Adenoviral expression of vascular endothelial growth factor-C induces lymphangiogenesis in the skin

The growth of blood and lymphatic vasculature is mediated in part by secreted polypeptides of the vascular endothelial growth factor (VEGF) family. The prototype VEGF binds VEGF receptor (VEGFR)-1 and VEGFR-2 and is angiogenic, whereas VEGF-C, which binds to VEGFR-2 and VEGFR-3, is either angiogenic or lymphangiogenic in different assays. We used an adenoviral gene transfer approach to compare the effects of these growth factors in adult mice. Recombinant adenoviruses encoding human VEGF-C or VEGF were injected subcutaneously into C57Bl6 mice or into the ears of nude mice. Immunohistochemical analysis showed that VEGF-C upregulated VEGFR-2 and VEGFR-3 expression and VEGF upregulated VEGFR-2 expression at 4 days after injection. After 2 weeks, histochemical and immunohistochemical analysis, including staining for the lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), the vascular endothelial marker platelet-endothelial cell adhesion molecule-1 (PECAM-1), and the proliferating cell nuclear antigen (PCNA) revealed that VEGF-C induced mainly lymphangiogenesis in contrast to VEGF, which induced only angiogenesis. These results have significant implications in the planning of gene therapy using these growth factors.     

肿瘤坏死因子促进内皮细胞微颗粒释放的实验研究

目的研究肿瘤坏死因子损伤人脐静脉内皮细胞促进内皮细胞微颗粒释放,提出内皮细胞微颗粒是反映内皮损伤和功能障碍的新指标。方法应用肿瘤坏死因子-α刺激人脐静脉内皮细胞,扫描电镜观察细胞表面形态及内皮细胞微颗粒的生成,应用流式细胞仪检测细胞培养液中血小板细胞黏附分子(CD31+)和玻连蛋白(CD51+)微颗粒的水平。结果扫描电镜观察到静息状态下内皮细胞生成的微颗粒较少,经肿瘤坏死因子-α刺激24h后内皮细胞表面呈“出疹样”改变,小泡数目明显增多,直径大小约1.0μm。流式细胞仪检测证实细胞培养液中肿瘤坏死因子-α刺激组较正常对照组内皮细胞微颗粒水平明显增高[CD31+内皮细胞微颗粒,(164±63)/1000内皮细胞比(42±10)/1000内皮细胞,P<0.05;CD51+内皮细胞微颗粒,(260±108)/1000内皮细胞比(19±4)/1000内皮细胞,P<0.05]。结论肿瘤坏死因子损伤内皮细胞导致内皮细胞微颗粒释放增多,内皮细胞微颗粒有望成为评估内皮损伤替代指标之一。     

Tumor necrosis factor-alpha induces endothelial dysfunction in the prediabetic metabolic syndrome

Inflammation is a condition that underscores many cardiovascular pathologies including endothelial dysfunction, but no link is yet established between the vascular pathology of the metabolic syndrome with a particular inflammatory cytokine. We hypothesized that impairments in coronary endothelial function in the obese condition the prediabetic metabolic syndrome is caused by TNF-alpha overexpression. To test this, we measured endothelium-dependent (acetylcholine) and -independent vasodilation (sodium nitroprusside) of isolated, pressurized coronary small arteries from lean control and Zucker obese fatty (ZOF, a model of prediabetic metabolic syndrome) rats. In ZOF rats, dilation to ACh was blunted compared with lean rats, but sodium nitroprusside-induced dilation was comparable. Superoxide (O2*-) generation was elevated in vessels from ZOF rats compared with lean rats, and administration of the O2*- scavenger TEMPOL, NAD(P)H oxidase inhibitor (apocynin), or anti-TNF-alpha restored endothelium-dependent dilation in the ZOF rats. Real-time PCR and Western blotting revealed that mRNA and protein of TNF-alpha were higher in ZOF rats than that in lean rats, whereas eNOS protein levels were reduced in the ZOF versus lean rats. Immunostaining showed that TNF-alpha in ZOF rat heart is localized in endothelial cells and vascular smooth muscle cells. Expression of NAD(P)H subunits p22 and p40-phox were elevated in ZOF compared with lean animals. Administration of TNF-alpha more than 3 days also induced expression of these NAD(P)H subunits and abrogated endothelium-dependent dilation. In conclusion, the results demonstrate the endothelial dysfunction occurring in the metabolic syndrome is the result of effects of the inflammatory cytokine TNF-alpha and subsequent production of O2*-.     

