弓形虫影响前列腺素E2合成的细胞内信号调节途径

目的　探讨弓形虫感染巨噬细胞过程中花生四烯酸 (AA)及前列腺素E₂ (PGE₂ )的产生及其相关的细胞内信号调节途径。　方法　构建刚地弓形虫 小鼠巨噬细胞侵染模型 ,应用气相色谱、酶联免疫吸附测定 (ELISA)、逆转录 聚合酶链反应 (RT-PCR)和蛋白质印迹法 (Westernblotting)检测钙离子调节剂乙二醇双 ( 2-氨基乙醚 )四乙酸 (EG-TA)、钙离子螯合剂 (BAPTA/AM )、钙调蛋白抑制剂三氟拉嗪 (TFP)及蛋白激酶C (PKC)抑制剂 1-( 5-磺酰基 ) 异喹啉-2-甲基-哌嗪盐酸盐 (H7)对弓形虫诱导的AA、PGE₂ 含量及促细胞分裂剂诱导性环加氧酶-2 (COX-2 )mRNA和蛋白质表达水平的影响。　结果　EGTA、BAPTA/AM及TFP均可抑制弓形虫诱导的巨噬细胞AA和PGE₂ 合成 ;PKC抑制剂H7可明显抑制弓形虫和脂多糖 (LPS)诱导的巨噬细胞PGE₂ 合成 ,并伴随着COX-2mRNA和蛋白质表达呈剂量依赖性减少。　结论　弓形虫侵染巨噬细胞过程可能通过钙信号转导途径调节COX-2底物AA的含量和PKC依赖的COX-2代谢途径调节PGE₂ 的合成。     

黄连素抑制结肠癌细胞环氧合酶-2的作用

目的 探讨黄连素对结肠癌细胞系HT—29的作用及其相关机制,为阐明黄连素作为一种新的结肠癌化学治疗药物进行理论上的准备并提供相关实验结果。方法 黄连素0．1、0．3、3．0、30．0μmol／L加入到HT—29结肠癌细胞系培养液中,每天测量各有关值。同时以NS—398为环氧合酶(COX-2)活性抑制剂,对比观察黄连素对COX—2活性的影响。采用氮蓝四唑盐实验法检测细胞的生长和增殖,逆转录—PCR法检测COX—2 mRNA,免疫细胞化学法检测COX—2蛋白表达,ELISA法检测前列腺素(PG)E2的含量。结果 黄连素在浓度大于0．3μmol／L时则有明显的量效关系。黄连素在浓度大于0．3μmol／L时对COX—2 mRNA水平和蛋白的表达有明显的抑制作用。黄连素对PGE2的生成有显著抑制作用。结论 黄连素抑制COX—2在mRNA水平和蛋白质水平的表达,同时也抑制COX—2活性,进而抑制PGE2的生成,这可能为黄连素抑制HT—29细胞生长和增殖的机制之一。     

环氧合酶-1和前列腺素E2在多潘立酮对大鼠胃黏膜保护中的作用

目的　研究多潘立酮对大鼠胃黏膜损伤是否具有保护作用 ,并探讨胃黏膜细胞中环氧合酶 1(COX 1)及前列腺素 (PG)E2是否参与其中。方法　研究分为对照组和实验组。后者分别用多潘立酮 0 .5mg/kg、1mg/kg和 2mg/kg灌胃 ,3次 /d ,连续 3d。各组大鼠灌入无水乙醇后 ,肉眼观察胃黏膜损伤指数 (LI) ,光镜下观察黏膜缺损深度 ,并计算黏膜缺损深度与胃壁全层厚度百分比。放射免疫法测定各组胃黏膜PGE2的水平。免疫组织化学方法检测COX 1和COX 2蛋白表达水平并以平均吸光度值表示其强度。RT PCR检测胃黏膜COX 1和COX 2mRNA表达变化。结果　多潘立酮 1mg/kg组的LI及黏膜缺损深度与胃壁全层厚度百分比显著低于对照组 (P <0 .0 5 ) ,0 .5mg/kg组和 2mg/kg的组LI亦显著低于对照组 (P <0 .0 5 )。多潘立酮 1mg/kg组大鼠胃黏膜COX 1蛋白表达水平及PGE2水平显著高于空白对照组 (P <0 .0 1)。各实验组和对照组在胃黏膜细胞内均无COX 2蛋白表达。三个实验组COX 1mRNA表达量与对照组比较差异均有显著性 (P <0 .0 1)。各组均未检测到COX 2mRNA表达。结论　多潘立酮对胃黏膜损伤具有保护作用 ,其机制之一可能与其增加胃黏膜COX 1mRNA和COX 1蛋白表达及促进胃黏膜PGE2分泌有关。     

