Human chorionic gonadotropin-induced ovarian hyperstimulation syndrome is associated with up-regulation of vascular endothelial growth factor

Ovarian hyperstimulation syndrome (OHSS), a life-threatening complication occurring in stimulated ovarian cycles, arises from treatment with gonadotropin for induction of follicular maturation in infertile women. Clinical characteristics of OHSS include ascites and pleural effusion induced by increased vascular permeability, where vascular endothelial growth factor (VEGF) was suspected to be the culprit. To test whether the effects of human CG (hCG) on the pathogenesis of OHSS were mediated through the VEGF produced by luteinized granulosa cells, we measured estradiol, VEGF, IGF-II levels in serum, and follicular fluid and analyzed their mRNA expression in luteinized granulosa cells obtained from 101 women (58 with OHSS and 43 controls) who underwent in vitro fertilization and embryo transfer. This study presents the first evidence that hCG up-regulated VEGF expression of granulosa cells in the OHSS, not the control groups, and that follicular VEGF worked through an autocrine mechanism using its kinase insert domain-containing receptor, not the fms-like tyrosine kinase receptor. We calculated total follicular production of VEGF, by multiplying follicular concentrations by follicular volumes, and verified that an increase in total follicular production of VEGF accounted for elevated serum levels of VEGF, which was associated with the development of OHSS. These findings demonstrate that through up-regulation of VEGF, hCG plays a significant role in the pathogenesis of OHSS.     

血管内皮生长因子及其受体在肺气肿患者肺组织中的表达

目的探讨血管内皮生长因子(VEGF)及其受体2(VEGF受体2/KDR)在肺气肿患者肺组织中的表达及其与肺气肿的相关性。方法取35例行肺叶切除术患者[A组(吸烟伴肺气肿组)16例,B组(不吸烟肺功能正常组)14例,C组(吸烟但肺功能正常组)5例]的外周肺组织标本,ELISA法检测肺组织匀浆中VEGF的含量,免疫组化法检测KDR蛋白表达,RT PCR检测VEGF和KDRmRNA水平,TUNEL法检测肺泡隔细胞的凋亡。结果A组患者肺组织VEGF、KDR表达均低于B组(P<0.01),肺泡隔细胞凋亡率高于B组(P<0.01)。C组与B组相比,VEGF及KDR表达差异无统计学意义(P>0.05)。结论VEGF及KDR水平减少与肺泡隔细胞凋亡的增加可能与肺气肿的发生相关。     

血管内皮细胞生长因子在大鼠心脏移植急性排斥期的表达研究

目的:观察血管内皮细胞生长因子(VEGF)在大鼠心脏移植急性排斥期中的表达及与排斥反应的关系。方法:实验分为对照组和环孢霉素A(CSA)组,每组27只。采用颈部心脏异位移植术式建立移植模型,于心脏移植手术后分别静脉给予0.85%氯化钠溶液及CSA干预。常规监测排斥反应发生情况。每组7只用于观察移植物存活时间,余20只移植术后1,3,7,11d各切取5例移植心标本。样本采用逆转录聚合酶链反应(RTPCR)的方法检测移植心VEGF的DNA表达水平。结果:CSA组移植心存活时间[(21.1±2.9)d]长于对照组[(12.4±2.3)d],P<0.01;对照组各采样时段VEGF的DNA表达强度均强于CSA组,P<0.01。结论:VEGF高表达与移植心的炎性浸润以及急性排斥有密切关系。     

