小鼠局灶性脑缺血再灌注后IL-33及其受体的时程表达

Time course expression of Interleukin-33 and its receptors after focal cerebral ischemia/reperfusion in mice

目的检测白细胞介素-33(IL-33)及其膜受体ST2和可溶型受体sST2在小鼠局灶性脑缺血再灌注后不同时程的表达特征。方法利用线栓法闭塞大脑中动脉(MCAO)30 min诱导建立小鼠可逆性局灶性脑缺血再灌注损伤模型,通过半定量RT-PCR检测脑缺血再灌注后6 h、24 h和3 d缺血脑组织中IL-33及其膜受体ST2、凋亡相关蛋白Caspase-8和Caspase-3的mRNA表达水平,并通过免疫组织化学染色观察了IL-33在不同缺血脑区(运动皮质、感觉皮质、海马和纹状体)的时程表达情况;ELISA法检测了小鼠MCAO模型再灌注后不同时间点血清中IL-33及其可溶型受体sST2的表达水平。结果 IL-33 mRNA在缺血后6 h和3 d表达减少,但在24 h无明显改变;凋亡相关蛋白Caspase-3和Caspase-8在缺血后3个时间点均显著增高,且Caspase-3在6 h和3 d的mRNA表达水平较24 h高;ST2 mRNA在缺血后6 h无减少,但在24 h和3 d有明显减少;除了MCAO 24 h组运动皮质和纹状体阳性染色增加外,IL-33阳性细胞数在缺血后不同时程各脑区均有不同程度减少;缺血后外周血中IL-33的表达量无明显升高或降低,而sST2的表达水平在缺血后6 h即已显著升高。结论脑缺血再灌注后IL-33/ST2信号通路被下调,其与sST2表达增多的效应发挥和神经元凋亡有关。

Objective To examine the expression patterns of Interleukin（ IL）-33 and its receptor ST2 and soluble ST2（ sST2） in the different stages following transient cerebral ischemia. Methods Adult C57BL/6 mice were subjected to either sham-operation or middle cerebral artery occlusion（ MCAO） for 30 min. At 6 h,24 h and 3 d after the onset of reperfusion,the expression levels of IL-33,ST2,Caspase-8 and Caspase-3 mRNA in the ischemic brains were examined by semiquantitative RT-PCR. We also observed the expression of IL-33 in the different ischemic brain areas including the sensory and motor cortex,hippocampus and striatum（ caudoputamen）. Moreover,the serum levels of IL-33 and sST2 after MCAO in mice were determined by ELISA. Results Compared to the corresponding sham group,the mRNA level of IL-33 was significantly decreased at 6 h and 3 d after MCAO,but not at 24 h,while ST2 mRNA expression was down-regulated at 24 h and 3 d but not at 6 h after MCAO. The expression of Caspase-3 and Caspase-8 was significantly increased from 6 h after MCAO,and the level of Caspase-3 was higher at 6 h and 3 d than 24 h. Moreover,the numbers of IL-33-positive cells were decreased in the different ischemic brain regions,except for the motor cortex and striatum at MCAO 24 h. No obvious changes were examined in the serum level of IL-33,while the level of sST2 was significantly increased at 6 h after MCAO. Conclusion The IL-33/ST2 signaling pathway was down-regulated after cerebral ischemia/reperfusion,which was related to the increased expression of sST2 and neuronal apoptosis.