE)-induced airway mucus hypersecretion by regulating Notch signaling pathway. The human airway epithelial cell 16HBE was cultured in vitro, and the cells in logarithmic growth phase were used for the experiments. (1) Intervention condition screening experiment: the 16HBE cells were grouped, methylthiazolyldiphenyl-tetrazolium (MTT) method and enzyme-linked immunosorbent assay (ELISA) were used to detect the effects of different concentrations of CSE (2.5%, 5%, 10%, 20%, 40%), different concentrations of BYF drug-containing serum (5%, 10%, 20%, 40%), and different concentrations of Notch signal pathway blocker DAPT (5, 10, 20, 40 μmol/L) on cell activity and secretion of mucin 5AC (MUC5AC) levels. In addition, a blank control group was set up to screen out the best conditions for preparing CSE-induced cell mucus hypersecretion model and BYF and DAPT intervention. (2) Intervention experiment: the 16HBE cells were divided into four groups. The blank control group was not given any treatment; the 16HBE cells were induced by 10% CSE for 24 hours to prepare mucus hypersecretion model in the CSE model group; the cells in the CSE+BYF group and CSE+DAPT group were given 10% BYF or 20 μmol/L DAPT, respectively, for intervention at the same time for 24 hours. Real-time fluorescent quantitative polymerase chain reaction (qPCR) was used to detect the mRNA expressions of MUC5AC, Notch3 and hairy and enhancer of split 1 (HES1) in the cells. Western blotting was used to detect the protein expressions of Notch3 and HES1 in the cells. (1) Results of the screening experiment of intervention conditions: compared with the blank control group, 10% CSE induction for 24 hours was the best condition for establishing cell mucus hypersecretion model that neither affected cell viability nor increased the secretion of MUC5AC; while 10% BYF and 20 μmol/L DAPT was the optimal intervention condition. (2) Intervention experiment results: compared with the blank control group, the mRNA expressions of MUC5AC, Notch3, and HES1 and the protein expressions of Notch3 and HES1 in the CSE model group were significantly increased, indicating that CSE activated Notch3 and HES1 signal activation and induced 16HBE cells to secrete mucus protein. Compared with the CSE model group, BYF and DAPT could significantly down-regulate the mRNA and protein expressions of MUC5AC, Notch3, and HES1 in cells [MUC5AC mRNA (2-ΔΔCT): 1.03±0.13, 0.96±0.05 vs. 1.35±0.07, Notch3 mRNA (2-ΔΔCT): 1.10±0.14, 1.10±0.02 vs. 1.31±0.15, HES1 mRNA (2-ΔΔCT): 1.26±0.10, 1.14±0.15 vs. 1.45±0.08, Notch3 protein (Notch3/GAPDH): 0.10±0.03, 0.16±0.03 vs. 0.31±0.09, HES1 protein (HES1/GAPDH): 0.37±0.06, 0.34±0.08 vs. 0.50±0.05, all P < 0.05]. The mechanism of BYF attenuating mucus hypersecretion of 16HBE cells induced by CSE was associated with the inhibition of Notch signaling pathway activation.

Analysis of mucus secretion and inflammatory process in in vitro model of human airway epithelial cells able

