腺病毒E1A蛋白对大鼠肺泡上皮细胞谷胱甘肽活性的影响及其机制探讨

目的 研究腺病毒E1A蛋白潜伏感染对大鼠肺泡上皮细胞谷胱甘肽(GSH)活性的影响及其机制.方法 构建稳定表达腺病毒E1A蛋白的大鼠肺泡上皮细胞,观察氧化剂刺激时细胞内GSH含量变化,检测GSH合成限速酶γ-谷氨酰半胱氨酸合成酶(γ-GCS)催化活性的变化,通过观察γ-GCS 催化亚单位(GCLC)基因蛋白表达水平、mRNA表达水平和5′-上游调控序列调控的荧光素酶活性的改变,了解影响酶活性改变的机制.结果 腺病毒E1A蛋白表达抑制氧化应激时GSH的合成,抑制γ-GCS 催化活性和蛋白表达水平,抑制GCLC 基因mRNA表达,与5′-上游调控序列报导系统获得的结果一致.结论 腺病毒潜伏感染可能通过抑制GCLC基因 5′-上游调控序列的促转录活性,抑制了γ-GCS的表达和催化活性,从而抑制了氧化应激时GSH的合成,削弱机体的抗氧化作用,加重氧化损伤,可能是腺病毒潜伏感染参与慢性阻塞性肺病(COPD)发病的机制之一.     

腺病毒E1A蛋白抑制大鼠肺泡上皮细胞γ-谷氨酰半胱氨酸合成酶催化亚单位表达的机制研究

目的： 研究腺病毒E1A蛋白抑制大鼠肺泡上皮细胞γ-谷氨酰半胱氨酸合成酶催化亚单位（GCLC）表达的机制。方法: 构建稳定表达腺病毒E1A蛋白的大鼠肺泡上皮细胞，将GCLC基因5’-上游调控序列不同长度的缺失体-萤火虫荧光素酶报道系统转染后分析转录活性的变化；检测AP-1、NF-κB、USF与GCLC基因调控序列的结合活性。结果: GCLC基因5’-上游调控序列报道系统检测结果显示大部分（9/11）缺失体的转录活性抑制，AP-1、NF-κB、USF与GCLC基因的结合活性增强，而对应的功能元件的转录活性降低。结论: 腺病毒E1A蛋白通过抑制GCLC基因 5’-上游调控序列的转录活性，扩大大鼠肺泡上皮细胞氧化应激时的氧化/抗氧化失衡,其机制可能涉及E1A对辅助转录因子的抑制。     

慢性阻塞性肺疾病大鼠中磷酸化蛋白激酶B与γ-谷氨酰半胱氨酸合成酶的表达研究

目的通过观察慢性阻塞性肺疾病（COPD）大鼠模型中γ-谷氨酰半胱氨酸合成酶（γ-GCS）与磷酸化蛋白激酶B（p-PKB）的表达,研究p-PKB和γ-GCS在COPD中可能的参与机制。方法28只健康雄性Wistar大鼠随机分为COPD组和对照组。采用每日熏香烟和两次气管内注入脂多糖（LPS）法制作COPD大鼠模型。检测肺组织中1-GCS活性,原位杂交检测肺组织中γ-GCS mRNA的表达,免疫组化和Western印迹分析肺组织中γ-GCS与p-PKB蛋白水平。结果γ-GCS活性在COPD组大鼠中明显高于对照组,组间差异有统计学意义（P〈0．05）。原位杂交显示COPD组大鼠支气管、肺泡上皮细胞与小动脉平滑肌细胞γ-GCS mRNA广泛表达,与对照组比较差异有统计学意义（P〈0．05）。COPD组大鼠γ-GCS与p-PKB免疫组化可见肺泡、支气管壁细胞及小血管平滑肌细胞胞浆有较强蛋白阳性信号;图像定量分析显示COPD组γ-GCS与p-PKB蛋白表达高于对照组,两组比较差异有统计学意义（P〈0．05）。Westernblot显示,γ—GCS与p-PKB在COPD组蛋白表达高于对照组,且差异有统计学意义（P〈0．05）。SPSS10．0直线相关分析得出p-PKB蛋白表达与γ-GCS活性、mRNA及蛋白表达呈正相关。结论COPD大鼠肺组织1．GCS蛋白和mRNA表达增高,p-PKB蛋白也有相应高表达,提示p-PKB和γ-GCS可能在COPD的发病机制中起作用,且PKB可能参与了γ-GCS的信号转导。     

