Objective To investigate the effects of knocking down Racl gene (ras-related C3 botulinum toxin substrate 1) by small hairpin RNA (shRNA) on retinal neovascularization in a mouse model of oxygen-induced retinopathy (OIR). Methods One hundred and eight 7-day-old C57BL/6J mice were divided into three groups randomly. The OIR was induced by Smith protocol in 2 groups. OIR mice received an intravitreal injection of Racl-shRNA plasmid or the nonsense plasmid in the gene-intervention group and control group respectively at the age of postnatal day 11 (P11). Non-OIR mice also received an intravitreal injection of Racl-shRNA plasmid at P11 as the blank-intervention group which lived in the normoxic environment. Retinal neovascularization was investigated on flat-mounts after fluorescence angiography at P15 and P17. Endothelial cell nuclei breaking through the internal limiting membrane were counted on pathological section at P17. The expression of Racl and NF-κB p65 subunit was measured by immuohistochemistry, Western blot, real-time polymerase chain reaction (RT-PCR) and in situ hybridization. Results Compared with the blank-control group, the level of Racl mRNA in the geneintervention group decreased obviously(t=4.5, P = 0. 001 ); the retinal non-perfusion areas, fluorescence leakage, neovascularization and the number of endothelial cell nuclei breaking through the internal limiting membrane were reduced significantly(t = 6. 521, P< 0. 001) ; the level of NF-κB p65 nuclear translocation decreased(t= 16. 008, P<0. 001)while the expression of NF-κB p65 mRNA was reduced obviously(t=3. 354, P=0. 006), which was positively correlated with the expression of Ratl mRNA (P=0. 012).Conclusion Intravitreal injection of Racl-shRNA with liposome in mice can effectively inhibit the expression of Racl, and inhibit the retinal neovascularization under relative hypoxia via blocking the ROS-NF-κB pathway.%目的 观察Ras相关的C3肉毒毒素底物1的小发夹RNA(Racl-shRNA)在小鼠氧致视网膜病变中对视网膜新生血管(RNV)生成的抑制作用及对活性氧(ROS)-核因子κB(NF-κB)通路的影响.方法 将108只7日龄C57BL/6J小鼠随机平均分为3组.其中2组Smith法建立氧致视网膜病变模型;11日龄时玻璃体腔注射Racl-shRNA表达质粒或无意义质粒,分别作为基因干预组和空白对照组.第3组于正常氧环境中饲养,11日龄时玻璃体腔注射Racl-shRNA表达质粒作为空白干预组.15、17日龄时行荧光视网膜铺片,观察视网膜血管发育及新生血管情况.17日龄时计数眼球切片中突破内界膜的血管内皮细胞核数.17日龄时进行原位杂交法和荧光实时定量逆转录-聚合酶链反应法检测小鼠视网膜Racl和NF-κB p65亚单位的mRNA含量;免疫组织化学和蛋白质免疫印记检测Racl和NF-κB p65的蛋白表达.结果 基因干预组视网膜Racl的mRNA水平较空白对照组明显下调(t=4.500,P=0.001).与空白对照组比较,基因干预组视网膜铺片中无灌注区、荧光渗漏和新生血管丛明显减轻,突破内界膜的血管内皮细胞核显著减少(t=6.521,P<0.001);视网膜NF-κB p65的核易位水平明显下降(t=16.008,P<0.001),同时mRNA表达亦明显下调(t=3.354,P=0.006),与Racl mRNA表达呈正相关(r=0.580,P=0.012).结论 小鼠玻璃体腔注射脂质体包裹的Racl-shRNA表达质粒可有效沉默视网膜Racl基因表达,阻断ROSNF-κB通路而参与抑制相对缺氧状态下RNV生成.
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