LPS对大鼠雪旺氏细胞iNOS表达的影响

目的：探讨内毒素脂多糖（Lipopolysaccharide,LPS）对大鼠雪旺氏细胞（Schwann cells,Scs）诱导型一氧化氮合酶（Inducible nitric-oxide synthase,iNOS）基因表达及一氧化氮（Nitric oxide,NO）生成的影响。方法：用不同浓度（1、10、100μg/ml）和同一浓度不同时间（1、2、4、6小时）的LPS刺激雪旺氏细胞,分别用RT-PCR和亚硝酸盐含量测定观察细胞iNOS mRNA的表达量和细胞培养液中亚硝酸盐的水平,同时用免疫荧光细胞化学染色检测iNOS的细胞定位。结果：用LPS10μg/ml刺激2小时后,iNOS mRNA的表达增加,4小时表达活性最高。细胞上清中的亚硝酸盐含量高峰在6小时。免疫细胞化学证明LPS诱导雪旺氏细胞iNOS的表达定位在胞浆。结论：LPS可在转录水平上诱导雪旺氏细胞iNOS mRNA表达,促进NO的合成,提示雪旺氏细胞在周围神经系统炎症过程中可能发挥免疫调节作用。     

氧化型低密度脂蛋白对人脐静脉内皮细胞ICAM-1及NO表达的影响

目的研究氧化型低密度脂蛋白(oxidized low density liprotein,ox-LDL)对脐静脉内皮细胞细胞间黏附分子-1(intercellular adhesion molecule-1,ICAM-1)及一氧化氮(nitric oxide,NO)表达的影响.方法采用细胞ELISA法测定细胞表面ICAM-l的含量,硝酸还原酶法测定细胞培养上清液中NO,免疫组化法结合图象分析测定细胞一氧化氮合酶(nitric oxide synthase,NOS)含量.结果 ox-LDL可明显增加脐静脉内皮细胞ICAM-l的表达,并减少NO及NOS的表达,且有浓度依赖性,但无明显的时间依赖性.结论 ox-LDL可损害内皮细胞的功能,减少内皮细胞NO、NOS的表达并增加内皮细胞ICAM-1的表达.这可能为ox-LDL促进动脉粥样硬化的机制之一.     

人抗菌肽FALL-39在大肠杆菌中高效表达

为构建抗菌肽的原核表达系统，解决抗菌肽获取困难的难题，满足研究和开发的需求。提取人肺腺上皮细胞株SPC—A—I总RNA，设计合成相应引物，应用RT—PCR从其总RNA中扩增FALL-39成熟肽cDNA，以pGEX-1λT为载体，构建抗菌肽FALL-39基因大肠杆菌表达载体。该载体表达的融合蛋白GST-FALL-39经亲合层析、凝血酶酶切、胶回收后获得高度纯化的FALL-39肽，对纯化产物进行的MEC、MIC、MBC等试验证明其具有较强的杀菌活性。本结果为深入研究FALL-39的结构与功能以及开发打下了良好的基础。     

人参二醇组皂苷对内毒素休克大鼠脑皮质TLR4 mRNA表达的影响

目的：通过观察内毒素休克大鼠脑皮质中NOS活性、NO含量和TLR4 mRNA的表达及人参二醇组皂苷（PDS）对其的影响，探讨内毒素引起脑组织损伤的分子机制。 方法： 大鼠随机分为实验对照（control）组、内毒素休克（LPS）组、地塞米松（LPS+Dex）组和人参二醇组皂苷（LPS+PDS）组。大鼠静脉注射内毒素（4 mg/kg）4 h后测定脑组织中NOS活性、NO含量及TLR4 mRNA的表达。 结果： LPS+Dex组和LPS+PDS组NOS活性、NO2-/NO3-含量显著低于LPS组（P＜0.05），TLR4 mRNA表达亦明显低于LPS组。 结论： PDS能够下调脑组织中TLR4 mRNA的表达，降低NOS活性、NO含量，对中枢神经系统具有保护作用。     