香烟提取物和腺病毒E1A基因对肺泡上皮细胞ICAM-1表达的影响

目的:探讨香烟提取物(CSE)致肺泡上皮细胞细胞间粘附分子-1(ICAM-1)表达的作用及腺病毒E1A基因的影响.方法:通过脂质体转染的方法将腺病毒E1A基因转染A549细胞,获取E1A阳性表达A549细胞,不同浓度的CSE活化,测定细胞ICAM-1的表达.结果:CSE显著增加A549细胞ICAM-1表达,且呈浓度依赖性;与未转染和对照质粒转染A549细胞相比较,CSE活化后E1A阳性表达A549细胞ICAM-1表达显著增加.结论:CSE能够诱导肺泡上皮细胞ICAM-1表达,而腺病毒E1A基因显著增加CSE所致的肺泡上皮细胞ICAM-1表达,提示腺病毒潜伏感染放大吸烟所致的气道炎症反应.     

γ-谷氨酰半胱氨酸合成酶基因调控的初步研究

目的研究抗氧化基因——大鼠γ-谷氨酰半胱氨酸合成酶（γ-GCS）基因的功能区及其调控表达。方法克隆1．76kb大鼠γ-GCS基因的重链亚单位——GCLC基因的上游调控序列，并构建含荧光素酶基因的报道载体GCLC—Luc（GCLC／pGL-3）。利用嵌顿缺失方法构建GCLC基因的缺失体，并将其表达载体转染大鼠肺泡上皮细胞，在细胞中分析该基因的调控区域。通过该方法初步发现GCLC基因的上游调控序列的-745～-705bp属负性调控区域。利用EMSA和supershift证实大鼠肺泡上皮细胞GCLC基因负调控区域的E—box元件能与转录因子USF1／USF2特异性的结合。将USF的真核表达载体和逆转录病毒表达载体分别导入肺泡上皮细胞，观察GCLC基因的转录活性和GCLC蛋白的表达情况。结果GCLC基因的-403～-111bp和-705～-613bp区段属正调控区域；-745～-705bp属负调控区域。EMS和supershifl证实上游刺激因子（USF）能与该负调控区域的E—box元件结合抑制GCLC基因的转录和表达。结论发现GCLC基因其中2个正调控区域（-403～-111bp与-705～-613bp）和1个负调控区域（-745～-705bp），其中负调控区域-745～-705bp上的E—box元件通过与USF结合介导GCLC基因的负性表达调控。     

红霉素对吸烟大鼠肺内TGF-β1和γ-GCS表达的影响

目的： 探讨红霉素对吸烟大鼠肺内转化生长因子-β₁（TGF-β₁）和γ-谷氨酰半胱氨酸合成酶（γ-GCS）的影响以及在慢性阻塞性肺疾病治疗中的抗氧化作用。方法: Wistar大鼠30只，随机抽取20只被动吸烟4周后，10只继续吸烟8周作为吸烟组、10只吸烟加红霉素灌胃作红霉素治疗组，另10只作对照组。测定气道阻力和肺顺应性，采用免疫组织化学法、免疫细胞化学法和原位杂交法检测气道上皮细胞TGF-β₁和γ-GCS蛋白、肺泡巨噬细胞两者蛋白及其mRNA表达。结果: 吸烟组大鼠气道阻力增高，肺顺应性降低，TGF-β₁和γ-GCS蛋白及其mRNA表达均明显增高（P<0.05），红霉素治疗组气道阻力有所降低、肺顺应性增高，TGF-β₁和γ-GCS蛋白及其mRNA表达均低于吸烟组，但高于对照组（P<0.05）。吸烟组TGF-β₁与γ-GCS表达呈正相关（P<0.05），而红霉素治疗组无明显相关性。结论: 红霉素干预后吸烟大鼠肺内TGF-β₁和γ-GCS表达降低，提示红霉素可能在COPD治疗中发挥一定的抗氧化作用。     

