A novel therapeutic approach for Alzheimer Disease (AD)

项目摘要 阿尔茨海默病（AD）是一种慢性神经系统疾病， 功能障碍、进行性记忆衰退和认知障碍。烟酰胺腺嘌呤二核苷酸（NAD+） 是参与细胞生物能量学、基因组稳定性、线粒体稳态 适应性应激反应和细胞存活。越来越多的证据表明，NAD+下降是 伴随着AD的进展。在哺乳动物细胞中，NAD+生物合成的补救途径是： NAD+生物合成的主要途径，其中烟酰胺磷酸核糖基转移酶（Nampt）是NAD+生物合成的速率。 限制酶因此，系统地维持升高的NAD+水平以增强细胞增殖的生理手段是必需的。 脑中的代谢活动可能代表有效的抗AD干预。红细胞（RBC）， 从骨髓（BM）中的造血干/祖细胞（HSPC）分化并释放到血液中 成熟后的循环系统，是全身最丰富的细胞类型，因此，NAD+增加 使用遗传干预在这些细胞中进行合成可以提供系统和 通过循环系统持续升高全身的NAD+。在这里，我们开发了一种创新的 方法，即，使用血清型辅助病毒依赖性腺病毒（HD-Ad 5）在RBC中过表达NAMPT 随后在小鼠模型中体内转导自体HSPC。我们假设纳普特 RBC中的过表达（OE）提供系统和持续的NAD+产生以增加代谢活性， 并抵消AD中的NAD+下降并改善AD状况。为了验证我们的假设，我们提出了 有两个具体目标。目的1将测试RBC中的Nampt OE可以系统地提高 代谢活跃的器官，并增强在细胞和有机体水平的代谢活性。我们将 通过含有Nampt基因的HD-Ad 5-Nampt载体在RBC中过表达Nampt， 检查NAD+水平和代谢在大脑和整个动物在一个长期的时间。目标2将测试 RBC中的Nampt OE可以抵消APP/PS1 AD小鼠模型中的NAD+下降并减轻AD病理。 使用不同的方法，我们将确定红细胞中Nampt OE对神经元变性、淀粉样变性和细胞凋亡的影响。 AD小鼠模型中的β（Aβ）负荷、成年神经发生、认知下降和痴呆。本申请是 在概念、假设和方法上具有高度创新性。使用遗传方法靶向红细胞进行治疗 除了血液系统中的遗传性疾病之外，AD可能会改变基因治疗的范式， 一种新的治疗策略根据我们的初步数据，我们的项目是高度可行的，因此， 以及对AD和其他脑部疾病的翻译意义。

Project Summary Alzheimer's Disease (AD) is a chronic neurological disorder causing cellular and organismal metabolic dysfunction, progressive memory decline and cognitive impairments. Nicotinamide adenine dinucleotide (NAD+) is an essential metabolite that is involved in cellular bioenergetics, genomic stability, mitochondrial homeostasis, adaptive stress responses, and cell survival. A growing body of evidence indicates that NAD+ decline is accompanied with progression of AD. In mammalian cells, the salvage pathway of NAD+ biosynthesis is the predominant pathway for NAD+ biosynthesis, where nicotinamide phosphoribosyltransferase (Nampt) is the rate- limiting enzyme. Thus, physiological means to systematically maintain elevated NAD+ levels to augment cellular metabolic activity in the brain may represent an efficient anti-AD intervention. Red blood cells (RBCs), differentiated from hematopoietic stem/progenitor cells (HSPCs) in bone marrow (BM) and release to blood circulation system after maturation, are the most abundant cell type in whole body, and thus, increase in NAD+ synthesis in these cells using genetic interventions may provide a physiological means for systematic and sustained elevation of NAD+ in whole body through the circulation system. Here we developed an innovative approach, i.e., using serotype helper-dependent adenovirus (HD-Ad5) to overexpress NAMPT in the RBCs following in vivo transduction of autologous HSPCs in mouse model. We hypothesize that Nampt overexpression (OE) in RBCs provides systematic and sustained NAD+ production to increase metabolic activity, and counteract NAD+ decline in AD and ameliorate AD conditions. To test our hypothesis, we propose the following two specific aims. Aim 1 will test that Nampt OE in RBCs can systematically elevates NAD+ levels in metabolically active organs and enhances metabolic activity at cellular and organismal levels. We will transduce HSPCs by HD-Ad5-Nampt vectors containing Nampt gene to overexpress Nampt in RBCs and subsequently examine the NAD+ levels and metabolism in the brain and whole animal over a long-term period. Aim 2 will test that Nampt OE in RBCs can counteract NAD+ decline and alleviate AD pathologies in APP/PS1 AD mouse model. Using different methods, we will determine the effect of Nampt OE in RBCs on neuronal degeneration, Amyloid β (Aβ) burden, adult neurogenesis, cognitive decline, and dementia in AD mouse model. This application is highly innovative in concept, hypothesis and approach. Targeting RBCs using genetic approach for the therapy of genetic diseases here AD other than in the blood system may change gene therapy paradigm and represents a novel therapeutic strategy. Our project is highly feasible based on our preliminary data, thus, has both scientific and translational significances for AD and other brain diseases.