肺炎链球菌性脑膜炎小鼠B7-H3蛋白对巨噬细胞炎性蛋白2 mRNA表达的影响

摘要

Objective To investigate the effect of B7-H3 protein,a collaborative signal molecule,on macrophage-inflammatory protein 2 (MIP-2) mRNA level in Streptococcus pneumococcal meningitis mouse models.Methods Forty-eight healthy male BALB/C mice at the age of 1.5-2.0 months were randomly divided into 4 groups:9 g/L saline group(NS group),B7-H3 protein group(B7-H3 group),Streptococcus pneumoniae group(SP group),and Streptococcus pneumoniae plus B7-H3 protein group(combination group),12 mice in each group.Mouse models were established by intracerebral ventricular injection with 9 g/L saline,B7-H3 protein,Streptococcus pneumoniae type 3 or Streptococcus pneumoniae type 3 plus B7-H3 protein.Neurobehavior of different groups was evaluated according to loeffler rule after injection for 6 h and 24 h,then the mice were sacrificed and MIP-2 mRNA levels were tested by Real-time PCR.The results were analyzed by SPSS 18.0 software.Results Neurobehavior scoring results showed that there were no significant differences between B7-H3 group and NS group (P ＞ 0.05) after infection for 6 h and 24 h,while the score of SP group was decreased compared with that of NS group (P ＜ 0.05),and the score of combination group was significantly decreased compared with that of SP group (P ＜ 0.05).Real-time PCR results showed that,compared with the NS group,the relative MIP-2 mRNA level in SP group increased after injection for 6 hours (1.210 ±0.932 vs 1.000 ± 0.008),but the difference was not significant (P ＞ 0.05),while at 24 h post infection,the relative MIP-2mRNA expressions in SP group were significantly increased compared with that of NS group(12.880 ± 7.792 vs 1.000 ±0.091),the difference was significant (P ＜ 0.05).At 6 h post infection,SP + B7-H3 treatment enhanced the MIP-2mRNA production compared to SP infection alone,but the difference was not significant [(1.240 ± 0.804) vs (1.210 ± 0.932)] (P ＞ 0.05) ; while at 24 h post infection,the difference was significant (38.760 ± 6.601 vs 12.880 ± 7.792) (P ＜ 0.05).Conclusion Collaborative signal molecule B7-H3 protein may increase MIP-2 mRNA level in Streptococcus pneumococcal meningitis mouse model,and exaggerate the clinical disease condition.%目的 探讨协同信号分子B7-H3对肺炎链球菌性脑膜炎小鼠模型中炎性趋化因子巨噬细胞炎性蛋白2(MIP-2)mRNA表达的影响.方法 1.5 ～2.0个月健康雄性BALB/C小鼠48只,随机分为4组:9 g/L盐水组(NS组)、B7-H3蛋白组(B7-H3组)、肺炎链球菌组(SP组)、肺炎链球菌+B7-H3蛋白组(联合组),每组12只；经小鼠侧脑室穿刺分别注入9 g/L盐水、B7-H3蛋白、肺炎链球菌3型、肺炎链球菌3型+B7-H3蛋白建立动物模型.注射后6、24 h依据loeffler 5分制评分方法对各组小鼠进行神经行为评分,然后麻醉处死小鼠,取脑组织,用Real-time PCR方法检测小鼠脑组织内MIP-2 mRNA的相对表达量.应用SPSS 18.0软件进行统计学分析.结果 侧脑室穿刺注射6、24h后各组小鼠神经行为学评分结果:B7-H3组神经行为评分与NS组比较差异无统计学意义(P＞0.05)；SP组评分较NS组明显降低,差异具有统计学意义(P＜0.05)；联合组较SP组评分更明显降低,差异具有统计学意义(P＜0.05).Real-time PCR方法检测结果:SP组在注射6h后MIP-2 mRNA的相对表达量较NS组升高[(1.210 ±0.932)比(1.000±0.008)],但差异无统计学意义(P＞0.05)；在注射24 h后SP组MIP-2 mRNA的相对表达明显高于NS组[(12.880±7.792)比(1.000±0.091)],差异具有统计学意义(P＜0.05)；联合组与SP组比较:6 h MIP-2相对表达量增高[(1.240±0.804)比(1.210±0.932)],但无统计学差异(P＞0.05),24h相对表达量明显升高[(38.760±6.061)比(12.880±7.792)],差异具有统计学意义(P＜0.05).结论 在肺炎链球菌性脑膜炎模型中,协同信号分子B7-H3使炎性趋化因子MIP-2 mRNA的表达上调,促进病情进展.