生长激素释放多肽对高糖诱导视网膜色素上皮细胞的保护作用

目的：探讨生长激素释放多肽(Ghrelin)对高糖环境下人视网膜色素上皮(retinal pigment epithelium,RPE)细胞氧化应激的影响。

方法：将体外培养的RPE细胞分为阴性对照组、高糖组、Ghrelin低浓度组、Ghrelin高浓度组。通过CCK-8法检测细胞存活率,氧敏感荧光探针H₂DCFDA染色法观察细胞氧化损伤程度,流式细胞技术检测细胞内活性氧(reactive oxygen species,ROS)的变化,分光光度计比色法检测细胞内超氧化物歧化酶(superoxide dismutase,SOD)活力和丙二醛(malondialdehyde,MDA)含量。

结果：CCK-8结果显示,分别用10^-9mol/L、10^-6mol/L Ghrelin预处理后,RPE细胞存活率分别为54.79%±3.43%和79.16%±3.29%,与高糖组(41.65%±3.42%)比较,差异均有统计学意义(P<0.05)。H₂DCFDA荧光探针染色结果显示,Ghrelin预处理后RPE细胞内ROS生成量下降,氧化损伤细胞减少。分光光度计比色法结果显示,与高糖组相比,Ghrelin组细胞SOD活力增加,MDA含量下降。

结论：Ghrelin可以抑制高糖诱导的人RPE细胞氧化损伤,其在糖尿病视网膜病变的发生发展过程中可能具有一定的细胞保护作用。     

磷脂酰肌醇-3激酶信号通路在缺氧诱导的人视网膜色素上皮细胞VEGF表达中的作用

目的:探讨磷脂酰肌醇-3激酶(phosphatidylinositol3-ki-nase,PI3K)信号转导通路对缺氧诱导的视网膜色素上皮(retinalpigmentepithelium,RPE)细胞表达VEGF的影响。方法:利用CoCl2建立培养的人RPE细胞缺氧模型,分为单纯缺氧组和30μmol/LPI3K特异性阻断剂LY294002阻断处理组,在缺氧条件下分别培养0,1,4,8,12和24h。细胞免疫荧光法检测磷酸化PI3K表达水平;酶联免疫吸附试验(enzymelinkedimmunosorbentassay,ELISA)检测RPE细胞上清中VEGF的含量。结果:缺氧刺激1,4,8,12和24h,RPE细胞膜上PI3K磷酸化表达水平逐渐增高(P<0.05);随缺氧时间延长,RPE细胞上清液中VEGF含量逐渐增加(P<0.05);LY294002处理组VEGF含量显著低于对照组(P<0.05)。结论:PI3K信号转导通路参与了缺氧引起的人RPE细胞VEGF表达的调控。     

缺氧和高糖对视网膜色素上皮细胞增生及VEGF、TGF-β1表达的影响

目的 探究缺氧、高糖环境对体外培养的视网膜色素上皮(retinal pigment epithelium,RPE)细胞生长、增生及血管内皮生长因子(vascular endothelial growth factor,VEGF)、转化生长因子-β1(transforming growth factor-β1,TGF-β1)表达变化的影响.方法 采用酶消化法进行C57小鼠RPE细胞的体外原代培养.通过组织形态学观察和免疫化学染色对培养的RPE细胞进行鉴定.实验缺氧组:在DMEM培养液中加入CoCl2,使其浓度分别为50μmol·L-1、100μmol·L-1、200μmol·L-1;实验高糖组:在DMEM培养液中加入D-葡萄糖,使其浓度分别为15 mmol·L-1、30 mmol·L-1、45 mmol·L-1.分别向培养的RPE细胞中加入上述培养液,共6组,每组3份;正常对照组加入含5.5 mmol·L-1葡萄糖、不含CoCl2的培养液.观察各组细胞在不同培养条件下的活力、倍增时间及增生情况.采用ELISA法检测各组细胞在培养不同时间后(24 h、48 h、72 h)上清液中VEGF及TGF-β1表达量的变化.结果原代培养及传代早期的RPE细胞生长较为旺盛;在缺氧和高糖培养条件下所培养的细胞活力和分裂次数均较正常对照组有所降低或减少,而倍增时间较正常对照组延长.在缺氧和高糖培养条件下培养24 h、48 h、72 h后,细胞上清液中VEGF和TGF-β1表达量均较正常对照组高(P<0.05);当CoCl2浓度为100 μmol·L-1和D-葡萄糖浓度为30mmol·L-1时,VEGF和TGF-β1在24 h、48 h、72 h表达均高于其他浓度,缺氧状态下48 h表达量分别为(43.28±0.88)ng·L-1和(8.90±1.38)ng·L-1,高糖状态下分别为(39.76±0.56)ng·L-1和(8.81±0.92)ng·L-1;缺氧组2种细胞因子表达量在48 h达到高峰,而高糖组在72 h达到高峰.结论 应用酶联合消化法可获得纯度较高的体外C57小鼠培养RPE细胞;缺氧和高糖状态可对RPE细胞增生起到明显抑制作用,但能够明显上调RPE细胞的VEGF、TGF-β1表达量.     

