Epidermal growth factor and trefoil factor family 2 synergistically trigger chemotaxis on BEAS-2B cells via different signaling cascades

Injured areas of the respiratory epithelium are subject to rapid repair by the migration of adjacent epithelial cells, a process termed "restitution". Rapid re-epithelialization is promoted by interactions between migrating cells and the extracellular matrix proteins. Furthermore, epidermal growth factor (EGF) as well as trefoil factor family (TFF) peptides are well known regulators of epithelial restitution due to their motogenic effects. Migration of the human bronchial epithelial cell line BEAS-2B in modified Boyden chambers was used as a model system for airway restitution. EGF or recombinant human TFF2 or TFF3 showed mainly chemotactic activity. The motogenic response was strictly dependent upon a haptotactic substrate, but to different degrees. EGF induced phosphorylation of extracellular signal-regulated kinases (ERK) 1/2, c-Jun-N-terminal kinase, p38, Akt, and p70S6K in BEAS-2B cells. Using specific inhibitors, the signaling cascades responsible for the motogenic response were shown to differ drastically when EGF was compared with TFF2. The motogenic effect of TFF2 was previously demonstrated to depend on ERK1/2 and protein kinase C activation; whereas the EGF-triggered motogenic response was completely independent of ERK1/2 activation but sensitive to the inhibition of phosphoinositide 3-kinase, p38, protein kinase C, or nuclear factor kappaB. However, the motogenic effects of EGF and TFF2 are additive. These data suggest that luminal EGF and TFF peptides can act synergistically in the human respiratory epithelium to enhance rapid repair processes in the course of diseases such as asthma.     

己糖激酶2通过抑制线粒体凋亡通路减少LPS引起的人肺上皮BEAS-2B细胞凋亡

目的:探讨脂多糖(LPS)诱导人正常肺上皮BEAS-2B细胞凋亡的分子机制,并对己糖激酶2(HK2)在该效应中的作用进行分析。方法:采用不同浓度的LPS作用于BEAS-2B细胞建立损伤模型,CCK-8实验检测细胞存活率; Hoechst 33342染色及Annexin V/PI双染法分析细胞凋亡水平;通过使用线粒体凋亡通路抑制剂或者外在凋亡通路抑制剂鉴定细胞凋亡通路;在BEAS-2B细胞中转染HK2过表达质粒以验证HK2对上述效应的影响。Western blot法确认HK2过表达效果;免疫荧光实验检测HK2亚细胞定位。结果:CCK-8实验结果显示,LPS以时间和剂量依赖性方式降低BEAS-2B细胞活力; Hoechst 33342染色结果表明,给予LPS处理后的BEAS-2B细胞核出现固缩和碎裂;同时Annexin V/PI双染实验结果表明,处于凋亡状态的细胞由2. 89%增加至42. 4%,细胞凋亡率明显升高(P 0. 05)。线粒体凋亡通路执行蛋白caspase-9特异性抑制剂可显著抑制细胞凋亡,而caspase-8抑制剂却无此效应。在BEAS-2B细胞的凋亡过程中伴随着HK2的表达下调,而HK2过表达可以有效阻止以上事件的发生。结论:己糖激酶2可通过抑制线粒体凋亡通路减少LPS引起的人肺上皮细胞凋亡。     

Oxidant generation promotes iron sequestration in BEAS-2B cells exposed to asbestos

Lung injury after asbestos exposure is associated with an oxidative stress that is catalyzed by iron in the fiber matrix, complexed to the surface, or both. We tested the hypothesis that the cellular response to asbestos includes the transport and sequestration of this iron through (1) generation of superoxide for ferrireduction, (2) up-regulation of divalent metal transporter-1 (DMT1) for intracellular transport of Fe2+, and (3) increased production of cellular ferritin where the metal is stored in a catalytically less reactive state. BEAS-2B cells with normal and elevated Cu,Zn superoxide dismutase (SOD) expression were employed for in vitro investigations. After exposure of these cells to asbestos, we demonstrated by fluorescence methodology a significantly increased generation of SOD with ferrireductive capacity. Fiber exposure also increased DMT1 protein and mRNA expression in the BEAS-2B cells. Incubation with asbestos elevated cellular iron and ferritin concentrations, and these responses were diminished in cells with an enhanced expression of SOD. Finally, fiber exposure increased supernatant concentrations of interleukin 8, but this inflammatory mediator was actually increased in cells with elevated SOD expression. We conclude that the response of respiratory epithelial cells to asbestos includes oxidant-mediated mechanisms to sequester catalytically active iron associated with the fiber.     

