神经调节蛋白1调节NLRP3/Caspase-1/GSDMD通路在早期糖尿病大鼠视网膜神经节细胞焦亡中的作用

Effect of neuregulin 1 on pyroptosis of retinal ganglion cells in early-stage diabetic rats by regulating NOD-like receptor family pyrin domain containing protein 3/Caspase-1/Gasdermin D pathway

目的观察神经调节蛋白-1(NRG-1)对Zucker糖尿病肥胖(ZDF)大鼠视网膜神经节细胞(RGCs)的影响,探讨NRG-1对视网膜发挥神经保护作用的机制。方法选取8周龄的ZDF雄性大鼠24只(24眼),通过食用高脂高糖饲料(Purina5008)建立糖尿病肥胖大鼠模型,16周后随机分为ZDF组和NRG-1组(每组各12只)。NRG-1组大鼠通过玻璃体内注射人重组NRG-1(每周1次,共2次),ZDF组大鼠作为阴性对照,同时选取健康Zucker(ZLC)大鼠(12只12眼)作为空白对照(ZLC组)。通过免疫荧光染色观察各组大鼠RGCs数量变化,通过免疫组织化学和Western blot检测各组大鼠视网膜NOD样受体热蛋白结构域相关蛋白3(NLRP3)、半胱氨酸天冬氨酸蛋白酶1(Caspase-1)、GasderminD(GSDMD)蛋白表达。结果在进食高脂饲料16周后,与ZLC组相比,ZDF组大鼠空腹血糖明显升高,差异有统计学意义(P<0.001)。免疫荧光染色结果显示,ZLC组大鼠RGCs排列连续整齐,与ZLC组相比,ZDF组大鼠RGCs数量减少,差异有统计学意义(P<0.001)。与ZDF组相比,NRG-1组大鼠RGCs数量增多,差异有统计学意义(P<0.01)。免疫组织化学检测结果显示,各组大鼠视网膜NLRP3、Caspase-1和GSDMD平均光密度值总体比较差异均有统计学意义(均为P<0.01);与ZLC组相比,ZDF组大鼠视网膜NLRP3、Caspase-1和GSDMD平均光密度值均增加(均为P<0.01)。与ZDF组相比,NRG-1组大鼠视网膜NLRP3、Caspase-1和GSDMD平均光密度值均明显降低(均为P<0.05)。Western blot检测结果显示,各组大鼠视网膜Brn3a、NLRP3、Caspase-1和GSDMD蛋白表达水平总体比较差异均有统计学意义(均为P<0.01)。与ZLC组相比,ZDF组大鼠视网膜Brn3a蛋白表达水平明显降低,而NLRP3、Caspase-1和GSDMD蛋白表达均明显增加,差异均有统计学意义(均为P<0.01);与ZDF组相比,NRG-1组大鼠Brn3a蛋白表达水平明显增加,而NLRP3、Caspase-1和GSDMD蛋白表达水平均明显降低,差异均有统计学意义(均为P<0.01)。结论糖尿病大鼠视网膜发生病变后,NLRP3、Caspase-1和GSDMD均有显著激活,NRG-1可降低NLRP3、Caspase-1和GSDMD的表达,减少对RGCs的损伤。

Objective To observe the effect of neuregulin-1(NRG-1)on retinal ganglion cells(RGCs)in Zucker Diabetic Fatty(ZDF)rats and explore the mechanism of NRG-1 in exerting neuroprotective effects on the retina.Methods Twenty-four 8-week-old male ZDF rats(24 eyes)were selected.Diabetic obese rat models were established by feeding a high-fat and high-sugar diet(Purina 5008).After 16 weeks,they were randomly divided into the ZDF group and the NRG-1 group(12 rats in each group).Rats in the NRG-1 group received intravitreal injection of human recombinant NRG-1(once a week for a total of two times),rats in the ZDF group were used as negative controls,and Zucker lean control(ZLC)rats were selected as blank controls(ZCL group).The changes in the number of RGCs in rats of each group were observed by immunofluorescence staining.The protein expressions of NOD-like receptor family pyrin domain containing protein 3(NLRP3),Caspase-1,and Gasdermin D(GSDMD)in the retina of rats in each group were observed by immunohistochemistry and Western blot.Results After 16 weeks of eating a high-fat diet,compared with the ZLC group,the fasting blood glucose of rats in the ZDF group significantly increased(P<0.001).The results of immunofluorescence staining showed that the RGCs of rats in the ZLC group were continuously and neatly arranged;compared with the ZLC group,the number of RGCs of rats in the ZDF group significantly decreased(P<0.001);compared with the ZDF group,the number of RGCs of rats in the NRG-1 group significantly increased(P<0.01).The immunohistochemical results showed that there were statistically significant differences in the average optical density values of NLRP3,Caspase-1 and GSDMD in the retina of rats in each group(all P<0.01);compared with the ZLC group,the average optical density values of NLRP3,Caspase-1 and GSDMD in the retina of rats in the ZDF group were higher(all P<0.01);compared with the ZDF group,the average optical density values of NLRP3,Caspase-1 and GSDMD in the retina of rats in the NRG-1 group significantly decreased(all P<0.05).Western blot results showed that there were statistically significant differences in the protein expression levels of Brn3a,NLRP3,Caspase-1 and GSDMD in the retina of rats among all groups(all P<0.01);compared with the ZLC group,the protein expression of Brn3a significantly decreased,while the protein expressions of NLRP3,Caspase-1 and GSDMD significantly increased in the ZDF group(all P<0.01);compared with the ZDF group,the protein expression of Brn3a significantly increased,while the protein expressions of NLRP3,Caspase-1 and GSDMD significantly decreased in the NRG-1 group(all P<0.01).Conclusion After retinal lesions occur in diabetic rats,NLRP3,Caspase-1 and GSDMD are all significantly activated.NRG-1 can reduce the expressions of NLRP3,Caspase-1 and GSDMD,reducing damage to RGCs.