Chronic Obstructive pulmonary disease (COPD) is a lung disease characterized by chronic inflammation, and mucus hypersecretion. Currently, curative treatment does not exist, and some patients develop resistance to corticosteroid drugs. Gene therapy could be a novel approach to treat the disease. However, the effectiveness of gene vectors in the airways is decreased by the presence of mucus that acts as a barrier. The aim of this study is to develop an in vitro model, able of cytokine production and mucus secretion; in the perspective of testing new drug including mucolytic gene therapy vectors. We used three human airway epithelial lines (A549, Calu-3 and NCI-H292) stimulated with different concentrations of CSE (Cigarette Smoke Extract) alone or in association with LPS (lipopolysaccharides) , for 24 or 48 hours. NCI-H292 and Calu-3 cells were also co-cultured in the same conditions. Then, we evaluated MUC5AC, IL8/CXCL8, GROα/CXCL1 and MCP1/CCL2 gene expression by RT-qPCR and their secretion by ELISA. Finally, we also observed MUC5AC production from NCI-H292 by immunohistochemistry. CSE alone or with LPS did not impact MUC5AC gene expression, in A549 cells. In contrast, LPS (0.1 μg/mL) increased IL8/CXCL8, GROα/CXCL1 and MCP1/CCL2 release. When CSE associated with LPS, there was an additive effect on cytokine release. Regarding Calu-3 cells, treatment with CSE, LPS, or both, did not affect MUC5AC gene expression, neither cytokine secretions. For NCI-H292 cells, CSE alone increased MUC5AC gene expression and an additive effect was observed when CSE was associated with LPS. LPS at low concentrations triggered some MUC5AC and IL8/CXCL8 release, which was more important when LPS was associated with CSE; but not for GROα/CXCL1. NCI-H292 cells did not release MCP1/CCL2. In the NCI-H292 and Calu-3 co-culture, CSE and LPS increased MUC5AC gene expression, but CSE did not affect cytokine secretion. LPS alone increased IL8/CXCL8 secretion, but not GROα/CXCL1 or MCP1/CCL2. Our results show that NCI-H292 cells appear as the best model to evaluate the efficacy of gene vectors, as they are able to produce mucins and cytokines, after CSE and LPS exposure.

Effect of cigarette smoke extract on mitochondrial heme-metabolism: An in vitro model of oral cancer progression

Tobacco smoking is considered as one of the major risk factors for development of oral cancer. In vitro studies indicate that cigarette smoke initiates transformation of epithelial cells toward development of oral cancer through altering mitochondrial metabolic pathways. However the present in vitro models need to be improved to correlate these molecular changes with epithelial transformations. In present study, we investigated the association of mitochondrial metabolic events with oral cancer progression under cigarette smoke extract (CSE). In this regard, an in vitro model of oral keratinocyte cell line (MOE1A) was developed by exposing them with different concentrations of CSE. Alterations in cellular phenomena were confirmed by Fourier-transform infrared spectroscopy (FTIR) study, which indicated changes in important functional groups of CSE-induced oral cells. Enhanced reactive oxygen species (ROS) of exposed cells altered the mitochondrial metabolic activities in terms of increased mitochondrial mass and DNA content. Further, mitochondrial heme-metabolism was investigated and real-time PCR study showed altered expression of important genes like ALAS1, ABCB6, CPOX, FECH, HO-1. Both transcriptomic and proteomic studies showed up- and down-regulation of important biomarkers related to cellular cancer progression. Overall data suggest that CSE alters mitochondrial heme metabolic pathway and initiates cancer progression through modifying cellar biomarkers in oral epithelial cells.

The stimulation of human pulmonary artery endothelial cells by cigarette smoke extract contributed to cell senescence and induced human pulmonary artery smooth cell migration

Objective: To observe the senescent effect of human pulmonary arterial endothelial cells (HPAEC) stimulated by cigarette smoke extract (CSE) and the effect of secretion of senescent cells on human pulmonary arterial smooth muscles cell (HPASMC) proliferation and migration. Methods: HPAEC was treated with different concentrations of CSE in vitro and cell proliferation was determined by CCK8, senescence cells analyzed by detecting the β-gal activity, and the senescent proteins of cells measured by Western blot. The concentration of senescence-associated secretory phenotype (SASP) was detected by ELISA and the expression of MCP-1 and TGF-β1 was measured by Real-time PCR. The number of the proliferated cells was measured by Transwell assay and immunoflurescence. Results: The HPAEC was aging with the stimulation concentration of CSE increasing and the stimulation time prolonging (P<0.05). Western blot indicated that the senescent associated protein p53 or p21 increased markedly after 48 h and 72 h CSE-exposure (n=3, P<0.05). The SA-β-Gal staining showed that the number of senescent cells increased as the exposure time prolonged. Compared with the control group, cell viability of 48 h group(1.8±0.1) and 72 h group (1.8±0.1) decreased significantly. The flow cytometry showed a significant difference between the CSE group(14.1±1.2) and the control group(28.5±1.8) in S phase(P<0.01), indicating cell cycle arrest. The SASP was increasing as the CSE-exposure prolonged. Compared with the control group(177±39), the 48 h group(460±43) and the 72 h group(609±64) showed a marked increase in MCP-1(P<0.05). For TGF-β1, it had a same tendency and a significant difference between the control group(121±18) and the 48 h group(413±32) or 72 h group(606±67, both P<0.05). In the meantime, the bFGF increased after 48 h stimulation(291±13, P<0.05). Besides MCP-1, TGF-β1 showed a significant difference between the control group and the 72 h CSE-exposure group (P<0.01). Premature cells could secrete SASP which induced HPASMC proliferation. After different times of conditioned medium stimulation, HPASMC proliferated especially at 72 h(P<0.05) . The immnoflorescence and Transwell assay confirmed this finding. Conclusion: CSE could induce senescence of HPAEC and SASP production which improved HPASMC proliferation and migration.