血管内皮生长因子水平与大鼠支气管哮喘模型发病机制关系的研究

目的 探讨大鼠支气管哮喘(简称哮喘)模型支气管肺泡灌洗液(BALF)中血管内皮生长因子(VEGF)水平与哮喘嗜酸粒细胞(EOS)炎症及气道血管通透性之间的关系,以及吸入性激素的作用.方法 SD大鼠18只,随机分为对照组,哮喘模型组和地塞米松干预组各6只.以腹腔注射1%卵蛋白致敏和2%卵蛋白雾化吸入激发复制哮喘模型,干预组在每次激发前给予地塞米松干预.检测大鼠气道反应性,BALF中EOS百分数,VEGF(酶联免疫吸附法)及气道血管渗透指数.结果 BALF中EOS百分数,VEGF水平,气道反应性及气道血管渗透指数哮喘组明显高于对照组(P<0.05或P<0.01);经过6周吸入性激素治疗后,地塞米松组BALF中VEGF水平,EOS百分数,气道反应性及气道血管渗透指数较哮喘组明显降低(P<0.05或P<0.01),与对照组比较差异无统计学意义.相关分析显示,BALF中VEGF水平与EOS百分数呈正相关(r=0.76,P<0.01);VEGF水平与气道血管渗透指数呈正相关(r=0.84,P<0.01);VEGF水平与PC50呈负相关(r=-0.68,P<0.01).结论 大鼠哮喘模型BALF中VEGF水平增高,并与气道EOS百分数,气道反应性和气道血管渗透指数密切相关.该结果提示VEGF可能在哮喘的发病机制中起着重要作用.     

血管内皮生长因子水平与大鼠支气管哮喘模型发病机制关系的研究

目的 探讨大鼠支气管哮喘（简称哮喘）模型支气管肺泡灌洗液（BALF）中血管内皮生长因子（VEGF）水平与哮喘嗜酸粒细胞（EOS）炎症及气道血管通透性之间的关系,以及吸人性激素的作用.方法 SD大鼠18只,随机分为对照组,哮喘模型组和地塞米松干预组各6只.以腹腔注射1%卵蛋白致敏和2%卵蛋白雾化吸入激发复制哮喘模型,干预组在每次激发前给予地塞米松干预.检测大鼠气道反应性,BALF中EOS百分数,VEGF（酶联免疫吸附法）及气道血管渗透指数.结果 BALF中EOS百分数,VEGF水平,气道反应性及气道血管渗透指数哮喘组明显高于对照组（P〈0.05或P〈0.01）;经过6周吸人性激素治疗后,地塞米松组BALF中VEGF水平,EOS百分数,气道反应性及气道血管渗透指数较哮喘组明显降低（P〈0.05或P〈0.01）,与对照组比较差异无统计学意义.相关分析显示,BALF中VEGF水平与EOS百分数呈正相关（r=0.76,P〈0.01）;VEGF水平与气道血管渗透指数呈正相关（r=0.84,P〈0.01）;VEGF水平与PC50呈负相关（r=-0.68,P〈0.01）.结论 大鼠哮喘模型BALF中VEGF水平增高,并与气道EOS百分数,气道反应性和气道血管渗透指数密切相关.该结果提示VEGF可能在哮喘的发病机制中起着重要作用.     

Vascular endothelial cadherin regulates vascular permeability: Implications for ovarian hyperstimulation syndrome

CONTEXT: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of treatment with fertility drugs. It is characterized by increased vascular permeability and simultaneous overexpression of vascular endothelial growth factor (VEGF) in ovarian cells. OBJECTIVE: We tested the hypothesis that the endothelium and endothelial cell-to-cell junctions are downstream targets of VEGF during OHSS pathogenesis. We investigated the potential involvement of vascular endothelial (VE)-cadherin, an interendothelial adhesion molecule, in the capillary hyperpermeability in OHSS. DESIGN: Human endothelial cells from umbilical veins (HUVEC) were used as an in vitro model of OHSS. INTERVENTION: Cell cultures were treated with varying doses of estradiol (E2), human chorionic gonadotropin (hCG), VEGF, and antihuman VEGF antibodies, either alone or in combination, and the effect on VE-cadherin release was evaluated at different time points. Permeability assays were performed using fluoresceinisothiocyanate-labeled albumin, and actin filaments rearrangement was evaluated by fluorescent microscopy. RESULTS: Culturing of HUVEC with high doses of E2 produced no significant changes in VE-cadherin concentration, but hCG and VEGF produced a significant increase in VE-cadherin release. Time-course experiments showed that VE-cadherin was secreted 12 h after VEGF addition. Antihuman VEGF antibodies prevented these changes. Permeability assays demonstrated that, although E2 did not alter the arrangement of HUVEC in vitro, hCG and VEGF caused changes in the actin fibers indicative of increased capillary permeability. VEGF also induced an increase in paracellular permeability of HUVEC at the same doses used in the previous experiments. CONCLUSIONS: Adhesion molecules like VE-cadherin may play a role in the development and progression of increased capillary permeability in severe OHSS.     