丝裂原激活蛋白激酶在内毒素脂多糖诱导大鼠施万细胞一氧化氮合酶表达中的作用

目的 主要研究丝裂原激活蛋白激酶(MAPK)信号途径在内毒素脂多糖(LPS)诱导大鼠施万细胞(Scs)诱导型一氧化氮合酶(iNOS)基因表达和一氧化氮(NO)产生中的作用.方法 先用3种MAPK的特异性抑制剂PD98059(ERK1/2)、SB202190(P38 MAPK)和SP600125(JNK)以不同浓度预处理细胞1h,再用LPS作用施万细胞4 h后,用RT-PCR检测细胞中iNOS mRNA、IL-6 mRNA和TNF-α mRNA的表达;Western blotting观察iNOS蛋白水平的表达变化;通过测定细胞培养液中亚硝酸盐含量来观察NO的水平.结果 LPS可显著激活施万细胞中MAPK信号通路诱导iNOS表达.MAPK的抑制剂预处理细胞后,可显著抑制细胞iNOS mRNA和NO的合成及IL-6 mRNA和TNF-α mRNA的表达.结论 MAPK信号通路参与了LPS介导的大鼠施万细胞iNOS基因表达和NO产生,通过阻断细胞内信号转导通路来减少iNOS及其他细胞因子的产生,为抑制周围神经损伤后的炎症以及免疫反应发生提供了一条新思路.     

诱生型一氧化氮合酶抑制剂硫酸甲基异硫脲对内毒素血症大鼠肠系膜淋巴管一氧化氮合酶表达的影响

目的 :研究内毒素血症中诱生型一氧化氮合酶 (induciblenitricoxidesyhthases,iNOS)抑制剂硫酸甲基异硫脲(S Methy1isothioureasulfate,SMT)对大鼠肠系膜淋巴管一氧化氮合酶 (nitricoxidesyhthase,NOS)表达的影响。探讨在内毒素血症中一氧化氮 (nitricoxide,NO)对肠系膜淋巴微循环的影响。方法 :利用NADPH 黄递酶组织化学染色方法观察NOS在大鼠肠系膜淋巴管的表达 ,用硝酸还原酶法测定血清中NO的含量。结果 :脂多糖(lipopolysaccharide,LPS)组大鼠随时间延长肠系膜淋巴管染色强度明显加深 ,血清NO含量显著升高。LPS SMT组染色强度比LPS组降低 ,血清NO含量显著下降。结论 :在内毒素血症中 ,SMT可能通过抑制NOS的活性而起保护作用。     

PYNOD对LPS活化的BV2小胶质细胞炎症因子释放的影响

 目的:观察PYNOD对LPS活化的BV2小胶质细胞炎症因子释放的影响。方法: 将表达PYNOD的重组质粒pEGFP-C2-PYNOD瞬时转染BV2细胞后,加入LPS作用24 h,Griess 法检测一氧化氮（nitric oxide, NO）的释放,实时荧光定量PCR（real-time PCR）检测诱导型一氧化氮合酶（inducible NO synthase, iNOS）和白细胞介素-1β（interleukin-1β,IL-1β）mRNA的表达,此外Western blotting和ELISA法检测iNOS和IL-1β的蛋白表达。结果: 转染PYNOD重组质粒能显著抑制LPS诱导的BV2小胶质细胞炎症因子NO的释放（P＜0.05）。Real-time PCR证实PYNOD可抑制iNOS和 IL-1β 的mRNA表达,差异有统计学意义（P＜0.05）。ELISA和Western blotting证实PYNOD可下调iNOS和 IL-1β 蛋白的表达（P＜0.05）。结论: PYNOD蛋白可以在转录水平和翻译水平显著抑制LPS刺激的BV2小胶质细胞活化产生的炎症反应。     

川芎嗪对内毒素性休克大鼠脑损伤的作用

目的:研究川芎嗪(ligustrazine,Lig)对内毒素性休克大鼠脑损伤的作用并探讨其作用机制。方法:将48只健康Wistar大鼠随机分为正常组、LPS组和LPS+Lig组,每组16只,上述每组再分为2个亚组:6 h组和12 h组,各8只大鼠。以尾静脉注射5 mg/kg脂多糖(LPS)建立内毒素性休克大鼠模型,腹腔注射盐酸川芎嗪注射液200 mg/kg,分别在相应时点进行眼球摘除采血并断头取脑组织,ELISA法检测血清中神经元特异性烯醇化酶(neuron-specific enolase,NSE)含量,脑组织匀浆检测一氧化氮(nitric oxide,NO)含量,TUNEL染色法检测脑组织中海马区细胞凋亡情况,Western blot法检测Bax和Bcl-2蛋白的表达。结果:与LPS组相比,川芎嗪能降低内毒素性休克所致大鼠NSE和NO含量的上升,同时抑制海马区细胞的凋亡,增加Bax的蛋白表达并降低Bcl-2的蛋白表达。结论:川芎嗪通过降低NSE和NO含量,减轻内毒素性休克大鼠的脑损伤程度,可能与其调节Bax和Bcl-2蛋白的表达有关。     