薯蓣皂苷对高糖诱导的视网膜色素上皮细胞损伤的保护作用

目的 探讨薯蓣皂苷(Dio)对高糖(HG)诱导的视网膜色素上皮(RPE)细胞损伤的保护作用,并分析其机制.方法 用细胞计数试剂8(CCK-8)法筛选葡萄糖浓度和无细胞毒性的Dio剂量范围.将ARPE-19细胞分为对照组(5 mmol·L-1葡萄糖处理48 h)、模型组(50 mmol·L-1葡萄糖处理48 h)和低、中...     

高糖环境下内脏脂肪素在人视网膜色素上皮细胞中的作用

目的：观察体外高糖诱导环境,对人视网膜色素上皮细胞中内脏脂肪素(Visfatin)的表达影响,以及研究高糖环境下重楼皂苷I(Polyphyllin I)对Visfatin表达情况的影响。

方法：人视网膜色素上皮细胞培养后分3组,正常对照组、高糖组和高糖加Polyphyllin I药物干预组,干预培养12h后进行检测。正常对照组：5.5mmol/L葡萄糖浓度常规培养; 高糖组：将25mmol/L的高糖加入培养基建立模型; 高糖加Polyphyllin I药物干预组：高糖25mmol/L和3μg/L Polyphyllin I药物加入培养基。免疫荧光染色法观察人视网膜色素上皮细胞中Visfatin和血管内皮细胞生长因子(VEGF)表达; 实时荧光定量PCR检测上皮细胞中Visfatin和VEGF mRNA的表达; Western-blot法检测上皮细胞中Visfatin和VEGF蛋白的表达。

结果：免疫荧光检测发现Visfatin和VEGF在正常组视网膜色素上皮细胞中表达呈弱阳性。但在高糖组视网膜色素上皮中可见Visfatin和VEGF呈强阳性表达。药物干预组中Visfatin和VEGF荧光较高糖组明显减弱。RT-PCR显示高糖组Visfatin mRNA表达水平较正常组和干预组明显增高(t=4.24、3.89,均P<0.05)。高糖组VEGF mRNA表达水平较正常组和干预组明显增高(t=3.53、2.57,均P<0.05)。Western-blot结果示Visfatin蛋白水平,高葡萄糖组表达量显著高于正常对照组(t=3.62,P=0.01),干预组表达低于高糖组(t=3.79,P<0.01)。

结论：高糖环境可刺激视网膜色素上皮细胞中Visfatin的表达增加,Polyphyllin I可抑制高糖环境下视网膜色素上皮细胞中Visfatin的表达,可能为治疗糖尿病视网膜病变提供新的思路。     

p42/p44 MAPK信号转导通路在缺氧诱导的人视网膜色素上皮细胞VEGF表达中的作用

目的　探讨p4 2 /p4 4丝裂原活化蛋白激酶(mitogen-activedproteinkinase ,MAPK)信号转导通路对缺氧诱导的人视网膜色素上皮(retinalpigmentepithelium ,RPE)细胞VEGF表达中的作用。方法　利用CoCl2 建立培养的人RPE细胞缺氧模型,用2 0μmol·L-1p4 2 /p4 4MAPK特异性阻断剂PD980 5 9处理RPE细胞,在缺氧条件下分别培养0min、5min、10min、30min、6 0min和12 0min ,用Westernblot方法检测磷酸化p4 2 /p4 4MAPK表达;培养人RPE细胞1h、3h、6h、12h和2 4h ,用酶联免疫吸附试验(en zymelinkedimmunosorbantassay ,ELISA)检测缺氧条件下RPE细胞上清中VEGF的含量。结果　缺氧刺激5min、10min、30min、6 0min和12 0min时,磷酸化p4 2 / p4 4MAPK水平逐渐增高;相应PD980 5 9处理组磷酸化p4 2 / p4 4MAPK水平降低,只可见磷酸化p4 2MAPK条带。在缺氧1h、3h、6h、12h和2 4h时,RPE细胞上清液中VEGF含量随时间逐渐增加(P <0 .0 1) ,PD980 5 9处理组VEGF含量较对照组显著减少(P <0 .0 1)。结论　p4 2 /p4 4MAPK信号转导通路可能参与了缺氧引起的人RPE细胞VEGF的表达     

