Aβ亚单位疫苗接种Tg2576鼠对脑内淀粉样斑块沉积和行为学的影响

THE EFFECT OF INOCULATING Aβ SUBUNIT VACCINE ON AMYLOID PLAQUES OF BRAIN AND COGNITIVE BEHAVIOR IN Tg2576 MICE

目的探讨Aβ亚单位疫苗接种对Tg2576鼠淀粉样斑块沉积和行为学损害的影响。方法24只Tg2576鼠随机分为Aβ1-15组、Aβ36-42组、Aβ42组和对照组，9月龄时开始分别接种相应的疫苗，间接ELISA法检测血清和脑匀浆上清液特异性抗体的滴度；免疫组织化学染色观察脑内淀粉样斑块沉积；Morris水迷宫测试行为学变化；组织染色观察脑、肝、脾、肺和肾的组织学变化。结果第2次接种后各实验组即明显有抗Aβ42抗体产生，抗体滴度随接种次数的增加而增加。停止接种，抗体滴度下降。脑匀浆上清液中也检测出低滴度的抗Aβ42抗体；疫苗接种6个月后，Aβ42、Aβ1-15和Aβ36-42组鼠皮层和海马淀粉样斑块沉积量与对照组相比均明显减少（P〈0．01），其认知能力显著高于对照组（P〈0．01）。Aβ1-15组和Aβ42组相比差异无显著性（P〉0．05），但优于Aβ36-42组（P〈0．01）；各组鼠的脑、肝、脾、肺和肾均未发现病理变化。结论邯亚单位疫苗接种能有效阻抑Tg2576鼠淀粉样斑块形成和认知功能退化，未发现不良反应。提示用Aβ1-15疫苗替代其全肽疫苗而用于AD免疫治疗，值得进一步研究。

Objective To investigate the effects of Aβ subunit vaccine immunization on amyloid plaques and behavioural impairment in Tg2576 mice. Methods Twenty-four Tg2576 mice were randomly divided into Aβ1-15 group, Aβ36-45 group, Aβ42 group and control group. Tg2576 mice were inoculated by corresponding vaccine in 9 month old. Indirect ELISA was used to assay antibody against Aβ42 in the serum and homogenate of brain. The method of immunohistochemical staining was performed to observe deposition of amyloid plaques and using method of Morris water maze to test mouse＇ s learning and memory. Histochemical staining was used to observe the morphology of brain,liver, spleen, lung and kidney to assess safety of subunit vaccine. Results After the second inoculating, antibody against Aβ42 began to develop in experimental group mice. The titer increased with inoculating times. Once the inoculating was stopped, the titer of antibody was decreased. The low titer of antibody against Aβ42 could be also detected in supernatant of homogenated brain. After six month inoculating,amyloid deposition in cortex and hippocampi were significantly reduced in Aβ42, Aβ1-35 and Aβ36-42 group. Compared with control group, they were greatly decreased in experimental groups（ P 〈 0.01） ,and their cognitive behavior was significantly improved（ P 〈 0.01）. There were no difference between Aβ42 group and Aβ1-15 group（ P 〉 0.05）. The effect of Aβ1-15 subunit vaccine had more superior than that of Aβ36-42 vaccine （P 〈 0.01 ）. No morphological damage was detected in the brain, liver, spleen, lung, kidney of the experiment mice. Conclusion Aβ subunit vaccine immunization reduces both Aβ deposition and behavioural dysfunction in the Tg2576 murine model of Alzheimer disease. No side effects are observed after inoculating Aβ subunit vaccine. The experiment demonstrates that of Aβ1-15 subunit vaccine can be used instead complete peptide and it would be worth for further study.