白细胞介素—10抑制人肾系膜细胞环氧化酶—2及磷脂酶A2基因及蛋白表达的实验研究

目的：观察白细胞介素－10（IL－10）对IL－1β诱导的人系膜细胞（HMC）前列腺素E2（PGE2）释放和胸浆型磷脂酶A2（cPLA2）及环氧化酶－2（COX－2）和蛋白表达的影响。方法：利用体外培养的人系膜细胞（HMC）,设立对照组、IL－10（25ng/L）处理组、IL－1β（10ng/L）处理组及IL－10＋IL－1β处理组;采用放射免疫测定法检测各组HMC培养上清中PGE2,应用RT－PCR和Western Blot检测各组cPLA2、COX－2mRNA和蛋白水平。结果：正常情况下,HMC低水平表达cPLA2、COX-2 mRNA和蛋白并释放少量的PGE2;IL－1β能显著上调HMC PGE2释放及cPLA2、COX－2mRNA和蛋白的表达（P均＜0.01）;IL－10对基础状态下的HMC PGE2释放及cPLA2、COX－2mRNA和蛋白表达无明显影响（P均＞0.05）,但可显著下调IL－1β诱导的PGE2释放及cPLA2、COX－2mRNA和蛋白表达（P均＜0.01）。结论：IL－10抑制IL－1β诱导的HMC PGE2释放及cPLA2和COX－2表达,提示IL－10对HMC具有多方面抗炎作用。     

肌苷对脑缺血再灌注后COX-2表达的调节作用

目的　研究肌苷对大鼠脑缺血再灌注后COX 2mRNA及其蛋白表达的影响 ,探讨其神经保护作用机制。方法　应用线栓法建立大鼠脑缺血再灌注动物模型 ,腹腔注射肌苷 (1 0 0mg/kg) ,原位杂交法和免疫组织化学法检测大鼠脑缺血再灌注后COX 2mRNA及蛋白的表达。 结果　①对照组皮质和纹状体区COX 2mRNA表达于脑缺血再灌注 6h开始增强 ,1 2h达高峰 ,持续 2 4h～ 3d ,然后逐渐降低 ,至 1 4d降至再灌注 2h水平 ,同一时间点皮质区高于纹状体区。肌苷组COX 2mRNA表达于脑缺血再灌注 2h～ 1 4d较对照组显著减低 (P <0 0 1 )。②对照组皮质和纹状体区COX 2蛋白表达的变化趋势与COX 2mRNA相似 ,但其高峰出现在 2 4h ,较COX 2mRNA略延迟 ,且持续时间短 ,至 7d已降至再灌注 2h水平 ,同一时间点皮质区高于纹状体区。肌苷组COX 2表达于脑缺血再灌注 2h～ 1 4d较对照组显著减低 (P <0 0 1 )。结论　肌苷对脑缺血的保护作用可能是通过下调COX 2mRNA及蛋白表达而实现的     

