1Implication of soluble receptors of VEGF, sVEGFR-1 and sVEGFR-2, in angiogenesis

Introduction:  sVEGFR-1 and sVEGFR-2 are soluble forms of the membrane-bound receptors of VEGF. sVEGFR-1 is detected in plasma of pre-eclamptic women, during ischemia and in some cancer cases. sVEGFR-2, was recently detected in plasma of healthy people, in leukaemia and in systemic erythematosus lupus cases. sVEGFR-1 has anti-angiogenic properties in vitro and in vivo but sVEGFR-2 remains uncharacterized and its physiological or pathological role is still unknown.
Material and Methods:  The aim of this study was to understand and to characterize the role of sVEGFR2 in angiogenesis and in endothelial function.
Results:  In aortic ring assay, an ex vivo model of angiogenesis, sVEGFR1 and sVEGFR2 were able to abolish VEGF-induced angiogenesis. However, when used alone, they induced the formation of a "network", supposed to be vascular in visible microscopy. As they were able to abolish the effect of VEGF on endothelial function but showed no direct effect alone, we performed an immuno-staining of the "vascular network" induced by the soluble receptors. It showed that there were a few endothelial cells but mostly pericytes/smooth muscle cells (PC/SMC). Our first in vitro experiments on PC/SMC showed that sVEGFR-1 and sVEGFR-2 were able to promote the migration of PC/SMC, only in presence of endothelial cells.
Conclusions:  Our results evidence that sVEGFR1 and sVEGFR2 inhibit VEGF-induced angiogenesis in a similar way. However, they have also a direct effect on PC/SMC, promoting their migration. Our results suggest that these soluble receptors could act, not only on endothelial cells themselves, but by a direct effect on PC/SMC too. These results contribute to identify factors by which it could be possible to regulate the balance between pro-angiogenic and anti-angiogenic factors, especially in the case of the anti-VEGF drugs used now as anti-cancer therapies in clinics, where a transient "normalization" of the vessels is observed.     

丁苯酞通过激活VEGF/VEGFR2-Notch1/Dll4信号促进HUVECs形成血管

目的:探索缺血缺氧(H/I)条件下丁苯酞(NBP)通过激活血管内皮生长因子(VEGF)/VEGF受体2(VEGFR2)-Notch1/Delta样配体4(Dll4)信号促进人脐静脉内皮细胞(HUVECs)血管形成的机制。方法:利用无血清培养基和缺氧罐模拟H/I条件,HUVECs传代培养后设置正常对照(control)组、H/I组、NBP高剂量(H/I+NBP_(high))组和NBP低剂量(H/I+NBP_(low))组,其中control组为常规培养的HUVECs,H/I组为H/I条件下培养的HUVECs,H/I+NBP_(high)组为在H/I环境下使用20μmol/L丁苯酞干预的HUVECs,H/I+NBP_(low)组为在H/I环境下使用5μmol/L丁苯酞干预的HUVECs。CCK-8法检测各组细胞的细胞活力,细胞划痕实验检测各组细胞的迁移能力,体外血管形成实验检测各组细胞成管能力,Western blot法检测VEGFR2、Notch1和Dll4的表达,ELISA法检测培养基中VEGF的表达,qPCR检测VEGF、VEGFR2、Notch1和Dll4的mRNA表达水平。结果:丁苯酞可以提高H/I条件下HUVECs的存活率,促进细胞的迁移和体外血管的形成能力,且H/I+NBP_(high)组比H/I+NBP_(low)组更加显著。丁苯酞可以提高VEGF、VEGFR2、Notch1和Dll4的mRNA及蛋白表达。结论:丁苯酞可以在H/I条件下促进HUVECs形成血管,其机制可能与VEGF/VEGFR2-Notch1/Dll4信号的激活有关。     

