细胞外基质与脉络膜新生血管

脉络膜新生血管(CNV)是引起视力障碍的重要原因之一。在CNV形成过程中，多种细胞外基质(ECM)分子通过与整合素(integrin)结合，调节细胞内信号通路，影响血管内皮细胞在ECM中移行和侵入。这一过程可被尿激酶样纤维蛋白水解酶激活物(uPA)和基质金属蛋白酶(MMPs)的蛋白水解作用加强，也受金属蛋白酶组织抑制剂(TIMPs)的调控。研究CNV发生过程中ECM的作用，将为预防CNV的生成提供新的思路。(中华眼底病杂志,2005,21:60-63)     

大鼠模型中用尿激酶纤溶酶原激活剂和受体系统的肽抑制剂抑制脉络膜新生血管形成

目的：为确定在动物模型中尿激酶型纤溶酶原激活剂（uPA）和尿激酶型纤溶酶原激活酶受体系统（uPAR）在脉络膜新生血管形成（CNV）中所起的作刷及其系统是否抑制脉络膜新生血管范嗣。方法：用裂隙灯激光释放系统光凝来引发鼠脉络膜新生血管形成。在这些动物的视网膜脉络膜上刷逆转录酶-多聚酶链反应和免疫细胞化学分析测验尿激酶型纤溶酶原激活酶的表达。两周后动物腹腔注射尿激酶型纤溶酶原激活酶．     

整合素在脉络膜新生血管生成中的作用

整合素是一类异二聚体家族,作为细胞外基质(extracellular matrix,ECM)的受体,选择性表达于激活的内皮细胞的有腔和无腔表面,参与内皮细胞的移行、增生、分化和毛细血管样管腔结构的形成,并最终形成新生血管.在脉络膜新生血管形成过程中,整合素与多种细胞因子如碱性成纤维细胞生长因子、血管内皮生长因子、血小板衍生生长因子等.以及基质金属蛋白酶协同作用,介导细胞向细胞间和ECM的移行和黏附,并调控细胞周期.整合索及其ECM配体的结合引发一系列复杂的胞内级联信号,包括黏着斑激酶的酪氨酸磷酸化、细胞内钙离子水平增加、细胞周期蛋白合成以及早期基因表达等;阻断整合素及其配体的作用能抑制细胞生长或诱导细胞凋亡.已有的研究结果提示,整合素可能是未来治疗脉络膜新生血管的有效靶点之一.     

基质金属蛋白酶和组织金属蛋白酶抑制剂在年龄相关性黄斑变性发病中的作用

年龄相关性黄斑变性(AMD)是导致老年人中心视力丧失的主要视网膜疾病之一,其发病机制目前尚未完全清楚.近年来的临床研究和基础研究表明,受基质金属蛋白酶(MMPs)和组织金属蛋白酶抑制剂(TIMPs)调控的细胞外基质(ECM)的代谢障碍在AMD的发病过程中起重要作用.研究表明,MMPs与TIMPs平衡的失调导致Bruch膜不同的病理性改变,参与玻璃膜疣的形成,调控脉络膜新生血管(CNV)的形成；而ECM降解产物弹性蛋白衍生肽(EDPs)的水平反映了MMPs水平及其活性,EDPs水平的升高可增加早期AMD向新生血管性AMD转化的风险.就MMPs和TIMPs及ECM降解产物EDPs在AMD发病机制中的研究进展进行综述.     

视网膜新生血管的治疗研究进展

视网膜新生血管的发生是众多促血管生成因子间协同作用的结果.病理状态下以基质金属蛋白酶、促红细胞生成素、整合素为代表的促血管生成因子,可通过不同的作用途径,促进视网膜新生血管的发生.有研究者将促视网膜新生血管形成因子作为"靶点"进行靶向治疗研究,可有效地抑制视网膜新生血管的发生.为进一步了解其靶向治疗的机制和效果,有必要就视网膜新生血管形成中的靶分子和靶向治疗研究进展予以阐述,以期为视网膜新生血管的临床治疗提供理论依据.     