Role of MAP kinase activation in interleukin-8 production by human BEAS-2B bronchial epithelial cells submitted to cyclic stretch

Overstretching the airways during positive pressure mechanical ventilation or attacks of acute severe asthma is associated with important biologic responses. Interleukin (IL)-8-dependent neutrophil recruitment seems to play a critical role in the process of mechanical stress-induced airway inflammation. Herein, we show that human bronchial epithelial BEAS-2B cells submitted to cyclic stretch in vitro produce IL-8, at both the mRNA and protein levels. This cellular stress "turns on" activator protein (AP)-1 and cyclic AMP (cAMP)-responding elements. The mitogen-activated protein (MAP) kinases (MAPK) p44/42, SAPK/JNK, and p38 were all rapidly activated (phosphorylated) after the initiation of the cyclic strain (5-10 min). The blockade of p38 with the pharmacologic inhibitor SB203580 abrogated IL-8 production by cell stretching, and an inhibitor of the p44/42 pathway, PD98059, partially inhibited the IL-8 response. A nonspecific tyrosine kinase inhibitor, genistein, also blocked the stretch-induced IL-8 production. This suggests that MAPK, and p38 in particular, are proximal and key intracellular signaling molecules mediating cell activation in response to cyclic stretch, a mechanical strain similar to that applied to lung epithelial cells during mechanical ventilation. Pharmacologic inhibition of the p38 pathway holds promise as a new therapeutic avenue in ventilated patients.     

Hyperexpression of NOD2 in intestinal mast cells of Crohn's disease patients: preferential expression of inflammatory cell-recruiting molecules via NOD2 in mast cells

NOD2, an intracellular sensor of bacteria-derived muramyl dipeptide (MDP) has been implicated as a key player in intestinal immune health and disease. Mast cells (MCs) have been reported to be increased in the gut of patients with inflammatory bowel disease. However, NOD2 expression and its role in human primary MCs are unknown. The number of NOD2(+) intestinal MCs was significantly increased in the Crohn's disease (CD) specimens compared to Ulcerative colitis (UC) specimens and controls. IFN-gamma upregulated NOD2 expression in MCs. CXCL10 and urokinase-type plasminogen activator (uPA) upregulation was specific to MCs activated by MDP compared to MCs activated by LPS and IgE/anti-IgE. MDP-induced upregulation of ICAM-1, VCAM-1, and uPA was specific to MCs compared to mononuclear cells. The number of CXCL10(+)NOD2(+) intestinal MCs was significantly increased in the CD patients. Our results suggest that NOD2(+) MCs have specific pathogenic roles that involve the recruitment of inflammatory cells in CD.     

Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice

Type 1 diabetes is characterized by T-cell-mediated destruction of the insulin-producing β cells in pancreatic islets. A number of islet antigens recognized by CD8 T cells that contribute to disease pathogenesis in non-obese diabetic (NOD) mice have been identified; however, the antigenic specificities of the majority of the islet-infiltrating cells have yet to be determined. The primary goal of the current study was to identify candidate antigens based on the level and specificity of expression of their genes in mouse islets and in the mouse β cell line MIN6. Peptides derived from the candidates were selected based on their predicted ability to bind H-2K^d and were examined for recognition by islet-infiltrating T cells from NOD mice. Several proteins, including those encoded by Abcc8, Atp2a2, Pcsk2, Peg3 and Scg2, were validated as antigens in this way. Interestingly, islet-infiltrating T cells were also found to recognize peptides derived from proglucagon, whose expression in pancreatic islets is associated with α cells, which are not usually implicated in type 1 diabetes pathogenesis. However, type 1 diabetes patients have been reported to have serum autoantibodies to glucagon, and NOD mouse studies have shown a decrease in α cell mass during disease pathogenesis. Our finding of islet-infiltrating glucagon-specific T cells is consistent with these reports and suggests the possibility of α cell involvement in development and progression of disease.     

