Oxidative stress-induced vascular pathology and dysfunction in Alzheimer’s disease

项目总结/摘要 血管对认知障碍和痴呆的贡献（VCID）与阿尔茨海默病高度共病 疾病（AD），其中它加剧并加速功能缺陷。血管病理机制研究 其形成及其对脑功能的影响，特别是在AD中是有限的。开发平移成像， 应用于混合病理模型对于理解复杂的病理生理过程是必要的 连接VCID和AD。最近，我们修改和优化了氧化应激诱导的光血栓形成 靶向啮齿动物个体毛细血管的方案（即IV注射虎红染料的光活化）。的 这种新的血管氧化应激模型的主要优点是血管失速、闭塞， 使用多光子成像，可以真实的时间在活小鼠的单个毛细血管中跟踪微出血。在 对于R21，我们的目标是将该技术应用于5xFAD小鼠，以产生和表征新型AD/VCID小鼠 纤维连接蛋白是一种支持血管结构和完整性的基质蛋白， 脑血管疾病和AD引起的氧化应激的指标。我们正在进行的工作 对死后人脑标本的研究表明，星形胶质细胞衍生的纤连蛋白强烈共定位于 与氧化应激标志物硝基酪氨酸（NT），尤其是血管周围和Aβ沉积有关。 脑小动脉的光血栓形成显示纤维连接蛋白/NT共定位的积累， 血管内和附近的血管周围区域，类似于我们在人类AD脑组织中观察到的。这里我们 建议使用尖端的生理学方法，结合人类死后的大脑标本， 我们在桑德斯-布朗老龄化中心的世界级大脑银行，以测试氧化的假设， 应激--通过NT掺入纤维连接蛋白--加剧脑血管和突触 AD背景下的功能障碍。在目标1中，我们将确定微血管氧化应激对 WT和5xFAD小鼠的神经血管功能。多光子成像技术将用于应用和 实时观察微血管病变的发展，包括血管失速、血管阻塞、血管扩张、血管扩张和血管扩张。 闭塞（梗塞）和微出血以及它们对神经血管偶联的影响。小鼠脑 来自具有确认的血管病理学和AD病理学的人的组织和死后样本也将 用于评估纤连蛋白/NT与血管的相互作用，并交叉验证我们的新的 混合AD/VCID病理学的光血栓形成小鼠模型。在目标2中，我们将测试氧化的假设， 5xFAD小鼠中应激诱导的微血管病理导致认知的全面恶化， 在AD样病理学背景下的突触功能。拟议的研究将填补一个关键的知识空白 围绕脑血管病和AD病理后遗症的会聚。此外，委员会认为， 建立一种新的AD/VCID混合病理小鼠模型将有助于提供新的治疗策略 患有AD和血管病变的个体。

PROJECT SUMMARY/ ABSTRACT Vascular contributions to cognitive impairment and dementia (VCID) is highly comorbid with Alzheimer's disease (AD) where it exacerbates and hastens functional deficits. Mechanistic studies of vascular pathology formation and its effects on brain function, especially in AD, is limited. Developing translational imaging for application to mixed pathology models is necessary to understand the complex pathophysiological processes that link VCID and AD. Recently, we modified and optimized the oxidative stress-induced photothrombosis protocol (I.e. photoactivation of IV-injected Rose Bengal dye) for targeting individual capillaries in rodents. The major advantage of this novel vascular oxidative stress model is that vessel stalls, occlusion, and microhemorrhage can be followed in single capillaries in living mice, in real time, using multiphoton imaging. In this R21, we aim to apply this technique to 5xFAD mice to generate and characterize a novel AD/VCID mouse model en route to determining fibronectin— a matrix protein that supports vascular structure and integrity—as an indicator for the oxidative stress that arises from both cerebrovascular disease and AD. Our ongoing work on postmortem human brain specimens has revealed that astrocyte-derived fibronectin strongly colocalizes with the oxidative stress marker, nitrotyrosine (NT) especially around cerebrovessels and Aβ deposits. Photothrombosis of small cerebral arterioles revealed accumulation of fibronectin/NT colocalization at intravascular and nearby perivascular regions, similar to what we observe in human AD brain tissue. Here, we propose to use cutting edge physiology approaches combined with human postmortem brain specimens from our world class brain bank at the Sanders-Brown Center on Aging, to test the hypothesis that oxidative stress—indicated by NT incorporation into fibronectin— exacerbates cerebrovascular and synaptic dysfunction in the context of AD. In Aim 1, we will determine the effect of microvascular oxidative stress on neurovascular function in WT and 5xFAD mice. Multiphoton imaging techniques will be used to apply and to observe, in real-time, the development of microvascular pathologies including blood vessel stalls, vessel occlusion (infarct), and microhemorrhage as well as their effects on neurovascular coupling. Mouse brain tissues and postmortem samples from humans with confirmed vascular pathology and AD pathology will also be used to assess fibronectin/NT interactions with blood vessels, and to cross-validate our novel photothrombotic mouse model of mixed AD/VCID pathology. In Aim2, we will test the hypothesis that oxidative stress-induced microvascular pathology in 5xFAD mice leads to the global exacerbation of cognition and synaptic function in the context of AD-like pathology. The proposed studies will fill a critical knowledge gap surrounding the convergence of pathologic sequelae in cerebrovascular disease and AD. Moreover, establishment of a novel mouse model for mixed AD/VCID pathology will help inform new strategies for treating individuals with both AD and vascular pathology.