VEGF在糖尿病视网膜病变发病机制中作用的研究新进展

糖尿病视网膜病变(diabetic retinopathy,DR)是糖尿病最常见的微血管并发症之一,其基本病理改变是血-视网膜屏障(blood-retinal barrier,BRB)破坏、新生血管形成,后期新生血管膜收缩牵拉引起视网膜脱离。DR的发病机制十分复杂,至今尚未完全阐明。任何病理改变在本质上均是体内动态平衡的失调,新生血管的形成亦然,血管刺激因素增强和(或)抑制因素减少使两者平衡失调即所谓的"血管生成开关"形成。血管内皮生长因子(vascularendothelial growth factor,VEGF)是体内促新生血管形成的主要因子之一,近年来在DR的发病机制以及治疗的研究中广受关注。我们旨在阐述VEGF在DR发病机制中的作用。     

血管生成促进因子在糖尿病视网膜病变新生血管形成中的作用

糖尿病视网膜病变(diabetic retinopathy,DR)是糖尿病最常见和最严重的并发症之一.目前,DR的发病机制尚不明确,但近年来研究表明,血管生成促进因子与DR新生血管的发生、发展密切相关,是导致视网膜新生血管形成的主要致病因子.本文就血管生成促进因子在DR新生血管形成中的作用进行综述.     

糖尿病视网膜病变患者血清中血管内皮生长因子和色素上皮衍生因子水平的变化

糖尿病视网膜病变(DR)基本病理改变是血视网膜屏障破坏,新生血管形成.血管内皮生长因子(VEGF)是促进血管生成的重要因子之一,通过促进内皮细胞增生,改变细胞外基质及增加血管通透性促进血管新生.色素上皮衍生因子(PEDF)可以通过抑制炎症以及氧化应激反应,促进内皮细胞凋亡等抑制新生血管形成.为了解VEGF与PEDF水平在DR发生发展过程中的变化,我们对一组糖尿病患者和DR患者的血清VEGF与PEDF进行了测定,现将结果报道如下.     

VEGF家族及其受体与糖尿病视网膜病变发病的关系

视网膜新生血管形成和黄斑水肿是糖尿病视网膜病变(diabetic retinopathy,DR)的主要临床表现,也是DR主要的致盲原因。目前研究表明血管内皮生长因子(vascular endothelial growth factor,VEGF)在糖尿病视网膜微血管并发症的发生中发挥重要作用,因此VEGF成为当今DR治疗干预的一个研究热点。本文就VEGF家族及其受体在DR中的表达与DR病变发病的关系研究进展进行综述。     

糖尿病大鼠视网膜血管铺片中碱性成纤维细胞生长因子的表达与血管超微结构的改变

糖尿病视网膜病变(diabetic retinopathy，DR)是以新生血管形成为主要病理改变的疾病。目前已公认这种新生血管形成与生长因子相关。笔者的前期研究结果也证明：DR与血管内皮生长因子(vascular endothelial growth factor，VEGF)及碱性成纤维细胞生长因子(basic—fibroblast growth factor，bFGF)有相关性，但生长因子与血管本身病变的关系     

PEDF与视网膜新生血管

近年来糖尿病性视网膜病变、视网膜静脉阻塞、Eales病、早产儿视网膜病变、年龄相关性黄斑变性的发病率越来越高,已经成为致盲的主要眼病。新生血管形成是这些眼病共有的病理性改变,并且是其致盲的主要原因。研究发现新生血管形成因子与抑制因子之间的平衡失调是新生血管形成的重要机制,抑制血管增生已经成为治疗这类疾病的新靶点。色素上皮细胞衍生因子(pigmentepitheli-umderivedfactor,PEDF)是目前最有效的血管增生抑制剂之一。本文将对PEDF的概况,PEDF与视网膜新生血管的关系,PEDF在视网膜新生血管性疾病中的用途等方面进行综述。     

密蒙花提取物对高糖下人视网膜血管内皮细胞增生及VEGF表达的影响

糖尿病视网膜病变（diabetic retinopathy，DR）是糖尿病严重的微血管并发症之一，其病理特征为视网膜新生血管形成，血管内皮生长因子（vascular endothelial growth factor，VEGF）能特异性地作用于视网膜血管内皮细胞，是最直接的眼内新生血管形成因子之一。密蒙花是用于治疗眼部疾病的一种中药，具有维生素P样作用，能降低皮肤和小肠血管的通透性及脆性。     

microRNAs在糖尿病视网膜病变发病机制中的作用

糖尿病视网膜病变(diabetic retinopathy，DR)是糖尿病最常见的并发症之一，可引起糖尿病性黄斑水肿和视力丧失。DR中血管的变化与血-视网膜屏障(blood-retinal barrier，BRB)毛细血管的细胞损伤和病理变化相关。多种细胞因子参与诱导新生血管形成，这些细胞因子通过激活不同的信号通路导致DR并发症的发生。microRNAs(miRNAs)是调节细胞因子表达的关键因子，在视网膜细胞的新生血管形成中起着关键作用。有研究表明，microRNAs水平的改变在DR患者血管变化的病理生理学中具有重要作用。本文通过文献回顾，对microRNAs通过激活新生血管形成通路在DR发病机制中的作用进行综述。     