H1N1亚型流感病毒在A549和BEAS-2B细胞中复制情况的初步研究

目的 探讨不同宿主来源的H1N1亚型流感病毒在A549和BEAS-2B细胞的复制情况.方法 用分离自人、禽、猪三种宿主的7株H1N1甲型流感病毒分别接种A549和BEAS-2B细胞,分析病毒感染细胞后不同时段的特点;应用受体类型不同的红细胞进行微量血凝试验,检测流感病毒的受体结合特性;同时检测了A549和BEAS-2B细胞表面的受体分布情况.结果 三种宿主来源的H1N1亚型流感病毒感染A549细胞,24 h后CPE十分明显,36 h病毒滴度达到最高值;而感染BEAS-2B细胞后,从24 h-120 h CPE都不是很明显,且所有病毒的病毒滴度都很低.对6株H1N1流感病毒的受体结合特性进行了筛查,发现部分测试病毒具有SA a-2,6Gal受体结合特异性.而A549和BEAS-2B细胞表面均含有SA a-2,3Gal及SA a-2,6Gal受体,且A549细胞表面糖受体含量明显高于BEAS-2B细胞.结论 不同宿主来源的H1N1亚型流感病毒对A549细胞都易感并能有效增殖复制,而对具有相似受体特性、上皮组织来源的BEAS-2B细胞不易感,提示支持流感病毒有效感染、复制存在宿主内的调节机制.     

H5N1禽流感病毒NS1蛋白与干扰素诱导蛋白10表达的相关性研究

目的 研究高致病性禽流感(HPAI)H5N1病毒NS1蛋白对干扰素诱导蛋白10(IP-10)的影响.方法 分别将禽流感病毒A/Anhui/1/2005(H5N1)的NS1基因、插入80-84位缺失氨基酸的NS1突变基因及流感病毒A/Puerto Rico/8/1934(H1N1)的NS1基因克隆至真核表达载体pEGFP-N1,转染人支气管上皮细胞BEAS-2B,流式细胞仪检测转染细胞内IP-10的表达情况.结果 与pEGFP-N1对照组相比,三种NS1蛋白均能下调BEAS-2B细胞IP-10的表达(P<0.01),但三者之间下调程度差异无统计学意义(P>0.01).结论 A/Anhui/1/2005(H5N1)禽流感病毒单一NS1蛋白能够抑制BEAS-2B细胞IP-10表达,但这并不能完全阐明其与病毒致病性之间的关系.     

Increased NF-kappa B activity in B cells and bone marrow-derived dendritic cells from NOD mice

Type 1 diabetes results from the breakdown of peripheral tolerance. As regulators of T cell activation, antigen-presenting cells (APC) modulate peripheral tolerance and hence contribute to the immune dysregulation characteristic of insulin-dependent diabetes mellitus (IDDM). We initially observed an increased importance of NOD B cell APC function in a T cell priming assay as compared to non-autoimmune strains. Consistent with this increased APC function, we found that NF-kappa B nuclear translocation is increased in unmanipulated NOD and NOD.B10Sn-H2(b) B cells and that, in addition, NOD B cells are more sensitive to NF-kappa B-activating stimuli. We obtained similar results using NOD bone marrow-derived dendritic cell (BMDC) cultures. As costimulatory molecules have been shown to be NF-kappa B responsive, we examined the expression of these markers on NOD APC. Both B cells and BMDC expressed elevated levels of CD80 and CD40. Finally, NOD B cells provided better allostimulation than B cells from non-autoimmune strains. Therefore, hyperactivation of NF-kappa B and increased expression of CD80 and CD40 by NOD B cells and BMDC may be a contributing factor in the selection of effector T cells observed in IDDM.     

组胺对人结肠肥大细胞类胰蛋白酶释放的调节作用

探讨组胺对人结肠肥大细胞类胰蛋白酶释放的调节作用。经酶消化后获取人结肠组织肥大细胞,激发后行多种干预实验。用酶联免疫吸附试验法测定类胰蛋白酶。结果发现组胺可诱导人结肠肥大细胞释放类胰蛋白酶,浓度为100μg/L时组胺释放量最大,为基础值的3．5倍。浓度为10μg/L时对人肥大细胞的刺激强度与10mg/L的抗IgE抗体相似。组胺的作用从加样后10s开始,5min后完成。百日咳毒素和抗霉素A联合2．脱氧-D-葡萄糖可显著抑制组胺诱导人结肠肥大细胞释放类胰蛋白酶。100及1000μg/L的组胺与抗IgE抗体或离子载体钙同时加入细胞中,诱导类胰蛋白酶释放的能力低于组胺单独作用组。结论为组胺可激活人结肠肥大细胞,还以自身放大机制调节肥大细胞的脱颗粒过程。     