金纳多对内毒素诱导小鼠急性肺损伤保护作用机制的初步研究

目的：初步探讨银杏叶提取物金纳多（Ginaton）对内毒素（lipopolysaccharide, LPS）诱导小鼠的急性肺损伤(acute lung injury, ALI)保护作用的可能机制。方法：于小鼠腹腔注射LPS（10 mg/kg）复制ALI动物模型。将小鼠随机分为对照组、LPS组、Ginaton组和Ginaton＋LPS组。观察各组肺组织病理学改变,测量肺湿/干重比,支气管肺泡灌洗液蛋白含量及乳酸脱氢酶（lactate dehydrogenase, LDH）活性,测量丙二醛（malondialdehyde, MDA）、一氧化氮合酶（nitric oxide synthase, iNOS）和髓过氧化物（myeloperoxidase,MPO),免疫组织化学方法检测血红素加氧酶（heme oxygenase HO-1）及iNOS蛋白表达。结果： 金纳多可有效减轻LPS所致肺组织病理学变化,并降低肺湿/干重比和肺泡灌洗液中蛋白含量,降低肺泡灌洗液中LDH活性、肺组织MPO和iNOS活性,同时MDA和NO含量下降。免疫组织化学结果显示,LPS组iNOS表达上升（P＜0.01）,而血红素加氧酶（HO-1）蛋白表达未见明显变化;而预先给予Ginaton可显著提高HO-1的表达,降低iNOS的表达（P＜0.01）。结论：Ginaton可减轻LPS所致急性肺组织损伤,其机制可能与诱导HO-1的表达,下调iNOS的表达和活性有关。     

iNOS抑制剂SMT对内毒素血症大鼠淋巴管动力学的影响

目的 :研究一氧化氮 (NO)在急性内毒素血症中对淋巴管运动的调节作用及诱生型一氧化氮合酶 (iNOS)抑制剂硫酸甲基异硫脲(SMT)对内毒素血症中淋巴微循环的作用。方法 :用倒置显微镜和图像处理系统对肠系膜淋巴管进行动态观测 ,并用硝酸还原酶法测定血清中NO的含量。结果 :LPS组肠系膜淋巴管管径比正常扩大 ,运动频率降低 ,淋巴管运动指数下降。LPS +SMT组则有显著改善。随时间延长LPS组血清NO含量显著升高 ,LPS +SMT组则有明显下降。结论 :内毒素血症中NO过量产生 ,使肠系膜淋巴管扩张 ,收缩减弱。内毒素血症早期应用iNOS抑制剂SMT可维持淋巴微循环于正常水平。     

Induction of nitric oxide production by bovine alveolar macrophages in response toPasteurella haemolyticaA1

We assessed the kinetics of inducible nitric oxide synthase (iNOS) mRNA expression and production of nitric oxide (NO) in bovine alveolar macrophages (AMs) stimulated with purified lipopolysaccharide (LPS) fromPasteurella haemolyticastrain 12296. The effect of LPS on iNOS gene expression was dose-dependent and was expressed maximally at 24 h after stimulation with 10 μg/ml of LPS. Production of NO measured as secreted nitrite in supernatants took place in a time and dose-dependent manner with peak production at 24 h after LPS stimulation. Recombinant bovine gamma interferon (rbγIFN) augmented the LPS-induced iNOS gene expression and production of NO. The ability of LPS to induce iNOS gene expression and NO production either alone or in combination with rbγIFN was significantly abrogated by polymyxin B. In addition, the iNOS inhibitor N^G-monomethyl-Larginine (L-NMMA) significantly inhibited LPS and rbγIFN+LPS induced NO production. Our results also demonstrated that NO produced from an exogenous NO donor sodium nitroprusside (SNP), and NO generated from LPS-stimulated AMs (endogenous) caused cytotoxic injury to bovine pulmonary artery endothelial cells in a dose-dependent manner. The cytotoxic injury caused by NO generated from LPS stimulated AMs was inhibited by polymyxin B or L-NMMA. There was a markedly increased concentration of nitrite in the lung lavage fluids of calves followingP. haemolyticainfection. These findings support a role for NO in the pathogenesis of lung injury in bovine pneumonic pasteurellosis.     

