靶向血管内皮生长因子的RNA干扰抑制氧诱导视网膜病变小鼠视网膜新生血管生成的研究

目的探讨玻璃体腔注射靶向血管内皮生长因子（VEGF）的RNA干扰慢病毒抑制氧诱导视网膜病变（OIR）小鼠视网膜新生血管生成的作用及其机制。方法实验研究。构建4对针对靶基冈小鼠VEGF的siRNA干扰载体,筛选并进行慢病毒包装。60只C57Bif6J小鼠分成4组（每组15只）：正常对照组．OIR模型组,OIR＋空载体组,OIR＋VEGF-RNA干扰组。OIR＋空载体组和OIR＋VEGF-RNA干扰慢病毒组的小鼠在生后第5天玻璃体腔注射相应的1μ1的7.5×10^7空载体慢病毒和VEGF-RNA干扰慢病毒。后3组小鼠在生后第7天建立OIR模型。第17天时FITC-Dextran灌注视网膜铺片观察4组小鼠视网膜血管形态及面积变化,视网膜铺片免疫荧光染色检测紧密连接蛋白Claudin-5和Occludin的分布变化．Westernblot检测VEGF、磷酸肌醇3激酶（P13K）、酪氨酸蛋白激酶SRC、磷酸化细胞外信号调节激酶（P-ERK）蛋白表达量的变化。数据采用单因素方差分析进行比较。结果FITC-Dextran灌注视网膜铺片显示正常组视网膜血管分布呈均匀网状;RNA干扰组新生血管面积（0．271399mm^2）明显较OIR模型组（1.212782mm^2）、空载体组（1．152504mm^2）少（F=449．924,P〈0．01）。OIR模型组和空载体组间差异无统计学意义,其余两两间差异均有统计学意义（P〈0．01）。视网膜铺片免疫荧光染色显示紧密连接蛋白Claudin-5和Occludin在RNA干扰组中与正常组相似,呈均匀光滑线性分布,而在OIR模型组、空载体组的分布中断、不均匀,在新生血管团中可见团块状的强荧光;VEGF的RNA干扰组中VEGF、P13K、酪氨酸蛋白激酶SRC和p-ERK的蛋白表达量较OIR模型和空载体组低。结论玻璃体腔注射靶向VEGF的RNA干扰慢病毒能有效抑制OIR小鼠模型中VEGF及其下游通路蛋白的表达．从而抑制视网膜新生血管的形成．为临床上早产儿视网膜病变的防治提供了新思路和新途径。     