广州市PM2.5的污染状况及其有机提取物对BEAS-2B细胞IL-8、IL-1β表达的影响

目的调查广州市交通干道附近PM2.5的污染状况,并探讨PM2.5有机提取物对BEAS-2B细胞的炎性损伤效应。方法使用PM2.5采样器采集广州市交通干道附近的PM2.5,分析天平称重计算日平均浓度;索氏提取器提取PM2.5吸附的有机物作用于BEAS-2B细胞,ELISA检测IL-8、IL-1β的表达水平。结果广州市PM2.5日平均浓度为0.057～0.194mg/m3,其超标倍数为0.88～2.98;BEAS-2B细胞受到PM2.5有机提取物作用后,随着PM2.5有机提取物染毒剂量的增加,IL-8、IL-1β的分泌也明显增加;且随着各剂量作用时间的延长,IL-8、IL-1β的表达也增高。结论广州市交通干道旁PM2.5污染相当严重;PM2.5有机提取物能够刺激BEAS-2B细胞释放IL-8、IL-1β等炎性因子,吸引大量的炎性细胞释放炎性介质,从而形成气道的炎症损伤。     

Sulforaphane induces antioxidative and antiproliferative responses by generating reactive oxygen species in human bronchial epithelial BEAS-2B cells

Sulforaphane (SFN) is a naturally occurring compound which is known to induce the phase II antioxidant genes via Nrf2 activation, although the underlying mechanism has not been fully elucidated. In this study, we investigated Nrf2 induction in response to SFN in human bronchial epithelial BEAS-2B cells and determined the signaling pathways involved in this process. SFN treatment reduced cell viability. Prior to cell death, intracellular reactive oxygen species (ROS) were generated at a high rate within a minute of commencing SFN treatment. Pretreatment with antioxidant N-acetylcysteine (NAC) blocked SFN-induced decrease in cell growth. Erk1/2 was activated within 30 min of SFN addition, whereas Akt phosphorylation did not significantly change until the first 8 hr after SFN treatment but then became substantially low until 48 hr. Inhibition of Erk1/2 phosphorylation attenuated SFN-induced loss of cell viability. Nrf2 protein levels in both nuclear and whole cell lysates were increased by SFN treatment, which was dependent on ROS production. Knockdown of Nrf2 with siRNA attenuated SFN-induced heme oxygenase-1 (HO-1) up-regulation. Induction of the Nrf2/HO-1 after SFN treatment was potently suppressed by pretreatment with NAC. Overall, our results indicate that SFN mediates antioxidative and antiproliferative responses by generating ROS in BEAS-2B cells.     

Effect of acrylamide on BEAS-2B normal human lung cells: Cytotoxic,oxidative, apoptotic and morphometric analysis

Due to the broad toxic relevance of acrylamide, many measures have been taken since the 1900s. These measures increased day by day when acrylamide was discovered in foods in 2002, and its toxic spectrum was found to be wider than expected. Therefore, in some countries, the products with higher acrylamide content were restricted. On the other hand, the effects of acrylamide on the respiratory system cells have yet to be well understood. In this study, we aimed at investigating the effect of acrylamide on lung epithelial BEAS-2B cells. Initially, the cytotoxic effect of acrylamide on BEAS-2B was determined by MTT assay. Then, cellular oxidative stress was measured. Flow cytometry analysis was conducted for Annexin-V and caspase 3/7. Furthermore, Bax, Bcl-2 and Nrf-2 proteins were evaluated by immunocytochemistry. Finally, acrylamide-induced cellular morphological changes were observed under confocal and TEM microscopes. According to MTT results, the IC50 concentration of acrylamide was 2.00 mM. After acrylamide treatment, oxidative stress increased dose-dependently. Annexin V-labelled apoptotic cells and caspase 3/7 activity were higher than untreated cells in acrylamide-treated cells. Immunocytochemical examination revealed a marked decrease in Bcl-2, an increase in Bax and Nrf-2 protein staining upon acrylamide treatment. Furthermore, in confocal and TEM microscopy, apoptotic hallmarks were pronounced. In the present study, acrylamide was suggested to display anti-proliferative activity, decrease viability, induce apoptosis and oxidative stress and cause morphological changes in BEAS-2B cells.     