Src contributes to IL6-induced vascular endothelial growth factor-C expression in lymphatic endothelial cells

Formation of lymphatic capillaries by lymphatic endothelial cells (LECs) occurs both in normal tissues as well as in pathological processes including tumor metastasis. Interleukin-6 (IL-6), a potent pro-inflammatory cytokine, has been shown to be highly elevated in various cancers. IL-6 has also been shown to increase tumor lymphangiogenesis through vascular endothelial growth factor-C (VEGF-C) induction in tumor cells. Although lymphangiogenesis is associated with lymph node metastasis and also resistance to conventional therapy in various cancers, the precise mechanisms of lymphangiogenesis in LECs remain unclear. This study aimed to investigate the signaling cascade involved in IL-6-induced VEGF-C expression in murine LECs (SV-LEC). The VEGF-C mRNA and protein levels were increased in SV-LECs exposed to IL-6. IL-6 time-dependently induced Src phosphorylation and downstream phosphorylation of ERK1/2 and p38MAPK. In contrast, PP2, an inhibitor of Src signaling, abrogated IL-6′s effects on ERK1/2 and p38MAPK phosphorylation. IL-6 exposure also led to increase in VEGF-C promoter-luciferase activity as well as C/EBPβ- and κB-luciferase activities. VEGF-C promoter-, C/EBPβ- and κB-luciferase activities were all suppressed by Src, ERK1/2 or p38MAPK signaling blockades despite presence of IL-6. Finally, C/EBPβ and p65 binding to the VEGF-C promoter region were increased after IL-6 exposure in SV-LECs. Taken together, we report a Src-mediated ERK1/2 and p38MAPK activation resulting in C/EBPβ and p65 binding to the promoter region of VEGF-C, leading to VEGF-C expression in IL-6-exposed SV-LECs.     

Tumor necrosis factor-alpha blockade in the treatment of rheumatoid arthritis

The use of TNF alpha antagonists in RA has been extremely instructive. They have taught us that selective targeting of a pathogenic element can provide substantial clinical benefit. They have reinforced the concept of TNF alpha as a pivotal cytokine in the pathogenesis of RA. Pharmacodynamic studies of TNF alpha antagonists have further clarified the pathogenic processes involved in the disease. TNF alpha antagonists have set a new therapeutic standard for RA. Indeed, they are one of the most important advances in the history of the treatment of the disorder. If clinical efficacy is sustained and the safety profile remains benign over the long term, TNF alpha antagonists may replace MTX as the gold standard and become the agent of choice for combination therapy in RA. Further studies are needed to clarify their ultimate position in the therapeutic algorithm.     

Expression of vascular endothelial growth factor-C in human hepatocellular carcinoma