Effect of Phospholipid Transfer Protein on Cigarette Smoke Extract-Induced IL-8 Production in Human Pulmonary Epithelial Cells.

To investigate the effect of phospholipid transfer protein (PLTP) on the cigarette smoke extract (CSE)-induced production of interleukin-8 (IL-8) in human pulmonary epithelial cells, male Wistar rats were exposed to air and cigarette smoke (n = 10/exposure) for 6h/day on three consecutive days. Their lungs were sectioned and bronchoalveolar lavage fluid (BALF) examined. The expression of PLTP and IL-8 in the lung was detected immunohistochemically. Lung injury was accompanied by the upregulation of PLTP and IL-8 in the CSE-exposed rat model, and the number of white blood cells in the BALF was significantly increased compared with those of the controls. Both neutrophils and macrophages were clearly increased. Human alveolar epithelial cells (A549) and human bronchial epithelial cells (HBECs) were treated with different concentrations of CSE for various times. The cells were also transfected with small interfering RNA directed against PLTP, and U0126, an inhibitor of the ERK1/2 pathway, was administered before CSE exposure. The expression of PLTP and IL-8 mRNAs and PLTP, IL-8, total ERK, and phosphorylated ERK proteins was analyzed. The expression of IL-8 and phosphorylated ERK was significantly increased in A549 cells and HBECs after CSE stimulation, and CSE upregulated the expression of PLTP in A549 cells. In contrast, CSE inhibited the expression of PLTP in HBECs. The CSE-induced expression of IL-8 and p-ERK was significantly increased by the knockdown of PLTP. Therefore, PLTP may regulate CSE-induced IL-8 expression via the ERK1/2 signaling pathway in human pulmonary epithelial cells.

Periostin mediates cigarette smoke extract-induced proliferation and migration in pulmonary arterial smooth muscle cells.

Cigarette smoking is an important risk factor for pulmonary arterial hypertension (PAH). Pulmonary arterial smooth muscle cells (PASMCs) play a critical role in the pathogenesis of PAH-associated arterial remodeling. This study was done to explore the expression and biological roles of periostin in PASMCs following exposure to cigarette smoke extract (CSE). PASMCs were exposed to different concentrations of CSE and tested for gene expression and reactive oxygen species (ROS) production. PASMCs were incubated with recombinant periostin protein or transfected with small interfering RNA targeting periostin before CSE exposure and then examined for cell proliferation and migration. Compared to control cells, exposure to CSE led to a significant upregulation of periostin. Pretreatment with 5mM N-acetyl-l-cysteine (an inhibitor of ROS formation) or 10μM U0126 (an inhibitor of ERK1/2) significantly prevented the induction of periostin in CSE-treated PASMCs. The addition of recombinant periostin protein significantly enhanced the proliferation and migration of PASMCs. In contrast, knockdown of endogenous periostin counteracted the proliferation and migration of PASMCs induced by CSE treatment. In conclusion, CSE induces the expression of periostin in PASMCs via promotion of ROS and activation of ERK1/2. Periostin mediates the effects of CSE on PASMC proliferation and migration. These findings warrant further exploration of the roles of periostin in cigarette smoking-associated pulmonary arterial remodeling.

