NEURONAL & VASCULAR PATHOBIOLOGY IN ALZHEIMER'S DISEASE

本课程重点介绍AD新发现的病理生物学特征，特别与散发性AD(SAD)和血管危险因素的作用有关。总体目标是验证这样一种假说，即内吞途径(EP)和溶酶体系统(LS)异常，包括迄今在SAD脑中发现的最早的病理变化，与SAD的淀粉样蛋白形成和神经变性有关，是AD血管和实质病理之间的关键纽带。该计划的主要目标是通过建立AD，特别是SAD和血管病理的改进的小鼠模型，并通过应用生化、细胞生物学、形态测量和活体磁共振成像方法来阐明AD的潜在细胞机制。第一个项目将调查神经元内吞作用的异常，以及向早期内小体和纯化内小体部分运输增加的蛋白酶，将分析与疾病发生和进展的关系。将对转基因细胞、转基因和突变小鼠建立EP和蛋白酶运输改变的模型，以确定这些异常如何影响Abeta的形成和清除以及神经元和血管内皮细胞的存活。另一个项目测试了神经元LS激活促进细胞萎缩和神经退化的假设。与其他AD神经病理和APOE基因相关的LS激活的开始和进展将在SAD脑中确定。在选择性调节的转基因FAD小鼠中，LS激活的前驱因素及其与神经病理的关系将被评估。溶酶体介导的细胞死亡的潜在机制将被定义。另一个项目，脑淀粉样血管病和人类载脂蛋白E的缺血模型和转基因小鼠模型将用于阐明血管损伤和载脂蛋白E同型如何调节EP和LS异常，并促进AD神经病理。Abeta清除将在AD和血管小鼠模型中进行体内研究，并在人和小鼠血脑屏障的器官模型中进行体外研究。最后一个项目，纵向磁共振成像将应用于转基因小鼠模型，以表征进行性β淀粉样蛋白沉积对大脑结构和功能的影响。这些测量可直接翻译为人类成像研究和其他小鼠模型，包括脑区域体积、脑血流和弥散定量神经病理学。预计该计划将建立用于药物发现的改进的动物模型，推进磁共振成像的临床诊断，并确定新的发病机制，这将成为AD治疗的基础。

This program focuses on newly identified features of AD pathobiology, having particular relevance to sporadic AD (SAD) and the role of vascular risk factors. The overall goal is to test the hypothesis that endocytic pathway (EP) and lysosomal system (LS) abnormalities, which include the earliest pathological changes yet demonstrated in SAD brain, are centrally involved in amyloidogenesis and neurodegeneration in SAD and are a critical link between vascular and parenchymal pathology in AD. The Program's main objectives are to elucidate underlying cellular mechanisms in AD by developing imporoved mouse models of AD, particular SAD, and of vascular pathology and by applying biochemical, cell biological, morphometric, and in vivo MR imaging approaches to these models. The first project investigate abnormalities of neuronal endocytosis and increased protease trafficking to early endosomes and purified endosome fractions will be analyzed in relation to disease onset and progression. Transfected cells and transgenic and mutant mice that model EP and protease trafficking alterations will be characterized to establish how these abnormalities influence Abeta formation and clearance and the survival of neurons and vascular endothelia. Another project tests the hypothesis that neuronal LS activation promotes cell atrophy and neurodegeneration. The onset and progression of LS activation in relation to other AD neuropathology and APOE genotype will be determined in SAD brain. Antecedents to LS activation and relationships to neuropathology will be evaluated in transgenic FAD mouse selectively modulated. Mechanisms underlying lysosome- mediated cell death will be defined. Another project, ischemia models and transgenic mouse models of cerebral amyloid angiopathy and of human APOE will be used to clarify how vascular injury and ApoE isotype modulate EP and LS abnormalities and promote AD neuropathology. Abeta clearance will be studied in vivo in AD and vascular mouse models and in vitro in organotypic models of the human and mouse BBB. The last project, longitudinal MR imaging will be applied to transgenic mouse models to characterize the effects of progressive beta-amyloid deposition on brain structure and function. The measures, which are directly translatable to human imaging studies and other mouse models, including brain regional volumes, cerebral perfusion (blood flow), and diffusion quantitative neuropathology. It is anticipated that this Program will establish improved animal models for drug discovery, advance clinical diagnosis by MR imaging, and define novel cellular mechanisms of pathogenesis that will be the basis for AD therapies.