Targeting microglial cell iron-handling in Alzheimer’s Disease

项目摘要 阿尔茨海默病（AD）是痴呆症的最常见原因，并且其发病率持续上升。这 神经退行性疾病与细胞外淀粉样蛋白β（Aβ斑块）的积累有关， 神经元内tau蛋白缠结，其导致神经元损失的渐进级联变化， 萎缩和认知能力下降然而，并非所有表现出AD相关改变的个体（即，Aβ 斑块）发展为临床痴呆，这表明其他会聚性病理学协同作用有助于推动痴呆的发生。 疾病越来越多的证据表明，神经炎症和小胶质细胞 在AD患者的大脑中激活。我们和其他人已经明确表明，这些AD中的铁负荷增加- 相关的小胶质细胞，脑铁含量增加与更大的Aβ斑块沉积相关， 认知能力恶化有趣的是，我的初步体外研究表明， 它们在年龄和Aβ诱导的炎症期间的铁处理功能。这些细胞优先上调 亚铁输入者，二价金属转运蛋白1（DMT 1）响应于Aβ，允许输入高度 活性铁，如果过量，可能会加重炎症。然而，许多著名的协会 体内细胞铁负荷和小胶质细胞炎症之间的关系已经显示在疾病晚期， 人类和动物模型，目前尚不清楚是否早期改变小胶质细胞铁稳态 导致下游炎症和疾病功能障碍。因此，该项目旨在针对一个关键的 铁处理功能的小胶质细胞在早期症状前阶段，以确定如何 小胶质细胞铁处理和相关的炎症状态有助于疾病进展。这么做我 将利用一种新的转基因小鼠模型，在AD背景下改变小胶质细胞铁处理 鼠标线。在抑制小胶质细胞DMT 1-我们的AD小鼠模型中的关键铁进口商-之后，我将 评估认知和记忆能力、神经炎症标志物以及脑铁和Aβ斑块负荷。 行为分析、免疫组化方法和无偏倚的基因表达分析将是 进行评估操纵小胶质细胞铁处理对与AD进展相关的标志物的影响。 最终，该项目旨在解决该领域对早期小胶质细胞的理解中的一个关键空白。 AD的功能障碍。我假设在疾病进展的早期抑制小胶质细胞DMT 1， 将阻止过度和慢性Aβ诱导的铁输入，从而减少下游炎症 并改善AD的标志物。除了该项目的科学目标外， 进行这项工作将支持我成为一名独立的学术研究人员的长期目标 和导师具体而言，所提出的培训计划强调培养技术、分析和 在学术界取得成功所需的沟通技巧。跨学科，协作， 范德比尔特大学的良好环境为该项目的成功奠定了坚实的基础。

Project Summary Alzheimer’s Disease (AD) is the most common cause of dementia, and its incidence continues to rise. This neurodegenerative disease is associated with the accumulation of extracellular amyloid beta (Aβ plaques) and intraneuronal tau tangles, which contribute to a progressive cascade of changes leading to neuronal loss, brain atrophy, and cognitive decline. However, not all individuals who exhibit AD-associated alterations (i.e., Aβ plaques) develop clinical dementia, suggesting other convergent pathologies that synergize to help drive the disease. Increasing evidence demonstrates the significant presence of neuroinflammation and microglial activation in the brains of AD patients. We and others have specifically shown enhanced iron load in these AD- associated microglia, and increased brain iron content is associated with greater Aβ plaque deposition and worsened cognitive decline. Interestingly, my preliminary in vitro studies suggest that microglia specifically shift their iron-handling function in age and during Aβ-induced inflammation. These cells preferentially upregulate the ferrous iron importer, divalent metal transporter 1 (DMT1) in response to Aβ, allowing the import of highly reactive iron which could worsen inflammation if in excess. However, much of the prominent associations between cellular iron load and microglial inflammation in vivo have been shown in late disease stages in humans and animal models, and it is not known whether early alterations in microglial iron homeostasis contribute to downstream inflammation and disease dysfunction. Thus, this project aims to target a critical iron-handling function of microglial cells at an early pre-symptomatic stage of AD to determine how microglial iron handling and linked inflammatory status contribute to disease progression. To do this, I will utilize a novel transgenic mouse model with altered microglial iron-handling on the background of an AD mouse line. Following inhibition of microglial DMT1 – the key iron importer in our AD mouse model –, I will assess cognition and memory performance, markers of neuroinflammation, and brain iron and Aβ plaque load. Behavioral assays, immunohistochemical approaches, and unbiased gene expression analyses will be performed to assess the effect of manipulating microglial iron-handling on markers related to AD progression. Ultimately, this project seeks to address a critical gap in the field’s understanding of early microglial cell dysfunction in AD. I hypothesize that inhibiting microglial DMT1 early during the progression of disease will disallow excessive and chronic Aβ-induced iron import, and thus reduce downstream inflammation and improve markers of AD. In addition to the scientific goals of the project, the training received while conducting this work will support my long-term goal of becoming an independent academic researcher and mentor. Specifically, the training plan set forth places emphasis on fostering the technical, analytical, and communication skills needed to achieve a successful career in academia. The interdisciplinary, collaborative, and supportive environment at Vanderbilt University provides a strong foundation for this project to succeed.