Cigarette smoke extract alters the cell cycle via the phospholipid transfer protein/transforming growth factor-β1/CyclinD1/CDK4 pathway

This study was aimed to investigate the effect of phospholipid transfer protein (PLTP) on cigarette smoke extract (CSE)-induced alteration of the cell cycle and the possible mechanism. Male Wistar rats and the rat alveolar epithelial cell line (RLE-6TN) were exposed to normal air or different concentrations of CSE. Then PLTP siRNA was transfected into cells and an inhibitor of transforming growth factor-β1 (TGF-β1) was administered prior to CSE exposure. Histological changes and cell cycle stage were recorded, as were the expression levels of PLTP, TGF-β1, CyclinD1 and CDK4. Resulting morphological changes included diffuse interstitial substance incrassation and elevated alveolar rupturing. Flow cytometry analysis revealed an increase in the number of cells in the G1 phase in a time- and dose-related manner. Both PLTP and TGF-β1 were up-regulated at protein and mRNA levels, whereas CyclinD1 and CDK4 expression was down-regulated after CSE exposure. Furthermore, PLTP siRNA significantly suppressed CSE-induced TGF-β1 expression, resulting in up-regulation of CyclinD1 and CDK4, but the TGF-β1 inhibitor was not able to abrogate CSE-induced PLTP over-expression. In conclusion, PLTP may operate upstream of the TGF-β1/CyclinD1/CDK4 pathway and may mediate the CSE-induced G1 arrest in RLE-6TN cells. Our work provides some new insight into the relation between PLTP and cell cycle progression.

Cigarette smoke extract induces apoptosis of rat alveolar Type II cells via the PLTP/TGF-β1/Smad2 pathway

Apoptosis of alveolar epithelial cells has been implicated in the pathogenesis of acute lung injury. Phospholipid transfer protein (PLTP) may play a role in apoptosis. In the present study, the effect of the novel function of PLTP in cigarette smoke extract (CSE)-induced apoptosis of alveolar epithelial cells and the possible mechanism were examined. Male Wistar rats were exposed to air and cigarette smoke (n=10/exposure) for 6h/day on 3 consecutive days, then the lungs were sectioned and examined. To investigate effects on alveolar epithelial cells, rat alveolar epithelial cells (RLE-6TN) were treated with different concentrations of CSE for various times. siRNA for PLTP was transfected into cells and an inhibitor of the transforming growth factor-β1 (TGF-β1) type I receptor was administered prior to CSE exposure. Apoptosis was measured, and mRNA expression of PLTP and TGF-β1 and protein levels of PLTP, TGF-β1, p-Smad2 and cleaved caspase-3 were analyzed. The results showed that apoptosis, as well as expression of PLTP, TGF-β1, p-Smad2 and cleaved caspase-3 were all significantly increased after CSE stimulation (P<0.05). Furthermore, the expression of TGF-β1, p-Smad2 and cleaved caspase-3 induced by CSE could be partly abrogated by knockdown of PLTP. The expression of PLTP showed no significant change as a result of TGF-β1 receptor inhibition, while cleaved caspase-3 showed a remarkable reduction. PLTP may act as an upstream signal molecule of the TGF-β1/Smad2 pathway and is likely to be involved in CSE-induced apoptosis of alveolar epithelial cells.

Does cigarette smoke exposure contributes to the progression of ovarian cancer? (844.7)

Rationale and Objective: Investigating risk factors for ovarian cancer is at extreme importance due to the asymptomatic nature of this disease during early stages. Although a correlation between history of cigarette smoking in women and risk of ovarian cancer occurrence has been reported, there is no primary literature linking cigarette smoke (CS) as a causative factor in ovarian cancer development. Here we conducted an in‐vitro approach to detect effects of CS exposure on ovarian cancer progress. We hypothesized that cigarette smoke exposure cause promotion of ovarian cancer via attenuating apoptosis and increasing proliferation of cancer cells. Methods: A2780 ovarian cancer cells were used as the experimental model. Cigarette smoke extract (CSE) was created using a modification of a published method. Following serum starvation, A2780 cells were treated with either control (serum free media) or different concentrations of CSE for 24 hours. To detect effects of CSE on ovarian cancer cell apoptosis, apostain and tryphan blue exclusion assays were performed. To detect CSE effects on cell proliferation, BrdU cell proliferation assay was conducted. Results: 24 hour Exposure of CSE caused increase in cancer cell proliferation, and decrease in cancer cell apoptosis. Conclusions: CS promotes ovarian cancer progression via accelerating cancer cell proliferation and attenuating apoptotic cell death.Grant Funding Source: Sullivan University Faculty Development Grant