骨髓间充质干细胞介导的血红素氧合酶-1促进大鼠心肌梗死后血管再生简

 目的 探讨骨髓间充质干细胞 (MSCs) 介导的血红素氧合酶-1 (HO-1) 对心肌梗死后心 脏血管再生及左心室功能的影响。方法 取大鼠骨髓,体外分离扩增培养 MSCs,HO-1 腺病毒转染。结扎左前降支 1 h 后,分别将 HO-1-MSCs、MSCs 多点注射到大鼠心肌梗死区周边,对照组注射等量 PBS。 结果 MSCs 介导的HO-1能在体外及体内获得稳定表达;HO-1-MSCs组促血管生长因子VEGF、FGF2的表达及毛细血管密度明显高于 MSCs 组和对照组 (P < 0.01);但促血管再生的作用可被HO抑制剂阻断。HO-1-MSCs组心肌细胞凋亡及纤维化明显低于MSCs 组和对照组 (P < 0.01);HO-1-MSCs组左室收缩功能各项指标明显优于其他两组(P < 0.01)。HO-1-MSCs组心室壁变厚,心室腔明显缩小。结论 MSCs介导的血红素氧合酶-1能促进心肌梗死后心脏血管再生,改善左心室功能。     

HIV-1 Nef蛋白通过调控 PTEN／PI3 K信号通路促进KSHV vIL-6诱导血管生成

目的探讨HIV-1 Nef蛋白能否通过调控PTEN/PI3K信号通路促进卡波氏肉瘤病毒（KSHV） vIL-6诱导血管生成。方法用脂质体转染的方法将pPTEN-cDNA、PI3K-DN及其对照空载体质粒分别转染稳定表达KSHV vIL-6和HIV-1 Nef蛋白的内皮细胞,采用微管形成试验观察微管形成状况,将这些细胞接种鸡胚绒毛尿囊膜（CAM）检测血管生成情况。 Western blot进一步检测转染了上述质粒后细胞内源性PTEN和PI3K信号分子的表达水平。结果过表达PTEN或抑制PI3K表达均可抑制Nef促进vIL-6诱导的内皮细胞微管形成和CAM血管生成。结论 HIV-1 Nef蛋白通过调控PTEN/PI3K信号通路促进KSHV vIL-6诱导血管生成。     

uPA和PAI-1在人脑胶质瘤的表达及其与肿瘤血管生成的关系

目的探讨uPA、PAI鄄1和VEGF与人脑胶质瘤病理分级和侵袭行为的关系及各因子间的相互联系。方法采用免疫组化SP方法检测42例人脑胶质瘤和8例正常脑组织uPA、PAI鄄1和VEGF蛋白的表达。结果12例中低度恶性胶质瘤中,uPA、PAI鄄1和VEGF阳性表达率分别为58.3%、50.0%、33.3%,30例高度恶性胶质瘤的阳性率分别为96.7%、86.7%、93.3%,两组间各指标相比较,uPA和VEGF差异有极显著性(P<0.01),PAl鄄1差异有显著性(P<0.05)。uPA、PAI鄄1和VEGF阳性染色主要定位于血管内皮细胞和瘤细胞胞浆,以肿瘤侵袭边缘和坏死组织周围多见。uPA与VEGF、PAI鄄1与VEGF之间均呈明显正相关(P<0.05)。8例正常脑组织除1例有PAl鄄1微弱表达外,其余均为阴性。结论随脑胶质瘤恶性度增高,uPA、PAl鄄1和VEGF表达增强,三者协同作用,可作为胶质瘤恶性度高和侵袭能力强潜在的分子生物学指标。     

