雷帕霉素对兔眼准分子激光角膜切削术后haze的影响

Effects of Rapamycin on corneal haze after photorefractive keratectomy in rabbits

目的:探究调节自噬活性对兔眼准分子激光角膜切削术(PRK)术后角膜上皮下雾状混浊(haze)的影响。方法:新西兰大白兔64只行右眼PRK手术后,根据术后局部用药不同,随机分为4组:单纯手术组、14μmol/L二甲基亚砜组(DMSO)、50μmol/L雷帕霉素组、100μmol/L雷帕霉素组,每组16只。根据分组情况,术后2h开始给予上述滴眼液治疗,每天3次,1次1滴,持续7d,另选取16只兔为正常对照组。术后每天用手持裂隙灯显微镜照相系统,观察兔眼术后炎症反应及角膜上皮愈合情况。裂隙灯显微镜照相系统采集PRK术后1、4wk时各组兔眼haze的形成情况。各组分别于术后1、4wk采用空气栓塞法处死8只兔子,摘取角膜组织,冻存备用。免疫组化检测转化生长因子-β1(TGF-β1)、α-平滑肌肌动蛋白(α-SMA)、基质金属蛋白酶-2(MMP-2)的表达水平。Real Time-PCR技术检测自噬因子-5(ATG5)、自噬因子-12(ATG12)、B淋巴细胞瘤基因-2(Bcl-2)、半胱氨酸天冬氨酸蛋白酶-3(Caspase3)基因的相对表达量。结果:PRK术后兔眼角膜上皮均在3~4d完全愈合,各组兔眼术后角膜上皮愈合时间比较无差异(F=0.745,P=0.530)。在观察期间,各组术后haze均于4wk时最明显,单纯手术组和14μmol/L DMSO组haze症状均较严重,其次为50μmol/L雷帕霉素组,100μmol/L雷帕霉素组haze症状较其他组明显减轻,各组兔眼术后不同时间点haze分级比较有差异(均P<0.05)。免疫组化显示,术后1、4wk,单纯手术组和14μmol/L DMSO组TGF-β1、MMP-2和α-SMA的表达均较强,其次为50μmol/L雷帕霉素组,100μmol/L雷帕霉素组较其他组表达明显减弱(均P<0.05)。PCR法检测显示,术后1、4wk,50、100μmol/L雷帕霉素组ATG5、ATG12和Bcl-2 mRNA相对表达量较单纯手术组和14μmol/L DMSO组明显升高(均P<0.05);50、100μmol/L雷帕霉素组Caspase3 mRNA相对表达量较单纯手术组和14μmol/L DMSO组明显降低(均P<0.05)。结论:雷帕霉素可以增强自噬水平,抑制凋亡水平,从而减轻兔眼PRK术后haze的形成。

AIM:To investigate the effect of modulated autophagy activity on subepithelial haze after photorefractive keratectomy(PRK)in rabbits.METHODS:Totally 64 New Zealand white rabbits were randomly divided into 4 groups according to different postoperative medication after PRK operation,including simple PRK group,14μmol/L DMSO group,50μmol/L rapamycin group and 100μmol/L rapamycin group.According to the group situation,two hours after the operation,eye drops were given,3 times a day for 7d.Another 16 rabbits were selected as normal control group.The postoperative inflammatory response and corneal epithelial healing were observed with slit-lamp microscope every day.Haze formation of each group at 1 and 4wk after PRK was collected by slit-lamp microscopy system.Eight rabbits in each group were killed by air embolization 1 and 4wk after PRK,and corneal tissue was extracted and frozen for later use.Immunohistochemistry was used to detect the expression levels of transforming growth factor-β1(TGF-β1),α-smooth muscle actin(α-SMA),and matrix metalloproteinase-2(MMP-2).Real-time PCR was used to detect the relative expression levels of autophage-5(ATG5),autophage-12(ATG12),B lymphocytoma gene-2(Bcl-2)and cysteine aspartic proteinase-3(Caspase3)genes.RESULTS:Corneal epithelium of all operative rabbits healed completely at 3-4d and no significant difference in healing time between the groups after operation(F=0.745,P=0.530).During the observation period,haze was the most obvious at 4wk after operation in all groups.The haze symptoms were more serious in the simple operation group and the 14μmol/L DMSO group,followed by the 50μmol/L rapamycin group.The haze symptoms in the 100μmol/L rapamycin group were significantly relieved than those in other groups.There was no significant difference in the haze grading with different time points after operation among all groups(all P<0.05).Immunohistochemistry showed that the expression of TGF-β1,MMP-2 andα-SMA was stronger in the operation group and 14μmol/L DMSO group,followed by 50μmol/L rapamycin group,and weakest in 100μmol/L rapamycin group than other groups at 1 and 4wk after operation(all P<0.05).The results of PCR showed that the relative expression of ATG5,ATG12 and Bcl-2 mRNA in 50μmol/L rapamycin group and 100μmol/L rapamycin group were significantly higher than those in simple operation group and 14μmol/L DMSO group at 1 and 4wk after operation(all P<0.05);The relative expression of Caspase3 mRNA in 50μmol/L rapamycin group and 100μmol/L rapamycin group was significantly lower than that in simple operation group and 14μmol/L DMSO group(all P<0.05).CONCLUSION:Rapamycin can enhance autophagy level and inhibit apoptosis level,thus reducing haze formation after PRK in rabbits.