Expressions of p-c-jun and cyclinD1 between vascular smooth muscle cells and endothelial cells exposured to cigarette smoke extract

To investigate the cell viabilities of vascular smooth muscle cells and vascular endothelial cells stimulated by cigarette smoke extract(CSE) . The CSE was prepared by smoke-bubbled phosphate buffered saline(PBS) generation.After culturing cells with different concentrations of CSE, we used the cell counting kit-8 to determine the cell viability.The expression levels of c-jun and cyclinD1 were analyzed through Western blot.The c-jun plasmid was transfected to detect the change of cyclinD1 expression. The smooth muscle cell viability increased when the CSE concentration ranged 0.625%-10%, whereas the endothelial cells viability decreased when exposed to the CSE concentration. After exposure to CSE for 48 hours, there was no difference in c-jun expression between toxin group and PBS group;however, the expression of p-c-jun in the smooth muscle cells significantly increased in the toxin groups than in the PBS group(P<0.05) and the expression of p-c-jun in the vascular endothelial cells significantly decreased(P<0.05) . The level of cyclinD1 significantly increased after exposed to CSE, and its expression level also increased in respond to the c-jun overexpression. CSE can enhance the proliferation of vascular smooth muscle cells and decrease in the activity of endothelial cells proliferation, which may be explained by the phosphorylation of c-jun and the expression of cyclinD1.

Smad3 mediates cigarette smoke extract (CSE) induction of VEGF release by human fetal lung fibroblasts

Cigarette smoke is the major cause of chronic obstructive pulmonary disease (COPD), yet pathogenic mechanisms are not fully understood. Vascular endothelial growth factor (VEGF) is one of the major regulators of endothelial cell survival and is believed to play a role in the pathogenesis of COPD. Fibroblasts are a significant source of VEGF in the lungs; however the effect of cigarette smoke exposure on VEGF release by fibroblasts is not fully understood. We hypothesized that cigarette smoke-induced disturbed VEGF release by human lung fibroblasts is a potential pathogenic mechanism that could contribute to COPD. Cigarette smoke extract (CSE) was prepared by modification of the methods of Carp and Janoff (American Review of Respiratory Disease, 1978). Human fetal lung fibroblasts (HFL-1) were exposed to different concentrations of CSE and for different durations. VEGF release into the media was measured using ELISA. TGF-β1 receptor (TβR1)/Smad3 as a potential pathway for CSE modulated VEGF release was also investigated using biochemical analyses and siRNA inhibition of Smad3 and siRNA and pharmacologic inhibition of TβR1. CSE induced VEGF release by HFL-1 in concentration and time dependent manner. This was confirmed in two additional types of primary human fetal lung fibroblasts. CSE induced Smad3 phosphorylation and nuclear translocation in HFL-1 cells. Silencing of Smad3 by siRNA not only eliminated the stimulatory effect of CSE on VEGF release but also inhibited baseline VEGF production. Suppression of TβR1 by the pharmacological inhibitor (SB431542) markedly reduced VEGF release by HFL-1 in response to CSE and this effect was confirmed by TβR1 siRNA. In contrast, nicotine inhibited VEGF release by HFL-1 in a dose and time dependent manner. Our findings indicate that CSE stimulates Smad3-mediated VEGF release by lung fibroblasts. Nicotine does not account for the CSE stimulation of VEGF in HFL-1. The ability of lung fibroblasts to produce VEGF may play a role in pathogenesis of cigarette smoke induced lung disease.

Cigarette Smoke Induces Apoptosis by Activation of Caspase-3 in Isolated Fetal Rat Lung Type II Alveolar Ep-ithelial Cells &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt;

