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目的:探讨还原型烟酰胺腺嘌呤二核苷酸氧化酶4(Nox4)在1型DM模型小鼠角膜病变中的致病作用及其可能机制。方法:选择 Nox4基因敲除( Nox4－/－)纯合子雄性小鼠40只，以鼠龄、性别匹配的野生型C57BL/6( Nox4＋/＋)小鼠120只作为对照。采用随机数字表法分别将2种小鼠随机分为DM组和非DM组，DM组小鼠采用链脲佐菌素腹腔内注射法构建1型DM模型。采用随机数字表法分别将 Nox4＋/＋小鼠DM组和非DM组分为普通饲料喂养小鼠和添加Nox4抑制剂GKT137831(GKT)饲料喂养小鼠。于DM造模后第16周采用酚红棉线法检测各组小鼠泪液分泌量；采用荧光素钠染色评分法评估角膜上皮完整性；采用激光扫描共聚焦显微镜观察角膜基质层神经纤维密度变化；采用CellROX荧光探针检测角膜上皮中活性氧簇(ROS)含量；采用免疫荧光染色法检测小鼠角膜上皮中E-Cadherin蛋白和核因子-κB(NF-κB)蛋白表达变化；采用角膜铺片TUBB3染色法检测角膜中央区神经纤维密度。 结果:Nox4＋/＋小鼠DM组和非DM组泪液分泌量分别为(2.40±1.18)和(5.30±1.02)mm/min，差异有统计学意义( P<0.01)； Nox4－/－小鼠DM组泪液分泌量为(4.19±0.63)mm/min，明显多于 Nox4＋/＋小鼠DM组，差异有统计学意义( P<0.05)；普通饲料喂养小鼠与GKT添加饲料喂养小鼠DM组泪液分泌量分别为(2.23±0.83)和(4.02±0.71)mm/min，差异有统计学意义( P<0.01)。与 Nox4＋/＋小鼠非DM组比较， Nox4＋/＋小鼠DM组角膜荧光素染色评分显著升高，角膜神经纤维密度显著降低，角膜上皮中ROS荧光强度明显增强，E-Cadherin蛋白表达荧光强度减弱，NF-κB蛋白表达荧光强度增强。 Nox4－/－或GKT添加饲料喂养小鼠DM组与非DM组比较角膜上皮中ROS荧光增强，E-Cadherin蛋白表达荧光减弱。 Nox4－/－和GKT添加饲料喂养小鼠DM组角膜上皮细胞中NF-κB蛋白荧光强度均较弱，与非DM组强度一致。角膜铺片免疫荧光染色显示， Nox4＋/＋小鼠DM组中TUBB3染色的神经纤维密度明显低于非DM组， Nox4－/－或GKT添加饲料喂养小鼠DM组角膜基质层神经纤维与非DM组比较无明显减少。 结论:Nox4参与了糖尿病角膜病变的致病过程，其机制可能与氧化应激诱导ROS产物聚集，激活NF-κB介导的炎症反应有关。

Objective:To investigate the pathogenic role and possible mechanism of NADPH oxidase 4 (Nox4) in type 1 diabetic keratopathy mouse models.Methods:Forty Nox4 knockout ( Nox4-/-) heterozygous male mice were selected and 120 age- and sex-matched wild-type C57BL/6 ( Nox4+ /+ ) mice were selected as controls. Nox4-/- and Nox4+ /+ mice were randomized into diabetic group (DM group) and non-DM group by random number method.Type 1 DM model was established in DM groups by intraperitoneal injection of streptozotocin.The DM and non-DM groups of Nox4+ /+ mice were randomized into regular feed group and Nox4 inhibitor GKT137831 (GKT) supplementary feed group by random number method.At 16 weeks after modeling, tear secretion of mice in different groups was measured by the phenol red thread test.Corneal epithelial integrity was evaluated by fluorescent staining.Changes in corneal never fiber density were observed by the in vivo laser scanning confocal microscopy.Reactive oxygen species (ROS) products in corneal epithelium were assayed by CellROX staining.The expressions of E-Cadherin and nuclear factor-κB (NF-κB) proteins were detected by immunofluorescence staining.Central corneal nerve fiber density was examined by flatmount staining with TUBB3 antibody.The use and care of laboratory animals complied with ARVO statement.The study protocol was approved by Laboratory Animal Care Committee of Xi'an Jiaotong University (No.XJTULAC201301). Results:In Nox4+ /+ mice, the tear secretion was (2.40±1.18)mm/minute in DM group, which was significantly less than (5.30±1.02)mm/minute in non-DM group ( P<0.01).The tear secretion was (4.19±0.63)mm/minute in DM group of Nox4-/- mice, which was significantly more than that in DM group of Nox4+ /+ mice ( P<0.05).Significant difference was found between (2.23±0.83)mm/minute of regular feed group and (4.02±0.71)mm/minute of GKT supplementary feed group ( P<0.01).In Nox4+ /+ mice, the DM group showed significantly increased corneal staining score, reduced corneal nerve fiber density, increased fluorescence intensity of ROS in corneal epithelium, weakened fluorescence intensity of E-Cadherin protein expression, and enhanced fluorescence of NF-κB protein expression compared with non-DM group.In Nox4-/- mice and mice fed with GKT supplementary feed, the increased fluorescence of ROS and decreased fluorescence of E-Cadherin protein expression were seen in the corneal epithelium of the DM groups compared with non-DM groups.In Nox4-/- mice and mice fed with GKT supplementary feed, NF-κB protein fluorescence was weak in corneal epithelial cells in DM groups, which was similar to that in non-DM groups.Immunofluorescence staining of corneal flatmount showed that the density of TUBB3-stained nerve fibers in DM group of Nox4+ /+ mice was significantly lower than that in non-DM group of Nox4+ /+ mice, and there was no significant reduction of nerve fibers in the corneal stromal layer in DM group of Nox4-/- mice or mice fed with GKT supplementary feed. Conclusions:Nox4 is involved in the pathogenic process of diabetic keratopathy, and its mechanism may be related to oxidative stress-induced aggregation of ROS products and activation of NF-κB-mediated inflammatory responses.