电离辐射对角膜新生血管形成的抑制作用

摘要

Background Corneal neovascularization ( CNV ) is a complication of many ocular surface diseases.It often worsen the pathological course.Effective therapy for CNV is still researching. Objective This study was to investigate the inhibitory effect of irradiation on CNV. Methods CNV models were established in 70 right eyes of 70 clean Wistar rats by corneal alkali burning.The models were randomized into β ray 10 Gy once irradiation group( 2 eyes),β ray 7 Gy multiple irradiation group( 17 eyes),β ray 10 Gy multiple irradiation group( 17 eyes),1％ cyclosporin A ( CsA ) eye drops group ( 17 eyes) and model group ( 17 eyes),and 6 matched normal rats were used as normal controls.All treatments started from the first day of the corneal alkali burning.CNV length and area were measured under the slit lamp every day.Corneal samples and homogenate were prepared 3,5,7 days after corneal alkali burning.The expressions of bcl-2,bax,vascular endothelial growth factor(VEGF) in rat corneas were detected by immunochemistry,VEGF proteins and VEGF mRNA were detected by Western blot and reverse transcription polymerase chain reaction (RT-PCR),respectively. Results Corneal ulceration was found in the βray 10 Gy once irradiation group and β ray 10 Gy multiple irradiation group.CNV length and area were much less in the β ray 7 Gy multiple irradiation group and 1％ CsA eye drops group compared with the model group on the seventh day after experiment( length:q=14.40,24.20,P＜0.01 ;area:q=17.80,14.00,P＜0.01 ).Immunochemistry revealed that compared with the model group,expressions of bcl-2 and VEGF proteins were weaker,but the expression of bax protein was stronger in the β ray 7 Gy multiple irradiation group and 1％ CsA eye drops group.RT-PCR showed that the expression of VEGF mRNA in cornea was lower in the β ray 10 Gy multiple irradiation group,β ray 7 Gy multiple irradiation group and 1％ CsA eye drops group in comparison with that in model group,and the results from Western blot showed the same pattern as RT-PCR. Conclusions Low dose irradiation of 90Sr-90Y ophthalmic applicator inhibits CNV formation after alkali burn.The study provide a new understanding of the irradiation for the treatment of CNV.%背景 角膜新生血管(CNV)可发生在多种跟表疾病中,常可加重病情,但有效的临床治疗方法仍在探索中. 目的 探讨电离辐射对角膜碱烧伤后新生血管的抑制作用.方法 76只清洁级Wistar纯系大鼠中70只用角膜碱烧伤的方法建立大鼠右眼CNV模型,然后按照随机数字表法将造模动物分为β射线10 Gy一次性照射组2只、β射线7 Gy分次照射组17只、β射线10 Gy分次照射组17只、质量分数1％环孢素A(CsA)点眼组17只和角膜碱烧伤模型组17只,6只正常兔6只眼(均取右眼)作为正常对照组.用90 Sr-90Y眼科敷贴器于右眼角膜碱烧伤后第1天开始沿角膜缘进行β射线照射,1％ CsA点眼组用药时间与照射时间相同.实验后每日行裂隙灯检查并计算CNV长度和面积.于角膜碱烧伤后3、5、7d制备角膜组织石蜡切片和匀浆,采用免疫组织化学法检测各组大鼠角膜组织中bcl-2、bax、血管内皮生长因子(VEGF)的表达,分别采用Western blot和逆转录聚合酶链反应(RT-PCR)检测各组大鼠角膜组织中VEGF蛋白及mRNA表达的变化.结果 角膜碱烧伤后7d,裂隙灯下可见β射线10 Gy一次性照射组、β射线10 Gy分次照射组均出现角膜溃疡,角膜碱烧伤模型组可见大量CNV生成,而β射线7 Gy分次照射组和1％CsA点眼组CNV明显较少.角膜碱烧伤后7d,β射线7 Gy分次照射组、1％ CsA点眼组CNV长度和面积均明显小于角膜碱烧伤模型组,差异均有统计学意义(长度:q=14.40、24.20,P＜0.01;面积:q=17.80、14.00,P＜0.01).免疫组织化学检测表明,与角膜碱烧伤模型组比较,β射线7Gy分次照射组、1％CsA点眼组大鼠角膜中bcl-2和VEGF蛋白表达均减弱,而bax蛋白表达均增强.RT-PCR检测表明,β射线7 Gy分次照射组、β射线10 Gy分次照射组、1％CsA点眼组VEGF mRNA表达强度明显低于角膜碱烧伤模型组,Western blot检测发现VEGF蛋白的表达与VEGFmRNA的表达遵循同样的规律.结论 90Sr-90Y跟科敷贴器小剂量分次放射治疗可明显抑制角膜碱烧伤后CNV的生长,并且以β射线7 Gy分次照射作用效果最佳.