Smoking during pregnancy is a major source of fetal exposure to numerous harmful agents present in tobacco smoke. Lung development involves complex biochemical processes resulting in dramatic changes which continue even after birth. In addition to type I cells which form the blood-air barrier, type II alveolar epithelial (AE) cells have important and diverse functions related to immunological protection and stabilization of the alveolus through synthesis and secretion of the pulmonary surfactant. Apoptosis or programmed cells death is an important physiological process during lung embryogenesis and for the proper maintenance of homeostasis. Caspases are proteases that play important roles in regulating apoptosis. Caspase-3 is the key executioner caspase in the cascade of events leading to cell death by apoptosis. We explored the hypothesis that cigarette smoke extract (CSE) induces apoptosis in fetal rat lung type II AE cells by activation of caspase-3. To analyze these factors, isolated fetal rat lung type II AE cells were used. The cells were exposed to different concentrations of CSE (5%, 10% or 15%) (v/v) for 60 min. The results of the present study showed that CSE induced apoptosis in fetal rat lung type II AE cells with a significant increase (p < 0.05) in caspase-3 activity and decrease in cell proliferation at CSE concentrations of 10% and 15% (v/v). These observations indicate that cigarette smoke extract induces apoptosis by activation of caspase-3 in fetal rat lung type II AE cells in a dose-dependent manner and may potentially alter the regulated development of the lung and the appearance of the surfactant-producing type II alveolar cells which are critical for the establishment of adequate gas exchange at birth.

Effects of cigarette smoke extracts on the growth and senescence of skin fibroblasts in vitro.

Epidemiological studies have shown that cigarette smoke (CS), a very common environmental factor, plays an important role in skin aging. Although some in vivo studies have suggested that CS affects skin aging, the detailed effects of CS on skin cells in vitro remain largely unknown. In this study, we investigated the effects of cigarette smoke extract (CSE) on the growth, proliferation, and senescene of skin fibroblasts and the possible mechanism underlying these effects. Primary cultured human fibroblasts were exposed to a range of concentrations of CSE. Cell viability and cell proliferation after CSE exposure were analyzed with the methyl thiazolyl tetrazolium (MTT) assay and bromodeoxyuridine incorporation assay, respectively. Growth curves of fibroblasts exposed to different concentrations of CSE were developed and prolonged CSE-exposed cells were observed. Morphological and ultrastructural changes in fibroblasts were assessed by inverted light microscopy and transmission electron microscopy (TEM). Dying cells were stained with senescence-associated β-galactosidase (SA β-gal). Intracellular reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity, and glutathione peroxidase (GSH-Px) activity were determined by a colorimetric method. We found that proliferative capacity and growth were inhibited by CSE exposure in a dose- and time-dependent manner. Fibroblasts exposed to even low concentrations of CSE for a long period of time (5 passages) showed significantly increased SA β-gal activity and typical features of aging cells. Meanwhile, CSE inhibited superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and augmented ROS levels. Our observations suggest that CSE exposure impairs fibroblast growth and proliferation and leads to features similar to those seen in senescent cells. Oxidative stress injury and inhibition of antioxidant defense activity may be involved in CSE-induced fibroblast senescence.

AP-2α expression and cell apoptosis of the lung tissue of rats with COPD and ECV304 cells stimulated by cigarette smoke extract

An increasing body of evidence suggests that apoptosis of structural cells in the lung might be an important upstream event in the pathogenesis of chronic obstructive pulmonary disease (COPD). AP-2α is one of the important transcription factors involved in the modulation of apoptosis in carcinogenesis and idiopathic-dilated cardiomyopathy. The relationship between AP-2α and apoptosis in COPD remains to be elucidated. The aim of the present study was to investigate the expression of AP-2α in the lung tissues of rats with COPD induced by smoking and its possible protective effect on cigarette smoke extract (CSE) induced endothelial cell apoptosis. Sprague-Dawley rats (n = 24) were randomly assigned to normal and COPD groups. The COPD group was exposed to smoke from 20 commercial unfiltered cigarettes for 80 d before morphological assessment of the lung tissue was performed. The expression of AP-2α in lung tissues was measured by Western blotting. To demonstrate the relationship between apoptosis and AP-2α, in vitro cell experiments were carried out. Cells were treated with different concentrations of CSE before proliferation was measured by MTT. Apoptosis was then determined by Hoechst staining and the expression of cleaved caspase-3 and AP-2α by Western blotting over time following treatment with 5% CSE. Cells were then infected with an AP-2α adenovirus vector and the expression of cleaved caspase-3 and AP-2α was compared to the control groups by Western blotting. The COPD group showed larger air spaces and significant decrease of FEV0.3/FVC compared with the rats in the control group (P<0.05). The expression of AP-2α was significantly higher in the lung tissue of rats with COPD compared with those of controls (P<0.05). In the ECV304 cells, CSE induced apoptosis (P<0.01) and caspase-3 activation in a time-dependent manner and reduced the cell proliferation rate in a dose-dependent manner (P<0.005). Moreover, 5% CSE treatment increased endogenous AP-2α protein expression. AP-2α overexpression inhibited 5% CSE-induced cell apoptosis and activated caspase-3 expression (P<0.05) AP-2α protects ECV304 cells against CSE-induced apoptosis and may play an important role in smoking induced-apoptosis in COPD.