胃癌中uPA、PAI-1表达及其与血管生成的关系

目的 观察胃癌组织中uPA、PAI-1mRNA及蛋白的表达，并探讨它们与肿瘤分化、血管生成及临床病理因素之间的关系。方法 用原位杂交及免疫组化S-P法检测110例胃癌组织中uPA、PAI-1的表达，根据CD34阳性的血管内皮细胞计数肿瘤组织微血管密度（MVD）。结果 （1）胃癌组织中uPA mRNA和蛋白、PAI-1 mRNA和蛋白阳性表达定位于胞质；uPA的表达随分化程度的降低有逐渐升高的趋势，PAI-1的表达随分化程度的降低有逐渐降低的趋势。（2）110例uPA mRNA及蛋白表达阳性组MVD值显著高于阴性组，差异均具有显著性（P值均＜0．05）。（3）uPA mRNA及蛋白的表达与临床分期呈正相关（P＜0．05），PAI-1的表达与临床分期和淋巴结转移无相关性。（4）uPA mRNA／蛋白与PAI-1 mRNA／蛋白的表达无相关性。结论uPA与促进胃癌的血管生成密切相关，阻断uPA的分泌和作用途径有望对胃癌浸润转移起抑制作用；胃癌组织中PAI-1可能担当重要的调节剂或者是肿瘤细胞防止自身降解的保护剂而不是这个系统的单纯抑制剂。     

VEGF通过上调CCN2促HUVEC迁移和血管生成

目的 探讨血管内皮生长因子(VEGF)诱导的成骨细胞中结缔组织生长因子(CTGF/CCN2)对人脐静脉血管内皮细胞(HUVECs)的影响.方法 用Real time PCR法及ELISA法检测VEGF诱导成骨细胞(OSE)中CCN2含量;制备成骨细胞(OSE)上清液;将细胞分为control组、OSE组和VEGF-OSE组(n=3).用小干扰RNA (siRNA)转染法抑制成骨细胞中CCN2的表达;Transwell法检测内皮细胞迁移;Matrigel实验检测管样结构形成能力.结果 VEGF呈时间和剂量依赖性上调成骨细胞中CCN2 mRNA和蛋白的表达;CCN2可促进内皮细胞的迁移和管样结构形成(P＜0.05),当CCN2被siRNA基因沉默或者加入CCN2抗体后,CCN2对内皮细胞迁移和管样结构形成的促进作用均受到明显抑制(P＜0.05).结论 VEGF通过上调成骨细胞中CCN2的表达,促内皮细胞(HUVECs)的迁移和血管生成.     

BANCR 对肝癌细胞HepG2 增殖、侵袭和血管新生的促进作用

目的:探索BANCR 对人肝癌细胞HepG2 的增殖、凋亡、侵袭和血管新生的影响。方法:实时定量PCR (qRT-PCR)检测BANCR 的表达。BANCR siRNA 和Scramble 分别转染HepG2 细胞,利用CCK-8 检测细胞增殖情况,流式细胞术分析细胞凋亡,Transwell 测试细胞侵袭能力,管腔形成实验分析血管新生能力,免疫印迹分析增殖细胞核抗原(PCNA)、Caspase-3 和基质金属蛋白酶9(MMP-9),血管内皮细胞生长因子VEGF、酸性成纤维细胞生长因子bFGF 和干扰素IFN-酌的蛋白表达。结果:肝癌细胞(HepG2)中BANCR 的表达高于正常干细胞L02(P<0.05)。与对照组相比,BANCR siRNA 组的细胞增殖倍数明显降低,且BANCR siRNA 组具有更高的细胞凋亡率和较低的侵袭细胞数(P<0.05)。免疫印迹结果显示,与对照组相比,BANCR siRNA 组细胞凋亡标记蛋白Caspase-3 和IFN-酌的表达明显上升(P<0.05),细胞增殖和侵袭标记蛋白PCNA、MMP-9、Fn、Vimentin 以及VEGF、bFGF 的表达都明显受到抑制(P<0.05)。结论:siRNA 干扰BANCR 后大大促进人肝癌细胞HepG2 的凋亡,严重抑制了细胞增殖、侵袭以及血管新生。     