Exaggerated hypotensive effect of vascular endothelial growth factor in spontaneously hypertensive rats

Vascular endothelial growth factor (VEGF) induces hypotension in normotensive subjects, which is considered to be a major side effect for treatment of ischemic diseases. However, the hypotensive effect of VEGF has not been investigated in the setting of hypertension. This study determined effects of VEGF on hemodynamics, pharmacokinetics, and release of NO and prostaglandin I2 (PGI2) in vivo and on vasorelaxation of mesentery artery rings in vitro in spontaneously hypertensive rats (SHR) compared with Wistar-Kyoto rats (WKY). Intravenous infusion of VEGF for 2 hours produced a dose-related decrease in arterial pressure, which was enhanced in conscious SHR compared with WKY (P<0.01), and an increase in heart rate in WKY but not in SHR. In response to similar doses of VEGF, compared with WKY, SHR had a higher plasma VEGF level and lower VEGF clearance (P<0.01). Circulating NO and PGI2 levels after VEGF administration were not increased in SHR versus WKY, and VEGF-induced vasorelaxation was blunted in SHR versus WKY in vitro, suggesting endothelial dysfunction in SHR. One-week VEGF infusion also caused greater hypotension (P<0.05) in the absence of tachycardia in SHR compared with WKY controls. Thus, despite blunted vasorelaxation in vitro because of endothelial dysfunction, SHR exhibited exaggerated hypotension without tachycardia in response to VEGF, which was independent of NO and PGI2. The exaggerated hypotensive response to VEGF in SHR may be owing to impaired baroreflex function and reduced VEGF clearance. The data may also suggest that more caution should be taken when VEGF is administered in patients with hypertension.     

Recombinant thrombomodulin inhibits thrombin-induced vascular endothelial growth factor production in neuronal cells

Thrombin is a serine protease which is generated from its precursor prothrombin by the activation of the blood coagulation cascade. Thrombin converts fibrinogen to fibrin, activates platelets and several coagulation factors, and plays a central role in thrombosis and hemostasis by regulating platelet aggregation and blood coagulation. Here, we show that thrombn enhanced vascular endothelial growth factor (VEGF) production in a dose- and time-dependent manner in the supernatant of cultured PC-12 cells, as determined by enzyme-linked immunosorbent assay (ELISA). Thrombin receptor agonist peptide (SFLLRNPNDKYEPF, TRAP) exerted an effect similar to thrombin on VEGF production. Thrombin-induced VEGF production was significantly attenuated by recombinant human thrombomodulin (rTM) and its minimal functional domain E456. Furthermore, the antioxidant N-acetyl-L-cysteine (NAC) markedly inhibited thrombin-induced VEGF production. Thus, rTM and NAC apparently inhibited the effect of thrombin on VEGF production in neuronal cells.     

Transforming growth factor-beta stimulates vascular endothelial growth factor production by folliculostellate pituitary cells

TGF-beta isoforms are expressed in the anterior pituitary and modulate the growth and function of endocrine pituitary cells. Recently, TGF-beta has been shown to stimulate growth and basic fibroblast growth factor secretion in nonendocrine folliculostellate (FS) pituitary cells. We therefore studied whether the production of FS cell-derived vascular endothelial growth factor (VEGF), the most important regulator of vascular permeability and angiogenesis, is affected by TGF-beta. We observed by RT-PCR that TtT/GF cells, which are FS mouse pituitary tumor cells, synthesize TGF-beta1, -beta2, and -beta3. They also express TGF-beta receptors types 1 and 2, as well as Smad2, Smad3, and Smad4 proteins, which are essential for TGF-betabinding and signaling. Stimulation of TtT/GF cells with either TGF-beta1 or TGF-beta3 induced a rapid translocation of Smad2 into the cell nuclei. Both TGF-beta isoforms dose dependently stimulated VEGF production in TtT/GF cells, but not in lactosomatotroph GH3 cells. Time-course studies and suppression of TGF-beta-induced VEGF production by cycloheximide suggest that TGF-beta induces de novo synthesis of VEGF in folliculostellate cells, which is completely blocked by dexamethasone. In primary rat pituitary cell cultures, TGF-beta1 and -beta3 stimulated VEGF production. TGF-beta stimulation of VEGF production by folliculostellate cells could modulate intrapituitary vascular permeability and integrity as well as angiogenesis in an auto-/paracrine manner.     