Background/Aims: Vascular endothelial growth factor‐C (VEGF‐C) is thought to be an important factor in tumor angiogenesis/lymphangiogenesis, but its role in hepatocellular carcinoma (HCC) has not yet been fully investigated. Methods: We immunohistochemically examined VEGF‐C expression in surgically resected tissues of 90 HCC. Results: In the 78 HCC with a single histological grade, VEGF‐C expression was significantly stronger in poorly differentiated HCC than in well‐ (P = 0.003) or moderately differentiated HCC (P = 0.0002). A ‘nodule‐in‐nodule’ case presented VEGF‐A expression in the well‐differentiated component and VEGF‐C expression in the moderately–poorly differentiated component. According to nodular diameter, VEGF‐C expression was significantly higher in nodules of 3.0 cm or larger (P = 0.0263). Extrahepatic metastases seen in seven cases expressed VEGF‐C. In 20 of the 28 cases who were able to be followed up, the frequency of intrahepatic recurrence tended to be higher and extrahepatic metastasis was significantly higher in the cases who had VEGF‐C expression in the tumor casts of the intrahepatic portal/hepatic vein branches than other cases without the expression (P = 0.0139). Disease‐free survival time tended to be shorter in cases with VEGF‐C expression in tumor casts of the portal/hepatic vein than in those without VEGF‐C expression (P = 0.053; log–rank test). Conclusions: VEGF‐C expression is related to the progression of HCC, and VEGF‐C expression in tumor casts of the intrahepatic portal/hepatic vein is considered to be a factor indicating recurrence/metastasis sites.     

Tumor necrosis factor-alpha and vascular angiotensin II in estrogen-deficient rats

Alterations in the vascular angiotensin II system may play a role in the pathophysiology of vascular disease after menopause. In previous studies we have shown that an increase in tumor necrosis factor (TNF)-alpha levels in aging rats because of estrogen deficiency may result in vascular dysfunction. In this study we investigated the effect of TNF-alpha inhibition in angiotensin II modulation of vascular function in aging female animals. Female rats approaching reproductive senescence (12 to 15 months old) were ovariectomized and treated with placebo, estrogen, or a selective TNF-alpha inhibitor (etanercept) for 4 weeks. Expression of angiotensin II in mesenteric arteries was evaluated by immunofluorescence, and the expression of angiotensin-converting enzyme and angiotensin type I receptor (AT(1)R) was investigated by Western immunoblot. Vascular function was assessed in mesenteric arteries using the myograph system, and the role of endogenous angiotensin II on adrenergic vasoconstriction was evaluated in vitro by selective AT(1)R blockade (Candesartan; 10 micromol/L). Our data demonstrate that estrogen-depleted rats have higher serum levels of TNF-alpha and greater sensitivity to phenylephrine vasoconstriction compared with estrogen-replaced animals, which was attenuated by AT(1)R blockade. In vivo TNF-alpha inhibition or estrogen replacement reduced phenylephrine constriction of mesenteric arteries and decreased the modulation of this vasoconstriction by candesartan. These functional changes were accompanied by a reduction in the vascular expression of angiotensin II, angiotensin-converting enzyme, and AT(1)R. These observations indicate that upregulation of TNF-alpha during estrogen deficiency may contribute to enhance vascular constriction by altering the vascular angiotensin II system.     

Tumor necrosis factor-alpha inhibits growth factor-mediated cell proliferation through SHP-1 activation in endothelial cells

Src homology 2-containing protein-tyrosine phosphatase 1 (SHP-1) is known to regulate signal transduction through the dephosphorylation of tyrosine kinases. In this study, we addressed the role of SHP-1 under tumor necrosis factor-alpha (TNF-alpha) stimulation in endothelial cells. The addition of recombinant vascular endothelial growth factor (50 ng/mL) or epidermal growth factor (50 ng/mL) significantly increased thymidine incorporation and c-fos promoter activity, whereas TNF-alpha (5 ng/mL) attenuated these effects in human or bovine aortic endothelial cells. In bovine aortic endothelial cells, we confirmed endogenous SHP-1 expression and that TNF-alpha activated SHP-1. Importantly, overexpression of dominant-negative SHP-1 attenuated the effect of TNF-alpha on thymidine incorporation and c-fos promoter activity. In addition, TNF-alpha attenuated vascular endothelial growth factor- and epidermal growth factor-induced extracellular signal-regulated kinase phosphorylation, whereas overexpression of dominant-negative SHP-1 prevented this inhibitory effect of TNF-alpha. Taken together, our results suggested that TNF-alpha inhibited growth factor-mediated cell proliferation through SHP-1 activation.     