Angiopoietin-1 promotes tumor angiogenesis in a rat glioma model

Angiopoietins have been implicated in playing an important role in blood vessel formation, remodeling, maturation, and maintenance. However, the role of angiopoietins in tumor angiogenesis remains uncertain. In this study, expression of human angiopoietin-1 (hAng-1) and angiopoietin (hAng-2) was amplified in the rat glioma cell line GS9L by stable transfection using an inducible tet-off system. Transfected cells were implanted intracerebrally into syngenic Fischer 344 rats. We demonstrated by means of magnetic resonance imaging that increased hAng-1 expression promoted a significant in vivo growth of intracerebral gliomas in rats. Overexpression of hAng-1 resulted in more numerous, more highly branched vessels, which were covered by pericytes. On the other hand, tumors derived from hAng-2-overexpressing cells were smaller than empty-plasmid control tumors. The tumor vasculature in these tumors was composed of aberrant small vascular cords, which were associated with few mural cells. Our results indicate that in the presence of hAng-1, tumors induce a more functional vascular network, which led to better tumor perfusion and growth. On the other hand, overexpression of hAng-2 led to less intact tumor vessels, inhibited capillary sprouting, and impaired tumor growth.     

Ang-1/Tie2系统与病理性血管形成的关系

血管生成素1(Ang-1)是继血管内皮生长因子(VEGF)之后,人们发现的又一重要的促血管生成因子。血管生成素家族包括Ang-l、Ang-2、Ang-3、Ang-4四种分子。其共同的特异性受体为Tie-2。目前对Ang-1/Tie2系统参与新生血管形成、促进血管成熟、抑制血管渗漏及炎症的作用研究相对深入,在创伤后修复、缺血后再通、肿瘤、糖尿病并发症及子宫内膜异位等多种病理性血管形成过程中起重要作用。     

Phagocytosis of maternal lymphocytes by the foetal trophoblast and the immunology of pregnancy

Immunologists have been striving to find an effective theory to explain the survival of the mammalian foetal allograft ever since the late 1950s. Embryologists had revealed that the blastocyst implants in the uterine decidua by a process involving cytolysis and phagocytosis. Brewer in 1937 had demonstrated a phagocytic property of the cytotrophoblast after implantation directed at all of the circulating blood cells. We advance the theory, supported in part by our recent studies using labelled leukocytes in pregnant mice, that the cytotrophoblast is phagocytic throughout most or all of pregnancy, and that after implantation a major source of nutrition of the embryo is phagocytosed blood cells. In particular we theorize that alloreactive lymphocytes are very likely to be phagocytosed. We also theorize that there are phagocytic foetal cells derived from the placenta in the foetus as a last line of defence against alloreactive cells from the mother. Some of the maternal lymphocytes seen in the foetus could have a surveillance function over abnormal cells arising from time to time in the foetus. Nonetheless runt disease will not occur in the embryo because of the elimination of alloreactive cells, a process which in theory can continue after the birth of the young.     

Adenosine A(2A) receptor activation promotes wound neovascularization by stimulating angiogenesis and vasculogenesis

Recent reports indicate that circulating endothelial progenitor cells (EPCs) may be recruited to sites of neovascularization where they differentiate into endothelial cells (EC). As we have previously demonstrated that adenosine A(2A) agonists promote neovascularization in wounds, we sought to determine whether adenosine A(2A) receptor agonist-augmented wound healing involves vessel sprouting (angiogenesis) or EPC recruitment (vasculogenesis) or both. Four weeks after bone marrow reconstitution from donor FVB/N Tie2GFP transgenic mice, two full-thickness excisional wounds were performed on the dorsum of FVB/N wild-type mice and treated with either an A(2A) receptor agonist (CGS-21680) or vehicle alone. Vessel density, as measured by CD31 staining, and density of EPC-derived vessels, as measured by GFP expression, were quantified in a blinded fashion using two-color fluorescence microscopy. We observed nearly a threefold increase in CD31-positive vessels and a more than 10-fold increase in GFP-positive cells in A(2A) agonist-treated 3-day old wounds, but by 6 days after wounding the differences between A(2A) agonist-treated and vehicle-treated wounds were no longer statistically significant. In conclusion, this is the first evidence that an exogenous agent such as an adenosine A(2A) receptor agonist increases neovascularization in the early stages of wound repair by increasing both EPC recruitment (vasculogenesis) and local vessel sprouting (angiogenesis).     

