miRNA在脉络膜新生血管发生发展中的作用研究进展

脉络膜新生血管（ｃｈｏｒｏｉｄａｌｎｅｏｖａｓｃｕｌａｒｉｚａｔｉｏｎ,ＣＮＶ）见于多种眼部疾病,是引起视力障碍的重要原因之一。近期多项研究表明,ｍｉＲＮＡ在ＣＮＶ的发生发展中起着重要作用。ｍｉＲＮＡ可参与新生血管形成的多个步骤,通过特异性调控多种靶蛋白的水平,与多种细胞、细胞因子及信号通路发生交互作用。因此,揭示ｍｉＲＮＡ在ＣＮＶ发病中的作用及其机制,是未来ＣＮＶ发病机制研究的重要方向,并可为ＣＮＶ的防治提供新的思路。     

Notch信号通路在视网膜细胞发育及血管生成中的作用

视网膜细胞变性和新生血管形成存在于多种常见眼病的发生和发展过程中,严重损害患者视力,甚至致盲.多项研究结果表明Noah信号通路参与调控多种器官和组织的发育及细胞分化过程,因此,有必要就Notch信号通路的组成及其在视网膜细胞发育和血管发生过程中的作用进行综述,以期为视网膜疾病的防治研究提供新的思路和作用靶点.     

脉络膜新生血管相关信号通路的研究进展

脉络膜新生血管(choroidal neovascularization,CNV)与许多眼底病变有关,是引起视力障碍的重要原因之一.细胞内信号转导通路的调节异常参与了CNV的发生和发展.新近的研究发现,PI3K/Akt、Wnt、STAT3、Notch等信号通路在CNV的形成中发挥了重要的作用.这些信号通路的研究对于更加深入地揭示CNV的发生发展机制及寻找新的治疗靶点具有重要意义.     

Notch信号通路在眼科疾病发生发展中的调控作用

Notch信号通路是一种进化上高度保守的信号通路,广泛存在于各类组织细胞中,在胚胎发育、细胞增殖、分化和凋亡,维持多细胞生物稳态、血管生成以及多种癌症的发生发展过程中起重要作用。近年来研究发现Notch信号通路在白内障、葡萄膜炎、视网膜病变等多种眼科疾病中会表现为异常活化,调控着相关眼科疾病的发生和发展过程。本文就Notch信号通路在眼科疾病发生发展过程中的调控作用做简要综述。     

微小RNA在脉络膜新生血管相关信号通路中的研究进展

脉络膜新生血管(CNV)是多种眼部疾病的最终病理表现，其发病机制极其复杂，涉及多种细胞、细胞因子及信号通路。微小RNA(miRNA)作为一种生物小分子，是由22个核苷酸组成的非编码RNA，可通过降解或抑制靶基因mRNA翻译调节基因表达。随着学者对其研究的深入，miRNA介导的信号通路参与各种疾病发展的机制逐渐被揭示。在眼科领域，miRNA通过各种信号通路靶向特定蛋白基因，从而起到促进或抑制CNV的作用。因此，揭示miRNA在CNV发病中的作用及其机制，是未来CNV发病机制研究的重要方向。本综述旨在阐述miRNA调控CNV中的磷脂酰肌醇3激酶/丝氨酸/苏氨酸蛋白激酶B(PI3K/Akt)、转化生长因子-β(TGF-β)、核因子-κB(NF-κB)、Notch及Wnt信号通路，为阐明CNV发病机制及其靶向治疗提供新思路。     

丝裂原活化蛋白激酶信号通路与眼底新生血管性疾病相关性的研究进展

丝裂原活化蛋白激酶(MAPK)信号通路中主要存在3种亚型,分别为细胞外信号调节激酶(ERK)、c-Jun氨基末端激酶(JNK)和p38 MAPK.它们在各亚群内部均存在着类似的、相互独立的三级级联反应,在适当刺激因素下作用于不同的底物可产生不同的细胞生物学效应.眼底新生血管是多种致盲眼病的病理基础,是多种因子相互作用导致促血管生成因子和抗血管生成因子间的平衡失调的结果;而有关多种因子发挥生物效应的MAPK信号通路在眼底新生血管发生发展过程中的作用越来越引起注意.MAPK信号通路在糖尿病视网膜病变、早产儿视网膜病变、老年性黄斑变性、视网膜静脉阻塞等疾病的新生血管形成中发挥重要的调控作用.通过对MAPK信号通路在眼底新生血管作用机制的探索,有助于深入详尽地了解眼部疾病的形成和发展规律,为预防和控制眼底新生血管形成和发展提供新的思路和方案.在未来,针对MAPK信号通路的靶向治疗将成为有效抑制眼底新生血管形成的重要治疗方案之一.     