Tumor necrosis factor-alpha gene polymorphism in severe and mild-moderate rheumatoid arthritis

OBJECTIVE: To examine whether severe rheumatoid arthritis (RA) carries a -238 or +489 tumor necrosis factor-alpha (TNF-alpha) genotype different from mild-moderate RA. METHODS: We investigated 163 patients (66 with severe disease) and 67 healthy blood donor controls. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: Patients with severe RA (all active disease despite disease modifying antirheumatic drug combination therapy) disclosed the -238 GG genotype in 100% of cases versus 92.8% of the mild-moderates and 92.5% of controls (OR 11.7, Cl 0.6-216, p = 0.03). The +489 AA genotype was seen less often in patients than in controls (OR 4.2. CI 0.97-18.4, p = 0.045), and the contribution to this trend appeared predominant in the anti-TNF treated subgroup. CONCLUSION: The -238 AG genotype was absent in severe RA; in contrast, patients with mild-moderate RA disclosed the same frequency as controls. Thus -238 GG homozygosity is associated with severe RA. The +489 AA genotype might instead protect against worse outcome in RA.     

大肠癌组织中生长抑素和血管内皮生长因子-C的表达及其临床意义

目的探讨大肠癌组织中生长抑素（SS）和血管内皮生长因子-C（VEGF-C）的表达及其临床意义。方法采用免疫组化法检测60例大肠癌组织及20例正常大肠黏膜组织中SS蛋白和VEGF-C蛋白的表达，采用VEGF-C受体FLT-4阳性脉管标记淋巴管计数，分析SS与大肠癌淋巴管生成、转移的关系。结果SS蛋白表达阳性率在大肠癌组及正常大肠黏膜组分别为37．7％和65％，VEGF-C在癌及正常组阳性表达率分别为60％和30％，差别均有显著性；SS表达与肿瘤分化程度、淋巴结转移、淋巴管侵犯及远处转移密切相关，与浆面膜受累无关；VEGF-C表达与肿瘤淋巴结转移，淋巴管侵犯及远处转移密切相关，而与肿瘤分化和浆面膜受累无关；大肠癌组织中SS和VEGF-C蛋白表达呈显著负相关。结论SS可能通过对VEGF-C／FLT-4信号通路的阻滞而抑制大肠癌淋巴管生成及转移。     

Tumor necrosis factor-alpha induces insulin resistance in endothelial cells via a p38 mitogen-activated protein kinase-dependent pathway

Chronic inflammation contributes to vascular insulin resistance and endothelial dysfunction. Systemic infusion of TNF-alpha abrogates insulin's action to enhance skeletal muscle microvascular perfusion. In skeletal muscle TNF-alpha induces insulin resistance via the p38 MAPK pathway. To examine whether p38 MAPK also regulates TNF-alpha-induced vascular insulin resistance, bovine aortic endothelial cells (bAECs) were incubated+/-TNF-alpha (5 ng/ml) for 6 h in the presence or absence of SB203580 (p38 MAPK specific inhibitor, 10 microM) after serum starvation for 10 h. For the last 30 min, cells were treated+/-1 nM insulin, and insulin receptor substrate (IRS)-1, Akt, endothelial nitric oxide synthase (eNOS), p38 MAPK, ERK1/2, c-Jun N-terminal kinase, and AMP-activated protein kinase (AMPK) phosphorylation, and eNOS activity were measured. TNF-alpha increased p38 MAPK phosphorylation, potently stimulated IRS-1 serine phosphorylation, and blunted insulin-stimulated IRS-1 tyrosine and Akt phosphorylation and eNOS activity. TNF-alpha also potently stimulated the phosphorylation of ERK1/2 and AMPK. Treatment with SB203580 decreased p38 MAPK phosphorylation back to the baseline and restored insulin sensitivity of IRS-1 tyrosine and Akt phosphorylation and eNOS activity in TNF-alpha-treated bAECs without affecting TNF-alpha-induced ERK1/2 and AMPK phosphorylation. We conclude that in cultured bAECs, TNF-alpha induces insulin resistance in the phosphatidylinositol 3-kinase/Akt/eNOS pathway via a p38 MAPK-dependent mechanism and enhances ERK1/2 and AMPK phosphorylation independent of the p38 MAPK pathway. This differential modulation of TNF-alpha's actions by p38 MAPK suggests that p38 MAPK plays a key role in TNF-alpha-mediated vascular insulin resistance and may contribute to the generalized endothelial dysfunction seen in type 2 diabetes mellitus and the cardiometabolic syndrome.     