缺氧对人视网膜色素上皮细胞增生和VEGF表达的影响

目的　观察缺氧对培养的人视网膜色素上皮 (retinalpigmentepithelial,RPE)细胞增生和血管内皮生长因子 (vascularendothelialgrowthfactor,VEGF)表达的影响。 方法将培养的人RPE细胞接种于 2 4孔板 ,分别放入正常和缺氧环境中培养 ,于 1、2、3、4、5d后用四甲基偶氮唑蓝 [3 ( 4 ,5 dimethylthiazole 2yl) 2 ,5 diphenyltetrazoliumbromide ,MTT]比色法检测RPE细胞的增生 ,于 6、12、2 4h后用免疫组织化学法检测RPE细胞对VEGF的表达 ,经计算机图像处理 ,定量分析。结果　缺氧组的MTT实验吸光度 (A值 )均高于正常组 (P <0 .0 1) ;抗VEGF抗体染色 ,缺氧组明显强于正常组 (P <0 .0 5 )。结论缺氧可促进RPE细胞的增生及其对VEGF的表达 ,控制RPE细胞的活动是抑制脉络膜新生血管生成的关键     

高糖条件下胰岛13细胞株MIN-β细胞对视网膜色素上皮细胞的保护作用

背景糖尿病视网膜病变（DR）与高糖所致的视网膜色素上皮（RPE）细胞的氧化损伤密切相关,近年来人们广泛地致力于保护RPE细胞的研究。目的研究胰岛B细胞株MIN-6细胞对RPE细胞高糖损伤的保护作用。方法将RPE细胞体外培养4d,待贴壁生长良好后分为正常对照组、高糖对照组和MIN-6细胞共培养组,ABC法鉴定RPE细胞。用含5mmol／L葡萄糖的RPE细胞培养液进行培养作为正常对照组,高糖对照组用含30mmol／L葡萄糖的培养液进行培养,MIN-6细胞共培养组为含5×10^4个MTN-6细胞以及30mmol／L葡萄糖的培养液进行培养。各组继续培养24h后,应用四甲基偶氮唑蓝（MTT）法测量高糖对已贴壁生长良好的RPE细胞的损伤作用以及MIN一6细胞对RPE细胞高糖损伤的保护作用。结果ABC法鉴定RPE细胞可见95％以上呈棕色着色,为阳性细胞。各组继续培养24h后,正常对照组、高糖对照组和MIN-6细胞共培养组RPE细胞的吸光度（A_540）值差异有统计学意义（F=19．94,P〈0．01）,正常对照组的A。值为0．44±0．02,高糖对照组为0．30±0．01,差异有统计学意义（t=6．85,P〈0．01）;MIN-6细胞共培养组的A。值为0．41±0．01,与高糖对照组的0．30±0．叭比较,差异有统计学意义（t=5．62,P〈0．01）。正常对照组RPE细胞的生存率为（97．5±3．3）％,高糖对照组为（68．2±4．5）％,差异有统计学意义（t=11．30,P〈0．01）。结论高糖导致贴壁生长良好的RPE细胞损伤,MIN-6细胞可以明显保护高糖所致的RPE细胞损伤。     

磷脂酰肌醇-3激酶信号转导通路在缺氧诱导的人视网膜色素上皮细胞增生中的作用

目的:探讨磷脂酰肌醇-3激酶(phosphatidylinositol3-kinase,PI3K)在缺氧诱导的人视网膜色素上皮(retinalpigmentepithelium,RPE)细胞增生中的作用。方法:利用CoCl2法建立培养细胞缺氧模型。在缺氧条件下培养人RPE细胞1,4,8,12和24h,流式细胞仪检测RPE细胞的增生活性,RT-PCR和Westernblot检测磷酸化PI3KmRNA和蛋白的表达水平。用30μmol/LPI3K特异性阻断剂LY294002处理RPE细胞,作为阻断实验组。结果:随缺氧时间延长,RPE细胞增生活性逐渐增高,磷酸化PI3KmRNA和蛋白表达水平逐渐增高。LY294002处理组较对照组RPE细胞增生活性显著降低(P<0.05)。结论:缺氧诱导的RPE细胞增生部分是通过PI3K信号转导通路实现的。     