红霉素对吸烟大鼠肺内TGF-β1和γ—GCS表达的影响

目的:探讨红霉素对吸烟大鼠肺内转化生长因子-β1(TGF-β1)和γ-谷氨酰半胱氨酸合成酶(γ-GCS)的影响以及在慢性阻塞性肺疾病治疗中的抗氧化作用。方法:Wistar大鼠30只,随机抽取20只被动吸烟4周后,10只继续吸烟8周作为吸烟组、10只吸烟加红霉素灌胃作红霉素治疗组,另10只作对照组。测定气道阻力和肺顺应性,采用免疫组织化学法、免疫细胞化学法和原位杂交法检测气道上皮细胞TGF-β1和γ-GCS蛋白、肺泡巨噬细胞两者蛋白及其mRNA表达。结果:吸烟组大鼠气道阻力增高,肺顺应性降低,TGF-β1和γ-GCS蛋白及其mRNA表达均明显增高(P<0.05),红霉素治疗组气道阻力有所降低、肺顺应性增高,TGF-β1和γ-GCS蛋白及其mRNA表达均低于吸烟组,但高于对照组(P<0.05)。吸烟组TGF-β1与γ-GCS表达呈正相关(P<0.05),而红霉素治疗组无明显相关性。结论:红霉素干预后吸烟大鼠肺内TGF-β1和γ-GCS表达降低,提示红霉素可能在COPD治疗中发挥一定的抗氧化作用。     

PPARγ影响γ-谷氨酰半胱氨酸合成酶活性及表达在大鼠慢性阻塞性肺疾病中的作用

目的： 探讨过氧化物酶体增生物激活受体γ(PPARγ)对慢性阻塞性肺疾病(COPD)大鼠肺γ-谷氨酰半胱氨酸合成酶(γ-GCS)活性及表达的影响,及在COPD发病中的作用。方法：用每天熏香烟和2次气管内滴入脂多糖（LPS）法制作大鼠COPD模型,同时利用PPARγ激活剂罗格列酮(RGZ)对其进行干预,测定3组大鼠肺功能和病理变化结果;并检测3组大鼠肺内ROS含量和γ-GCS活性;应用免疫组化、免疫印迹(Western blotting)、原位杂交和逆转录-聚合酶链反应（RT-PCR）方法检测PPARγ、γ-GCS mRNA及蛋白在3组大鼠肺组织中的表达情况。结果：RGZ干预组大鼠肺功能指标（FEV0.3、FEV0.3/FVC%与PEF）均较COPD组明显好转;光镜下COPD组肺组织病理变化符合COPD的特征性改变,RGZ干预组肺组织病理变化较COPD组显著减轻;RGZ干预组ROS含量较COPD组显著减少,而γ-GCS活性较COPD组升高;PPARγ、γ-GCS mRNA及其蛋白质表达在COPD组均较对照组明显增高（均P<0.01）,而在RGZ干预组均较COPD组增高（均P<0.0５）;直线相关分析显示PPARγ蛋白与γ-GCS活性呈正相关(r=０.634,P<0.01),与ROS含量无明显相关性(r=0.214, P>0.05);PPARγ蛋白与γ-GCS蛋白及mRNA表达呈正相关（r=0.553、r=0.442, 均P<0.01）。结论：RGZ活化PPARγ可减轻COPD氧化/抗氧化失衡程度,对COPD的防治起重要作用;另外,PPARγ可能通过减少肺内ROS的产生,增强γ-GCS活性及其基因表达而在COPD中起重要的抗氧化保护作用。     