夜间光照对氧诱导的视网膜病变小鼠视网膜新生血管形成的影响

背景 氧诱导的视网膜新生血管形成是多种视网膜血管性疾病的病理学基础,预防视网膜新生血管的形成可缓解视网膜病变对视网膜的损害程度.研究表明夜间睡眠时给予光照可能对早期糖尿病视网膜病变(DR)患者有利,但其对早产儿视网膜病变(ROP)患者视网膜新生血管有无影响报道较少.目的 观察夜间光照对氧诱导视网膜病变(OIR)小鼠视网膜新生血管形成的影响.方法 将64只SPF级新生C57BL/6J小鼠按随机数字表法随机分为正常对照组、单纯夜间光照组、OIR模型组、OIR联合夜间光照组,每组16只小鼠.正常对照组和单纯夜间光照组小鼠生长于正常空气(氧体积分数21％);OIR模型组和OIR模型联合夜间光照组小鼠于出生后第7天置于高氧环境(75％±2％)生长,出生第12天调整氧体积分数为正常;OIR联合夜间光照组和单纯夜间光照组于出生后第12～17天给予夜间光照,光照度为100 Ix.各组小鼠均于出生后第17天摘除眼球,采用ADP酶法制备视网膜铺片,了解视网膜血管的改变情况;视网膜组织切片行苏木精-伊红染色并计数突破视网膜内界膜的新生血管内皮细胞核数;免疫组织化学法观察各组小鼠视网膜中血管内皮生长因子(VEGF)的表达,实时荧光定量聚合酶链反应(PCR)法检测各组视网膜中VEGFmRNA的表达.实验动物的使用和喂养遵循ARVO声明.结果 正常对照组和单纯夜间光照组小鼠视网膜血管形态均无明显差异.OIR模型组视网膜铺片显示视网膜中央部大片无血管区,大量结构异常的新生血管形成.与OIR模型组相比,OIR模型联合夜间光照组视网膜中央无血管区面积以及新生血管分布密度减少.在实验后第17天时,正常对照组和单纯夜间光照组视网膜新生血管内皮细胞核数分别为(0.97±0.83)个和(1.00±0.72)个,OIR模型组为(38.57±5.01)个,而OIR联合夜间光照组小鼠视网膜新生血管内皮细胞核数为(16.92±3.39)个,总体差异有统计学意义(F=78.767,P=0.000),OIR联合夜间光照组视网膜新生血管内皮细胞核数明显少于OIR模型组,差异有统计学意义(t=20.446,P＜0.01).免疫组织化学法检测显示OIR模型联合夜间光照组中VEGF蛋白表达明显少于OIR模型组.正常对照组、单纯夜间光照组、OIR模型组和OIR联合夜间光照组小鼠视网膜VEGF mRNA相对表达量分别为1.00±0.00、0.94±0.07、2.08±0.50和1.43±0.21,各组间的总体差异有统计学意义(F=11.268,P=0.003),OIR模型联合夜间光照组表达较OIR模型组下调,差异有统计学意义(t=20.163,P＜0.05).结论 夜间光照可减少OIR小鼠视网膜新生血管的形成.     

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。     

抗血管内皮生长因子对氧诱导视网膜新生血管病变模型小鼠视网膜多巴胺含量的影响

目的　研究抗血管内皮生长因子（VEGF）融合蛋白康柏西普（Conbercept）玻璃体内注射对小鼠氧诱导视网膜新生血管病变（OIR）模型中视网膜多巴胺（DA）含量的影响。方法　普通级7 d龄C57BL/6小鼠100只,随机分为空白对照组、OIR组、OIR+生理盐水（NS）组及OIR+ Conbercept组,每组25只。其中空白对照组小鼠在常氧环境中饲养至17 d龄。OIR组、OIR+NS组及OIR+ Conbercept组小鼠通过高流量吸氧建立OIR模型,并在此环境中饲养至12 d龄,OIR+NS组和OIR+Conbercept组小鼠分别行右眼玻璃体内注射1 μL NS、1 μL Conbercept后,在常氧环境中饲养至17 d龄,处死。取各组小鼠右眼眼球行HE染色及视网膜铺片,观察突破内界膜的视网膜血管内皮细胞核数及血管分布;行Western blot检测各组小鼠视网膜中酪氨酸羟化酶（TH）、血管内皮生长因子（VEGF）表达量;行高效液相色谱仪检测各组小鼠视网膜DA含量。结果　空白对照组小鼠视网膜各层清晰,未见明显无灌注区及新生血管。与空白对照组相比,OIR组小鼠视网膜各层排列紊乱,视盘周围可见大片无灌注区,突破内界膜的血管内皮细胞核数、VEGF相对表达量均增加,TH相对表达量、DA含量均减少,差异均有统计学意义（均为P<0.05）;OIR+NS组与OIR组相比,小鼠视网膜中突破内界膜的血管内皮细胞核数、DA含量及VEGF、TH相对表达量差异均无统计学意义（均为P>0.05）;与OIR组及OIR+NS组相比,OIR+ Conbercept组小鼠视网膜各层排列较清晰,视盘周围可见小片状无灌注区,突破内界膜的内皮细胞核数、DA含量及VEGF、TH相对表达量均减少,差异均有统计学意义（均为P<0.05）。结论　OIR模型中视网膜DA含量及TH相对表达量均降低;玻璃体内注射Conbercept后,视网膜新生血管及VEGF相对表达量均减少,TH相对表达量、DA含量均进一步降低。     