高糖条件下糖康乐对兔视网膜色素上皮细胞超氧化物歧化酶表达的影响

目的:研究海藻萃取物糖康乐在高糖条件下对兔视网膜色素上皮(RPE)细胞超氧化物歧化酶(SOD)表达的影响。方法:应用体外培养的兔RPE细胞,分成空白对照组、高糖组(用25mmol/L)葡萄糖处理、糖康乐组和牛磺酸组4组(n=6),应用高浓度葡萄糖后,糖康乐组加以不同浓度的糖康乐,同时应用牛磺酸作为阳性对照,测定不同浓度的糖康乐对RPE细胞SOD表达的影响。结果:在高糖条件下,高糖组RPE细胞SOD含量明显降低(2024±91→747±353kat/L)(t=8.570,P<0.001),糖康乐在浓度为0.002mg/L(t=3.207,P<0.01)、0.02mg/L(t=4.235,P<0.01)和0.2mg/L(t=3.748,P<0.01)的时候可以显著地抑制SOD表达的降低,与高糖组相比较有显著的差异,与阳性对照组的牛磺酸组相比,未见明显差异。结论:糖康乐可保护高糖导致的RPE细胞SOD表达的降低。     

Inhibition of Obtusifolin on retinal pigment epithelial cell growth under hypoxia

AIM: To explore the effect of Obtusifolin on retinal pigment epithelial cell growth under hypoxia. METHODS: In vitro chemical hypoxia model of ARPE-19 cells was established using cobalt chloride (CoCl2). Cell viability was tested by cell counting kit-8 (CCK-8) assay. Western blot and real-time quantitative polymerase chain reaction were applied to detect proteins and mRNAs respectively. Flow cytometry was used to examine the cell cycle. Secretion of vascular endothelial growth factor (VEGF) was tested by using enzyme linked immunosorbent assay (ELISA). RESULTS: Under the chemical hypoxia model established by CoCl2, hypoxia inducible factor-1α (HIF-1α) mRNA and protein levels was up-regulated. Cell viability was increased and the proportion of S phase was higher. Obtusifolin could reduce cell viability under hypoxic conditions and arrest cells in G1 phase. Obtusifolin reduced the expression of Cyclin D1 and proliferating cell nuclear antigen (PCNA) in the hypoxic environment and increased the expression of p53 and p21. The levels of VEGF, VEGFR2 and eNOS proteins and mRNA were significantly increased under hypoxia while Obtusifolin inhibited the increasing. CONCLUSION: Obtusifolin can inhibit cell growth under hypoxic conditions and down-regulate HIF-1/VEGF/eNOS secretions in ARPE-19 cells.     

Vascular endothelial growth factor expression and secretion by retinal pigment epithelial cells in high glucose and hypoxia is protein kinase C-dependent

Retinal pigment epithelial (RPE) cells express vascular endothelial growth factor (VEGF) in response to high glucose or hypoxia. We hypothesised that VEGF expression and secretion by RPE cells in high glucose and hypoxia are regulated by protein kinase C (PKC). Primary cultured RPE cells from Sprague-Dawley rats were growth-arrested for 48 hr in 0.5% FBS in 5.6 or 30 mm D-glucose. Cells were exposed to hypoxic conditions (<1% O(2), 5% CO(2)) for the last 15-18 hr of growth-arrest. PKC -alpha, -beta(1), -delta, -epsilon, and -zeta were expressed by RPE cells and exposure to high glucose for 48 hr had no effect on expression as demonstrated by Western immunoblotting. High glucose, hypoxia or VEGF stimulated translocation of a number of the PKC isozymes to the membrane or particulate fractions implying activation. In response to high glucose or acute phorbol myristate acetate (PMA) stimulation, VEGF mRNA analysed by RT-PCR was increased. Intracellular VEGF protein identified by immunoblotting and confocal immunofluorescence imaging was significantly increased by high glucose, hypoxia or acute PMA stimulation. Calphostin C or a specific inhibitor of PKC-zeta prevented high glucose-stimulated VEGF expression in high glucose. VEGF secretion, as measured by ELISA in the culture medium, was enhanced in hypoxia but not in high glucose. Following exposure of RPE cells to PMA for 24 hr, PKC-delta was significantly down regulated, whereas PKC-alpha, -beta, -epsilon and -zeta remained unchanged. Secretion of VEGF in normal or high glucose, or hypoxia was significantly reduced following treatment with PMA for 24 hr but not with the PKC-zeta inhibitor. We conclude that in high glucose and hypoxia PKC isozymes are activated and are necessary for VEGF expression. Secretion of VEGF is enhanced in hypoxia and appears to be regulated by PKC-delta. RPE cells may contribute to the pathogenesis of retinopathy caused by high glucose and hypoxia through the expression and secretion of VEGF that are regulated by PKC isozymes.     