整合素α5β1在脉络膜血管新生中的研究进展

脉络膜血管新生(choroidal neovascularization,CNV)是眼内后极部病理性血管新生的重要表现,是造成视力损伤的主要病因之一。整合素α5β1因在CNV的形成过程中发挥重要作用而受到广泛关注。我们就整合素α5β1的结构、分布、活性调节,及在视网膜色素上皮细胞及脉络膜内皮细胞中的表达及对脉络膜新生血管的调节进行综述,探讨抑制血管新生的有效方法。     

分泌粒蛋白Ⅲ抗体治疗眼底新生血管的研究进展

分泌粒蛋白Ⅲ(SecretograninⅢ,Scg3/SgⅢ)是一个新近发现的血管生长因子,相关体内、体外研究已证实Scg3在眼底新生血管的形成中具有重要作用。近年来,将Scg3抗体应用于眼底新生血管的治疗也取得了一些进展,其作用机制与血管内皮生长因子(vascular endothelial growth factor,VEGF)不同,Scg3仅在病理性新生血管中表达,在正常血管中不表达,是一种新发现的具有高选择性表达的血管生长因子。本文从Scg3分子结构、信号传导通路以及其在眼底视网膜及脉络膜新生血管治疗中的最新进展进行了综述,旨在为视网膜及脉络膜新生血管的治疗提供一个新的治疗思路。     

MMP-2和VEGF在视网膜新生血管的表达

目的检测基质金属蛋白酶-2(matrix metalloproteinases-2,MMP-2)和血管内皮生长因子(vascular endothelial growthfactor,VEGF)在视网膜新生血管中的表达,探讨两者的相互关系。方法 取7 d龄C57BL/6J小鼠40只,随机分为高氧组和对照组,每组各20只。建立高氧诱导的视网膜新生血管小鼠模型。采用ADP酶组织化学染色、HE染色和免疫组化方法分别观察2组视网膜血管的变化、计数突破视网膜内界膜的内皮细胞核数目和检测MMP-2、VEGF的表达。结果 高氧组视网膜铺片可见大量视网膜新生血管形成,对照组未见新生血管形成;高氧组突破视网膜内界膜内皮细胞核数目为14(14.230±5.388),与对照组数目0(0.110±0.386)相比差异有统计学意义(t=23.537,P<0.001);对照组和高氧组视网膜组织中VEGF的积分光密度值分别为36.81±14.60、60.85±24.55,差异有统计学意义(t=3.348,P<0.01);对照组和高氧组视网膜组织中MMP-2的积分光密度值分别为16.33±4.13、21.12±6.29,差异有统计学意义(t=3.160,P<0.01)。高氧组视网膜组织中MMP-2和VEGF的表达呈正相关(r=0.633,P<0.01)。结论 在ROP小鼠模型的视网膜组织中,VEGF、MMP-2的表达同步升高,二者的高表达可能与视网膜新生血管形成密切相关。     

MMP-2和VEGF在视网膜新生血管中的表达及意义

目的探讨基质金属蛋白酶-2（MMP-2）和血管内皮生长因子（VEGF）在视网膜新生血管中的表达及意义。方法取C57BL/6J小鼠60只,随机分为高氧组和正常组,各30只。以高浓度氧诱导小鼠建立视网膜新生血管模型。采用ADP酶视网膜铺片、苏木精-伊红染色及免疫组织化学法分别观察视网膜血管的改变、计数视网膜新生血管内皮细胞数并检测MMP-2、VEGF蛋白的表达。结果高氧组视网膜可见大量新生血管形成;突破视网膜内界膜的新生血管内皮细胞核数为（33.51±2.55）个,与对照组相比差异有统计学意义（t=9.345,P〈0.05）。高氧组与对照组比较,MMP-2、VEGF蛋白在神经节细胞层、内丛状层、内核层和突破视网膜内界膜的新生血管中高表达,且二者表达呈正相关（r=0.825,P〈0.05）。结论MMP-2、VEGF共同促进视网膜新生血管的形成,且二者可能具有协同作用。     

增生性玻璃体视网膜病变过程中细胞外基质作用的研究进展

国内外多项有关增生性玻璃体视网膜病变(PVR)的研究结果表明,细胞外基质(ECM)的多种成分参与了PVR的形成,包括ECM结构蛋白、黏附蛋白、抗黏附蛋白、基质金属蛋白酶及其组织抑制因子等.其中,结构蛋白包括胶原、弹力纤维蛋白等,是视网膜前、后及玻璃体腔内形成增生膜的主要的非细胞成分,可以促进增生膜的收缩;黏附蛋白包括纤维连接蛋白、玻璃体连接蛋白、层黏连蛋白等,能促进增生膜中细胞与基质间的黏附,增进视网膜色素上皮的黏附、移行及分化功能等;抗黏附蛋白包括血小板反应蛋白-1、骨连接蛋白、韧连接蛋白等,可促进视网膜色素上皮的移行,促使增生膜再塑形;基质金属蛋白酶及组织抑制因子能降解多种ECM,增加增生膜中血管内皮通透性,促进新生血管的形成等.笔者就其目前国内外有关增生性玻璃体视网膜病变增生膜的研究结果予以综述,以供同道参考.(中华眼科杂志,2008,44:759-763)     