Novel vascular endothelial growth factor binding domains of fibronectin enhance vascular endothelial growth factor biological activity

Interactions between integrins and growth factor receptors play a critical role in the development and healing of the vasculature. This study mapped two binding domains on fibronectin (FN) that modulate the activity of the angiogenic factor, vascular endothelial growth factor (VEGF). Using solid-phase assays and surface plasmon resonance analysis, we identified two novel VEGF binding domains within the N- and C-terminus of the FN molecule. Native FN bound to VEGF enhanced endothelial cell migration and mitogen-activated protein (MAP) kinase activity, but FN that is devoid of the VEGF binding domains failed to do so. Coprecipitation studies confirmed a direct physical association between VEGF receptor-2 (Flk-1) and the FN integrin, alpha5beta1, which required intact FN because FN fragments lacking the VEGF binding domains failed to support receptor association. Thrombin-activated platelets released intact VEGF/FN complexes, which stimulated endothelial cell migration and could be inhibited by soluble high affinity VEGF receptor 1 and antibodies to alpha5beta1 integrin. This study demonstrates that FN is potentially a physiological cofactor for VEGF and provides insights into mechanisms by which growth factor receptors and integrins cooperate to influence cellular behavior.     

Vascular endothelial growth factor induces SHC association with vascular endothelial cadherin: a potential feedback mechanism to control vascular endothelial growth factor receptor-2 signaling

Vascular endothelial (VE)-cadherin is endothelium specific, mediates homophilic adhesion, and is clustered at intercellular junctions. VE-cadherin is required for normal development of the vasculature in the embryo and for angiogenesis in the adult. Here, we report that VE-cadherin is associated with VE growth factor (VEGF) receptor-2 (VEGFR-2) on the exposure of endothelial cells to VEGF. The binding parallels receptor phosphorylation on tyrosine residues, which is maximal at 5 minutes and then declines within 30 minutes. Tyrosine phosphorylation of VE-cadherin was maximal at 30 minutes after the addition of the growth factor. At this time point, the protein could be coimmunoprecipitated with the adaptor protein Shc. Pull-down experiments with different Shc domains and mutants of the VE-cadherin cytoplasmic tail have shown that Shc binds to the carboxy-terminal domain of the VE-cadherin tail through its Src homology 2 domain (SH2). We found that Shc phosphorylation lasts longer in endothelial cells carrying a targeted null mutation in the VE-cadherin gene than in VE-cadherin-positive cells. These data suggest that VE-cadherin expression exerts a negative effect on Shc phosphorylation by VEGFR-2. We speculate that VE-cadherin binding to Shc promotes its dephosphorylation through associated phosphatases.     

VEGF在大鼠慢性酒精性肝损伤中的表达

目的:观察大鼠慢性酒精性肝损伤过程中 VEGF的表达,探讨其在慢性酒精性肝损伤发生、发展中的作用．方法:56度的白酒(560 mL／L)平均以7 g／kg的剂量每日早晨灌胃一次制备肝纤维化模型,灌胃4 wk、12 wk及24 wk采用股静脉放血法分别处死大鼠,观察肝脏病理变化并采用半定量逆转录聚合酶链反应(RT-PCR)检测VEGF mRNA的表达．结果:对照组的VEGF未见表达,饲酒4 wk组表达VEGF mRNA比例最高,达到83．3％(5／6), 与对照组相比有非常显著性差异(P<0．01), 12 wk时下降到18．2％(2／11),且其表达与对照组相比无差异(P>0．05),而至24 wk VEGF表达阳性率上升到57．1％(4／7),与对照组相比有非常显著性差异(P<0．01)．另外,饲酒4 wk组 VEGF表达阳性率与12周相比差异也有非常显著性(P<0．01),而与24 wk相比无统计学差异．试验组大鼠肝细胞出现明显脂肪、空泡变性,坏死及胶原增生等病变．结论:VEGF可能在酒精性肝病中起重要作用,主要与酒精性肝炎及酒精性肝纤维化有关．     