Regulation of cell adhesion by PAI-1

Type I plasminogen activator inhibitor (PAI-1) is the primary inhibitor of tissue- and urokinase-type plasminogen activators. It circulates in plasma complexed with vitronectin (VN), the primary PAI-1 binding protein. The somatomedin B (SMB) domain of VN contains both the high affinity PAI-1 binding site and the specific site for urokinase plasminogen activator receptor (uPAR). PAI-1 is able to regulate uPAR-mediated cell adhesion by competing with uPAR for VN binding. Binding of PAI-1 to SMD may also affect integrin-mediated cell adhesion to VN by hindering integrin binding to the RGD sequence adjacent to the uPAR binding site.     

Granulocyte colony-stimulating factor promotes tumor angiogenesis via increasing circulating endothelial progenitor cells and Gr1+CD11b+ cells in cancer animal models

Recombinant granulocyte colony-stimulating factor (G-CSF) is used for cancer patients with myelosuppression induced by chemotherapy. G-CSF has been reported to progress tumor growth and angiogenesis, but the precise mechanism of tumor angiogenesis activated by G-CSF has not been fully clarified. N-terminal-mutated recombinant human G-CSF administration increased WBCs and neutrophils in peripheral blood and reduced bone marrow stromal cell-derived factor-1 in mice, indicating its biological relevance. Mice were inoculated with Lewis lung carcinoma cells (LLCs) or KLN205 cells and treated with G-CSF. G-CSF accelerated tumor growth and intratumoral vessel density, while it did not accelerate proliferation of LLCs, KLN205 cells or human umbilical vein endothelial cells in vitro. In the absence of tumors, G-CSF did not increase circulating cells that displayed phenotypic characteristics of endothelial progenitor cells (EPCs). In the presence of tumors, G-CSF increased circulating EPCs. In addition, G-CSF treatment increased immune suppressor and endothelial cell-differentiating Gr1+CD11b+ cells in tumor-bearing mice. We conclude that G-CSF promotes tumor growth by activating tumor angiogenesis via increasing circulating EPCs and Gr1+CD11b+ cells in cancer animal models.     

Pregnancy IFN-gamma responses to foetal alloantigens are altered by maternal allergy and gravidity status

Background: During pregnancy, variations in maternal–foetal cellular interactions may influence immune programming. This study was carried out to determine if maternal responses to foetal alloantigens are altered by maternal allergic disease and/or previous pregnancies. Methods: For this cohort study, peripheral blood was collected from allergic (n = 69) and nonallergic (n = 63) pregnant women at 20, 30, 36‐week gestation and 6‐week postpartum (pp). Cord blood was collected at delivery. Mixed lymphocyte reactions were used to measure maternal cytokine responses [interleukin‐6 (IL‐6), IL‐10, IL‐13 and (interferon‐γ) IFN‐γ] at each time point towards foetal mononuclear cells. Results: Maternal cytokine responses during pregnancy (20, 30 and 36 weeks) were suppressed compared to the responses at 6‐week pp. The ratio of maternal IFN‐γ/IL‐13 and IFN‐γ/IL‐10 responses were lower during pregnancy. Allergic mothers had lower IFN‐γ responses at each time‐point during pregnancy with the greatest difference in responses observed at 36‐week gestation. When allergic and nonallergic women were further stratified by gravidity group, IFN‐γ responses of allergic multigravid mothers were significantly lower than nonallergic multigravid mothers during pregnancy. Conclusions: During normal pregnancy, peripheral T‐cell cytokine responses to foetal alloantigens may be altered by both allergic status of the mother and previous pregnancies. These factors could influence the cytokine milieu experienced by the foetus and will be further explored in the development of allergic disease during early life.