The effect of circadian rhythm disruptions on the angiogenic response to hypoperfusion in the AD brain

项目概要/摘要 尽管阿尔茨海默病 (AD) 的病理生理学是复杂且多因素影响的，但血管合并症 近三分之二的 AD 患者出现脑血管供血不足。然而，脑血管如何 营养不足与 AD 的相互作用和促成因素仍知之甚少。最近，脑血管组（即 脑内皮细胞和周细胞的转录组谱）已被提议作为一个概念 研究中枢神经系统疾病血管机制的框架。回应 RFA-AG-23-014（机制 AD/ADRD 中的脑灌注不足），我们建议检验脑血管供血不足的假设 扰乱 AD 脑血管，最终导致认知障碍。 正常大脑通过诱导内源性血管重塑来补偿灌注不足 血管生成。 AD 的存在会干扰内源性血管生成和血管恢复反应 导致灌注不足，这会加剧 AD 的进展并使 AD 脑血管恶化。因为 已知昼夜节律和昼夜节律基因可调节血管生成，我们进一步假设 AD 破坏脑血管的昼夜节律稳态，从而干扰内源性血管生成 对低灌注的反应。 研究 AD、血管反应和昼夜节律之间的相互作用的重要性在于 我们的试点数据强调了这一点。例如，我们发现大脑的转录组谱存在更大的差异。 在活动（清醒）阶段进行测试时，野生型小鼠与 AD 小鼠的内皮细胞和周细胞进行了比较 到非活动（睡眠）阶段。为了检验我们的假设，我们提出了三个综合目标。目标 1 将显示 AD 大脑因灌注不足而表现出较低的代偿性血管生成能力，目标 2 将表明 AD 大脑中的昼夜节律被打乱，并且昼夜节律被打乱会抑制 血管生成反应。最后，目标 3 将检查重新正常化昼夜节律是否可以改善 脑血管组并促进 AD 小鼠灌注不足后的血管生成。 AD 大脑在脑灌注不足后是否以及如何失去代偿性血管生成能力尚不清楚。 因此，我们设计了一个多学科多实验室项目，通过研究如何填补这一知识空白。 昼夜节律的扰动会破坏脑血管并加剧 AD 的低灌注。

PROJECT SUMMARY/ABSTRACT Although the pathophysiology of Alzheimer’s Disease (AD) is complex and multifactorial, vascular comorbidities and cerebrovascular insufficiency occur in almost two-thirds of AD patients. However, how cerebrovascular insufficiency interacts with and contributes to AD remains poorly understood. Recently, the brain vasculome (i.e. transcriptome profiles of cerebral endothelial cells and pericytes) has been proposed as a conceptual framework to investigate vascular mechanisms in CNS diseases. In response to RFA-AG-23-014 (Mechanisms of Brain Hypoperfusion in AD/ADRD), we propose to test the hypothesis that cerebrovascular insufficiency perturbs the AD brain vasculome, eventually leading to cognitive impairment. The normal brain compensates for hypoperfusion by inducing endogenous vascular remodeling and angiogenesis. The presence of AD interferes with endogenous angiogenesis and vascular recovery in response to hypoperfusion, and this exacerbates AD progression and worsens the AD brain vasculome. Because circadian rhythms and circadian genes are known to regulate angiogenesis, we further hypothesize that AD disrupts circadian homeostasis in the brain vasculome, thus interfering with the endogenous angiogenic response to hypoperfusion. The importance of investigating these interactions between AD, vascular responses, and circadian rhythms is emphasized by our pilot data. For example, we show a greater difference in transcriptome profiles of cerebral endothelial cells and pericytes of wild-type vs AD mice when tested during the active (awake) phase compared to the inactive (sleep) phase. For testing our hypotheses, we propose three integrated aims. Aim 1 will show that AD brains exhibit a lower capacity of compensatory angiogenesis in response to hypoperfusion, and Aim 2 will show that circadian rhythms are disrupted in AD brains and that disrupted circadian rhythms suppress angiogenic response. And finally, Aim 3 will examine whether re-normalizing circadian rhythms improves the brain vasculome and promotes angiogenesis after hypoperfusion in AD mice. Whether and how AD brains lose compensatory angiogenesis capacity after cerebral hypoperfusion is unknown. Therefore, we have designed a multi-disciplinary multi-lab project to fill this gap of knowledge by examining how perturbations in circadian rhythms disrupt the brain vasculome and worsen hypoperfusion in AD.