血管内皮生长因子及血管内皮生长因子受体在急性肺损伤中作用的研究

血管内皮生长因子是作用于血管内皮细胞的重要血管调节因子,它通过与内皮上的特异受体结合,可发挥促进内皮细胞增殖、分化、诱导血管生成、增加微血管通透性等多种功能.近年研究显示血管内皮生长因子在不同原因、不同阶段急性肺损伤中所起的作用不同.     

Intrathecal production and secretion of vascular endothelial growth factor during Cryptococcal Meningitis

BACKGROUND: Patients with cryptococcal meningitis (CM) show elevated intracranial pressure (ICP) and blood-brain barrier (BBB) disruption in most cases. Elevated ICP is an important contributor to mortality. Vascular endothelial growth factor (VEGF) might be the mediator of BBB disruption during CM. METHODS: We measured VEGF levels in serum, plasma, and cerebrospinal fluid (CSF) of 95 patients and 63 control subjects, and we analyzed the required trigger and cellular source of VEGF secretion in vitro. RESULTS: Cryptococcus neoformans and its capsular antigens dose-dependently induced VEGF secretion by polymorphonuclear neutrophils, monocytes, and peripheral blood mononuclear cells (PBMCs). VEGF production by PBMCs induced by antigens strongly exceeded production by monocytes (P<.001). The addition of major histocompatibility complex class II antibody inhibited this production of VEGF (P=.005). Confirming the in vitro data, patients with CM showed significantly elevated VEGF levels in CSF (P<.001), plasma (P=.028), and serum (P<.001), compared with healthy control subjects. Calculated VEGF indices demonstrated that VEGF was produced intrathecally. CONCLUSIONS: Our findings suggest that VEGF plays a role in the pathophysiology of CM. We propose that CD4(+) T lymphocytes--stimulated by monocytes acting as antigen-presenting cells--are the cells that produce VEGF in response to cryptococcal antigens.     

Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model

No specific treatment is available for ovarian hyperstimulation syndrome (OHSS), the most important complication in infertile women treated with gonadotropins. OHSS is caused by increased vascular permeability (VP) through ovarian hypersecretion of vascular endothelial growth factor (VEGF)-activating VEGF receptor 2 (VEGFR-2). We previously demonstrated in an OHSS rodent model that increased VP was prevented by inactivating VEGFR-2 with a receptor antagonist (SU5416). However, due to its toxicity (thromboembolism) and disruption of VEGFR-2-dependent angiogenic processes critical for pregnancy, this kind of compound cannot be used clinically to prevent OHSS. Dopamine receptor 2 (Dp-r2) agonists, used in the treatment of human hyperprolactinemia including pregnancy, inhibit VEGFR-2-dependent VP and angiogenesis when administered at high doses in animal cancer models. To test whether VEGFR-2-dependent VP and angiogenesis could be segregated in a dose-dependent fashion with the Dp-r2 agonist cabergoline, a well-established OHSS rat model supplemented with prolactin was used. A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed VEGFR-2-dependent VP without affecting luteal angiogenesis through partial inhibition of ovarian VEGFR-2 phosphorylation levels. No luteolytic effects (serum progesterone levels and luteal apoptosis unaffected) were observed. Cabergoline administration also did not affect VEGF/VEGFR-2 ovarian mRNA levels. Results in the animal model and the safe clinical profile of Dp-r2 agonists encouraged us to administer cabergoline to oocyte donors at high risk for developing the syndrome. Prophylactic administration of cabergoline (5-10 microg/kg x d) decreased the occurrence of OHSS from 65% (controls) to 25% (treatment). Therefore, a specific, safe treatment for OHSS is now available.