Role of Cortical Microvascular Lesions in Amyloid-Beta Accumulation

皮质微血管病变在β-淀粉样蛋白积累中的作用

• 批准号: 7826969
• 负责人: CHRIS B SCHAFFER
• 金额: $ 18.24万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-15 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7826969
• 关键词: Address; Affect; Age; Alzheimer disease prevention; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein Precursor; Amyloid deposition; Animals; Antibodies; Biological; Birth; Blood Vessels; Blood capillaries; Blood flow; Brain; Caliber; Cells; Cerebrum; Chronic; Clinical; Clinical Data; Clinical Research; Coagulation Process; Congo Red; Data; Dementia; Deposition; Development; Diabetic Angiopathies; Disease; Disease Progression; Elderly; Event; Excision; Figs - dietary; Fluorescence; Fluorescence Microscopy; Functional disorder; Gene Mutation; Health; Hemorrhage; Hour; Image; Individual; Inflammation; Inherited; Injection of therapeutic agent; Injury; Investigation; Label; Lasers; Lead; Lesion; Life; Link; Location; Measures; Microscopy; Mus; Optical Methods; Optics; Pathogenesis; Pathology; Pathway interactions; Patients; Peptides; Play; Presenile Alzheimer Dementia; Production; Proteins; Reactive Oxygen Species; Relative (related person); Rodent; Role; Seeds; Senile Plaques; Severities; Site; Techniques; Testing; Time; TimeLine; Tissues; Transgenic Mice; Transgenic Organisms; Traumatic Brain Injury; Trees; Vascular Dementia; Vascular Diseases; Work; abeta accumulation; amyloid pathology; arteriole; capillary; in vivo; injured; irradiation; mouse model; mutant; neurotoxic; prevent; public health relevance; research study; tool; two-photon

DESCRIPTION (provided by applicant): Clinical evidence suggests a strong link between Alzheimer's disease (AD) and cerebral microvascular dysfunction, but it remains unclear whether they contribute independently to dementia, or if AD pathology triggers microvascular disease, or vice versa. In AD, amyloid-¿ (A¿) peptides aggregate to form neurotoxic oligomers and eventually accumulate as amyloid plaques. Aggregation of A¿ depends on concentration, so events that increase production or decrease clearance of A¿ could be triggers for AD. A major pathway for the removal of A¿ from the brain is through the vasculature, suggesting that microvascular lesions could interfere with A¿ clearance. In addition, vascular lesions can lead to increased reactive oxygen species and to inflammation, which are linked to A¿ increase. We recently developed optical methods to create lesions in individual, specifically-targeted microvessels in rodent cortex. We now propose to test the hypothesis that microvascular lesions initiate or accelerate A¿ accumulation and amyloid plaque formation. To perform these studies, femtosecond laser irradiation will be used to injure a specifically targeted blood vessel, causing the formation of a microhemorrhage and/or of a clot that stops blood flow. We will produce microvascular clots and hemorrhages in individual cortical penetrating arterioles and capillaries in transgenic AD mice that express amyloid precursor protein (Mo/HuAPP695swe) and mutant presenilin1 (PS1-dE9), as well as in age-matched controls. Amyloid plaques will be labeled in vivo with systemic injections of methoxy-X04, a Congo-red derivative. The location of the lesions will be imaged daily over several days with two-photon excited fluorescence microscopy to determine the persistence of the occlusion or hemorrhage and the presence of previously existing and new amyloid plaques. Post-mortem labeling with thioflavin-S and A¿ antibodies will be used to further elucidate the impact of the microvascular lesion on A¿ accumulation and amyloid plaque formation. In Aim 1, we test whether microvascular clots and hemorrhages trigger rapid amyloid plaque formation for lesions at different locations in the vascular tree, and where amyloid plaques form relative to the lesion site. In Aim 2, we determine the time required for amyloid plaques to form following microvascular lesions and whether amyloid plaques that are initiated by microvascular lesions are stable over time. In the final Aim, we investigate how the age of the animal, or the pre-existing plaque burden, influences the seeding of amyloid plaques by microvascular lesions. In preliminary work, we found that microvascular clots led to the formation of new amyloid plaques within one day (3/3 clots in 3 animals, see Fig. 7). New plaques were formed both on the clotted microvessel and in the nearby parenchymal tissue. Nearby vessels of similar diameter that were not lesioned showed no new amyloid plaques. These initial results indicate that a severe decrease in blood flow resulting from the occlusion of a single microvessel can trigger amyloid plaque formation. These data suggest that microvascular clots could play an important role in Alzheimer's disease pathogenesis. PUBLIC HEALTH RELEVANCE: Alzheimer's disease (AD) is the leading cause of dementia in the elderly and although some recent treatments modestly slow progression of disease, there is no cure. Clinical research has shown that vascular health is an important factor in the severity of AD in patients, yet the mechanisms that link vascular dysfunction and AD remain unclear. This work uses a unique combination of optical and biological tools to directly study how microvascular clots and hemorrhages in the brain affect the development of AD and our preliminary results show that microvascular dysfunction may play a role in initiating AD, suggesting that successful AD prevention will depend on treatment of vascular disease.