Role of nitric oxide in lipopolysaccharide-induced hepatic injury in D-galactosamine-sensitized mice as an experimental endotoxic shock model

The role of nitric oxide (NO) in lipopolysaccharide (LPS)-induced hepatic injury was studied in D-galactosamine (D-GalN)-sensitized mice. The inducible isoform of NO synthase (iNOS) was immunohistochemically detected on hepatocytes around blood vessels in livers of mice injected with D-GalN and LPS not on hepatocytes in mice injected with D-GalN or LPS alone, although mRNA for iNOS was found in those mice. Nitrotyrosine (NT) was also found in livers of mice injected with D-GalN and LPS. The localization of NT was consistent with that of iNOS, and the time courses of NT and iNOS expression were almost the same. Expression of iNOS and NT was detected exclusively in the hepatic lesions of mice injected with D-GalN and LPS. Anti-tumor necrosis factor alpha neutralizing antibody inhibited iNOS and NT expression and hepatic injury. The results suggested that NO from iNOS may play a role in LPS-induced hepatic injury on D-GalN-sensitized mice as an experimental endotoxic shock model.     

Stimulation of production of glial cell line-derived neurotrophic factor and nitric oxide by lipopolysaccharide with different dose-responsiveness in cultured rat macrophages

To understand the molecular basis of inflammation-induced neurotrophic influences, we investigated the effects of lipopolysaccharide (LPS) on production of glial cell line-derived neurotrophic factor (GDNF) in the injured rat spinal cord or in cultured rat macrophages in comparison with the effects on synthesis/secretion of inducible nitric oxide synthase (iNOS) and nitric oxide (NO). We found that GDNF mRNA expression lasted longer than that of iNOS mRNA in the injured spinal cord after injection of the high-dose LPS that had improved locomotor function, suggesting that the GDNF expression and its balance with NO generation were critical for injury regeneration. Therefore, we next investigated the effects of LPS on cultured macrophages. Levels of iNOS mRNA and secreted NO were enhanced by LPS at lower concentrations (10 ng/mL and above), whereas mRNA expression and secretion of GDNF were elevated only at higher concentrations (100 ng/mL and above). The culture medium of macrophages treated with 10 ng/mL of LPS was actually neurotoxic against cultured cortical neurons, whereas that conditioned at 1000 ng/mL was not. These observations suggest that neurotoxicity partly based on NO is induced by a lower degree of inflammation, whereas neurotrophic effects based on GDNF are manifested at a higher degree of inflammatory activity.     

Effect of inducible nitric oxide synthase on apoptosis in Candida-induced acute lung injury

Excessive nitric oxide (NO) generated by inducible nitric oxide synthase (iNOS) aggravates acute lung injury (ALI) by producing peroxinitrite. We previously showed that the expression of iNOS and lung injury were suppressed by inhalation of a novel iNOS inhibitor, ONO-1714, in mice with Candida-induced ALI, and that nitric oxide produced by iNOS and apoptosis of epithelial cells were found to have a crucial role in Candida-induced ALI. In the present study, we investigated the effect of NO on the apoptosis of alveolar epithelial cells in Candida-induced ALI. Mice were pretreated by inhalation of ONO-1714 or saline (vehicle control of ONO-1714), and were given an intravenous injection of Candida albicans to induce ALI. After 24 h from injection of Candida albicans, we performed bronchoalveolar lavage and removed lung tissues. We assessed apoptosis on the basis of TUNEL staining and caspase 3 activity. Our results showed that apoptosis was suppressed by inhibition of iNOS-derived NO production by ONO-1714 inhalation. The augmented production of NO increased FasL, TNF-alpha, and mRNA production of Bax of lung that induced apoptosis of alveolar epithelial cells. Inhibition of iNOS-derived NO production by ONO-1714 inhalation ameliorated Candida-induced ALI and improved survival by suppressing apoptosis of alveolar epithelial cells.     