血管内皮生长因子干扰RNA对鼠视网膜中血管内皮生长因子mRNA表达的抑制作用

目的 研究血管内皮生长因子（vascular endothelial cell growth factor,VEGF）小片段干扰RNA（small interference RNA,siRNA）对鼠视网膜VEGF mRNA的抑制作用,探讨其对视网膜新生血管治疗的可行性.方法 体外培养人鼻咽癌细胞（CNE-2Z）,分成正常氧培养组（20% O2）和低氧培养组（1% O2）.采用脂质体（LF 2000）将VEGF siRNA转染两组细胞,RT-PCR检测VEGF mRNA的表达,确立VEGF siRNA对VEGFmRNA的抑制效率.然后,建立高浓度氧（75%）诱导的C57BL./6J小鼠视网膜新生血管动物模型,以脂质体为载体,将VEGF siRNA重组质粒注射到鼠玻璃体腔内,RT-PCR检测视网膜组织中VEGF mRNA的表达水平.结果 正常氧培养的CNE-2Z细胞有VEGF mRNA表达,低氧状态下VEGFmRNA表达增多,两者之间差异有显著性（P＜0.01）;与未转染组和转染空载体组相比,在正常氧和低氧状态下,VEGFsiRNA均能明显抑制VEGFmRNA的表达（P＜0.01）;正常氧状态下VEGF siRNA的抑制效率比低氧状态高.高浓度氧诱导的C57BL/6J小鼠视网膜新生血管动物模型中,玻璃体腔注射VEGF siRNA组视网膜组织中VEGF mRNA表达明显下降（P＜0.01）.结论 VEGF特异的siRNA能有效地抑制人鼻咽癌细胞CNE-2Z和C57BL/6J 小鼠视网膜新生血管动物模型视网膜中VEGF mRNA的表达.     

玻璃体腔注射VAS2870对小鼠氧诱导视网膜病变的保护作用

目的：观察玻璃体腔注射VAS2870对C57小鼠氧诱导视网膜病变的影响。方法：将新生C57 BL/6 J小鼠随机分为3组,分别为正常对照组、VAS2870注射 OIR 组和无菌 PBS 缓冲液注射OIR组。将后两组小鼠在出生后第7 d ( P7)至P12置于体积分数为75%±2%的恒定高氧氧箱中以构建OIR模型,在 P12时给予幼鼠双眼玻璃体腔注射 VAS2870(0.5μL),另一组幼鼠双眼注射同等剂量的无菌PBS缓冲液。三组小鼠均在 P17时取右眼行视网膜铺片和Lectin染色,观察视网膜中央无血管区及病理性新生血管的情况;取右眼行视网膜组织定量检测 ROS/RNS 含量;取左眼应用RT-PCR检测Nox4 mRNA含量,并应用Western-blot测定视网膜组织中VEGF的表达。结果：VAS2870注射OIR组小鼠视网膜中央无血管区面积较无菌PBS缓冲液注射OIR组明显减少( P<0.05),病理性新生血管数目明显减少( P<0.05);VAS2870注射OIR组小鼠视网膜组织Nox4 mRNA的表达量明显低于无菌PBS缓冲液注射组;VAS2870注射OIR组小鼠视网膜组织ROS含量较无菌PBS缓冲液注射组明显降低( P<0.05);VAS2870注射OIR组小鼠视网膜组织VEGF的表达明显低于无菌PBS缓冲液注射组( P<0.05)。结论：在小鼠OIR模型中, VAS2870可抑制Nox4 mRNA的表达,减少ROS/RNS,下调VEGF的生成,在视网膜病变进程中具有保护作用。     

