Objective: To investigate the role of microglial pyroptosis in hypoxic-ischemic brain damage.
Methods: An oxygen-glucose deprivation/reoxygenation (OGD/R) model of rat microglial cells were cultured in vitro. Western blot was used to measure the expression of the pyroptosis-related proteins caspase-1, interleukin-1β (IL-1β), and N-terminal gasdermin D (GSDMD-N) at 0, 1, 3, 6, 12, and 24 hours after OGD/R. After the microglial cells were transfected with lentivirus-mediated silenced gasdermin D (GSDMD), immunofluorescence assay and Western blot were used to measure the transfection rate of GSDMD. Microglial cell lines were divided into three groups: normal control, negative control, and LV-sh_GSDMD (lentivirus-mediated GSDMD silencing). CCK-8 assay and LDH kit were used to observe the effect of GSDMD silencing on the viability and toxicity of microglial cells at 24 hours after OGD/R. Western blot was used to observe the effect of GSDMD silencing on the levels of caspase-1, GSDMD-N, and IL-1β in the microglial cells at 24 hours after OGD/R.
Results: The expression levels of the pyroptosis-related proteins caspase-1, GSDMD-N, and IL-1β in microglial cells were upregulated since 0 hour after OGD/R and reached the peak levels at 24 hours. A microglial cell model of lentivirus-mediated GSDMD silencing was successfully constructed. At 24 hours after OGD/R, compared with the normal control group, the GSDMD silencing group had a significant increase in the cell viability and a significant reduction in the cytotoxicity (P<0.05), as well as significant reductions in the protein expression levels of caspase-1, GSDMD-N, and IL-1β in microglial cells (P<0.05).
Conclusions: Lentivirus silencing of the key substrate protein for pyroptosis GSDMD can alleviate hypoxic-ischemic brain damage, suggesting that microglial pyroptosis aggravates hypoxic-ischemic brain damage.
目的: 初步探讨小胶质细胞焦亡在缺氧缺血性脑损伤中的作用。
方法: 建立体外培养大鼠小胶质细胞系氧糖剥夺再灌注（OGD/R）模型，用Western blot法检测OGD/R后0、1、3、6、12及24 h焦亡相关蛋白半胱氨酸天冬氨酸蛋白酶-l（caspase-1）、白细胞介素-1β（IL-1β）、Gasdermin D蛋白N端（GSDMD-N）的表达情况。用慢病毒构建的沉默Gasdermin D（GSDMD）序列转染小胶质细胞，使用免疫荧光和Western blot法检测GSDMD转染效率。将小胶质细胞系分为正常对照组、阴性对照组、LV-sh_GSDMD组（慢病毒沉默GSDMD），使用CCK-8和LDH试剂盒检测沉默GSDMD对OGD/R后24 h小胶质细胞活性和毒性的影响；通过Western blot法检测沉默GSDMD对OGD/R后24 h小胶质细胞中caspase-1、GSDMD-N、IL-1β含量变化的影响。
结果: 在OGD/R后0 h起小胶质细胞内焦亡相关蛋白caspase-1、GSDMD-N、IL-1β的表达水平即较OGD/R前发生了上调，并且在24 h达到高峰（P < 0.05）。成功地构建慢病毒沉默GSDMD转染小胶质细胞模型。OGD/R后24 h，与正常对照组相比，沉默GSDMD可提高细胞活性和降低细胞毒性（P < 0.05），降低小胶质细胞内caspase-1、GSDMD-N、IL-1β蛋白水平（P < 0.05）。
结论: 慢病毒沉默细胞焦亡关键底物蛋白GSDMD可减轻缺氧缺血性脑损伤，提示小胶质细胞焦亡加重缺氧缺血性脑损伤。