Delta样配体4-Notch信号在眼底血管发育和新生血管生成中的作用

新生血管可见于多种眼部疾病，是引起视力损害的重要原因之一。近期研究表明，Delta样配体4(Dll4)-Notch信号在生理性和病理性的血管新生过程中起着关键性的作用。Notch信号通过相邻细胞间的信号传递来调控细胞分化，进而影响细胞命运。Dll4是Notch1和Notch4在细胞膜上的配体，选择性地表达在生长的内皮细胞和一些肿瘤内皮中，并可由血管内皮生长因子和低氧环境诱导。Dll4-Notch信号的发现和认识、以及它与新生血管关系的阐明，对于相关眼部疾病的基础和临床研究将具有重要意义。     

血管内皮生长因子诱发脉络膜新生血管的分子机制

脉络膜新生血管（CNV）是多种眼底疾病引起视力障碍的重要原因之一；血管内皮生长因子 (VEGF)在CNV的发生中起着重要的作用。VEGF在眼内的生成及其诱发CNV的信号转导通路已部分明确，但由于CNV发生是一多因素共同作用的复杂过程，为阐明其发生机制，还需进一步深入研究。 (中华眼底病杂志, 2005, 21: 409-412)     

Hedgehog信号通路在视网膜细胞发育及病理性血管生成中的作用

视网膜细胞发育障碍和眼部血管的病理性生长可见于多种眼部疾病,严重影响患者视力.Hedgehog信号转导通路已被证实参与视网膜神经节细胞、无长突细胞、视锥细胞、视杆细胞、Müller胶质细胞、视网膜色素上皮(RPE)细胞等细胞生长发育的多个过程.近年来研究表明,Hedgehog信号通路可以调控视网膜细胞的分化和发育,并在眼部新生血管生成中起到关键性作用.本文从Hedgehog信号通路的组成、Hedgehog信号通路与视网膜细胞发育、视网膜再生、Hedgehog信号通路与眼部病理性血管生成4个方面就Hedgehog信号通路在视网膜细胞发育及病理性血管生成中的作用进行综述,以期为视网膜及眼部血管性疾病的治疗提供新的靶点.     

血小板源性生长因子及血管周细胞与新生血管性眼病

血小板源性生长因子及其受体通过对血管周细胞增殖和迁移的调控参与了血管的新生和成熟过程.该通路调控的周细胞改变与糖尿病视网膜病变、早产儿视网膜病变和脉络膜新生血管性疾病密切相关.本文回顾了血小板源性生长因子及其受体的结构和功能、其对周细胞的调控作用、以及在相关眼病发生和发展中的作用机制等,并探讨了通过该通路发挥作用的药物在抗新生血管眼病治疗中的应用前景.     

Notch-Dll4在激光诱导的大鼠脉络膜新生血管生成中的作用

目的探讨Notch信号通路中Delta样配体4(Delta-like ligand4,Dll4)在激光诱导的大鼠脉络膜新生血管(choroidal neovascularization,CNV)生成中的作用机制。方法将雄性棕色挪威(brown-Norway,BN)大鼠分为正常组、光凝组、实验组和对照组。光凝组、实验组、对照组利用532nm激光诱导建立双眼CNV模型。实验组在建立CNV模型后立刻玻璃体内注射25g.L-1Avastin10μL,对照组注射0.01mmol.L-1PBS10μL。采用免疫荧光染色检测Dll4和血管内皮生长因子(vascular endo-thelial growth factor,VEGF)在正常组和光凝组光凝后7d中的表达;采用Western-blotting和RT-PCR检测正常组和光凝组(光凝后1d、3d、7d、14d)实验组、对照组(注射后7d)Dll4和VEGF的蛋白和mRNA表达;通过HE染色和视网膜色素上皮-脉络膜-巩膜铺片检测实验组和对照组(注射后14d)CNV生成的厚度和面积。结果Dll4和VEGF在CNV区域有共表达。Dll4和VEGF蛋白及其mRNA的表达趋势...     

Notch信号通路与视网膜神经节细胞的发育

Notch信号在无脊椎动物和脊椎动物中广泛存在且在进化过程中高度保守。其信号途径主要通过邻近细胞间的相互作用,实现细胞内信号转导和核内转录,从而精确调控各谱系细胞和组织的分化,在机体的整个生长发育过程中发挥着重要的作用。视网膜神经节细胞(RGCs)是由视网膜前体细胞分化而来,并由其内部信号和视网膜微环境的外部信号共同决定。Notch信号在其发育过程中起着重要的调节作用。就Notch信号通路的组成、活化,及其在RGCs发育中的研究进展做一综述。     

Phosphorothioate oligonucleotides induction into experimental choroidal neovascularization by HVJ-liposome system.