阻断MEK1上调支气管上皮细胞谷氨酰半胱氨酸合成酶的表达

目的探讨MEK1信号通路与支气管上皮细胞(16-HBE)谷氨酰半胱氨酸合成酶(γ-GCS)表达的关系。方法应用MEK1抑制剂PD9805950μmol/L分别孵育16-HBE 2、8、16及24h。用Western印迹方法和荧光定量PCR检测细胞γ-GCS重链蛋白和mRNA的表达。用显色方法检测细胞内谷胱甘肽(GSH)的含量。用Western印迹方法检测细胞c-jun的水平。结果经PD98059孵育4、8、16及24h后,γ-GCS重链蛋白和mRNA的表达和细胞内GSH的含量较对照组均增加。各时间段c-jun表达较各对照组减少。结论在支气管上皮细胞中MEK1抑制剂PD98059对16-HBE的γ-GCS和GSH有明显的上调作用。阻断激活蛋白-1(AP-1)途径不能减少γ-GCS和GSH的合成。     

阻断MEK1上调支气管上皮细胞谷氨酰半胱氨酸合成酶的表达

目的 探讨MEK1信号通路与支气管上皮细胞(16-HBE)谷氨酰半胱氨酸合成酶(γ-GCS)表达的关系.方法 应用MEK1抑制剂PD98059 50μmol/L分别孵育16-HBE 2、8、16及24 h.用Western印迹方法和荧光定量PCR检测细胞γ-GCS重链蛋白和mRNA的表达.用显色方法检测细胞内谷胱甘肽(GSH)的含量.用Western印迹方法检测细胞c-jun的水平.结果 经PD98059孵育4、8、16及24 h后,γ-GCS重链蛋白和mRNA的表达和细胞内GSH的含量较对照组均增加.各时间段c-jun表达较各对照组减少.结论 在支气管上皮细胞中MEK1抑制剂PD98059对16-HBE的γ-GCS和GSH有明显的上调作用.阻断激活蛋白-1(AP-1)途径不能减少γ-GCS和GSH的合成.     

Cell-specific regulation of gamma-glutamylcysteine synthetase in human interstitial lung diseases

The pathogenesis of interstitial lung diseases (ILDs) is known to be associated with reactive oxygen and nitrogen metabolites and increased oxidant stress. One of the major antioxidants in human lung is glutathione (GSH) and enzymes linked to its synthesis. The rate-limiting enzyme of GSH synthesis is gamma-glutamylcysteine synthetase (γ-GCS) containing catalytically active heavy (γ-GCSh) and regulatory light (γ-GCSl) subunits. It can be hypothesized that γ-GCS is the major determinant in explaining reduced GSH levels in fibrotic lung disorders. We investigated the regulation of γ-GCS by transforming growth factor beta₁ (TGF-β₁) and tumor necrosis factor alpha (TNF-α) in human lung cells and its expression and distribution in fibrotic (biopsy-proven idiopathic pulmonary fibrosis, for instance, usual interstitial pneumonia, UIP, n = 15), inflammatory, and granulomatous diseases of human lung parenchyma (desquamative interstitial pneumonia, n = 10; ILD associated with collagen diseases, n = 10; sarcoidosis, n = 19 and allergic alveolitis, n = 8). In human lung alveolar epithelial cells, γ-GCSh was decreased by TGF-β₁, whereas TNF-α caused a transient enzyme induction. In normal lung, γ-GCS was mainly localized to the bronchiolar epithelium. In UIP, the highest immunoreactivities were observed in the airway epithelium and metaplastic alveolar epithelium, but fibroblastic foci were negative. In sarcoidosis, the highest reactivities were detected in the epithelium, alveolar macrophages and pulmonary granulomas. γ-GCS was ultrastructurally localized to the cytoplasm of regenerating type II pneumocytes and macrophages. In conclusion, γ-GCS is widely expressed in sarcoidosis and regenerating epithelium but is low in the fibrotic areas of usual interstitial pneumonia, probably because of enzyme down-regulation.     

