牛蒡子苷元抑制HMGB1/TLR4/NF-κB信号通路对肺炎链球菌脑膜炎大鼠神经元凋亡的影响

Influence of arctigenin on neuronal apoptosis in rats with Streptococcus pneumoniae meningitis by inhibiting HMGB1/TLR4/NF-κB signaling pathway

目的探讨牛蒡子苷元(ATG)抑制HMGB1/TLR4/NF-κB信号通路对肺炎链球菌脑膜炎大鼠神经元凋亡的影响。方法通过脑内注射Ⅲ型肺炎链球菌建立脑膜炎大鼠模型,并随机分为模型组、ATG低(ATG-L)、中(ATG-M)、高(ATG-H)剂量组以及ATG-H+重组高迁移率组蛋白B1(rHMGB1)组,另取正常大鼠为对照组,10只/组。治疗结束后,对各组大鼠进行神经系统评分;分离大鼠脑组织,检测其病理变化、含水量、IL-1β、IL-6、TNF-α水平以及神经元细胞凋亡,同时检测HMGB1/TLR4/NF-κB信号通路蛋白表达水平。结果与对照组比较,模型组大鼠神经系统评分显著下降(P<0.05),脑组织含水量、IL-1β、IL-6、TNF-α、HMGB1、TLR4、p-NF-κB p65/NF-κB p65水平及TUNEL荧光染色阳性细胞数量均显著增加(均P<0.05);ATG-L组、ATG-M组、ATG-H组小鼠神经系统评分均较模型组显著增加(均P<0.05),脑组织含水量、IL-1β、IL-6、TNF-α水平、TUNEL荧光染色阳性细胞数量、HMGB1、TLR4、p-NF-κB p65/NF-κB p65均较对照组显著下降(均P<0.05);ATG-H+rHMGB1组较ATG-H组神经系统评分显著下降(P<0.05),脑组织含水量、IL-1β、IL-6、TNF-α、HMGB1、TLR4、p-NF-κB p65/NF-κB p65水平及TUNEL荧光染色阳性细胞数量均显著增加(均P<0.05)。结论ATG可抑制肺炎链球菌脑膜炎大鼠神经元凋亡,减轻炎症反应,其机制可能与抑制HMGB1/TLR4/NF-κB信号通路有关。

Objective To investigate the influence of arctigenin(ATG)on neuronal apoptosis in rats with Streptococcus pneumoniae meningitis by inhibiting HMGB1/TLR4/NF-κB signaling pathway.Methods Rat models of meningitis were established by intracerebral injection of typeⅢS.pneumoniae and were randomly grouped into model group,ATG low(ATG-L),medium(ATG-M),high(ATG-H)dose groups and ATG-H+recombinant high mobility histone B1(rHMGB1)group,and normal rats were taken as control group,with 10 rats/group.After the treatment,the rats in each group were scored for the nervous system;the rat brain tissue was isolated,and its pathological changes,water content,levels of IL-1β,IL-6,TNF-αand neuronal apoptosis were detected,and the expression levels of HMGB1/TLR4/NF-κB signaling pathway proteins were also detected.Results Compared with the control group,the neurological score of the model group(1.21±0.13 vs 5.00±0.00)was significantly decreased(all P<0.05),brain tissue water content(88.42±8.85 vs 53.24±5.33),IL-1β(3864.57±386.49 vs 24.37±2.44),IL-6(98.67±9.88 vs 22.34±2.24),TNF-α(2453.24±246.34 vs 12.35±1.26),HMGB1,TLR4,p-NF-κB p65/NF-κB p65 levels and the number of TUNEL positive cells(115.24±11.53 vs 5.37±0.55)were significantly increased(all P<0.05);Compared with the model group,the neurological scores of mice in the ATG-L(2.35±0.24),ATG-M(3.44±0.35),and ATG-H groups(4.25±0.43)were significantly increased(all P<0.05),brain water content(73.85±7.39,64.24±6.43,53.85±5.39),IL-1β(2176.34±218.64,1108.34±111.02,102.37±10.28),IL-6(68.49±6.85,42.81±4.29,26.37±2.64),TNF-αlevels(1257.38±126.78,672.15±67.53,99.24±9.54),the number of TUNEL positive cells(75.34±7.55,42.37±4.24,22.04±2.21),HMGB1,TLR4,p-NF-κB p65/NF-κB p65 were significantly decreased compared with the control group(all P<0.05);Compared with the ATG-H group,the nervous system score of the ATG-H+rHMGB1 group(2.28±0.23)was obviously decreased(P<0.05),the brain tissue water content(71.28±7.13),levels of IL-1β(2256.39±225.71),IL-6(59.37±5.95),TNF-α(1684.37±169.27),the number of TUNEL fluorescent(68.57±6.88)staining positive cells,HMGB1,TLR4,p-NF-κB p65/NF-κB p65 were obviously increased(P<0.05).Conclusion ATG can inhibit neuronal apoptosis and reduce inflammatory response in rats with S.pneumoniae meningitis,which may be related to the inhibition of HMGB1/TLR4/NF-κB signaling pathway.