磷脂酰肌醇-3-激酶/丝氨酸-苏氨酸激酶抑制剂LY294002对小鼠视网膜新生血管形成的抑制作用

目的　探讨磷脂酰肌醇-3-激酶（phosphatidylinositol-3-kinase,PI3K）/丝氨酸-苏氨酸激酶（Serine/threonine kinase,AKT）信号转导通路抑制剂LY294002对小鼠氧诱导视网膜病变（oxygen-induced retinopathy,OIR）的视网膜新生血管（retinal neovascularization,RNV）形成的影响。方法　取C57BL/6J小鼠60只,随机分为实验组和对照组,每组各30只,均制备OIR模型。小鼠出氧箱前1 d即鼠龄11 d时实验组玻璃体内注射0.5 μL的LY294002,对照组玻璃体内注射等体积的PBS。病理切片计数突破视网膜内界膜的新生血管内皮细胞核数,免疫组织化学和RT-PCR法检测pAKT、VEGF蛋白及mRNA的表达情况。结果　实验组小鼠新生血管内皮细胞核数为（12.53±1.71）个,较对照组（25.31±1.42）个明显减少（P<0.05）;实验组小鼠pAKT、VEGF的蛋白表达呈弱阳性,阳性细胞的吸光度值（9.12±1.35、13.91±1.49）均较对照组（15.11±2.17、19.72±2.61）明显下降（均为P<0.05）;实验组小鼠AKT、VEGF mRNA相对表达量均较对照组明显下降（均为P<0.05）。结论　LY294002通过抑制PI3K/AKT信号转导通路,可有效抑制小鼠OIR的RNV形成,LY294002有望成为防治血管增生性视网膜病变的一种有效方法。     

CREB1在氧诱导视网膜病变小鼠模型中的表达变化

目的研究CREB1在氧诱导视网膜病变（OIR）小鼠模型视网膜新生血管形成中的表达变化,探寻视网膜新生血管形成的可能机制。方法实验研究。选用7日龄健康清洁级C57BL/6J小鼠134只,随机分为正常对照组（67只）和OIR模型组（67只）。将小鼠与哺乳母鼠共同置于（75±2）％氧环境内饲养5 d后转移至正常环境中饲养5 d,建立小鼠OIR模型,17日龄的OIR鼠在空气中再继续饲养4 d,正常对照组在正常氧环境中饲养21 d。出生后第17 d时取OIR模型组和正常对照组小鼠制备视网膜切片HE染色法和FITC-dextran心脏灌注视网膜铺片法观察视网膜新生血管情况,以及视网膜组织冰冻切片免疫荧光染色观察P-CREB1表达情况。取2组鼠第7、9、12、14、17、21 d的视网膜采用实时定量聚合酶链反应（real-time PCR）法和Western Blot法检测CREB1mRNA和蛋白在小鼠视网膜中的表达情况。数据分析采用独立样本t检验和两因素方差分析方法,两两比较采用Bonferronipost-test检验。结果17 d时OIR模型组较正常对照组突破视网膜内界膜的内皮细胞核数明显增加（t=11.31,P<0.05）,且模型组视网膜新生血管区及无灌注区面积分别为（21.40±2.72）%和（30.61±3.12）%。与正常对照组相比,模型组小鼠视网膜中可见大量P-CREB1蛋白荧光,主要表达在内核层和神经节细胞层。Real-time PCR和Western Blot结果表明,正常对照组第7、9、12、14、17天的CREB1mRNA和蛋白在视网膜中的表达水平逐渐升高,21 d时开始出现下降的趋势;在各相应时间点OIR模型组里的CREB1相对表达量除第7天外,其余时间点均高于正常对照组,差异均有统计学意义（P<0.05）。结论CREB1的表达水平与视网膜新生血管的形成存在时空对应关系,CREB1的高表达可能参与了OIR模型中视网膜新生血管的形成过程。     

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。     

特异性抑制富含半胱氨酸蛋白61干扰RNA对小鼠视网膜新生血管形成的抑制作用观察

目的 观察特异性抑制富含半胱氨酸蛋白61(CCN1)对氧诱导视网膜病变(OIR)模型小鼠视网膜新生血管(RNV)的抑制作用.方法 7日龄C57BL/6J小鼠120只,随机分为对照组和实验组,每组各60只.参照文献方法制备OIR模型.小鼠出氧箱前1d即鼠龄11d时,对照组、实验组小鼠玻璃体腔分别注射空载体质粒、CCN1siRNA表达质粒各1μl.视网膜铺片观察视网膜血管形态,病理切片计数突破视网膜内界膜的血管内皮细胞核数,免疫组织化学、蛋白免疫印迹法、实时定量聚合酶链反应检测CCN1、血管内皮生长因子(VEGF)蛋白及mRNA的表达情况.结果 与对照组比较,实验组小鼠视网膜血管分布规则、分支良好、新生血管密度减少.两组间突破视网膜内界膜的血管内皮细胞核数量比较,差异有统计学意义(t=8.756,P＜0.05);CCN1、VEGF蛋白表达量比较,差异均有统计学意义(t=3.253、5.365,P＜0.05);CCN1、VEGF蛋白相对表达量比较,差异均有统计学意义(t=4.573、5.323,P＜0.05);CCN1、VEGFmRNA相对表达量比较,差异均有统计学意义(t=6.724、9.153,P＜0.05).结论 特异性抑制CCN1能有效抑制OIR模型小鼠RNV形成.     