描述（由申请人提供）：临床证据表明阿尔茨海默病 (AD) 与脑微血管功能障碍之间存在密切联系，但尚不清楚它们是否独立地导致痴呆，或者 AD 病理是否会引发微血管疾病，反之亦然。在 AD 中，淀粉样蛋白 (A¿) 肽聚集形成神经毒性寡聚体，并最终积聚为淀粉样斑块。 A¿ 的聚集取决于浓度，因此增加 A¿ 产量或减少 A¿ 清除率的事件可能会触发 AD。从大脑中清除 A¿ 的主要途径是通过脉管系统，这表明微血管病变可能会干扰 A¿ 的清除。此外，血管病变可导致活性氧增加和炎症，这与 A¿ 增加有关。我们最近开发了光学方法，可以在啮齿动物皮层的个体、特定目标微血管中产生损伤。我们现在提议检验以下假设：微血管病变启动或加速A¿积累和淀粉样斑块形成。为了进行这些研究，将使用飞秒激光照射来损伤特定的目标血管，导致微出血和/或阻止血流的凝块的形成。我们将在表达淀粉样前体蛋白 (Mo/HuAPP695swe) 和突变早老素 1 (PS1-dE9) 的转基因 AD 小鼠以及年龄匹配的对照小鼠的个体皮质穿透小动脉和毛细血管中产生微血管凝块和出血。淀粉样斑块将通过全身注射甲氧基-X04（一种刚果红衍生物）进行体内标记。将在几天内每天使用双光子激发荧光显微镜对病变的位置进行成像，以确定闭塞或出血的持续性以及先前存在的和新的淀粉样斑块的存在。死后用硫黄素-S 和 A¿ 抗体进行标记将用于进一步阐明微血管病变对 A¿ 积累和淀粉样蛋白斑形成的影响。在目标 1 中，我们测试微血管凝块和出血是否会触发血管树中不同位置病变的淀粉样斑块快速形成，以及淀粉样斑块相对于病变部位的形成位置。在目标 2 中，我们确定微血管病变后淀粉样斑块形成所需的时间，以及微血管病变引发的淀粉样斑块是否随时间稳定。在最终目标中，我们研究了动物的年龄或预先存在的斑块负担如何影响微血管病变引起的淀粉样斑块的播种。在初步工作中，我们发现微血管凝块导致一天内形成新的淀粉样斑块（3只动物中有3/3的凝块，见图7）。在凝结的微血管和附近的实质组织中都形成了新的斑块。附近直径相似且未受损的血管未显示出新的淀粉样斑块。这些初步结果表明，单个微血管闭塞导致的血流量严重减少可以引发淀粉样斑块的形成。这些数据表明微血管凝块可能在阿尔茨海默病的发病机制中发挥重要作用。公共健康相关性：阿尔茨海默病 (AD) 是老年人痴呆的主要原因，尽管最近的一些治疗方法可以适度减缓疾病的进展，但无法治愈。临床研究表明，血管健康是导致 AD 患者严重程度的重要因素，但血管功能障碍与 AD 之间的联系机制仍不清楚。这项工作使用光学和生物工具的独特组合来直接研究大脑中的微血管凝块和出血如何影响 AD 的发展，我们的初步结果表明微血管功能障碍可能在 AD 的引发中发挥作用，这表明成功的 AD 预防将取决于血管疾病的治疗。