Inhibition of pathological retinal angiogenesis by the integrin αvβ3 antagonist tetraiodothyroacetic acid (tetrac)

Retinal angiogenesis is a major cause of blindness in ischemic retinopathies including diabetic retinopathy and retinopathy of prematurity. Integrin αvβ3 is a promising therapeutic target for ocular angiogenesis, modulating the pro-angiogenic actions of multiple growth factors. In this study, we sought to determine the effects of the integrin αvβ3 antagonist tetra-iodothyroacetic acid (tetrac) on the angiogenic actions of VEGF and erythropoietin (EPO) in cultured human retinal endothelial cells. In addition, we investigated the effect of tetrac and a nanoparticulate formulation of tetrac on retinal angiogenesis in?vivo, in the mouse oxygen-induced retinopathy (OIR) model. Tetrac inhibitory activity was evaluated in human retinal endothelial cells treated with VEGF and/or EPO. Endothelial cell proliferation, migration, and tube formation were assessed, in addition to phosphorylation of ERK1/2. For the studies of the oxygen-induced retinopathy model, C57BL/6 mice were exposed to 75% oxygen from postnatal day (P)7 to P12, and then returned to room air. Tetrac and tetrac-nanoparticle (tetrac-NP) were administered at P12 and P15 by either intraperitoneal or intravitreal injection. Retinal neovascularization was quantitated at P18. Tetrac significantly inhibited pro-angiogenic effects of VEGF and/or EPO on retinal endothelial cells, indicating that the angiogenic effects of both growth factors are dependent on integrin αvβ3. Retinal neovascularization in the OIR model was significantly inhibited by both tetrac and tetrac-NP. These results indicate that the integrin αvβ3 antagonist, tetrac, is an effective inhibitor of retinal angiogenesis. The ability of tetrac to inhibit the pro-angiogenic effect of both VEGF and EPO on retinal endothelial cells suggests that tetrac (and antagonism of integrin αvβ3) is a viable therapeutic strategy for proliferative diabetic retinopathy.     

整合素αVβ3在糖尿病视网膜病变发生发展中的作用

糖尿病视网膜病变(diabetic retinopathy,DR)作为长期高血糖诱导的进展性微血管病变,视网膜微血管的缺血、缺氧状态贯穿DR发病、进展的整个过程.整合素αVβ3(integrin αVβ3,ITGαVβ33)作为重要的细胞黏附分子,在高血糖状态下其自身及其配体表达均上调,并通过促进视网膜微血管通透性增加...     

Role of urokinase inhibitors in choroidal neovascularization

Cell migration is a critical step in the angiogenesis cascade that involves proteolysis of the basement membrane and extracellular matrix around existing blood vessels. The urokinase plasminogen activator (uPA) system has been involved in cellular invasion, angiogenesis and tumor growth. Similar expression of urokinase and its receptor (uPAR) is seen in both retinal and choroidal neovascularization. Significant inhibition of choroidal neovascularization (CNV) has been observed when cell surface associated uPA-uPAR activity is prevented with a specific inhibitor of this proteinase system. As the current treatments of CNV are not optimal, the urokinase-uPAR system appears to be an attractive target for alternative pharamacological therapy for CNV.     

Reduction in endothelial tip cell filopodia corresponds to reduced intravitreous but not intraretinal vascularization in a model of ROP

