T_(2)* mapping MR成像评价脊髓缺血再灌注后铁死亡的机制研究

The mechanism of ferroptosis after spinal cord ischemia-reperfusion evaluated by T_2* mapping MR

目的:通过7.0T T_(2)*mapping MR成像技术检测脊髓缺血再灌注(Spinal cord ischemia-reperfusion,SCIR)损伤后脊髓前角铁沉积变化,并分析其与铁死亡蛋白变化的关系,以此反映SCIR后铁死亡的作用机制。方法:选取48只Wistar大鼠(雄性,280~300 g),随机分为假手术组(n=8)和SCIR实验组(n=40)。实验组按缺血再灌注后不同恢复时间分为6 h组(n=8),12 h组(n=8),24 h组(n=8),48 h组(n=8)和72 h组(n=8)。建模完成后进行7.0T MR扫描。扫描后进行脊髓组织溶质载体家族11成员2(Solute carrier family 11 member 2,SLC11A2)、铁蛋白重链1(Ferritin heavy chain 1,FTH1)、谷胱甘肽过氧化物酶4(Glutathione peroxidase 4,GPX4)的免疫组化染色。采用方差分析、Tukey检验比较各组T_(2)*值和蛋白质表达水平的差异。结果:SCIR后6 h,脊髓前角T_(2)*值显著降低(P<0.001,Tukey检验),至24 h达到最低(P<0.001,Tukey检验),48 h组回升(P<0.001)。SCIR损伤后6 h,SLC11A2表达具有轻度增加趋势,FTH1表达显著降低(P=0.007,Tukey检验),SCIR损伤后24 h,SLC11A2、FTH1、GPX4表达均显著降低(P=0.031,P=0.009,P=0.004,Tukey检验)。结论:SCIR损伤后脊髓前角T_(2)*值、SLC11A2、FTH1、GPX4均出现一过性降低过程,且T_(2)*变化与GPX4蛋白变化一致,提示T_(2)*mapping可通过检测脊髓铁沉积的变化进一步反映铁死亡的作用机制。

Objective:To examine the changes of iron deposition in the spinal cord by 7.0T T_2*mapping MR imaging after spinal cord ischemia-reperfusion (SCIR) and analyze the relationship between T_2*and protein of ferroptosis,to reflect the mechanism of ferroptosis after SCIR.Methods:Forty-eight Wistar rats (male,280~300 g) were selected and randomly divided into sham group(n=8) and SCIR group(n=40).The SCIR group was divided into 6 h(n=8),12 h(n=8),24 h(n=8),48 h(n=8) and72 h (n=8) subgroups.A 7.0T MR scan was performed after the modeling was completed.After scanning,immunohistochemical staining of family 11 member 2 (SLC11A2),ferritin heavy chain 1 (FTH1),glutathione peroxidase 4 (GPX4) were performed.Analysis of variance and Tukey test were used to compare the differences in T_2*values and protein expression levels in each group.Results:At 6 h after SCIR,the T_2*value of the anterior spinal horn decreased significantly (P<0.001,Tukey test)reaching the lowest at 24 h (P<0.001,Tukey test),and the 48 h subgroup recovered (P<0.001).At 6 h after the SCIR injury,SLC11A2 expression showed a slight increase trend,while FTH1 expression was significantly reduced(P=0.007,Tukey test).At24 h after the SCIR injury,the expression of SLC11A2,FTH1,and GPX4 were significantly decreased (P=0.031,P=0.009,P=0.004,Tukey test).Conclusion:After SCIR injury,the T_2*value,SLC11A2,FTH1,and GPX4 all show a transient decrease,and the T_2*change is consistent with the GPX4 protein change,suggesting that T_2*mapping can further reflect the mechanism of ferroptosis by detecting the changes in spinal iron deposition.