Src-JNK-dependent pathway in cigarette smoke-induced mucous hypersecretion in airway epithelial cells

The aim of this work was to find out whether Src kinase family and c-Jun N-terminal kinase (JNK) are involved in the ROS signaling pathway that could induce mucin MUC5AC expression in cultured cells of airway epithelia (BEAS-2B). For this purpose, the impact of cigarette smoke extract (CSE) on ROS production and MUC5AC expression in BEAS-2B cells was studied. Effects of ROS scavenger dimethylthiourea (DMTU), JNK specific inhibitor SP600125, and Src specific inhibitor PP2 in the CSE-induced ROS generation and MUC5AC expression were also assessed. A dose-dependent increase of ROS production in cells exposed to different concentrations of CSE was detected. DMTU inhibited cigarette smoke-induced Src phosphorylation, suggesting the ROS involvement in activation of Src kinase. Furthermore, SP600125 reduced the expression of MUC5AC. The activation of JNK was suppressed by PP2 but not by TACE inhibitor TAPI-1 or EGFR inhibitor PD153035. These results suggest that Src kinase participate in JNK activation and MUC5AC synthesis, which is independent of the TACE/EGFR activation. We conclude that ROS-Src-JNK signal cascade plays a particular role in cigarette smoke-induced mucin MUC5AC expression in BEAS-2B cells.

Effect of cigarette smoke extract on proliferation of rat pulmonary artery smooth muscle cells and the relevant roles of protein kinase C

Increased proliferation of pulmonary vascular cells and muscularisation of pulmonary vessels are frequently observed in human smokers and in animals exposed to cigarette smoke. To elucidate the molecular mechanisms leading to these changes, we studied the in vitro effect of cigarette smoke extract (CSE) on proliferation of pulmonary artery smooth muscle cells (PASMCs) and activation of protein kinase C (PKC), an important kinase implicated in cell proliferation. PASMCs cultured from 12 normal Wistar rats were studied in the following conditions: (1) PASMCs were exposed to different concentrations of CSE for 24 hours, then MTT colorimetric assay was used for detection of cell proliferation. Cell viability was assessed by trypan blue exclusion. (2) PASMCs were pre-incubated with phorbol 12-myristate 13-acetate (PMA) for 24 hours or Ro31-8220 for 30 minutes before exposure to 5% CSE for 24 hours. Cell proliferation was examined by MTT colorimetric assay, cell cycle analysis and proliferating cell nuclear antigen (PCNA) immunocytochemical staining. (3) PASMCs were exposed to 5% CSE for 24 hours. Then PKC-alpha mRNA expression was detected by reverse transcription-polymerase chain reaction (RT-PCR) and protein expression by Western blotting, while PKC-alpha translocation was observed by immunofluorescence staining and confocal microscopy. (4) PASMCs were transfected with specific antisense oligodeoxynucleotides against PKC-alpha 6 hours before exposure to 5% CSE for 24 hours. PKC-alpha protein expression and cell proliferation were detected by methods described previously. (1) Low concentration of CSE (5%) increased proliferation of PASMCs, whereas high concentrations (20%, 30%) were inhibitory as a result of cytotoxicity. (2) The value of absorbance (Value A), proliferation index (PI), S-phase cell fraction (SPF) and average optical density of PCNA staining in PASMCs from 5% CSE exposure group (0.306 +/- 0.033, 0.339 +/- 0.033, 0.175 +/- 0.021, 0.315 +/- 0.038, respectively) were significantly increased compared with those of control group (0.249 +/- 0.018, 0.177 +/- 0.055, 0.092 +/- 0.023, 0.187 +/- 0.022, respectively) (P < 0.05). PKC down-regulation by PMA pretreatment or PKC inhibition by Ro31-8220 pre-incubation abolished the effect of 5% CSE on PASMCs proliferation. (3) After exposure to 5% CSE for 24 hours, PKC-alpha mRNA and protein expression in PASMCs (1.054 +/- 0.078, 1.185 +/- 0.041, respectively) were much higher than in untreated cells (0.573 +/- 0.054, 0.671 +/- 0.055, respectively) (P < 0.01). Moreover, 5% CSE induced a translocation of PKC-alpha from cytoplasm toward the perinuclear area and into the nucleus. (4) Specific antisense oligodeoxynucleotides against PKC-alpha reduced 5% CSE-induced expression of PKC-alpha protein (0.713 +/- 0.047 vs 1.180 +/- 0.056), also abolished the effect of 5% CSE on PASMCs proliferation significantly. CSE can be cytotoxic at high concentrations. But at low concentrations, it makes a mitogenic effect on cultured PASMCs. PKC, especially its alpha isozyme, seems to play an important role in CSE-induced proliferation of PASMC.

