Potentiation of CAA-mediated endothelial dysfunction by cardiovascular risk factors

项目概要/摘要 脑血管系统的损伤显著促进阿尔茨海默病（AD）和痴呆。在 除了脑淀粉样血管病（CAA），这是目前在超过90%的AD患者和许多 认知正常的老年人，慢性心血管（CV）风险因素也已知会损害大脑 微血管功能。然而，CAA和慢性CV危险因素的相互作用性质以及 它们导致脑血管功能障碍和认知能力下降的机制很差 明白我们的初步工作确定了负责淀粉样蛋白β（Aβ）介导的 脑内皮功能障碍我们建议澄清Aβ和过度表达/激活之间的相互作用， TRAIL（TNF相关凋亡诱导配体）死亡受体（DR）DR 4和DR 5， 对细胞应激/死亡的巨大影响。DR激活触发线粒体功能障碍，释放前- 凋亡因子和活性氧（ROS）。有趣的是，慢性CV风险因素与 脑血管病理学，如灌注不足、高血压和高同型半胱氨酸血症（HHC）， 导致类似的EC死亡和线粒体功能障碍途径。我们将检验这个假设， 慢性心血管风险因素，如高血压、HHC和低灌注，协同增强了心血管疾病的风险。 脑血管Aβ在CAA中的作用，增强TRAIL DR活化和线粒体功能障碍 在脑内皮细胞中，从而导致阿尔茨海默病的神经血管单位衰竭。在 目的1、利用体外培养的人脑内皮细胞，验证慢性心血管病危险因素 增加内皮细胞对Aβ的脆弱性，增强DR-和BRA-介导的途径。我们将 分析低灌注和HHC对Aβ介导的内皮DR激活的相对贡献， 线粒体毒性和血脑屏障通透性的研究。在目标2中， 我们将在体内检验慢性心血管危险因素增强DR和AKA介导的 内皮功能障碍和增加脑血管淀粉样蛋白负荷， 导致神经血管和认知障碍。我们将在Tg 2576小鼠中评估这些机制 在发生CAA之前或之后暴露于慢性CV风险因素（高血压或HHC）。我们将 检查这些应激途径对BBB功能障碍、微血管形成、淀粉样蛋白沉积 神经免疫激活和认知功能。在目标3中，我们将检验以下假设： 减少DR激活（DR沉默）和线粒体功能障碍（碳酸酐酶抑制剂）将 预防或逆转由Aβ和慢性炎症联合诱导的内皮损伤和BBB通透性 脑血管挑战伴随CV风险。这项研究将揭示可改变的分子机制 潜在的混合性脑血管疾病和痴呆，这对临床实践有巨大的影响， 公共卫生

Project Summary/Abstract Damage to the brain vasculature significantly contributes to Alzheimer's disease (AD) and dementia. In addition to Cerebral Amyloid Angiopathy (CAA), which is present in more than 90% of AD patients and in many cognitively normal elderly people, chronic cardiovascular (CV) risk factors are also known to impair brain microvascular function. However, the interactive nature of CAA and chronic CV risk factors and the mechanisms through which they contribute to cerebrovascular dysfunction and cognitive decline are poorly understood. Our preliminary work identified molecular mechanisms responsible for amyloid beta (Aβ)-mediated brain endothelial dysfunction. We propose to clarify the interplay between Aβ and overexpression/activation of the TRAIL (TNF-related apoptosis inducing ligand) death receptors (DR) DR4 and DR5, unexplored targets of enormous impact for cell stress/death. DR activation triggers mitochondrial dysfunction, with release of pro- apoptotic factors and reactive oxygen species (ROS). Intriguingly, chronic CV risk factors associated with cerebrovascular pathology, such as hypoperfusion, hypertension and hyperhomocysteinemia (HHC), contribute to similar EC death and mitochondrial dysfunction pathways. We will test the hypothesis that chronic CV risk factors, such as hypertension, HHC, and hypoperfusion, synergistically potentiate the effects of cerebrovascular Aβ in CAA, enhancing TRAIL DR activation and mitochondrial dysfunction in cerebral endothelial cells, and thus leading to neurovascular unit failure in Alzheimer's disease. In Aim 1, using human cerebral endothelial cells in vitro, we will test the hypothesis that chronic CV risk factors increase endothelial vulnerability to Aβ, potentiating DR- and mitochondria-mediated pathways. We will analyze the relative contribution of hypoperfusion and HHC to Aβ-mediated endothelial DR activation, mitochondrial toxicity and BBB permeability through molecular, biochemical and imaging approaches. In Aim 2, we will test in vivo the hypothesis that chronic CV risk factors potentiate DR- and mitochondria-mediated endothelial dysfunction and increase cerebrovascular amyloid burden in a mouse model of amyloidosis, contributing to neurovascular and cognitive impairment. We will assess these mechanisms in Tg2576 mice exposed to chronic CV risk factors (hypertension or HHC) before or after the development of CAA. We will examine the effects of these stress pathways on BBB dysfunction, microhemorrhages, amyloid deposition, neuroimmune activation, and cognitive function. In Aim 3 we will Test the hypothesis that manipulations that decrease DR activation (DR silencing) and mitochondrial dysfunction (carbonic anhydrase inhibitors) will prevent or reverse endothelial damage and BBB permeability induced by the combination of Aβ and chronic cerebrovascular challenges that occur with CV risk. This study will reveal modifiable molecular mechanisms underlying mixed cerebrovascular disease and dementia, which have enormous impact on clinical practice and public health.