尼美舒利对人胃癌SGC-7901细胞PGE2合成及COX-2、VEGF表达的影响

目的观察尼美舒利对人胃癌SGC-7901细胞前列腺素E2（PGE2）合成及环氧合酶（COX）-2、血管内皮生长因子（VEGF）表达的影响，探讨其抑制胃癌血管生成的机制。方法对人胃癌SGC-7901细胞进行培养．免疫组织化学、放射免疫法检测不同浓度尼美舒利作用后细胞COX-2、PGE2、VEGF的表达。结果与阴性对照组相比。尼美舒利100、200μmol／L作用48h后SGC-7901细胞的COX-2、VEGF表达明显降低（P〈0．05），COX-2与VEGF的表达呈正相关（r=0．8080，P〈0．05）；随着尼美舒利浓度的升高，PGE2分泌逐渐降低。结论抑制COX-2的活性与表达、减少PGE。的合成及由此引起的VEGF表达降低，在抑制胃癌血管生长中可能具有一定作用。     

环氧合酶-2抑制剂对结肠癌细胞株的体外研究

目的 观察选择性环氧合酶-2（COX-2）抑制剂对COX-2高表达的结肠癌细胞株HT-29增殖和凋亡的影响，明确以COX2为靶点治疗结肠癌的作用途径以及与COX-2活性、表达水平的相关关系。方法 将选择性COX-2抑制剂NS-398作用于结肠癌细胞系HT29，运用MTT法检测细胞增殖状态。流式细胞仪观察NS-398对细胞凋亡的影响。进一步用逆转录聚合酶链式反应（RT-PCR）检测药物作用前后HT-29中COX-2mRNA表达。ELISA法测定前列腺素E2（PGE2）水平。Western blot检测药物作用前后细胞周期素D1、Bcl-2的表达。结果 结肠癌细胞系HT-29中COX-2 mRNA高表达，NS-398呈时间和剂量依赖性抑制HT-29细胞增殖，促进其凋亡。加入NS-398的HT-29细胞中COX-2mRNA表达水平无明显变化（P〉0．05），PGE2却显著下降（P〈0．01）。72h时空白组与NS-398（75μmol／L）处理组细胞周期素D1、Bcl-2表达水平比值分别为2．21和3．25（P〈0．01），两者表达水平随作用时间延长而下降。结论 选择性COX-2抑制剂NS-398不影响结肠癌细胞COX-2 mRNA表达水平，而与其活性相关（PGE2水平）．可能通过细胞周期素D1、Bcl-2影响结肠癌细胞系HT-29的增殖与凋亡，揭示了COX-2为靶点治疗结肠癌的分子机制。     

抑制COX-2/PGE2通路对胶质瘤细胞免疫抑制因子表达的影响

目的 探讨celecoxib对脑胶质瘤细胞环氧化酶(COX)-2表达的影响,以及对免疫抑制因子前列环素E2( PGE2)、转化生长因子(TGF)-B、血管内皮生长因子(VEGF)等的影响.方法 利用Western印迹检测不同浓度celecoxib作用后,C6细胞COX-2蛋白表达水平;RT-PCR检测celecoxib对C6细胞TGF-β、VEGF mRNA表达的影响;酶联免疫法(ELISA)检测celecoxib作用后C6细胞上清PGE2、TGF-β、VEGF分泌水平.结果 celecoxib可呈浓度依赖性下调C6细胞COX-2蛋白表达水平;celecoxib作用后,C6细胞TGF-β、VEGF mRNA的表达水平明显下调(P＜0.01),相应细胞上清中PGE2、TGF-β、VEGF分泌水平亦明显下降(P＜0.01).结论 celecoxib可通过抑制COX-2蛋白活性,降低肿瘤局部微环境中的PGE2水平,并进一步下调TGF-β、VEGF的表达,从而改善胶质瘤微环境中免疫抑制状态.     

