Oxidative stress in response to high glucose levels in endothelial cells and in endothelial progenitor cells: Evidence for differential glutathione peroxidase-1 expression

Endothelial cells and endothelial progenitor cells (EPCs) play a key role in the pathogenesis of vascular disease. Both cell types are affected by the oxidative stress but their susceptibility may be different.This study aimed to investigate the antioxidative enzymes activated in EPCs after high constant glucose exposure as compared to endothelial cells (HUVECs).Both cells were incubated in the presence of normal (5 mM) and high constant (25 mM) d-glucose, as well as l-glucose as osmotic control for 48 and 96 h.After a 48-hour exposure to high d-glucose, cell viability was significantly decreased both in EPCs and HUVECs as compared with normal d-glucose (p < 0.01). However, after 96 h there was no difference between EPCs grown on normal or high d-glucose, while HUVEC viability was affected by high d-glucose at 96 h too (p < 0.001).High d-glucose exposure induced a significant increase in reactive oxygen species (ROS) production in both cell types at 48 h; however, after 96 h, a significant decrease in ROS production (p < 0.01) and a parallel marked increase in glutathione peroxidase type 1 (GPx-1) expression (p < 0.01) and activity (p < 0.01) were observed in EPCs compared to HUVECs.These data suggest that EPCs have a well-adaptive response to oxidative stress induced by constant and sustained high glucose exposure. This resistance to high glucose levels might be due to increased expression and activity of glutathione peroxidase allowing better cell survival.     

DAPT在ox-LDL损伤HUVECs过程中的细胞保护作用

目的:探究γ-分泌酶抑制剂N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester(DAPT)在氧化低密度脂蛋白(oxidized low-density lipoprotein,ox-LDL)损伤人脐静脉内皮细胞(human umbilical vein endothelial cells,HUVECs)模型中的细胞保护作用及其对Notch信号通路的调控。方法:体外培养HUVECs,用oxLDL处理HUVECs构建细胞损伤模型。实验分为对照组、ox-LDL处理组、DAPT处理组和DAPT+ox-LDL处理组。用倒置相差显微镜观察不同处理方法下细胞的形态变化;CCK-8法检测细胞存活率;Western blot法检测蛋白Notch1、Notch4和Jagged1的表达情况。结果:体外培养HUVECs,倒置相差显微镜下发现ox-LDL处理组细胞死亡和碎片增多,经DAPT预处理后,ox-LDL作用造成的细胞损伤死亡较少,细胞碎片较少。通过CCK-8法检测发现ox-LDL处理组细胞存活率降低,DAPT处理组细胞存活率升高,DAPT预处理后ox-LDL造成存活率降低的幅度变小。在ox-LDL作用下,Notch1和Jagged1蛋白表达量降低,Notch4表达量升高;而DAPT作用下Notch1和Jagged1表达量升高,Notch4表达量降低;ox-LDL与DAPT共同作用时蛋白接近正常水平。结论:ox-LDL对HUVECs具有损伤作用;DAPT减轻ox-LDL对HUVECs造成的损伤;DAPT保护HUVECs免受ox-LDL损伤的作用与Notch信号通路有关。     

金属硫蛋白2A重组质粒的构建及其在血管内皮细胞中的表达

目的 建立人血管内皮细胞金属硫蛋白2A(MT2A)上调表达细胞模型.方法 构建重组质粒pEGFP-N1-MT2A,转染至人脐静脉内皮细胞(HUVECs),荧光显微镜观察转染效果,RT-PCR及蛋白印迹法测定细胞MT2A表达水平.结果 测序证实pEGFP-N1-MT2A重组质粒构建正确,转染至HUVECs后,通过RT-PCR蛋白印迹实验证实细胞MT2A表达水平升高.结论 成功构建了重组质粒pEGFP-N1-MT2A,转染至HUVECs可使MT2A表达水平升高.     

