Nitration of Amyloid beta Alzheimer 's disease

阿尔茨海默病(AD)的特征是细胞外淀粉样β蛋白(Abeta)在老年斑中沉积。随之而来的是一种神经炎症，导致诱导型一氧化氮合酶2(NOS2)及其高活性产物一氧化氮(NO)的产生增加，从而能够引入翻译后修饰。这些NO介导的翻译后修饰之一是Abeta在酪氨酸10的硝化(硝化Abeta)。该物种定位于AD中淀粉样斑块的核心，并能够启动斑块的形成。此外，在AD小鼠模型(APP/PS1小鼠)中，去除NOS2可以减少Abeta的沉积和认知功能障碍。为了了解NOS2在AD中的诱导，并测试早期参与硝化Abeta的形成是否是一种潜在的治疗方法，提出了三个目标：1.确定哪些细胞类型和大脑区域表达NOS2，以及在野生型和AD小鼠模型中这种模式是如何受到年龄的影响的。目的：揭示APP/PS1小鼠脑细胞NOS2表达与斑块发生的时空相关性。我们将确定含有核心的淀粉样斑块是否特异性地发生在NOS2表达3的位置。测试针对硝化Abeta的免疫是否改善了APP/PS1小鼠的斑块病理和行为缺陷。我们将进行被动和主动免疫，以改善APP/PS1小鼠的记忆和学习表型，减少斑块。在第一和第二个目标中，将使用表达tdTomato和Cre重组酶的转基因小鼠与Cre-EYFP报告小鼠杂交来评估NOS2的表达。使用这种小鼠，可以监测NOS2的瞬时和间歇性表达。采用体内显微镜方法，我们将澄清淀粉样斑块是否出现在先前和/或正在进行的NOS2表达的部位。在被动免疫研究中，我们实验室最近开发的一种新的抗硝化Abeta抗体(4A4E8)将与N端Abeta抗体进行比较。将进行主动免疫研究，比较含有硝化Abeta表位的多肽和非硝化多肽的效果。治疗的有效性将通过测试记忆和学习以及斑块病理变化来监测。在这个项目中，将通过表征NOS2在AD中的早期表达以及使用只有在病理条件下才出现的翻译后修饰的Abeta表位进行预防性免疫来研究一种新的创新的AD治疗策略。因此，这种方法避免了预防性免疫中潜在的自身免疫问题，这种肽的作用至今仍不清楚。

Alzheimer's disease (AD) is characterized by the extracellular deposition of the amyloid beta (Abeta) peptide in senile plaques. Coming along with that is an neuroinflammation resulting in the increased production of the inducible form of the nitric oxide synthase 2 (NOS2) and its highly reactive product nitric oxide (NO), which is able to introduce post-translational modifications.One of these NO-mediated post-translational modification is the nitration of Abeta at tyrosine 10 (nitrated Abeta). This species is localized to the core of amyloid plaques in AD and is able to initiate the formation of plaques. Furthermore, ablation of NOS2 decreased Abeta deposition and cognitive dysfunction in an mouse model of AD (APP/PS1 mice).To understand the induction of NOS2 in AD and to test if early engagement with the formation of nitrated Abeta is a potential therapeutic approach, three objectives are proposed:1. To determine which cell types and brain areas express NOS2 and how this pattern is influenced by aging in wild type and in an AD mouse model.2. To reveal the spatial and temporal correlation of NOS2 expression in cells of the brain and the occurrence of plaques in APP/PS1 mice. We will determine whether core-containing amyloid plaques specifically develop at sites of NOS2 expression 3. To test if immunization against nitrated Abeta ameliorates the plaque pathology and the behavioral deficits in APP/PS1 mice. We will conduct passive and active immunization to improve the memory and learning phenotype and to reduce plaque in APP/PS1 mice.In the first and second objective, expression of NOS2 will be evaluated using a transgenic mouse that express a tdTomato and the CRE recombinase under the NOS2 promoter crossbred with a CRE-EYFP reporter mouse. Using this mouse it is possible to monitor transient as well as episodic expression of NOS2. Employing an in vivo-microscopy approach we will clarify if amyloid plaques appear at sites of previous and/or ongoing NOS2 expression. For passive immunization studies a new antibody against nitrated Abeta (4A4E8), recently developed in our laboratory, will be compared to an N-terminal Abeta antibody. Active immunization studies will be performed comparing the effect of a peptide comprising the nitrated Abeta epitope to the non-nitrated peptide. The effectiveness of the treatments will be monitored by testing memory and learning as well as changes in the plaque pathology.In this project a new and innovative therapeutic strategy for AD will be investigated by characterizing the early expression of NOS2 in AD and by conducting preventive immunizations using a post-translationally modified epitope of Abeta that only occurs under pathological conditions. This approach thus avoids the potential problem of autoimmunity in preventive immunizations against a peptide which function to this day is still unknown.