环氧合酶-2在大鼠酒精性肝炎中的表达及作用机制

目的　观察环氧合酶 2 (cyclooxygenase_2 ,COX_2 )在大鼠酒精性肝炎中的表达 ,探讨COX_2与酒精性肝炎的关系。方法　随机将 2 8只雄性SD大鼠分为正常组 7只 ,乙醇组 7只 ,以 10～ 12g·kg-1·d-1乙醇灌胃复制大鼠酒精性肝炎动物模型 ,实验组 2组 (每组 7只 ) ,以相同的方式复制动物模型后分别给予 0 4%和 0 8%的特异性COX 2抑制剂塞莱西布 (celecoxib)灌胃。测定肝组织中丙二醛 (malonaldehyde ,MDA)及血清ALT和AST水平 ,在光镜下观察肝脏的形态学改变 ,并应用RT_PCR技术检测COX 2mRNA在酒精性肝炎中的表达 ,其结果用凝胶分析系统测定相对表达量。结果　乙醇组大鼠肝组织中MDA含量较实验组大鼠和正常组大鼠明显增高 (P <0 .0 5 ) ;正常组和实验组大鼠血清ALT、AST浓度均明显低于乙醇组 (P <0 .0 5 )。HE染色光镜下见乙醇组大鼠肝细胞脂肪变性 ,炎性细胞浸润及细胞坏死。在正常组大鼠肝组织中COX 2mRNA无表达 ,乙醇组表达阳性 ,且显著高于两实验组COX_2mRNA的表达 (P <0 .0 5 )。结论　高表达的COX 2参与到酒精性肝炎的发生发展过程 ,应用特异性 (COX 2 )抑制剂塞莱西布有可能减轻乙醇诱导的肝损害     

辛伐他汀抑制人外周血单核巨噬细胞脂蛋白相关磷脂酶A2表达

目的 观察辛伐他汀对人外周血单核巨噬细胞脂蛋白相关磷脂酶A2(Lp-PLA2)表达的影响,并探讨其调控机制.方法 分离培养人外周血单核巨噬细胞,实验分为脂多糖(LPS)组、辛伐他汀组和丝裂原活化蛋白激酶(MAPK)干预组.LPS组:分别用不同浓度(0、1、10、102、103和104ng/ml)的LPS与细胞共同孵育6 h,观察不同浓度的辛伐他汀对LPS诱导的Lp-PLA2 mRNA和蛋白表达的影响;并用1μg/ml的LPS与细胞孵育不同时间(0、6、12、24和48 h),观察辛伐他汀作用不同时间对LPS诱导的Lp-PLA2 mRNA和蛋白表达的影响.辛伐他汀组:1 μg/ml的LPS+不同浓度的辛伐他汀(10-2～10-7mmol/L)与单核巨噬细胞共同孵育24 h,1 μg/ml LPS+10-3mmol/L的辛伐他汀与单核巨噬细胞孵育不同时间(0、6、24、24和48 h),观察辛伐他汀对LPS诱导的Lp-PLA2mRNA和蛋白表达及酶活性的影响.MAPK组:分别用10 μmol/L的p38抑制剂SB203580、20 μmol/L的ERK抑制剂U0126和20 μmol/L的JNK抑制剂SP600125预处理30 min后,将单核巨噬细胞与1μg/ml的LPS共同孵育24 h,观察MAPK信号通路在LPS介导的Lp-PLA2表达中的作用.逆转录-多聚酶链反应(RT-PCR)方法 检测Lp-PLA2 mRNA表达,比色法测定酶活性,Western blot方法 检测Lp-PLA2蛋白表达以及p38-MAPK蛋白及磷酸化水平.结果 (1)0.1μg/ml的LPS刺激6 h即可显著增加单核巨噬细胞Lp-PLA2 mRNA和蛋白的表达及其酶活性,并且随LPS浓度的增加和刺激时间的延长,该作用增强.(2)辛伐他汀可以明显抑制LPS诱导的Lp-PLA2的表达增加,并且降低酶活性,该作用呈浓度及时间依赖性.(3)辛伐他汀抑制LPS诱导的p38MAPK蛋白活化,p38MAPK的抑制剂SB203580可以完全阻断LPS介导的Lp-PLA2蛋白表达增加,与辛伐他汀作用相似.而MEK1/2的抑制剂U0126和JNK的抑制剂SP600125对LPS介导的Lp-PLA2蛋白表达的增加没有影响.结论 在培养的人外周血单核巨噬细胞中,辛伐他汀可以明显抑制LPS诱导的Lp-PLA2 mRNA和蛋白表达,降低Lp-PLA2酶活性,该作用至少部分由抑制p38MAPK信号转导通路介导.     