干扰人乳腺癌MDA-MB-231细胞 MK表达对内皮细胞增殖、迁移及脉管形成的影响

目的：观察干扰乳腺癌MDA-MB-231细胞中期因子( midkine, MK)表达对内皮细胞的增殖、迁移、脉管形成能力的变化,分析MK在肿瘤血管形成中的作用。方法采用shRNA法降低人乳腺癌MDA-MB-231细胞MK的表达,通过RT-PCR及Western blot法检测MK干扰效果,实验分为MK干扰组、空载体组及对照组;采用制备肿瘤条件培养基模拟肿瘤微环境培养HUVECs细胞,通过CCK-8法检测各组内皮细胞增殖能力、Transwell小室检测内皮细胞迁移能力、Matrigel检测内皮细胞脉管形成能力。结果与对照组及空载体组相比,MK干扰组细胞的增殖、迁移及脉管形成能力均明显降低(P<0．05)。结论干扰乳腺癌MDA-MB-231细胞MK的表达可抑制内皮细胞增殖、迁移、脉管形成能力,提示MK可能在肿瘤血管形成中起重要作用。     

Simvastatin suppresses vascular inflammation and atherosclerosis in ApoE?/? mice by downregulating the HMGB1-RAGE axis

Aim:

High mobility group box protein 1 (HMGB1) and receptor for the advanced glycation end product (RAGE) play pivotal roles in vascular inflammation and atherosclerosis. The aim of this study was to determine whether the HMGB1-RAGE axis was involved in the actions of simvastatin on vascular inflammation and atherosclerosis in ApoE^−/− mice.

Methods:

Five-week old ApoE^−/− mice and wild-type C57BL/6 mice were fed a Western diet. At 8 weeks of age, ApoE^−/− mice were administered simvastatin (50 mg·kg⁻¹·d⁻¹) or vehicle by gavage, and the wild-type mice were treated with vehicle. The mice were sacrificed at 11 weeks of age, and the atherosclerotic lesions in aortic sinus were assessed with Oil Red O staining. Macrophage migration was determined with scanning EM and immunohistochemistry. Human umbilical vein endothelial cells (HUVECs) were used for in vitro study. Western blots were used to quantify the protein expression of HMGB1, RAGE, vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1).

Results:

Vehicle-treated ApoE^−/− mice exhibited significant increases in aortic inflammation and atherosclerosis as well as enhanced expression of HMGB1, RAGE, VCAM-1, and MCP-1 in aortic tissues as compared to the wild-type mice. Furthermore, serum total cholesterol, triglyceride and LDL levels were markedly increased, while serum HDL level was decreased in vehicle-treated ApoE^−/− mice. Administration with simvastatin in ApoE^−/− mice markedly attenuated the vascular inflammation and atherosclerotic lesion area, and decreased the aortic expression of HMGB1, RAGE, VCAM-1, and MCP-1. However, simvastatin did not affect the abnormal levels of serum total cholesterol, triglyceride, LDL and HDL in ApoE^−/− mice. Exposure of HUVECs to HMGB1 (100 ng/mL) markedly increased the expression of HMGB1, RAGE and VCAM-1, whereas pretreatment of the cells with simvastatin (10 μmol/L) blocked the HMGB1-caused changes.

Conclusion:

Simvastatin inhibits vascular inflammation and atherosclerosis in ApoE^−/− mice, which may be mediated through downregulation of the HMGB1-RAGE axis.     

Antiangiogenic Effect of Bile Acid Acylated Heparin Derivative

Purpose Chemically modified heparin–DOCA was prepared and found to have markedly lower anticoagulant activity than heparin. In the present study, we elucidated the antiangiogenic and antitumoral activities of heparin–DOCA derivative.Methods To evaluate the antiangiogenic and antitumoral effects of heparin–DOCA, capillary-like tube formation assay, Matrigel plug assay in vivo, western blotting for FGFR phosphorylation, ERK and p38 MAPK activities, tumor growth of SCC in vivo and immunostaining of blood vessels in tumor tissues were performed.Results Heparin–DOCA inhibited capillary-like tubular structures of endothelial cells and bFGF-induced neovascularizations in Matrigel plug assays. Signaling experiments showed that heparin–DOCA significantly inhibited angiogenesis by suppressing the phosphorylation of FGFR and its downstream signal pathways (ERK and p38 MAPK activities). The antiangiogenic activity of this heparin derivative was found to be closely associated with antitumoral activity in a mouse model. In addition, histological evaluations supported the inhibitory effect of heparin–DOCA on blood vessel formation in tumor tissues.Conclusion Heparin–DOCA derivative exerted a significant antitumoral effect by inhibiting angiogenesis resulting from the disruption of FGF/FGFR and its downstream signal pathways, and could be applied to treat various angiogenic diseases.     