PURPOSE: The purpose of this study was to determine whether the inactivated hemagglutinating virus of Japan (HVJ)-liposome method can induce phosphorothioate oligonucleotides effectively into an experimentally-induced choroidal neovascularization of rats. We also examined whether antisense phosphorothioate oligonucleotides against VEGF could be induced into choroidal neovascularization as a therapeutic agent by the HVJ-liposome method. METHODS: The experiments were conducted on a rat model of choroidal neovascularization. FITC-labeled phosphorothioate oligonucleotides were coencapsulated in liposomes. The liposomes were coated with the envelope of inactivated HVJ and injected into the vitreous cavity following photocoagulation of pigmented rat eyes. The eyes were removed following injection, fixed, frozen and cut into thin sections. Induction of oligonucleotides was observed under a laser confocal scanning microscope for fluorescence and the development of choroidal neovascularization was evaluated histopathologically. RESULTS: Phosphorothioate oligonucleotides were effectively induced into ganglion cells and into the cells of the choroidal neovascularization induced by laser photocoagulation. Highly effective induction of oligos was observed 3 to 14 days after intravitreal injection of HVJ-liposomes after which the level decreased. Antisense oligonucleotides against VEGF were induced specifically into cells in the choroidal neovascularization, however neovascularization was still observed. CONCLUSIONS: Phosphorothioate oligonucleotides can be effectively induced into ganglion cells, and specifically into cells in choroidal neovascularization. Although antisense oligonucleotides against VEGF failed to prevent choroidal neovascularization, the HVJ-liposome method provided a highly effective means of inducing antisense oligos for in vivo antisense therapy.     

Effective transfection of a cis element "decoy" of the nuclear factor-kappaB binding site into the experimental choroidal neovascularization

PURPOSE: To evaluate the efficacy of the gene transfer of a double-stranded phosphorothioate oligonucleotides (ODNs), called a "decoy", against the NF-kappaB binding site into cells of an experimentally-induced choroidal neovascularization. METHODS: FITC-labeled decoy was injected into the subretinal space of rat eyes by the HVJ-liposome delivery system, and 3 days later, choroidal neovascularization was induced by laser photocoagulation. The eyes were removed and the transfected cells were detected by fluorescence microscopy and also detected by immunohistochemistry. The degree of neovascularization was evaluated by fluorescein angiography. RESULTS: The decoy was transfected into the retinal pigment epithelial (RPE) cells, inner and outer segment of the photoreceptors at 3 days after the injection. When choroidal neovascularization was induced, highly effective transfection of the decoy was observed 3 to 14 days after photocoagulation, after which the level decreased. Decoys were transfected into the RPE cells and macrophages in the choroidal neovascularization. The eyes transfected with NF-kappaB decoy showed a weaker leakage in fluorescein angiograms than that of the control eyes transfected with scrambled decoy. CONCLUSIONS: A decoy can be transfected into retinal cells and cells within a choroidal neovascularization by the HVJ-liposome method. The transferred NF-kappaB decoy reduced the degree of choroidal neovascularization. Decoy targeted against NF-kappaB may be considered as a potential therapy for neovascularization.     

Expression of transforming growth factor-beta receptors in normal rat retina and experimental choroidal neovascularization

PURPOSE: Transforming growth factor-beta (TGF-beta) plays an important role in the development of choroidal neovascularization. TGF-beta transduces signals through the mediation of type I and type II receptors. We investigated the expression of TGF-beta receptors in a normal rat retina and a model of experimentally induced choroidal neovascularization. METHODS: Choroidal neovascularization was induced by laser photocoagulation in rat eyes. The expression of TGF-beta receptors was determined using immunohistochemical and in situ hybridization methods. RESULTS: In normal adult rat retinas, immunoreactivity and mRNA expression of TGF-beta receptor type I (TbetaRI) and TGF-beta receptor type II (TbetaRII) were found in the ganglion cells. During the process of neovascularization, immunoreactivity and mRNA expression of TbetaRI and TbetaRII were widely distributed in laser lesions soon after photocoagulation; thereafter, these receptors were specifically detected in the endothelial cells of choroidal neovascularization. CONCLUSIONS: The expression of TGF-beta receptors in normal rat retinas suggests that TGF-beta plays an important role in the homeostasis of normal retina. The upregulation of TGF-beta receptors in choroidal neovascularization strongly suggests that TGF-beta is most likely transduced through specific receptors and plays an important role in the development of choroidal neovascularization.     