Captopril and vascular endothelial growth factor in a mouse model of retinopathy

PURPOSE: Angiotensin converting enzyme (ACE) inhibition has been shown in animal models of retinopathy and in patients with diabetes to improve retinal neovascularization. The mechanism is not clearly identified, but could potentially be mediated via vascular endothelial growth factor modification. The objective of this study was to determine the effect of captopril, an angiotensin converting enzyme (ACE) inhibitor, on retinal VEGF, VEGF-R1, and VEGF-R2 expression in a mouse model of oxygen induced retinopathy (OIR). METHODS: A mouse model of OIR was used and retinal tissue was obtained at P7, prior to oxygen exposure, at P12, just after oxygen exposure, and at P17, the time of maximal retinal neovascularization for VEGF, VEGF-R1 and VEGF-R2 assessment. A group of animals were treated with captopril (0.5 mg/kg/d SC from P7 for five days). RESULTS: Captopril plus OIR treated animals had higher levels of retinal VEGF mRNA and protein at P12 (p < 0.05) and lower levels at P17 (p < 0.05) than OIR animals. VEGF-R1 mRNA expression increased 16 fold from P7 to P17 (p < 0.05) in room air reared animals. VEGF-R1 mRNA expression was unaffected by OIR and/or captopril treatment. VEGF-R2 mRNA expression decreased from P7 to P17 by 1.5-fold in room air reared animals (p = 0.001). Retinal VEGF-R2 mRNA and protein expression were significantly higher at P12 in OIR plus captopril treated animals than OIR animals (p = 0.01). CONCLUSIONS: In summary, captopril maintains VEGF and increases VEGF-R2 expression during the period of hyperoxia when VEGF expression is normally suppressed. Captopril treatment during oxygen exposure is associated with a reduction in the angiogenic response at day 17 as manifested by decreased VEGF and VEGF-R2 expression in retinal tissue. Angiotensin converting enzyme inhibition is associated with changes in expression of VEGF and VEGF-R2 in the evolution of retinal neovascularization in the mouse model of retinopathy.     

CCR7/p-ERK1/2/VEGF signaling promotes retinal neovascularization in a mouse model of oxygen-induced retinopathy

AIM: To investigate the role of CCR7/p-ERK1/2/VEGF signaling in the mouse model of oxygen-induced retinopathy (OIR). METHODS: Neonatal C57BL/6J mice were evenly randomized into four groups: normoxia, OIR, OIR control (treated with scramble siRNA), and OIR treated (treated with CCR7 siRNA). Normoxia group was not specially handled. Postnatal day 7 (P7) mice in the OIR group were exposed to 75%±5% oxygen for 5d (P7-P12) and then maintained under normoxic conditions for 5d (P12-P17). Mice in the OIR control and OIR treated groups were given injections of scramble or CCR7 siRNA plasmid on P12 before returning to normoxic conditions for 5d (P12-P17). Retina samples were collected from all mice on P17, stained with adenosine diphosphatase (ADPase), and retinal neovascularization (RNV) was assessed. Retinas were also stained with hematoxylin and eosin (H&E) for RNV quantitation. The distribution and expression of CCR7, p-ERK1/2 and vascular endothelial growth factor (VEGF) were assessed via immunohistochemistry, Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: High oxygen promoted retinal neovascularization (P<0.05) and increased the number of endothelial nuclei in new vessels extending from the retina to the vitreous body; CCR7 promoted this process (P<0.05). CCR7 and VEGF mRNA were expressed at higher levels in the OIR and OIR control groups than in the normoxia and OIR treated groups. CCR7, p-ERK1/2, and VEGF protein were expressed in the retinas of mice in the OIR and OIR control groups. Intravitreal injection of CCR7 siRNA significantly reduced CCR7, p-ERK1/2, and VEGF expression in the OIR mouse model (all P<0.05). CCR7 significantly enhanced the neovascularization and non-perfusion areas in the OIR group (P<0.05). CCR7 siRNA significantly reduced levels of p-ERK1/2 and VEGF as compared to OIR controls (P<0.05). CONCLUSION: These results suggest that CCR7/p-ERK 1/2/VEGF signaling plays an important role in OIR. CCR7 may be a potential target for the prevention and treatment of retinopathy of prematurity.     

