Assessing the Functional Consequences of Tau-Related Vasculature Changes using In Vivo Imaging

项目概要/摘要 随着年龄的增长，血管变化越来越常见，并且是某些形式的认知障碍的风险因素 包括阿尔茨海默病（AD）。特别是，脑灌注的改变已被广泛报道， 在皮质和边缘区域观察到与淀粉样蛋白积累相关的血流减少 β斑和含tau的神经元缠结。虽然大脑中的细胞不表达 在死后，在血管内皮内观察到神经元蛋白tau 组织切片突出了它可能直接影响内皮细胞的有趣的可能性。在小鼠中， tau蛋白的过表达似乎改变了血管密度，降低了平均血管直径，特别是在血管壁内。 毛细血管床，并增加白细胞阻塞血管的发生率。这些发现可以解释，在 部分，阿尔茨海默病患者的脑灌注改变，这可能是一个关键因素， 认知能力下降该项目的总体目标是确定这些tau蛋白诱导的血管改变如何 在小鼠中观察到的影响脑灌注，并最终影响神经变性。将进行实验 在携带人P301 L突变（Tg 4510系）并在体内进展的老化tau过表达小鼠中， 成像方法为了评估脑灌注，将通过双光子成像在清醒小鼠中进行关键测量。 显微镜检查，包括红细胞流量，脑氧合，并使用 视觉刺激范式如果tau蛋白诱导早期血管功能障碍，那么通过降低血管内皮细胞的活性将是明显的。 血液动力学反应和不良的组织氧合，这将导致随后的神经元损失。此外，本发明还 通过观察到白细胞阻塞血管可以部分解释灌注减少。在第二 一组实验中，一种新的颅窗端口方法将用于管理标记的tau和蛋白质 以确定tau是否足以增加细胞粘附分子的表达 （CAM）并通过白细胞诱导血管阻塞。这些调查还将利用 强力霉素抑制性启动子关闭小鼠tau蛋白表达，并确定内皮细胞 CAM表达和白细胞阻断是可逆的，这是发展的重要考虑因素。 有针对性的治疗。这些研究的发现将进一步加深我们对非哺乳动物中tau生物学的理解。 神经元亚型以及血管改变对大脑健康的影响， 广泛的影响超出了阿尔茨海默病。最后，通过利用磁共振成像方法 开发用于评估体内肿瘤微血管，我们有一个独特的机会来验证使用 这些技术在神经退行性疾病模型中， 老鼠的工作到人类的AD研究。 !

Project Summary/Abstract Vascular changes are increasingly common with age and a risk factor for some forms of cognitive impairment including Alzheimer's disease (AD). In particular, alterations to cerebral perfusion have been widely reported, with decreased blood flow observed in cortical and limbic regions associated with the accumulation of amyloid beta plaques and tau-containing neurofibrillary tangles. Though not expressed by cells that make up cerebral vasculature, the neuronal protein tau has been observed inside of the vascular endothelium in post mortem tissue sections highlighting the intriguing possibility that it may directly affect endothelial cells. In mice, overexpression of tau appears to alter vascular density, reduce average vessel diameter particularly within the capillary bed, and increase the incidence of vessels blocked by leukocytes. These findings could explain, in part, altered cerebral perfusion changes in Alzheimer's disease patients, which may be a key contributor to cognitive decline. The overall goal of this project is to determine how these tau-induced vascular alterations observed in mice affect cerebral perfusion and, ultimately, neurodegeneration. Experiments will be carried out in aging tau overexpressing mice carrying the human P301L mutation (Tg4510 line) and advanced in vivo imaging methods. To assess cerebral perfusion, key measurements will be made in awake mice by two-photon microscopy including red blood cell flow, cerebral oxygenation, and of the hemodynamic response using a visual stimulation paradigm. If tau induces early vascular dysfunction, it will be evident by a reduction in hemodynamic response and poor tissue oxygenation, which will lead to subsequent neuron loss. Further, reduced perfusion could be partially explained by the observation of vessels block by leukocytes. In a second set of experiments, a novel cranial window port method will be used to administer labeled tau and protein directly into the parenchyma to determine if tau is sufficient to increase expression of cell adhesion molecules (CAMs) and induce blood vessel blockages by leukocytes. These investigations will also make use a doxycycline repressible promoter to turn off tau expression in mice and determine if changes in endothelial CAM expression and leukocyte blockage is reversible, which is an important consideration for the development of targeted therapeutics. Findings from these studies will further our understanding of tau biology in non- neuronal subtypes as well as the impact of vascular alterations on brain health more generally, which has broad implications beyond Alzheimer's disease. Finally, by utilizing magnetic resonance imaging methods developed for assessing tumor microvasculature in vivo, we have a unique opportunity to validate the use of these techniques in a neurodegenerative disease model such that we can directly translate the transgenic mouse work to human AD research.! !