益气活血复方含药血清对人脐静脉内皮细胞TLR4／NF—KB信号通路及TNF—a ICAM-1 mRNA表达的影响

目的：研究益气活血复方含药血清对脂多糖（LPS）诱导的人脐静脉内皮细胞（HUVECs）Toll样受体4（TLR4）／NF—KB及肿瘤坏死因子-a（TNF—a）、细胞间黏附分子（ICAM-1）mRNA表达的影响,探讨益气活血复方含药血清防治动脉粥样硬化（AS）的机制。方法：（1）选择新西兰大耳白兔20只,随机分为4组,即正常组、中药高浓度组、中药中浓度组、中药低浓度组,每组5只。以上各组白兔分别以生理盐水和高、中、低浓度益气活血复方连续灌胃7天。末次灌胃给药2h后,心脏采血,离心后分离血清。（2）体外培养人脐静脉内皮细胞,用LPS刺激后,分别加入高、中、低浓度益气活血复方含药血清干预24h,收集细胞,用荧光定量PCR方法测定TLR4、NF—KB、TNF—a及ICAM-1mRNA的表达。结果：用LPS刺激人脐静脉内皮细胞后,引起TLR4、NF-KB、TNF-a及ICAM-1 mRNA的高表达（与空白对照组比较P〈0．01）,用益气活血复方含药血清干预以后显著抑制TLR4、NF-KB、TNF-a及ICAM-1 mRNA的高表达（与模型组比较P〈0．01或P〈0．05）。结论：益气活血复方可阻断TLR4／NF—KB信号通路的高表达,同时抑制TNF—a及ICAM-1的表达,这可能是其发挥抗动脉粥样硬化作用的机制之一。     

Ang1、Ang2及Tie2在脐静脉内皮细胞的体外三维培养中的表达及意义

目的 探讨促血管生成素1、2及其受体(Ang1、Ang2及Tie2)在人脐静脉内皮细胞(HUVECs)体外三维培养的血管生成中的作用.方法 采用逆转录-聚合酶链式反应(RT-PCR)的方法检测10例体内HVUECs、体外二维培养的HVUECs和三维培养的血管样结构中Ang1、Ang2及Tie2的mRNA表达水平.结果 体外三维培养的血管样结构中Ang2、Tie2的mRNA表达水平均高于体内HVUECs和体外二维培养的HVUECs,差异有显著性(P<0.05);各组中Ang1的mRNA表达水平相比差异无显著性(P>0.05).结论 Ang/Tie2体系在体外血管生成中可能起重要的作用.     

Reducing agents induce thrombomodulin shedding in human endothelial cells

The level of thrombomodulin (TM) on cell surfaces reflects its biosynthesis, intracellular turnover, proteolytic cleavage, and release in soluble form (sTM). In the present study we examined the mechanisms mediating and regulating sTM release. Inducers of endothelial protein C receptor (EPCR) shedding, such as proinflammatory cytokines, phorbol ester, and ionomycin did not affect sTM release from human umbilical endothelial cells (HUVECs). In contrast, several natural and synthetic reducing compounds (i.e., glutathione, dihydrolipoic acid, homocysteine, N-acetyl-L-cysteine, dithiothreitol, and non-thiol cell-impermeable reductant, tris-(2-carboxyethyl)phosphine), but not oxidized glutathione or α-lipoic acid effectively up-regulated the release of sTM in endothelial cells. In addition, the direct activator of metalloproteases, 4-aminophenylmercuric acetate (APMA), was an effective inducer of TM shedding. Considerable inhibition of protein C activation was found with APMA, which is consistent with the effects of this agent on TM shedding. In addition to metalloproteases, serine proteases were shown by pharmacological inhibition studies to be involved in a similar degree in basal sTM release; however, serine proteases seem preferentially to be involved in thiol-induced TM proteolytic processing. From comparisons of non-thiol containing synthetic substrate with human recombinant TM it was demonstrated that disulfide bonds within TM are most likely modified by thiols making TM more susceptible to serine protease-mediated cleavage. In summary, the study shows that the extracellular redox state plays a crucial role in the regulation of TM shedding in HUVECs thereby offering new strategies to interfere with diminished activation of protein C during inflammatory diseases.