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

项目摘要/摘要 血管改变随着年龄的增长越来越常见，也是某些形式认知障碍的危险因素 包括阿尔茨海默病(AD)。特别是，脑部灌注的改变已经被广泛报道， 在皮质和边缘区域观察到与淀粉样蛋白积聚相关的血流减少 β斑块和含有tau的神经原纤维缠结。虽然不是由组成大脑的细胞表达的 血管系统，死后在血管内皮细胞内观察到神经元蛋白tau 组织切片强调了它可能直接影响内皮细胞的耐人寻味的可能性。在老鼠身上， Tau的过度表达似乎改变了血管密度，减少了平均血管直径，尤其是在 毛细血管床，增加血管被白细胞堵塞的发生率。这些发现可以解释，在 部分，阿尔茨海默病患者脑血流灌注改变，这可能是导致 认知能力下降。这个项目的总体目标是确定这些tau诱导的血管改变是如何 在小鼠身上观察到的结果会影响大脑灌注量，最终导致神经退化。将进行实验 在携带人P301L突变(Tg4510系)的衰老小鼠中过表达tau并在体内进展 成像方法。为了评估脑血流，将通过双光子对清醒小鼠进行关键测量。 显微镜检查包括红细胞流量、脑氧合和血液动力学反应。 视觉刺激范式。如果tau导致早期血管功能障碍，这将明显地表现为 血流动力学反应和组织氧合不良，这将导致随后的神经元丢失。此外， 血流灌注减少的部分原因可以通过观察到血管被白细胞堵塞来解释。一秒钟内 一组实验，将使用一种新的颅窗端口方法来管理标记的tau和蛋白质 直接进入实质以确定tau是否足以增加细胞黏附分子的表达 (CAMs)，并通过白细胞诱导血管阻塞。这些调查还将利用 多西环素可抑制启动子关闭小鼠tau的表达并确定内皮细胞的变化 CaM的表达和白细胞的阻断是可逆的，这是一个重要的发展考虑因素 有针对性的治疗方法。这些研究的发现将进一步加深我们对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更广泛地说，这有 阿尔茨海默氏症以外的广泛影响。最后，通过利用磁共振成像方法 为评估体内肿瘤微血管而开发，我们有一个独特的机会来验证 这些技术在神经退行性疾病模型中使我们可以直接将转基因 老鼠对人类AD的研究。！ 好了！

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.! !