细胞因子信号抑制因子3与糖尿病视网膜病变

糖尿痛视网膜病变(diabetic retinopathy,DR)是一种常见的糖尿病慢性并发症,早期的视网膜血管渗漏和晚期的新生血管形成是其重要的病理改变,而血管内皮生长因子以及各种炎症因子、瘦素、血管紧张素Ⅱ等在英发病中发挥重要作用.细胞因子信号抑制因子3作为调节细胞因子信号通路的一种重要蛋白,通过调节Janus激酶/信号转导转录激活因子(JAK/STAT)信号通路,抑制上述各种因子的作用,成为未来治疗DR的新靶点.本文就细胞因子信号抑制因子3在DR发病中的作用进行综述.     

糖尿病性视网膜病变发病机制研究进展

糖尿病性视网膜病变（DR）是糖尿病最常见和最严重的微血管并发症之一，DR的病理特征为视网膜新生血管形成和BRB破坏，它是糖尿病患者视力丧失的主要原因。高血糖是糖尿病并发症发生和发展的重要危险因素，而糖尿病最终如何导致DR发病的机制十分复杂。长期的高血糖症导致氧化酶损伤，微血栓形成，细胞粘附分子活化，白细胞郁积和细胞因子活化，继之，缺氧调节的生长因子的表达增加和细胞因子的产生。在这个机制中起主要作用的因子为VEGF、IGF-1、TNF-α、IL-1β、FGF等。多种因子相互作用引起视网膜新生血管形成和血—视网膜屏障（BRB）破坏在DR的发生和发展中起着关键作用。本文通过文献回顾，综述了糖尿病性视网膜病变发病机制的研究进展。     

Pigment-epithelium-derived factor is upregulated in photocoagulated human retinal pigment epithelial cells

There is much evidence that pigment-epithelium-derived factor (PEDF) is a potent antiangiogenic cytokine which inhibits retinal and choroidal neovascularization by inducing apoptosis in activated vascular endothelial cells. Furthermore, the regulation of PEDF appears to be linked to the regulation of vascular endothelial growth factor (VEGF), one of the most potent inducers of intraocular neovascularization. Previous studies have established that thermal photocoagulation, the mainstay in the therapy of various neovascular diseases of the posterior segment, results in a decrease in intraocular concentrations of VEGF and other angiogenic growth factors, thereby inhibiting active retinal neovascularization. In the current study, we sought to determine whether thermal photocoagulation has the potential to regulate the expression of PEDF in human retinal pigment epithelial (RPE) cells. Cultures of RPE cells were photocoagulated with a 532-nm diode laser. Subsequently, RNA was isolated for RT-PCR, and whole-cell extracts and precipitated cell culture supernatant were subjected to Western blot analysis. According to our results, PEDF mRNA and protein are significantly upregulated after photocoagulation. Moreover, PEDF protein was found to be secreted in the cell culture medium.     

Molecular mechanism for choroidal neovascularization in age-related macular degeneration

Choroidal neovascularization (CNV) in age-related macular degeneration (AMD) is the most common cause of severe visual loss in patients over age 60 years in developed countries. While much is unknown about the underlying pathogenesis of CNV, the increased production of vascular endothelial growth factor(VEGF) by retinal pigment epithelium (RPE) is thought to play a central role in the development of this condition. However, recent studies using gene-manipulated mice question the importance of VEGF alone in promoting CNV. Angiogenesis is thought to result from the balance between angiogenesis stimulation and inhibition. A potent antiangiogenic factor recently has been identified in the retina and shown to be secreted by RPE cells. The inhibitor, pigment epithelium-derived factor(PEDF) is considered the key factor associated with avascularity of the cornea, vitreous, and outer retinal layer of the eye. We recently demonstrated that an imbalance between PEDF and VEGF in RPE cells caused by aging and oxidative stress may contribute to the disregulation of endothelial cell proliferation in CNV. In this review, we also discuss the angiogenic role of inflammatory cells in CNV, age-related changes in Bruch's membrane, and the possibility of the development of animal models reflecting CNV in AMD.     