Leishmania donovani-induced macrophages cyclooxygenase-2 and prostaglandin E2 synthesis

Prostaglandin E2 (PGE2) secretion during Leishmania infection has been reported. However, the signalling mechanisms mediating this response are not well understood. Since cyclooxygenase-2 (COX-2) and cytosolic phospholipase A2 (cPLA2) are involved in PGE2 synthesis in response to various stimuli, the implication of these enzymes was evaluated in Leishmania-infected phorbol myristate acetate-differentiated U937 human monocytic cell line. Time-course experiments showed that PGE2 synthesis increased significantly in parallel with COX-2 expression when cells were incubated in the presence of Leishmania donovani promastigotes or lipopolysaccharides (LPS). Increase in cPLA2 mRNA expression was only detected when cells were stimulated with LPS. Indomethacin, genistein, and H7, which are antagonists of COX-2, protein tyrosine kinase (PTK) and protein kinase C (PKC), respectively, inhibited PGE2 production induced by L. donovani and LPS. However, only H7 inhibited COX-2 mRNA synthesis, and there was a significant correlation between PGE2 inhibition and reduced COX-2 expression. Collectively, our results indicate that infection of U937 by L. donovani leads to the generation of PGE2 in part through a PKC-dependent signalling pathway involving COX-2 expression. They further reveal that PTK-dependent events are necessary for Leishmania-induced PGE2 generation, but not for COX-2 expression. A better understanding of the mechanisms by which Leishmania can induce PGE2 production could provide insight into the pathophysiology of leishmaniasis and may help to improve therapeutic approaches.     

Effect of lipopolysaccharide on diarrhea and gastrointestinal transit in mice： Roles of nitric oxide and prostaglandin E2

AIM: To investigate the effect of lipopolysaccharide (LPS) on the diarrheogenic activity, gastrointestinal transit (GIT), and intestinal fluid content and the possible role of nitric oxide (NO) and prostaglandin E2 (PGE2) in gastrointestinal functions of endotoxin-treated mice. METHODS: Diarrheogic activity, GIT, and intestinal fluid content as well as nitric oxide and PGE2 products were measured after intraperitoneal administration of LPS in mice. RESULTS: LPS dose-dependently accumulated abundant fluid into the small intestine, induced diarrhea, but decreased the GIT. Both nitric oxide and PGE2 were found to increase in LPS-treated mice. Western blot analysis indicated that LPS significantly induced the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 in mice intestines. Pretreatment with NG-nitro-L-arginine-methyl ester (L-NAME, a non-selective NOS inhibitor) or indomethacin (an inhibitor of prostaglandin synthesis) significantly attenuated the effects of LPS on the diarrheogenic activity and intestine content, but reversed the GIT. CONCLUSION: The present study suggests that the pathogenesis of LPS treatment may mediate the stimulatory effect of LPS on nitric oxide and PGE2 production and NO/ prostaglandin pathway may play an important role on gastrointestinal function.     

Vascular endothelial growth factor up-regulates cyclooxygenase-2 expression in human endothelial cells

We investigated the effects of vascular endothelial growth factor (VEGF) on cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) (PGE(2)) synthesis in human microvascular endothelial cells (HMEC-1). Treatment of HMEC-1 with VEGF resulted in a dose- and time-dependent up-regulation of COX-2 mRNA and protein levels. This up-regulation was accompanied by a 1.6-fold increase in PGE(2) synthesis. Pretreatment of HMEC-1 with a selective COX-2 inhibitor, NS-398, abolished VEGF-induced PGE(2) synthesis, suggesting specific up-regulation of COX-2 activity by VEGF in HMEC-1. Transient transfection assays using deletion mutants of the human COX-2 promoter fused to the luciferase reporter gene indicated critical requirement of a regulatory region spanning -828/-123 bp for VEGF induction of COX-2 promoter activity in HMEC-1. Site-directed mutation analysis demonstrated that a GATA cis-acting element at -685/-680 bp was essential for VEGF- induced COX-2 promoter activity in HMEC-1. These observations are of particular importance given the recent demonstrations of critical requirement of COX-2 isoenzyme for tumor growth and angiogenesis.     