DNA损伤标志物γH2AX在氧诱导视网膜新生血管形成中的作用

背景 氧浓度变化诱导产生视网膜新生血管,并导致细胞DNA损伤反应.以往认为促血管生成因子过度表达是血管新生的原因,但DNA损伤是否与视网膜新生血管有关尚不清楚. 目的 探讨参与DNA损伤修复的磷酸化蛋白γH2AX与小鼠视网膜血管新生的关系. 方法 应用72只17日龄C57BL/6J小鼠按照随机数字表法随机分为正常对照组、氧诱导视网膜病变(OIR)模型组、OIR阳性对照组和OIR阴性对照组,每组18只.视网膜铺片免疫荧光法对比观察视网膜新生血管形态学变化及γH2AX表达情况.将人脐静脉血管内皮细胞(HUVECs)分为正常对照组、低氧模型对照组、阳性干扰组和阴性干扰组.细胞处理后12h,采用免疫荧光法比较并分析各组γH2AX的表达情况,采用Western blot法定量检测各组γH2AX的表达. 结果 正常对照组、OIR模型组、OIR阳性对照组和OIR阴性对照组17日龄小鼠视网膜新生血管面积和无灌注区面积比较,总体差异均有统计学意义(F=437.62、93.05,均P＜0.01),其中OIR模型组和OIR阴性对照组小鼠视网膜新生血管面积和无灌注区面积均较正常对照组明显增大;OIR阳性对照组小鼠视网膜新生血管面积和无灌注区面积均较OIR模型组和OIR阴性对照组明显减小,差异均有统计学意义(均P＜0.01).17日龄小鼠视网膜γH2AX焦点团聚集出现情况与新生血管和无灌注区面积大小变化趋势相一致.正常对照组、低氧模型对照组、阳性干扰组和阴性干扰组HUVECs中γH2AX焦点阳性细胞百分数比较,差异有统计学意义(F=64.97,P＜0.01),其中低氧模型对照组和阴性干扰组γH2AX焦点阳性细胞百分数均较正常对照组明显增大,差异均有统计学意义(均P＜0.01);阳性干扰组均较低氧模型对照组和阴性干扰组明显减小,差异均有统计学意义(均P＜0.01).各组HUVECs间γH2AX的表达量与免疫荧光趋势相一致.结论 缺氧环境下,γH2AX在小鼠视网膜血管和体外培养的HUVECs中均大量表达.γH2AX的表达与视网膜血管新生有关.低氧诱导的DNA损伤修复反应可能与视网膜血管新生有一定关系.     

The dipeptide Arg-Gln inhibits retinal neovascularization in the mouse model of oxygen-induced retinopathy