Idd-linked genetic regulation of TACIhigh expressing B cells in NOD mice

In NOD mice, B cells play a key role in the initiation of type 1 diabetes pathogenesis. We have identified a novel NOD-specific B cell-related trait, i.e. the increased percentage of TACI(high)-expressing splenic B cells, by comparing NOD mice with non-autoimmune C57BL/6 mice. Using athymic NOD mice, we determined that this trait was T cell independent. We mapped the loci contributing to the increased proportion of TACI(high) expressing splenic B cells and found that the control of TACI expression was strongly linked to chromosome 1, in a region which includes the insulin-dependent diabetes (Idd) 5 loci. Moreover, another locus potentially involved was detected in the vicinity of Idd22 on chromosome 8. Interestingly, when analyzing age-dependent contribution to the obtained LOD scores we observed that the linkage to chromosome 8 was explained solely by mice > or =61 days of age, suggesting a temporal genetic regulation of TACI expression. In addition, analysis of genetic interaction between chromosome 1 and chromosome 8 indicated that the two loci acted in an additive fashion. Our findings corroborate the notion that B cell deviations contribute to type 1 diabetes development, and suggest a temporal regulation of TACI(high) expression, possibly influenced by the ongoing autoimmune process.     

Involvement of miR-455 in the protective effect of H2S against chemical hypoxia-induced injury in BEAS-2B cells

The protective effect of hydrogen sulfide (H₂S) against hypoxia-induced injury via anti-apoptosis is well established, but the underlying mechanism remains unclear. The present study aimed to investigate whether miR-455 participated in the H₂S protection of lung epithelial cells against CoCl₂-induced apoptosis by regulating endoplasmic reticulum stress (ERS)-related genes. Human lung epithelial cells BEAS-2B were subjected to hypoxia injury with or without H₂S preconditioning. It was found that hypoxia injury increased apoptosis of BEAS-2B cells, down-regulated the expression of miR-455, and upregulated the expression of calreticulin (Calr). H₂S preconditioning attenuated lung epithelial cells apoptosis, enhanced cell viability, up-regulated the expression of miR-455, as well as down-regulated the expression of Calr following hypoxia injury. In addition, Calr, GRP78, C/EBP homologous protein (CHOP) and Caspase-12 protein was down-regulated by the miR-455 mimic and up-regulated by the miR-455 inhibitor. These results implicate miR-455 regulated H₂S protection of lung epithelial cells against hypoxia-induced apoptosis by stimulating Calr.     

Interleukin-8 differentially modulates interleukin-4- and interleukin-2-induced human B cell growth

The effect of interleukin-8 (IL)-8 on human B cell growth, as determined by thymidine uptake and viable cell numbers was studied. IL-8 inhibited IL-4-induced growth of B cells costimulated with anti-μ antibodies (Ab) or Staphylococcus aureus Cowan strain I (SAC) in a dose-dependent fashion. In contrast, IL-8 did not inhibit IL-2-induced growth of B cells. The IL-8-mediated inhibition was specific, since it was blocked by anti-IL-8 mAb but not by control IgG1. Moreover, anti-tumor necrosis factor-α (anti-TNF-α) Ab blocked IL-8-mediated inhibition. On the other hand, TNF-α, but not other cytokines including IL-1β, IL-3, IL-5, IL-6, interferon-α (IFN-α) or IFN-γ, inhibited IL-4-mediated growth, and inhibition by TNF-α was blocked by anti-TNF-α Ab but not by control IgG. IL-4 had no effect on TNF-α binding by B cells while it decreased TNF-α production by B cells. IL-8 had no effect in binding of IL-4, IL-2 or TNF-α by B cells, however, it enhanced TNF-α production by B cells. These results indicate that IL-8 inhibited IL-4-induced human B cell growth by enhancement of endogenous TNF-α production.     

Adherence of Streptococcus pneumoniae to Human Bronchial Epithelial Cells (BEAS-2B)

Pneumococcal adherence to alveolar epithelial cells and nasopharyngeal epithelial cells has been well characterized. However, the interaction of Streptococcus pneumoniae with bronchial epithelial cells has not been studied. We have now shown that pneumococci bind specifically to a human bronchial epithelial cell line (BEAS-2B cells). Pneumococci adhered to BEAS-2B cells in a time- and dose-dependent manner. These results suggest that the bronchial epithelium may serve as an additional site of attachment for pneumococci and demonstrate the utility of the BEAS-2B cell line for studying mechanisms of pneumococcal infection.