To determine the effect of a vascular endothelial growth factor receptor 2 tyrosine kinase (VEGFR2) inhibitor on intravitreous neovascularization (IVNV), endothelial tip cell filopodia, and intraretinal vascularization in a rat model of retinopathy of prematurity (ROP).Within 4 h of birth, newborn Sprague-Dawley rat pups and their mothers were cycled between 50% and 10% oxygen daily until postnatal day (p)12. Pups were given intravitreous injections of VEGFR2 inhibitor, SU5416, or control (dimethyl sulfoxide, DMSO) and returned to oxygen cycling until p14, then placed into room air. Intravitreous neovascularization (IVNV), avascular/total retinal areas, and endothelial tip cell filopodial number and length were determined in lectin-labeled neurosensory retinal flat mounts. Cryosections or fresh tissue were analyzed for phospho-VEGFR1, phospho-VEGFR2, activated caspase-3, or phospho-β3 integrin. Human umbilical venous (HUVECs) and human choroidal endothelial cells (ECs) were treated with VEGFR2 inhibitor to determine effect on VEGFR2 phosphorylation and on directed EC migration toward a VEGF gradient. Filopodial length and number of migrated ECs were also measured.Compared to control, the VEGFR2 inhibitor reduced VEGFR2 phosphorylation in HUVECs in vitro and clock hours and areas of IVNV but not percent avascular retina in vivo. Filopodial length and number of filopodia/EC tip cell were reduced in retinal flat mounts at doses that inhibited IVNV, whereas at lower doses, only a reduction in filopodial length/EC tip cell was found. There was no difference in phosphorylated β3 integrin and cleaved caspase-3 labeling in VEGFR2 inhibitor-treated compared to control in vivo. Doses of the VEGFR2 inhibitor that reduced filopodial length and number of filopodia/migrating EC corresponded to reduced EC migration in in vitro models.VEGFR2 inhibitor reduced IVNV and filopodial number and length/EC tip cell without interfering with intraretinal vascularization. Reducing the number and length of filopodia/endothelial tip cell may reduce guidance cues for endothelial cells to migrate into the vitreous without interfering with migration into the retina toward a VEGF gradient.     

新生血管抑制因子--色素上皮源因子研究进展

血管形成和抑制血管形成因子的平衡被打破是新生血管形成的关键。色素上皮源因子(PEDF)是重要的新生血管抑制因子,存在于大多数组织中。色素上皮源因子抑制新生血管形成的作用机制有PEDF受体学说、Fas/Fas L受体系统学说和细胞外基质连接学说等。PEDF的实验研究主要通过免疫学和分子生物学的方法进行。对PEDF的抑制血管生成的机制及常用的实验方法作一综述,并展望该因子的研究方向与策略。     

骨桥蛋白与眼部新生血管性疾病研究进展

眼部新生血管是眼部疾病中致盲的主要原因之一.常见的致盲眼病,如糖尿病视网膜病变、年龄相关性黄斑变性、感染性角膜炎等均与新生血管存在一定的关系.骨桥蛋白（OPN）是一种能够促进血管再生与组织修复的糖蛋白,在角膜、脉络膜和视网膜新生血管中表达增多,能够促进新生血管的发生.OPN与新生血管的关系为新生血管性疾病的研究和治疗提供了新的方向.从OPN促进角膜新生血管、脉络膜新生血管、视网膜新生血管生成3个方面对OPN与眼部新生血管性疾病的关系研究进展进行综述.     

Fibronectin fragments promote human retinal endothelial cell adhesion and proliferation and ERK activation through alpha5beta1 integrin and PI 3-kinase

PURPOSE: Extracellular matrix degradation is associated with neovascularization in diabetic retinas. Fibronectin fragments (Fn-fs) are generated during vascular remodeling. The effects of cellular fibronectin (Fn) and selected Fn-fs on adhesion, proliferation, and signal transduction in human retinal endothelial cells (HRECs) were characterized. METHODS: Relative quantitative RT-PCR, flow cytometry, and immunocytochemistry determined integrin expression on HRECs. Adhesion was evaluated by coating plastic with Fn or Fn-fs of 45, 70, 110, or 120 kDa, and MTT conversion was used to measure proliferation and survival. Peptide inhibitors and blocking antibodies determined adhesive sites and integrins used for adhesion. Pharmacologic inhibitors and Western analyses were used to evaluate intracellular signaling. RESULTS: HRECs produced significant levels of alpha(2), alpha(3), alpha(5), alpha(v), beta(1), beta(3), and beta(5) integrin subunit mRNA. Flow cytometry of surface integrin expression revealed high levels of alpha(3), alpha(5), and beta(1) and lower levels of alpha(1), alpha(v), beta(3), and beta(5). These results were confirmed by immunocytochemistry. For adhesion to Fn and Fn-fs. the alpha(5)beta(1) integrin was essential. Pharmacologic inhibitors of PI 3-kinase blocked adhesion to Fn and Fn-fs, whereas the mitogen-activated protein (MAP) kinase kinase (MEK) inhibitor PD98059 blocked phosphorylation. The 110- and 120-kDa Fn-fs showed a concentration-dependent increase in proliferation, whereas 500 ng of the 70 kDa Fn-f-induced proliferation. Addition of III1-C, a matrix assembly domain, increased the proliferative effect of these Fn-fs. CONCLUSIONS: Fn and its Fn-fs modulate HREC adhesion and proliferation through signal-transduction pathways involving coupling of the alpha(5)beta(1) integrin through PI 3-kinase. Mitogenic signals for endothelial cells from degraded extracellular matrix may contribute to the development of diabetic retinopathy.