The effects of anti-vascular endothelial growth factor agents on human retinal pigment epithelial cells under high glucose conditions

AIM: To investigate the effects of high glucose levels and anti-vascular endothelial growth factor (VEGF) agents (bevacizumab, ranibizumab and aflibercept) on retinal pigment epithelium (RPE) cells. METHODS: ARPE-19 cells were cultured at different glucose levels (5.5 mmol/L, 25 mmol/L, and 75 mmol/L). Cell viability was evaluated by MTT assay at 3d after treatment with D-glucose. Cell migration ability was measured by wound healing assay at 3d. A cell death detection kit was used to assess apoptosis at 3 and 14d. Cell proliferation was assessed by EdU assay at 3d. The culture medium was treated with anti-VEGF agents at clinically relevant concentrations. The experiment was then repeated at a different glucose level. RESULTS: The viability and migration of ARPE-19 cells were significantly decreased in the presence of 75 mmol/L as compared to 5.5 mmol/L glucose. The percentage of TUNEL-positive cells was significantly increased and the proliferative potential was decreased with 75 mmol/L compared to 5.5 mmol/L glucose. There were no significant differences in the results between 25 mmol/L and 5.5 mmol/L glucose. In the presence of 75 mmol/L glucose, the groups treated with anti-VEGF showed decreased cell viability and proliferation and increased apoptosis. However, there were no significant differences between the anti-VEGF groups. CONCLUSION: High glucose level decreases the viability, wound healing ability, and proliferation of RPE cells, while increasing apoptosis. Furthermore, anti-VEGF agents interfered with the physiological functions of RPE cells under high-glucose conditions, accompanied by decreases in cell viability and proliferation.     

新型海藻多糖化合物保护高糖诱导的RPE细胞异常增殖

目的:研究在高糖条件下,从海藻中萃取的新型多糖化合物对高糖诱导的视网膜色素上皮(RPE)细胞异常增殖的保护作用。方法:将体外培养的RPE细胞分为空白组、高糖组和多糖化合物组,空白组为正常RPE细胞培养液,高糖组为含30mmol/L葡萄糖的培养液,多糖化合物组为含30mmol/L葡萄糖和200mg/L多糖化合物的培养液。应用MTT法测量36h内不同时间点(6,12,24和36h)高糖以及多糖化合物对RPE细胞增殖影响。结果:高糖导致RPE细胞异常增殖,多糖化合物组RPE的细胞异常增殖明显得到保护,与高糖组比较差异具有统计学意义(P<0.01)。结论:从海藻中萃取的新型多糖化合物可以明显保护高糖所导致的RPE细胞的异常增殖。     

视网膜色素上皮细胞的功能及其抗新生血管作用

视网膜色素上皮（ retinal pigment epithelial,RPE）由一单层排列整齐的六角形细胞所组成,位于视网膜光感受器细胞层和脉络膜的Bruch's膜之间,其形态及功能的正常维持对于光感受器细胞至关重要,具有维持选择性转运营养和代谢物质、表达分泌多种生长因子、参与视循环、维持血－视网膜屏障和吞噬光感受器细胞脱落的外节盘膜等重要生理功能。 RPE细胞所构成的血－视网膜外屏障对于视网膜稳态的维持必不可少,其功能异常与许多眼底新生血管性疾病密切相关。本文对RPE正常结构、分泌生长因子、血－视网膜屏障功能、抗新生血管等方面进行综述。