Dehydroepiandrosterone improves hepatic antioxidant systems after renal ischemia-reperfusion injury in rabbits

This study evaluated the effects of dehydroepiandrosterone (DHEA) on the oxidant [malondialdehyde (MDA)] and antioxidant [superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione (GSH)] systems in liver after renal ischemia-reperfusion (IR) injury in rabbits. Thirty rabbits were randomly assigned to 3 groups of 10: group I (sham operation), group II (renal IR group), and group III (DHEA, 25 mg/kg, s.c., 15 min pre-ischemia). Renal IR injury in group II caused a decrease of SOD (25%), GPx (36%), and CAT (26%) activities and GSH levels (32%), and increases of MDA (30%) in liver and of ALT and AST activities in serum, compared to group I. DHEA administration decreased the hepatic MDA level (19%) and serum ALT activity (30%) (p <0.01 and p <0.05, respectively), and considerably increased hepatic GSH levels and GPx activities (p <0.01 for both) in group III, compared to group II. These results suggest that DHEA treatment has beneficial effects on antioxidant defenses against hepatic injury after renal IR in rabbits, possibly by augmenting GSH levels and lowering MDA production.     

Effect of Zingiber officinale on liver oxidative status and biochemical parameters in rats exposed to paraquat

Oxidative stress caused by reactive oxygen species is one of the major pathogenesis of important diseases of animals and human. Paraquat is widely used as herbicide. The toxicity of paraquat is through induction of oxidative processes in biological systems. Biochemically, this herbicide interferes with intracellular electron transfer system leading to the formation of superoxide anion. Zingiber officinale (ginger) is widely used as a spice and medical treatment for various diseases. The objective of this study was to assess the effect of different levels of ginger extract on antioxidant status and serum metabolites of rats. Sixty male albino Wistar rats were divided in six groups as follows: control (saline); ginger; paraquat; paraquat with 100, 200, and 400 ginger. After 30 days of treatment, the blood was collected by cardiac puncture. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), reduced glutathione (GSH), and lipid peroxidation were estimated. In paraquat-treated group, the serum levels of ALT, AST, and malondialdehyde (MDA) were markedly raised. Administration of ginger extract with paraquat reduced the serum levels of ALT, AST, and MDA. Hepatic SOD, CAT, GPx, GST, and GSH activities were significantly decreased in paraquat-treated group compared to those of control. However, concurrent administration of paraquat with all concentrations of ginger extract had the opposite effect, where it increased the hepatic SOD, CAT, GPx, GST, and GSH activities near to control. The present study demonstrates that administration of ginger extract to rats modulates the antioxidant enzymes and suggests a possible adaptive mechanism to counteract oxidative stress situation.     

aPKC及ERK在慢性阻塞性肺疾病大鼠中对NRF2-γ-GCS的调控作用

目的: 探讨慢性阻塞性肺疾病（COPD）大鼠模型中非典型蛋白激酶C(aPKC)、细胞外信号调节激酶(ERK)对红系衍生的核因子2相关因子2（NRF2）-γ-谷氨酰半胱氨酸合成酶（γ-GCS）的调控。方法: 雄性Wistar大鼠16只，随机分COPD模型组和对照组。检测γ-GCS活性，γ-GCS的基因表达和NRF2、磷酸化的aPKC（p-aPKC_ι/ζ）、磷酸化的ERK（p-ERK）的蛋白质表达。结果: （1）γ-GCS 活性在COPD组中明显高于对照组。（2）γ-GCS mRNA广泛高表达于COPD组支气管平滑肌细胞，而对照组在相应部位呈弱表达。对照组肺匀浆中有一定量γ-GCS mRNA表达，但相对于COPD组仍较低。（3） p-aPKC、p-ERK、NRF2、γ-GCS在COPD组支气管上皮细胞胞浆中高表达,而对照组相应部位呈弱表达。COPD组γ-GCS和p-aPKC、p-ERK、NRF2蛋白表达皆有明显上调。（4）NRF2蛋白表达与γ-GCS蛋白、mRNA表达呈正相关,p-aPKC_ι/ζ、p-ERK与NRF2蛋白表达也呈正相关。结论: aPKC、ERK可能通过使NRF2转录活性增加的方式上调NRF2，进而上调γ-GCS的表达，在COPD的氧化应激机制中可能起重要作用。     

