香菇多糖预处理对急性弓形虫感染小鼠中枢神经系统损伤的保护性作用研究

Protective effects of lentinan pretreatment on central nervous system injury in mice infected with Toxoplasma gondii

目的探究香菇多糖预处理对急性弓形虫感染小鼠脑中枢神经系统的保护性作用。方法将C57BL/6小鼠随机分为对照组(NC)、模型组(TDI)和香菇多糖预处理组(pre-10dLNT TDI)。弓形虫感染前10d,pre-10dLNT组小鼠连续10d腹腔注射LNT(1mg/kg体重,1次/d),弓形虫感染后无任何处理;TDI组小鼠腹腔注射弓形虫悬液0.5 mL/只鼠;NC组小鼠感染前10d开始腹腔注射同等体积的生理盐水(1次/d)。通过观察小鼠的死亡时间及数量计算各组小鼠的存活率,使用流式细胞仪检测感染后第8d小鼠脑组织中CD8+IFN-γ+T细胞百分比,ELISA法检测感染后第4d和第8d小鼠外周血中IFN-γ、GABA和DA水平,应用SoftMax Pro 4.3.1LS软件绘制标准曲线计算各项指标的含量(pg/ml)。采用Grapad 8.0软件进行处理和分析。结果TDI组小鼠第8d存活率为0%,pre-10dLNT TDI组小鼠第8d存活率为60%;与NC组相比,TDI组和pre-10dLNT TDI组CD8+IFN-γ+T细胞亚群水平均明显增高;与TDI组小鼠相比,pre-10dLNT预处理明显降低了弓形虫感染的C57BL/6J小鼠脑组织中CD8+IFN-γ+细胞数量(P<0.01)、明显降低了小鼠第4d和8d的外周血中IFN-γ产生水平(P<0.05;P<0.01)、第8d小鼠外周血中DA和GABA的产生水平显著增加(P<0.01)。结论LNT预处理可以显著提高急性弓形虫感染小鼠的存活率,通过减少CD8+T细胞通过血脑屏障进入CNS,降低神经系统的广泛炎症反应,通过降低脑组织中CD8+IFN-γ+T细胞数量,调节神经递质的分泌水平,从而改善小鼠脑部的炎症反应,对急性弓形虫小鼠中枢神经系统的损伤具有明显的保护作用。

Objective To investigate the protective effects of lentinan pretreatment on?central nervous system injury in mice with Toxoplasma gondii infection.Methods The C57BL/6mice were randomly divided into control group(NC),infection group(TDI)and lentinan 10days pretreatment group(pre-10dLNT TDI).Mice in pre-10dLNT TDI group were injected with lentinan(1mg/kg weight,once a day)10days before Toxoplasma gondii infection,then no treatment after infection;each mouse in TDI group were intraperitoneally injected with 0.5mL T.gondii;mice in NC group were injected with the same volume saline every day 10days before Toxoplasma gondii infection.The survival rate was got by recording the number and time of mice deaths;the percentage of CD8+IFN-γ+T cells in the brain tissue of mice on the 8th day after Toxoplasma gondii infection was detected by flow cytometry;the levels of IFN-γ,GABA and DA in peripheral blood plasma of mice on the 4th,8th day after Toxoplasma gondii infection were detected by ELISA;SoftMax Pro 4.3.1LS software caculate the levels(pg/mL)of every index by draw the standard curve.Then Grapad 8.0was used to analyze the data.Results The survival rate of mice in TDI group was 0%on 8th day,while it was 60%in pre-10dLNT TDI group;compared with NC group,the level of CD8+IFN-γ+cells was significantly higher in TDI and pre-10dLNT TDI group(P<0.01);compared with TDI group,pre-10dLNT pretreatment significantly decreased CD8+IFN-γ+cells in brain tissue of C57BL/6mice with Toxoplasma gondii infection(P<0.01)and the level of IFN-γin peripheral blood plasma on the 4th,8th day(P<0.05;P<0.01),while it significantly increased the levels of DAand GABA(P<0.01)in peripheral blood plasma on the 8th day.Conclusion Lentinan pretreatment can significantly improve the survival rate of mice injected with Toxoplasma gondii,and reduce the inflammation of brain to protect the central nervous system by decreasing CD8+cells to cross the blood-brain barrier into the CNS and reducing the number of CD8+IFN-γ+cells to regulate the levels of neurotransmitters.