The effect of selective cyclooxygenase-2 inhibitor on human osteoclast precursors to influence osteoclastogenesis in vitro

Abstract

The inducible prostaglandin synthesis enzyme, cyclooxygenase-2 (COX-2), is involved in bone resorption and osteoclastogenesis, and acts indirectly through prostaglandin E2 (PG E2) produced by osteoblastic cells. This study was undertaken to investigate whether celecoxib (a selective COX-2 inhibitor) has a direct effect on human osteoclast precursors to influence osteoclastogenesis in vitro. Human peripheral blood mononuclear cells (PBMCs) were cultured on glass coverslips and dentine slices with soluble receptor activator of NF-kB ligand (sRANKL) and macrophage colony stimulating factor (M-CSF). COX inhibitors including celecoxib were added to the cultures. Osteoclast formation was assessed as the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and the functional evidence of lacunar resorption pits on dentine slices was assessed. Celecoxib and indomethacin inhibited osteoclast formation and the extent of lacunar resorption in a dose-dependent manner, but the effect of indomethacin was less than that of celecoxib. Mofezolac affected neither the number of TRAP-positive MNCs nor the extent of lacunar resorption pits. These results indicate that celecoxib influences not only osteoclast formation through osteoblastic cells but also acts directly on circulating osteoclast precursors to influence human osteoclast differentiation. The effect of celecoxib on osteoclast precursors may be related to the COX-2 signal pathway.     

The effect of selective cyclooxygenase-2 inhibitor on human osteoclast precursors to influence osteoclastogenesis in vitro

The inducible prostaglandin synthesis enzyme, cyclooxygenase-2 (COX-2), is involved in bone resorption and osteoclastogenesis, and acts indirectly through prostaglandin E2 (PG E2) produced by osteoblastic cells. This study was undertaken to investigate whether celecoxib (a selective COX-2 inhibitor) has a direct effect on human osteoclast precursors to influence osteoclastogenesis in vitro. Human peripheral blood mononuclear cells (PBMCs) were cultured on glass coverslips and dentine slices with soluble receptor activator of NF-kB ligand (sRANKL) and macrophage colony stimulating factor (M-CSF). COX inhibitors including celecoxib were added to the cultures. Osteoclast formation was assessed as the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and the functional evidence of lacunar resorption pits on dentine slices was assessed. Celecoxib and indomethacin inhibited osteoclast formation and the extent of lacunar resorption in a dose-dependent manner, but the effect of indomethacin was less than that of celecoxib. Mofezolac affected neither the number of TRAP-positive MNCs nor the extent of lacunar resorption pits. These results indicate that celecoxib influences not only osteoclast formation through osteoblastic cells but also acts directly on circulating osteoclast precursors to influence human osteoclast differentiation. The effect of celecoxib on osteoclast precursors may be related to the COX-2 signal pathway.     

Selective increase of neuronal cyclooxygenase-2 (COX-2) expression in vulnerable brain regions of rats with experimental Wernicke’s encephalopathy: effect of nimesulide

Thiamine deficiency (TD) in both humans and experimental animals results in severe mitochondrial dysfunction and leads to selective neuronal cell death in diencephalic and cerebellar structures. We have investigated cyclooxygenase-2 (COX-2) expression in vulnerable (medial thalamus, inferior colliculus) and spared (frontal cortex) regions of rats with thiamine deficiency. Expression of COX-2 mRNA was selectively increased (twofold, p < 0.001) in vulnerable regions at symptomatic stages of encephalopathy (14 days) of TD compared to pair-fed controls or presymptomatic (days 12) rats. Induction of COX-2 expression was accompanied by a significant increase (two- to threefold, p < 0.001) in prostanglandin E2 (PGE2) synthesis in vulnerable regions at symptomatic stages of TD. COX-2 immunolabeling revealed a neuronal localization and COX-2 immunoreactive neurons were significantly increased at symptomatic stages of encephalopathy. Administration of nimesulide, a highly specific COX-2 inhibitor, significantly reduced PGE-2 levels in vulnerable regions but, rather than being neuroprotective, precipitated encephalopathy and exacerbated neuronal cell death due to TD. These findings suggest that newly synthesized prostanoids exert a neuroprotective role in TD.     