Choroidal neovascularization in long-standing case of Vogt-Koyanagi-Harada disease

The eyes in a case of Vogt-Koyanagi-Harada disease (VKH) with long-standing uveitis for 26 years after the onset were studied histopathologically. It was found that typical granulomatous inflammation was persistent in the uveal tract and the choroidal neovascularization occurred in the peripheral fundus accompanied by proliferation of the retinal pigment epithelial cells (RPE). Some of the new vessels under the pigment epithelium extended into the vitreous. It was concluded that the ocular inflammation of VKH was essentially granulomatous even in this long-standing case. Disappearance of choroidal melanocytes, existence of epithelioid cells containing pigment granules, and accumulation of lymphocytes and plasma cells in the lesion indicated that the inflammation was an autoimmune reaction against uveal melanocytes, although the trigger initiating the disease remains unknown. It was further concluded that the peripheral fundus as well as the peripapillary and macular areas was a predilected site for choroidal neovascularization in chronic uveitis. The choroidal neovascularization may develop in such a way that the uveal inflammation damages the Bruch's membrane and choriocapillaris and consequently causes retinal ischemia, thus stimulating the endothelium of the choriocapillaris and the overlying RPE to proliferate. There is a close relation between choroidal neovascularization and proliferation of RPE. Choroidal neovascularization may cause reactive proliferation of the RPE and vice versa.     

Targeting tissue factor for immunotherapy of choroidal neovascularization by intravitreal delivery of factor VII-Fc chimeric antibody

PURPOSE: ICON is a fusion protein composed of factor VII, the natural ligand for tissue factor, conjugated to the Fc domain of a human IgG1 immunoglobulin. It binds to the tissue factor expressed on neovascular endothelia and initiates a cytolytic immune attack that destroys the neovascular tissue. We previously showed that mouse factor VII-Fc chimeric antibody (mICON) dramatically decreases the frequency of choroidal neovascularization in a laser-induced choroidal neovascularization model in mice. Herein, we determined the safety and efficacy of mICON in destroying subretinal choroidal neovascularization in pig eyes. METHODS: mICON (150-1200 microg) was administered into the midvitreous cavity of the pig eye either before (on Day 0) or after (on Day 10) induction of choroidal neovascularization with laser photocoagulation. On Day 14, the incidence of choroidal neovascularization was determined using confocal microscopy. We also determined the binding specificity (% binding to choroidal neovascularization/% binding to non-choroidal neovascularization areas) of mICON to tissue factor expressed on endothelial cells of laser-induced choroidal neovascularization. RESULTS: We observed that mICON selectively destroyed choroidal neovascularization in a dose-dependent manner (r = -0.93; EDB50B = 571.3 microg). Obliteration of the choroidal neovascular complex was more prominent at doses > 300 microg (p < 0.05). No systemic or local complications (including retinal tear/detachment, inflammation, infection, cataract, or glaucoma) were observed. Binding specificities of hICON (2.2 +/- 0.2) and mICON (3.4 +/- 0.4) were significantly higher than that of anti-von Willebrand antibody (0.1 +/- 0.01, p < 0.001). CONCLUSIONS: Both hICON and mICON bound to the neovascular endothelia of choroidal neovascularization with greater specificity than anti-von Willebrand antibody. Furthermore, mICON can selectively obliterate already established choroidal neovascularization, which suggests that it may be useful for immunotherapy in patients with exudative (wet) macular degeneration.     

Expression of pigment epithelium-derived factor in normal adult rat eye and experimental choroidal neovascularization

PURPOSE: Pigment epithelium-derived factor (PEDF) is a protein produced by the retinal pigment epithelial (RPE) cells. Recent studies have implicated PEDF in activities that are inhibitory to angiogenesis. In this study, the expression of PEDF was investigated in normal rat eyes and in eyes with experimentally induced choroidal neovascularization and compared with the expression of vascular endothelial growth factor (VEGF). METHODS: Choroidal neovascularization was induced by laser photocoagulation in rat eyes. At intervals of up to 2 weeks after photocoagulation, the eyes were removed and prepared for in situ hybridization and immunohistochemical study. In situ hybridization was performed with digoxigenin-labeled PEDF riboprobes. Protein expression of PEDF and VEGF was studied immunohistochemically. RESULTS: In normal adult rat eyes, PEDF mRNA was observed mainly in the corneal epithelial and endothelial cells, lens epithelial cells, ciliary epithelial cells, retinal ganglion cells, and the RPE cells. During the development of choroidal neovascularization, PEDF mRNA, PEDF protein, and VEGF protein were strongly detected in many cells within the laser lesions at 3 days after photocoagulation, after which levels gradually declined. However, PEDF was still expressed in the RPE cells that proliferated and covered the neovascular tissues at 2 weeks, whereas VEGF protein was weakly expressed in endothelial cells in choroidal neovascularization. CONCLUSIONS: PEDF is expressed in different cell types of normal rat eyes. The expression of PEDF was detected in the choroidal neovascular tissues induced by photocoagulation, and these findings suggest that PEDF may modulate the process of choroidal neovascularization.