Transgenic Mice, Inflammation & the Alzheimer Phenotype

描述（由申请人提供）：迄今为止，阿尔茨海默病（AD）抵抗旨在减缓疾病进展的治疗方法。减少脑淀粉样蛋白及其后果是积极发展的一种治疗策略。限制淀粉样蛋白引起的损害的一种建议方法是使用基因疗法增加淀粉样蛋白清除率。Neprilysin是一种主要的淀粉样蛋白降解蛋白酶，也是抗淀粉样蛋白基因治疗的主要候选酶。目前，将治疗性基因引入大脑仅限于将病毒载体直接注入大脑的神经外科手术。除了手术风险外，这些方法只会影响大脑的一小部分。尽管许多中枢神经系统疾病可能受益于这种方法，但阿尔茨海默病的广泛病理分布使得通过肺实质内注射给药具有挑战性。作为另一种递送方法，我们建议评估单核细胞（通常在血液中发现的细胞）作为载体将治疗基因运输到大脑的使用。单核细胞基因治疗有几个优点。神经退行性疾病引起神经损伤和局部炎症。循环单核细胞自然地回到这些炎症部位并集中在这些区域。这正是治疗基因最有效的地方。由于转染的单核细胞寿命有限，如果发生不良反应，该治疗是可逆的。病人自己的细胞可以被收集起来使用，减少免疫反应的可能性。单核细胞通常处于有丝分裂后，转染方法不会将新的DNA整合到基因组中，从而降低了肿瘤发生的风险。所涉及的程序相对较小，只涉及静脉抽血和输液。在这个应用中，我们打算证明在淀粉样蛋白沉积的转基因小鼠模型中使用单核细胞基因治疗的可行性。我们将利用我们之前的努力来了解脑巨噬细胞在清除淀粉样斑块中的作用，我们的初步数据显示了使用转染单核细胞进行neprilysin基因治疗的益处。我们将确定最佳的单核细胞片段用于单核细胞基因治疗中枢神经系统。我们将确定单核细胞运输到淀粉样蛋白沉积小鼠中枢神经系统的动力学，以制定最佳给药策略。我们将指定几种可能的机制是活跃的清除淀粉样蛋白沉积使用基因工程，分泌形式的neprilysin。最后，我们将测试其他几种淀粉样蛋白降解蛋白酶，以评估它们是否可能是单核细胞基因治疗AD的有用候选者。小鼠模型的成功可能很快导致类似的基因治疗方法在阿尔茨海默病患者身上的测试。迄今为止，阿尔茨海默病（AD）一直抵制旨在减缓疾病进展的治疗方法。减少脑淀粉样蛋白及其后果是积极发展的一种治疗策略。限制淀粉样蛋白引起的损害的一种建议方法是使用基因疗法增加淀粉样蛋白清除率。在这个应用中，我们打算证明在淀粉样蛋白沉积的转基因小鼠模型中使用单核细胞作为基因治疗载体的可行性，单核细胞是炎症部位的天然宿主细胞。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) has, thus far, resisted therapeutic approaches designed to slow disease progression. Reducing brain amyloid and its consequences is a therapeutic strategy in active development. One proposed means of limiting the damage caused by amyloid is to increase the rate of amyloid clearance using gene therapy. Neprilysin is a major amyloid degrading protease, and a prime candidate for use in anti-amyloid gene therapy. At present, the introduction of therapeutic genes to the brain has been limited to neurosurgical procedures which inject viral vectors directly into the brain. In addition to surgical risks, only small portions of the brain are impacted by these methods. Although many CNS disorders will likely benefit from this approach, the broad distribution of pathology in AD makes delivery of therapeutics by intraparenchymal injections challenging. As an alternative delivery method, we propose to evaluate the use of monocytes, cells normally found in blood, as vectors to transport therapeutic genes to the brain. There are several advantages of monocyte gene therapy. Neurodegenerative disorders cause neural injury and localized inflammation. Circulating monocytes naturally home to these sites of inflammation and concentrate in these areas. This is precisely where the therapeutic gene can be most effective. The therapy is reversible in the event an adverse reaction ensues due to the limited lifespan of the transfected monocytes. The patient's own cells may be harvested for use, reducing the possibility of immune reactions. The monocytes are generally post-mitotic and the transfection method does not integrate new DNA into the genome, reducing the risk of oncogenesis. The procedures involved would be relatively minor, involving intravenous blood withdrawal and reinfusion. In this application we intend to prove the feasibility of using monocyte gene therapy in a transgenic mouse model of amyloid deposition. We will exploit our prior efforts to understand the role of brain macrophages in clearing amyloid plaques, and our preliminary data showing the benefits of neprilysin gene therapy using transfected monocytes. We will identify the best monocyte fraction to use for monocyte gene therapy of the CNS. We will determine the kinetics of monocyte trafficking into the CNS of amyloid depositing mice to develop optimal dosing strategies. We will specify which of several possible mechanisms are active in clearing the amyloid deposits using a genetically engineered, secreted form of neprilysin. Finally, we will test several other amyloid degrading proteases to evaluate whether they may be useful candidates for monocyte gene therapy for AD. Success in the mouse model may rapidly lead to tests of similar gene therapy approaches in AD patients. Alzheimer's disease (AD) has, thus far, resisted therapeutic approaches designed to slow disease progression. Reducing brain amyloid and its consequences is a therapeutic strategy in active development. One proposed means of limiting the damage caused by amyloid is to increase the rate of amyloid clearance using gene therapy. In this application we intend to prove the feasibility of using monocytes, cells which naturally home to sites of inflammation, as carriers for gene therapy in a transgenic mouse model of amyloid deposition.