胃癌组织中肝素酶和血管内皮生长因子-C的表达及其临床意义

目的探讨胃癌组织中肝素酶和血管内皮生长因子（VEGF）-C蛋白表达及其临床意义。方法采用免疫组化S-P法检测97例原发性胃癌组织、癌旁组织及20例正常胃黏膜组织中肝素酶和VEGFC蛋白的表达，并分析其与临床病理特征和预后的关系。结果胃癌组织肝素酶和VEGF—C蛋白表达阳性率分别为61．9％和66．0％，显著高于癌旁组织的7．2％和5．0％，正常胃组织的8．3％和5．0％（P值均〈0．01）；肝素酶表达与肿瘤分化程度无关，但与肿瘤直径、淋巴结转移、静脉侵犯、淋巴管侵犯、远处转移、浆膜面受累和TNM分期等密切相关；VEGF—C表达与肿瘤直径、分化程度、静脉侵犯及远处转移等无关，但与淋巴结转移、淋巴管侵犯、浆膜面受累和TNM分期等密切相关；肝素酶和VEGF—C阳性表达组术后生存率明显低于阴性组；在胃癌中肝素酶和VEGF—C阳性表达呈正相关。结论肝素酶及VEGF-C蛋白的阳性表达，可作为胃癌预后不良的参考指标。     

胃癌组织中血管内皮生长因子C表达及与淋巴结转移关系

目的探讨胃癌组织中血管内皮生长因子C(VEGFC)的表达及与肿瘤淋巴结转移的关系。方法取30例胃癌患者手术切除的新鲜标本和距癌灶5cm以外的胃组织各1块,采用半定量RTPCR法和免疫组化染色法检测胃癌组织及癌旁正常组织的VEGFC表达,图像分析仪检测VEGFC的免疫组化阳性指数(positiveindex,PI)。结果胃癌细胞呈高水平表达VEGFC,癌旁正常组织则未见表达。在胃癌组织中,有淋巴结转移(PI=1.345±0.079)、淋巴管浸润(PI=1.315±0.037)患者的VEGFC表达水平分别较无转移(PI=1.156±0.045)及无浸润者(PI=1.154±0.043)增高(P<0.05)。高分化胃癌患者的VEGFCmRNA[VEGFC/βactin比值(Ar)=0.846±0.042]和VEGFC表达(PI=1.372±0.023)均分别高于中低分化胃癌者(Ar=0.663±0.007,P<0.01和PI=1.126±0.078,P<0.05)。结论VEGFC阳性表达的胃癌患者可能更易发生淋巴结转移。     

VEGF-C基因靶向RNA干扰重组表达载体的构建和表达

目的:利用质粒pSilencer3.1-H_1构建针对人血管内皮生长因子-C(VEGF-c)基因的表达载体,测序鉴定并观察在胃癌细胞中的表达.方法:根据质粒pSilencer3.1-H_1要求设计两对小干扰RNA靶序列,退火形成互补的双链,通过与线性化的pSilencer3.0-H_1相应位点连接、转化大肠杆菌,扩增、纯化得到所需质粒,酶切电泳及测序鉴定后转染胃癌细胞株SGC-7901,Western blot检测转染前后VEGF-C基因的蛋白表达.结果:经酶切和测序鉴定,针对VEGF-C基因的siRNA表达载体构建成功.转染胃癌细胞株SGC-7901后,Western blot检测显示VEGF-C基因蛋白表达明显降低,pSilencer3.1-VEGF-C1组抑制效果明显,其抑制率为81.2%,与阴性对照组相比差异具有显著性(P<0.05).结论:成功构建了针对人VEGF-C基因的siRNA表达载体和稳定转染的胃癌细胞株SGC-7901.     