Hydrogen peroxide enhances LPS-induced nitric oxide production via the expression of interferon beta in BV-2 microglial cells

Activated microglia produces inflammatory cytokines and nitric oxide (NO) that involved in neuronal injury and neurodegenerative diseases. We report herein, that H(2)O(2) intensifies the LPS-triggered expression of iNOS in the microglia cell line, BV-2, resulting in an enhancement in the production of NO. The NO production induced by a combination of LPS and H(2)O(2) was blocked by the addition of an anti-interferonβ (IFNβ) neutral antibody, suggesting that IFNβ levels are correlated with the LPS/H(2)O(2)-induced production of NO. However, although the expression of IFNβ was induced by H(2)O(2) treatment alone, neither the expression of iNOS mRNA nor the production of NO were induced. In addition, the expression of IFN receptor (IFNR) was induced by LPS but not by H(2)O(2). These data indicate that although H(2)O(2) alone cannot induce iNOS expression because of the insufficient expression of IFNR, in the presence of LPS, H(2)O(2) enhances iNOS expression via the expression of IFNβ. Our findings suggest that H(2)O(2) produced by activated microglia further enhances NO production in various inflammatory states.     

Augmentation of nitric oxide production by gamma interferon in a mouse vascular endothelial cell line and its modulation by tumor necrosis factor alpha and lipopolysaccharide

The effect of gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and lipopolysaccharide (LPS) on nitric oxide (NO) production in the mouse vascular aortic endothelial cell line END-D was examined. LPS, TNF-alpha, and a low concentration of IFN-gamma inhibited NO production in END-D cells, while a high concentration of IFN-gamma definitely enhanced it. The NO production induced by a high concentration of IFN-gamma was further augmented by using IFN-gamma in combination with LPS or TNF-alpha. In sequential incubations of LPS and IFN-gamma, the enhancement of NO production required prior treatment with IFN-gamma. Stimulation of END-D cells with a high concentration of IFN-gamma led to the expression of inducible NO synthase (iNOS). The augmentation of NO production by IFN-gamma alone or in combination with LPS or TNF-alpha was completely blocked by several inhibitors of iNOS. It was strongly suggested that a high concentration of IFN-gamma itself enhanced NO production in END-D cells through inducing the expression of iNOS. LPS and TNF-alpha exclusively modulated the activity of iNOS once its expression was triggered by IFN-gamma. On the other hand, a low concentration of IFN-gamma, LPS, and TNF-alpha reduced NO production through down-regulating constitutive NOS (cNOS). The differential regulation of cNOS- and iNOS-mediated NO production by IFN-gamma, TNF-alpha, and LPS is discussed.     

Organ-specific and differential requirement of TYK2 and IFNAR1 for LPS-induced iNOS expression in vivo

Lipopolysaccharide (LPS) is an integral structural component of the outer membrane of Gram-negative bacteria and the principal active agent in the pathogenesis of endotoxin shock. LPS is a potent inducer of a variety of cytokines and inflammatory agents that lead to a profound alteration of gene expression patterns in cells and organs. The gene coding for the inducible nitric oxide synthase (iNOS) is highly responsive to LPS in vitro and in vivo and accounts for the production of nitric oxide (NO). The Janus kinase (JAK) family member tyrosine kinase 2 (TYK2) is a constituent of the interferon (IFN) type I response pathway and an important effector in the progression of endotoxin shock. Macrophages deficient for IFNalphabeta receptor chain 1 (IFNAR1) or TYK2 were shown to have an impaired LPS-induced iNOS expression. Here we determined the contribution of IFNAR1 and TYK2 to iNOS expression in vivo in a lethal LPS challenge model. TYK2 and IFNAR1 were found to be crucial for the LPS-induced iNOS mRNA and protein expression in spleen and lung that could be attributed to the Mac3-positive population. In liver LPS-induced iNOS mRNA expression was only partially impaired in TYK2-deficient mice and was unimpaired in IFNAR1-deficient mice, indicating organ specificity. TYK2(-/-) and IFNAR1(-/-) mice also differ with respect to IFNgamma production upon LPS challenge in that TYK2(-/-) mice show a defect while IFNAR1(-/-) mice do not. Our data suggest that iNOS is induced through IFNAR1 and TYK2 in Mac3-positive cells which are the main source of iNOS in spleen and lung. The LPS-induced iNOS expression in liver is independent of IFNAR1 and partially dependent on TYK2, which is most likely due to the lack of IFNgamma production in the absence of TYK2.