Differential effects of cigarette smoke on oxidative stress and proinflammatory cytokine release in primary human airway epithelial cells and in a variety of transformed alveolar epithelial cells

BackgroundCigarette smoke mediated oxidative stress and inflammatory events in the airway and alveolar epithelium are important processes in the pathogenesis of smoking related pulmonary diseases. Previously, individual cell lines were used to assess the oxidative and proinflammatory effects of cigarette smoke with confounding results. In this study, a panel of human and rodent transformed epithelial cell lines were used to determine the effects of cigarette smoke extract (CSE) on oxidative stress markers, cell toxicity and proinflammatory cytokine release and compared the effects with that of primary human small airway epithelial cells (SAEC).MethodsPrimary human SAEC, transformed human (A549, H1299, H441), and rodent (murine MLE-15, rat L2) alveolar epithelial cells were treated with different concentrations of CSE (0.2–10%) ranging from 20 min to 24 hr. Cytotoxicity was assessed by lactate dehydrogenase release assay, trypan blue exclusion method and double staining with acridine orange and ethidium bromide. Glutathione concentration was measured by enzymatic recycling assay and 4-hydroxy-2-nonenal levels by using lipid peroxidation assay kit. The levels of proinflammatory cytokines (e.g. IL-8 and IL-6) were measured by ELISA. Nuclear translocation of the transcription factor, NF-κB was assessed by immunocytochemistry and immunoblotting.ResultsCigarette smoke extract dose-dependently depleted glutathione concentration, increased 4-hydroxy-2-nonenal (4-HNE) levels, and caused necrosis in the transformed cell lines as well as in SAEC. None of the transformed cell lines showed any significant release of cytokines in response to CSE. CSE, however, induced IL-8 and IL-6 release in primary cell lines in a dose-dependent manner, which was associated with the nuclear translocation of NF-κB in SAEC.ConclusionThis study suggests that primary, but not transformed, lung epithelial cells are an appropriate model to study the inflammatory mechanisms in response to cigarette smoke.

Effect of cigarette smoke extract on the proliferation of human airway epithelial cells and expression and activation of FAK.

The effect of cigarette smoke extract (CSE) on the proliferation of human airway epithelial cells and the possible mechanism was studied. After airway epithelial cells were treated with different concentrations of CSE for 24 h, the cell proliferation was measured by MTT and the distribution of different cell cycles by flow cytometry. The FAK expression level was detected by Western blot and the degree of tyrosine phosphorylation by immunoprecipitation. The results showed that CSE could inhibit the proliferation of human airway epithelial cells, arrest the epithelial cells in G1 phase of cell cycle, dramatically decrease the number of epithelial cells in S and G2 phases; Meanwhile CSE could decrease the expression level of FAK and the degree of its tyrosine phosphorylation. The above effects of CSE were concentration-dependent. The expression of FAK and the degree of its phosphorylation was positively correlated to the increased number of epithelial cells in G1 phase, and negatively to the number of epithelial cells in S and G2 phases. It was concluded that the mechanism by which CSE could inhibit the proliferation of human epithelial cells was contributed to the increased expression and activation of FAK.