Tumor necrosis factor-alpha inhibition protects against endotoxin-induced endothelial glycocalyx perturbation

ObjectiveInflammatory stimuli profoundly increase the vulnerability of the vessel wall to atherogenesis. The endothelial glycocalyx, a layer of glycosaminoglycans and proteoglycans covering the luminal side of the vasculature, has recently emerged as an orchestrator of vascular homeostasis. In the present study, we investigated whether endotoxin-induced inflammatory reactions lead to a decrease of endothelial glycocalyx thickness in humans and whether tumor necrosis factor-α (TNFα) plays a role in this process.Design, subjects and interventionHealthy male volunteers received low-dose endotoxin (1 ng/kg) intravenously, with (n = 8) or without (n = 13) pre-treatment with the soluble TNFα receptor etanercept. Endothelial glycocalyx thickness and related parameters were determined after endotoxin challenge.ResultsEndotoxin resulted in a profound reduction in microvascular glycocalyx thickness (from 0.60 ± 0.1 to 0.30 ± 0.1 μm, p < 0.01). Concomitantly, plasma levels of the principal glycocalyx constituent hyaluronan (62 ± 18 to 85 ± 24 ng/mL, p < 0.05), monocyte activation and coagulation activation increased (F1 + 2; 0.3 ± 0.1 to 2.8 ± 1.5 nmol/L, p < 0.05 and d-dimer; from 0.2 ± 0.1 to 0.4 ± 0.1 mg/L, p < 0.05 compared to baseline). Inhibition of TNFα by etanercept attenuated loss of microvascular glycocalyx thickness (0.54 ± 0.1 to 0.35 ± 0.1 μm, p < 0.05). Changes in hyaluronan (58 ± 13 to 46 ± 10 ng/mL, p < 0.05) and coagulation activation were also attenuated (F1 + 2; 0.3 ± 0.1 to 2.1 ± 0.9 nmol/L and d-dimer; from 0.2 ± 0.1 to 0.3 ± 0.1 mg/L, p < 0.05 compared to baseline).ConclusionsThese data suggest that inflammatory activity, in part mediated by TNFα, leads to perturbation of the endothelial glycocalyx in humans. This may contribute to the vascular vulnerability induced by inflammation.     

Tumor necrosis factor-alpha induces clustering in ovarian theca-interstitial cells in vitro.

Tumor necrosis factor-alpha (TNF) has been implicated in the regulation of steroidogenesis in theca-interstitial cells (TIC). The purpose of this study was to evaluate any change in TIC morphology during the time course of TNF-induced inhibition of LH-stimulated androstenedione production. Ovaries from immature hypophysectomized rats were enzymatically digested and highly purified TIC were obtained by density gradient centrifugation. TIC treated with TNF (0.1-10 ng/ml) demonstrated distinct clustering in the presence and absence of LH (50 ng/ml). The number of clusters and the mean area per cluster were greatest after 4 days as a result of treatment with 1 or 10 ng TNF/ml. In addition, a dose-dependent inhibition of LH-supported androstenedione production was induced by TNF. TNF also inhibited LH-induced androstenedione in TIC after 2, 4, or 6 days of continuous LH treatment, and TIC clustering still occurred. TIC clustering was impeded by the protein kinase inhibitor H7 at 10 microM; however, the protein kinase inhibitor, HA 1004 (5 microM), did not inhibit TNF-induced clustering in TIC. Since H7 blocked TNF induced clustering, but did not block TNF inhibition of LH stimulated androstenedione synthesis, it is suggested that alternate signal transduction pathways for TNF induced inhibition of LH-stimulated androstenedione and stimulation of clustering of TIC may exist. The results also indicate that the TNF-induced TIC clustering may be independent of the TNF-induced inhibition of LH-stimulated androstenedione production and states of LH-induced differentiation of TIC.