Astaxanthin inhibits oxidative stress and apoptosis in diabetic retinopathy

BackgroundThe pathophysiology of diabetic retinopathy (DR) is thought to be influenced by oxidative stress. Astaxanthin (ASX) is a natural product with antioxidant effect, but it is not clear whether its mechanism of inhibiting the development of DR is related to anti-oxidation.MethodsRats were intraperitoneally injected with streptozotocin (60 mg/kg) to create DR rat models followed by ASX (20 mg/kg) for 45 days. Retinal tissue was examined by Hematoxylin and Eosin staining. By using Enzyme-linked immunosorbent assay (ELISA), 2,7-Dichlorodrhydrofluorescein diace (DCFH-DA) probes, immunohistochemistry and western blot, it was feasible to evaluate the contents of inflammation-related factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 and macrophage inhibitory cytokine-1 (MIC-1)), oxidative stress-related indicators (glutathione (GSH), malonic dialdehyde (MDA), glutathione peroxidase (GPx), reactive oxygen species (ROS) and Total antioxidant capacity (T-AOC)), antioxidant enzymes (hemoxgenase-1(HO-1) and Quinone Oxidoreductase 1 (NQO1)), and apoptosis-related proteins (Bcl-2, Bcl2 Associated X Protein (BAX), and cleaved-caspase-3). Additionally, antioxidant proteins downstream of the nuclear factor E2 related factors (Nrf-2) pathway, expression levels of Nrf2/ Kelch-like ECH-associated protein 1(Keap 1) pathway-associated proteins, and nuclear and cytoplasmic levels of Nrf2 were assessed using immunohistochemistry, western blot, or quantitative real-time polymerase chain reaction (qRT-PCR).ResultsASX alleviated retinal tissue damage by increasing overall retina thickness and ganglion cell layer (GCL) cell numbers and exerted the anti-inflammatory, anti-oxidative stress, and anti-apoptosis effects in DR rats. Additionally, ASX could inhibit the expression of Keap1, promote the transport of Nrf2 from cytoplasm to nucleus and facilitate the expressions of HO-1, NQO1, γ-glutamylcysteine synthetase, (γ-GCS) and GPx.ConclusionASX exerted antioxidant effects through Nrf2/keap1 pathway, thereby alleviating apoptosis, inflammation, and oxidative stress in retinal tissues of DR rats.     

Antioxidant enzyme immunoreactivity in rat von Ebner gland after nickel treatment

Our study was designed to clarify the role of antioxidant enzymes in the rat von Ebner gland during acute nickel toxicity. After treatment with nickel acetate, we monitored ultrastructural alterations in acinar and ductal cells, immunohistochemical staining for glutathione peroxidase (GPx) and glutathione S-transferases (GST mu and GST pi), and immunoreactivity for malondialdehyde (MDA). Immunoreactivity for MDA was present only in the acinar cells, and it was enhanced at 3 h after Ni treatment. In contrast, immunoreactivities for GPx and GSTs did not change in acinar cells but significantly increased in ductal cells after Ni treatment. Cytoplasmic vacuoles increased in acinar cells at 3 h after Ni treatment, but they almost completely disappeared at 24 h. No morphological changes were observed in taste bud cells from Ni-treated rats. Because lipid peroxidation, as monitored by immunoreactivity for MDA, was only transiently increased in the acinar cells, the enhanced antioxidant enzyme immunoreactivity in ductal cells of the von Ebner gland plays a crucial role in the self-defense system against nickel toxicity in the rat oral cavity.