Augmentation of allergic inflammation in the airways of cyclooxygenase-2-deficient mice

OBJECTIVE: Airway cyclooxygenase-2 (COX-2) is induced by cytokine-mediated inflammation such as occurs in asthma. However, the role of COX-2 in the pathophysiology of asthma is not fully understood. METHODS: Allergic inflammation, airway responsiveness to methacholine and mucous cell metaplasia after ovalbumin sensitization in the airways of COX-2 deficient (-/-) mice, COX-2 (+/+) mice and C57BL/6J mice treated with a selective COX-2 inhibitor, nimesulide were assessed. Histology, cell analysis, measurements of arachidonic acid metabolites and Th2 cytokine levels in bronchoalveolar lavage fluid (BALF), and measurement of serum IgE were performed. RESULTS: Eosinophil infiltration into the airway wall, and the number of eosinophils in BALF were greater in sensitized COX-2 (-/-) mice than in sensitized COX-2 (+/+) mice. The levels of cysteinyl leukotrienes (LTC4/D4/E4), prostaglandin E2 (PGE2) and interleukin (IL)-13 as well as airway responsiveness did not differ in COX-2 (-/-) mice and COX-2 (+/+) mice. However, sensitized COX-2 (-/-) mice had higher LTC4/D4/E4 and lower PGE2 concentrations compared with non-sensitized COX-2 (-/-) mice. The number of PAS/alcian blue-positive airway epithelial cells and serum IgE were elevated in COX-2 (-/-) mice. Nimesulide-treated mice showed augmented eosinophilic inflammation, LTC4/D4/E4 concentrations and mucous cell metaplasia. CONCLUSION: These data indicate that COX-2 deficiency augments allergic inflammation and mucous cell metaplasia.     

Cyclooxygenase-2 is required for tumor necrosis factor-alpha- and angiotensin II-mediated proliferation of vascular smooth muscle cells

Tumor necrosis factor-alpha (TNF-alpha) and angiotensin II (Ang II) induced a transient increase in vascular smooth muscle cell (VSMC) cyclooxygenase-2 (COX-2) mRNA accumulation, without affecting COX-1 mRNA levels. The kinetics of COX-2 mRNA accumulation were similar in VSMCs challenged with either TNF-alpha or Ang II; mRNA accumulation peaked at 2 hours and decreased to control levels by approximately 6 hours. Accumulation of COX-2 mRNA was associated with a time-dependent increase of COX-2 protein expression that displayed similar kinetics in response to either TNF-alpha or Ang II. Both the increase in COX-2 mRNA accumulation and protein expression in response to either TNF-alpha or Ang II were inhibited by the mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitor PD098059. In addition, the AT(1)-selective receptor antagonist losartan attenuated the Ang II-mediated increase in COX-2 mRNA accumulation; the AT(2)-selective antagonist PD123319 had no effect. Prostacyclin I(2) synthesis was tightly coupled to expression of COX-2, whereas prostaglandin E(2) and thromboxane A(2) (TXA(2)) synthesis may be associated with differential usage of COX-1 and COX-2. The COX-2-selective inhibitors NS-398 and nimesulide and the TXA(2) receptor antagonist BMS 180,291 inhibited TNF-alpha- and Ang II-mediated increases in DNA content and cell number by approximately 95%. These findings suggest that a prostanoid derived from COX-2, possibly TXA(2), may contribute to VSMC hyperplasia in vessel injury or pathophysiological conditions associated with elevated levels of either TNF-alpha or Ang II.