VEGF抑制剂治疗糖尿病性视网膜病变的研究进展

许多临床研究表明糖尿病性视网膜病变(diabetic retinopa-thy,DR)的发病机制与血管内皮生长因子(vascular endo-thelial growth factor,VEGF)有关,VEGF抑制剂主要通过与VEGF结合并阻断其生物活性而起作用。目前在DR新生血管形成及血管渗漏的治疗中取得了显著的成绩。我们对VEGF抑制剂的分类、作用机制、安全性以及治疗DR的相关应用进展作一综述。     

Vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor: implications for ocular angiogenesis

PURPOSE: Pigment epithelium-derived factor (PEDF) has been demonstrated to suppress ocular angiogenesis in several animal models. In this study, we sought to measure the levels of PEDF and vascular endothelial growth factor (VEGF) in the vitreous of patients with and without ocular neovascular disorders. DESIGN: Case-control study of patients undergoing intraocular surgery for a variety of neovascular and nonneovascular conditions. METHODS: Vitreous samples were collected from 65 eyes of 65 patients with no neovascular disorder (n = 24), choroidal neovascularization (n = 9), active proliferative diabetic retinopathy (n = 16), and inactive proliferative diabetic retinopathy (n = 16). The levels of VEGF and PEDF in these vitreous samples were determined by enzyme-linked immunosorbent assay. RESULTS: The VEGF levels were at or below the level of detectability in the reference and choroidal neovascularization groups. The VEGF levels were significantly elevated in both the active and inactive PDR groups, and significantly higher in the active PDR group as compared with the inactive PDR group. The PEDF levels, which were present at relatively high concentrations in all groups, were higher in patients with active PDR compared with the control and choroidal neovascularization groups. CONCLUSIONS: High levels of immunoreactive PEDF are present in the vitreous of individuals with or without ocular neovascularization, but PEDF levels are significantly higher in patients with active PDR compared with patients with choroidal neovascularization or nonneovascular retinal diseases. Although these results do not preclude the possibility that endogenous PEDF helps to modulate ocular neovascularization, they do not support ischemia-induced downregulation of PEDF as a mechanism for such modulation.     

大鼠角膜化学伤后PEDF和VEGF的不平衡表达

目的比较硝酸银化学伤后大鼠角膜和正常角膜色素上皮衍生因子（PEDF）和血管内皮生长因子（VEGF）表达水平，揭示两者与角膜新生血管的相关性。方法10只大鼠左眼角膜硝酸银化学伤后为实验组，右眼为正常对照组，伤后15d行免疫组织化学法定位及Western blot定量检测样本角膜PEDF、VEGF等的表达。结果免疫组织化学检查：实验组角膜VEGF、碱性成纤维细胞生长因子（bFGF）强表达，PEDF未见表达或弱表达。正常组角膜PEDF高表达，VEGF弱表达，bFGF几乎不表达。Western Blot分析：实验组角膜PEDF表达明显下降（t=8．0049，P〈0．01），VEGF表达显著升高（t=48．3637，P〈0．01）。结论角膜严重化学伤后新生血管抑制因子PEDF破坏，刺激因子VEGF产生增加，PEDF／VEGF比值降低，角膜血管新生。     

Regression of ocular neovascularization in response to increased expression of pigment epithelium-derived factor

PURPOSE: Several pharmacologic treatments have been shown to reduce ocular neovascularization when administered before the onset of angiogenic stimuli, but none have been shown to cause regression of already established ocular neovascularization. In this study, the authors tested the effect of adenoviral vectored pigment epithelium-derived factor (PEDF) gene transfer on established neovascularization in transgenic mice with expression of vascular endothelial growth factor (VEGF) in photoreceptors (rho/VEGF mice) and in a model of choroidal neovascularization. METHODS: Two weeks after the onset of VEGF transgene expression in rho/VEGF mice or 2 weeks after laser-induced rupture of Bruch's membrane in wild-type mice, subgroups of mice were killed, and the baseline amount of neovascularization was measured by image analysis. The remainder of the mice received an intravitreous or subretinal injection of adenoviral vector containing a PEDF expression construct (AdPEDF.11) or control vector (AdNull.11). RESULTS: Seven days after injection in rho/VEGF mice or 10 days after injection in the choroidal neovascularization model, the amount of neovascularization in AdPEDF.11-injected eyes was significantly less than the baseline level, indicating that regression of neovascularization had occurred. There was TUNEL staining within choroidal neovascular lesions in eyes injected with AdPEDF.11. Eyes given a subretinal injection of AdNull.11 had TUNEL-positive cells in the retina, but none within areas of choroidal neovascularization. CONCLUSIONS: These data indicate that increased expression of PEDF causes regression of ocular neovascularization by promoting apoptosis of cells within neovascular lesions and possibly represents a new treatment paradigm for patients with established ocular neovascularization.     

血管内皮生长因子抑制剂在糖尿病性视网膜病变中的应用

眼部新生血管是糖尿病性视网膜病变致盲的主要病理改变，而血管内皮生长因子（vascular endothelial growth factor，VEGF）在新生血管形成过程中起关键性刺激作用。VEGF抑制剂主要通过与VEGF结合并阻断其生物活性而起作用，从而达到抑制眼部新生血管生成的目的，在糖尿病性视网膜病变血管渗漏及新生血管形成的治疗中取得了显著的成绩。Bevacizumab（Avastin）是VEGF抑制剂之一，属于重组人源化单克隆抗体，因其疗效良好、价格低廉已被广泛应用于临床。现将VEGF抑制剂（尤其是Avastin）治疗糖尿病性视网膜病变的相关应用进展作一综述。