Aged EFAD mice as a model for the effects of APOE and sex on AD pathology

载脂蛋白E(ApoE)的载脂蛋白ε4等位基因是阿尔茨海默病最大的遗传危险因素 它与淀粉样蛋白-β多肽(A-β)以淀粉样蛋白和可溶性的形式加速蓄积有关 寡聚体Aβ(OAβ)，后者被认为是近端的一种神经毒素。重要的是，女性ε4携带者有更大的 阿尔茨海默病的终生风险，认知功能减退的速度增加和β的加速积累 与男性携带者相比。同样，雌性家族性AD(FAD)-TG小鼠有更大的认知缺陷和 与雄性小鼠相比，Aβ病理增加。APOE4和AD风险之间的联系可能是多因素的 人们仍然知之甚少；而女性ε4携带者增加的风险实际上仍未被探索。AS 散发性AD代表∼98%的病例，随着年龄的增加是关键的危险因素，这项提议的UH2期将检验 老年EFAD小鼠发生深刻的阿尔茨海默病病理的假说，受载脂蛋白E显著影响 基因和性别。为了研究人载脂蛋白E(h-APOE)与AD病理的相互作用，我们开发了 将h-APOE导入5xFAD-Tg小鼠体内。到6个月(M)时，E4FAD小鼠有更大的Aβ-和 与E3FAD相比，Tau病理、神经炎症和认知缺陷。在E4FAD与E3FAD中，以及 女性与男性相比，淀粉样蛋白和可溶性Aβ(Aβ42和OAβ)水平更高，apoE/Aβ复合体 再低一点。将这些观察结果统一到可检验假设中的关键组件是 APOE.在E4FAD和E3FAD大脑中，APOE的脂类含量较低，在女性和男性中，APOE的脂类含量较低。在人脑和脑脊液中， 而EFAD小鼠脑内载脂蛋白E脂化水平与可溶性Aβ呈负相关。因此，对于UH3阶段，我们的 数据支持这样的假设，即减少载脂蛋白E的脂化会导致载脂蛋白E/Aβ复合体水平的降低， 可溶性Aβ清除效率低下，突触丧失，记忆和认知障碍，以及痴呆症。UH2阶段： 目的1：建立18M只EFAD小鼠的饲养方案，并对AD病理进行基准检测。 (n=12)：apoE4♀&gt；apoe4♂≥apoe3♀&gt；apoe4♂。到第二年年底，措施将包括以下内容： 行为学、免疫组织化学和生化(BC)，包括载脂蛋白E、OA、β、 一辆β42。UH3期：衰老的EFAD小鼠是人类AD病理影响因素的可行模型吗， 特别是载脂蛋白E基因和性别，从而为测试前瞻性治疗干预措施提供了一个模型 以及机械假说，包括我们的“载脂蛋白脂化假说”？目标2.建立10米、14米(中间 年龄)和18M(老年)EFAD小鼠队列，通过详细分析行为和 与6M(成人)比较的组织(ε3和ε4；♂和♀)。分析包括多项认知测试，IHC 对于β和tau病理，神经炎症和神经元计数，BC用于载脂蛋白E和 Aβ、apoE脂化，以及OAβ、Aβ42、apoE和apoE/Aβ水平。AD临床试验的失败质疑 缺乏h-APOE的临床前AD-TG小鼠模型的预测有效性，h-APOE是AD的主要遗传风险因素。 然而，AD的最大风险因素是年龄；老年EFAD小鼠将解决这两个关键风险因素。

The APOE ε4 allele of apolipoprotein E (apoE) is the greatest genetic risk factor for Alzheimer's disease (AD) and is associated with accelerated amyloid-β peptide (Aβ) accumulation both as amyloid and soluble oligomeric Aβ (oAβ), the latter considered a proximal neurotoxin. Importantly, female ε4 carriers have a greater lifetime risk for developing AD, an increased rate of cognitive decline and accelerated accumulation of Aβ compared to male carriers. Similarly, female familial AD (FAD)-Tg mice have greater cognitive deficits and increased Aβ pathology than male mice. The link between APOE4 and AD risk is likely multi-factorial and remains poorly understood; while the increased risk for female ε4 carriers remains virtually unexplored. As sporadic AD represents ∼98% of cases, with age the key risk factor, the UH2 phase of this proposal will test the hypothesis that aged EFAD mice develop profound AD pathology, significantly influenced by APOE genotype and sex. To study the interaction between human APOE (h-APOE) and AD pathology, we developed EFAD mice by introducing h-APOE into 5xFAD-Tg mice. By 6 months (M), E4FAD mice have greater Aβ- and tau-pathology, neuroinflammation and cognitive deficits compared to E3FAD. In E4FAD vs. E3FAD, and females vs. males, the levels of amyloid and soluble Aβ (Aβ42 and oAβ) are greater and apoE/Aβ complex lower. The critical component uniting these observations into a testable hypothesis is the lipidation state of apoE. ApoE is less lipidated in E4FAD vs. E3FAD brains and in females vs. males. In human brain and CSF, and EFAD mouse brain, apoE lipidation negatively correlates with soluble Aβ. Thus, for the UH3 phase, our data support the hypothesis that reduced apoE lipidation results in reduced levels of apoE/Aβ complex, inefficient clearance of soluble Aβ, synaptic loss, memory and cognitive deficits, and dementia. UH2 Phase: Aim 1: Establish breeding program for 18M EFAD mice and perform benchmark testing for AD pathology. (N=12): APOE4♀ > APOE4♂ ≥ APOE3♀ > APOE4♂. By the end of Year 2, measures will include MWM for behavior, AD pathology by immunohistochemistry (IHC), and biochemistry (BC) including levels of apoE, oAβ, Aβ42. UH3 Phase: Are aging EFAD mice a viable model for the factors effecting AD pathology in humans, particularly APOE genotype and sex, thus providing a model for testing prospective therapeutic interventions and mechanistic hypotheses, including our “apoE lipidation hypothesis”? Aim 2. Establish 10M, 14M (middle age) and 18M (aged) EFAD mouse cohorts to define disease progression by detailed analysis of behavior and tissue for comparison with 6M (adult) (ε3 and ε4; ♂ and ♀). Analyses will include multiple cognitive tests, IHC for Aβ- and tau-pathology neuroinflammation and neuron counts, and BC for extraction profiles of apoE and Aβ, apoE lipidation, and levels of oAβ, Aβ42, apoE, and apoE/Aβ. The failure of AD clinical trials questions the predictive validity of preclinical AD-Tg mouse models that lack h-APOE, the major genetic risk factor for AD. However, the greatest risk factor for AD is age; aged EFAD mice will address both these critical risk factors.