PURPOSE: Premature infants undergoing intensive care are highly vulnerable to amino acid deprivation. Supplementation of glutamine or arginine has resulted in beneficial effects in human neonates. This study was conducted to examine the effect of the dipeptide arginyl-glutamine (Arg-Gln) on vascular endothelial cell growth factor (VEGF) levels in primary human retinal pigment epithelial (hRPE) cell cultures and on inhibition of neovascularization in the oxygen-induced retinopathy (OIR) model. METHODS: The effects of Arg-Gln on VEGF levels were measured in supernates from hRPE cells by using ELISAs. For in vivo studies, mouse pups received twice-daily intraperitoneal injections of Arg-Gln, a control dipeptide (Ala-Gly) or were not injected. Retinal flatmounts from one cohort were prepared and retinal vessel morphology examined. The contralateral eyes were embedded, sectioned, and stained to count preretinal neovascular nuclei. RNA was isolated from retinas of selected animals and was used to quantify VEGF mRNA by real-time RT-PCR. RESULTS: Treatment of hRPE cells with Arg-Gln decreased VEGF levels in a dose-dependent manner. In the OIR model, Arg-Gln at 5 g/kg per day reduced preretinal neovascularization by 82%+/-7% (P<0.005), when compared with the control dipeptide Ala-Gly, and reduced VEGF mRNA by 64%+/-9% (P<0.001). CONCLUSIONS: Arg-Gln dramatically inhibited retinal neovascularization in the OIR model. This effect was associated with a reduction in retinal VEGF mRNA levels. Similarly the dipeptide reduced VEGF expression in hRPE cells, a cell type likely to respond to retinal hypoxia by expressing VEGF. Arg-Gln appears to be safe and, with future studies in human infants, may prove beneficial in the prevention of ROP.     

Matrix metalloproteinase-9 and vascular endothelial growth factor expression change in experimental retinal neovascularization

AIM: To investigate the signal transduction mechanism of matrix metalloproteinase-9 (MMP-9) mediated- vascular endothelial growth factor (VEGF) expression and retinal neovascularization (RNV) in oxygen-induced retinopathy (OIR) model. METHODS: C57BL/6J mice were divided into four groups: control group, OIR group, OIR control group (phosphate-buffered saline by intravitreal injection) and treated group [tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) by intravitreal injection]. OIR model was established in C57BL/6J mice exposed to 75%±2% oxygen for 5d. mRNA level and protein expression of MMP-9, TIMP-1 and VEGF were measured by real-time polymerase chain reaction and Western blotting, and located by immunohistochemistry. RESULTS: Levels of MMP-9 and VEGF in retina were significantly increased in animals with OIR and OIR control group. Levels of TIMP-1 in retina was significantly reduced in animals with OIR and OIR control group. Furthermore, a significant correlation was found between MMP-9 and VEGF. Intravitreal injection of TIMP-1 significantly reduced MMP-9 and VEGF expression of the OIR mouse model (all P<0.05). CONCLUSION: These results demonstrate that MMP-9-mediated up-regulation of VEGF promotes RNV in retinopathy of prematurity (ROP). TIMP-1 may be a potential target for the prevention and treatment of ROP.     

The effects of oxygen stresses on the development of features of severe retinopathy of prematurity: knowledge from the 50/10 OIR model

The objective of this study is to determine growth factor expression and activation of signaling pathways associated with intravitreous neovascularization and peripheral avascular retina using a model of retinopathy of prematurity (ROP) relevant to today with oxygen monitoring in neonatal units. Studies using 50/10 oxygen-induced retinopathy (OIR) and 50/10 OIR+SO models were reviewed. Repeated fluctuations in oxygen increased retinal vascular endothelial growth factor (VEGF) even while peripheral avascular retina persisted and prior to the development of intravitreous neovascularization. Repeated fluctuations in oxygen increased VEGF₁₆₄ expression but not VEGF₁₂₀. Neutralizing VEGF bioactivity significantly reduced intravitreous neovascularization and arteriolar tortuosity without interfering with ongoing retinal vascularization. Repeated oxygen fluctuations led to retinal hypoxia and increased reactive oxygen species (ROS). Inhibiting ROS with NADPH oxidase inhibitor, apocynin, reduced avascular retina by interfering with apoptosis. Supplemental oxygen reduced retinal VEGF concentration and exacerbated NADPH oxidase activation to contribute to intravitreous neovascularization through activation of the JAK/STAT pathway. Oxygen stresses relevant to those experienced by preterm infants today trigger signaling of different pathways to cause avascular retina and intravitreous neovascularization. Increased signaling of VEGF appears important to the development of both avascular retina and intravitreous neovascularization.