IL-18结合蛋白在创伤性颅脑损伤大鼠认知功能障碍中的作用及其机制

Effect and mechanism of IL-18BP in relieving cognitive dysfunction of rats with traumatic brain injury

目的探究IL-18结合蛋白(IL-18BP)在创伤性脑损伤(TBI)大鼠认知功能障碍中的作用及其机制。方法120只健康雄性SD大鼠按随机数字表法分为假手术组、TBI组、TBI+IL-18BP组(经尾静脉注射IL-18BP 1.5 mg/kg)与TBI+IL-18BP+ADU-S100组(经尾静脉注射IL-18BP1.5 mg/kg,经腹腔注射ADU-S10020 mg/kg),每组30只。应用自由落体法建立TBI模型,造模后30 d行水迷宫实验检测大鼠认知功能,ELISA法检测大鼠血清IL-18、IL-18BP浓度,免疫荧光染色检测海马区星形胶质细胞GFAP、IL-18和cleaved-caspase-3荧光强度,Western blotting检测大鼠海马区干扰素基因刺激蛋白(STING)、磷酸化TANK结合激酶1(p-TBK1)、TBK1、磷酸化干扰素调节因子3(p-IRF3)、IRF3蛋白相对表达量。结果与假手术组比较,TBI组、TBI+IL-18BP组和TBI+IL-18BP+ADU-S100组大鼠逃逸潜伏期明显延长,穿越平台次数减少,目标象限活动时间百分比降低(P<0.0001),血清IL-18、IL-18BP浓度升高,海马区IL-18和cleaved-caspase-3荧光强度明显增强,STING、p-TBK1、p-IRF3表达明显上调(P<0.05);与TBI组比较,TBI+IL-18BP组大鼠逃逸潜伏期缩短,穿越平台次数增多,目标象限活动时间百分比增高(P<0.0001),血清IL-18浓度降低,IL-18BP浓度升高,海马区IL-18和cleaved-caspase-3荧光强度明显减弱,STING、p-TBK1、p-IRF3表达明显下调(P<0.05);与TBI+IL-18BP组比较,TBI+IL-18BP+ADU-S100组大鼠逃逸潜伏期延长,穿越平台次数减少,目标象限活动时间百分比降低(P<0.0001),血清IL-18浓度升高,IL-18BP浓度降低,海马区IL-18和cleaved-caspase-3荧光强度增强,STING、p-TBK1、p-IRF3表达明显上调(P<0.05)。结论IL-18BP可改善TBI大鼠的认知功能,其机制可能与抑制星形胶质细胞凋亡及抑制STING/TBK1/IRF3信号通路激活有关。

Objective To explore the role of interleukin-18 binding protein(IL-18BP)in alleviating cognitive dysfunction of traumatic brain injury(TBI)rats and the related mechanisms.Methods A total of 120 adult male SD rats were randomly divided into 4 groups(30 each):sham group,TBI group,TBI+IL-18BP group(administered 1.5 mg/kg IL-18BP by tail vein),and TBI+IL-18BP+ADU-S100 group(administered 1.5 mg/kg IL-18BP by tail vein,and 20 mg/kg ADU-S100 by intraperitoneal injection).The rat model of TBI was established using the free falling body method.At 30 d after modeling,cognitive function of rats was measured by Morris water maze test.The serum levels of IL-18 and IL-18BP were detected by ELISA.The integrated fluorescence intensity of GFAP,IL-18 and cleaved-caspase-3 in hippocampus were detected by immunofluorescence.The relative expression levels of stimulator of interferon genes(STING),phosphorylated TANK-binding kinase 1(p-TBK1),TBK1,phosphorylated interferon regulating factor 3(p-IRF3),and IRF3 in hippocampus were detected using Western blotting.Results Compared with sham group,rats in TBI,TBI+IL-18BP and TBI+IL-18BP+ADU-S100 groups had longer escape latency and decreased times of crossing the platform and reduced time of acting in the targeted quadrant(P<0.0001),with increased concentration of IL-18 and IL-18BP in the blood,enhanced fluorescence intensity of IL-18 and cleaved-caspase-3,up-regulated expression levels of STING,p-TBK1 and p-IRF3 in the hippocampus(P<0.05);Compared with TBI group,the escape latency was shortened,the times of crossing platform and the percentage of target quadrant activity time were increased in TBI+IL-18BP group(P<0.001),the concentration of serum IL-18 decreased while of serum IL-18BP increased,and the fluorescence intensity of IL-18 and cleaved-caspase-3,the expressions of STING,p-TBK1 and p-IRF3 in the hippocampus were down-regulated significantly in TBI+IL-18BP group(P<0.05);Compared with TBI+IL-18BP group,the latency was significantly prolonged,the platform crossing times remarkably reduced,the time spent in the target quadrant was considerably shortened,the concentration of serum IL-18 increased while of IL-18BP decreased,the fluorescence intensity of IL-18 and cleaved-caspase-3,the expression levels of STING,p-TBK1 and p-IRF3 in hippocampus were increased in TBI+IL-18BP+ADU-S100 group(P<0.05).Conclusion IL-18BP can improve the cognitive function of TBI rats to some extent,and its mechanism may be related to the inhibition of astrocytes apoptosis and STING/TBK1/IRF3 signaling pathway.