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）和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导致痴呆，或者AD病理是否触发微血管疾病，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，并最终积累为淀粉样蛋白斑块。A的聚集取决于浓度，因此增加A的产生或减少A的清除的事件可能是AD的触发因素。从大脑中清除A的主要途径是通过血管系统，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，在啮齿动物皮层中的个体、特异性靶向微血管中产生病变。我们现在提出检验微血管病变启动或加速A？积聚和淀粉样斑块形成的假设。为了进行这些研究，将使用飞秒激光照射损伤特定靶血管，导致形成微出血和/或阻止血流的凝块。我们将在表达淀粉样蛋白前体蛋白（Mo/HuAPP 695 swe）和突变型早老素1（PS1-dE 9）的转基因AD小鼠以及年龄匹配的对照组中，在单个皮质穿透性小动脉和毛细血管中产生微血管凝块和血栓。淀粉样蛋白斑块将通过全身注射甲氧基-X 04（一种刚果红衍生物）进行体内标记。在几天内每天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。死后用硫磺素-S和A？抗体标记将用于进一步阐明微血管病变对A？积累和淀粉样斑块形成的影响。在目标1中，我们测试微血管凝块和血管扩张是否触发血管树中不同位置病变的快速淀粉样斑块形成，以及淀粉样斑块相对于病变部位形成的位置。在目标2中，我们确定微血管病变后淀粉样蛋白斑块形成所需的时间，以及微血管病变引发的淀粉样蛋白斑块是否随时间稳定。在最后一个目标中，我们研究了动物的年龄，或预先存在的斑块负荷，如何影响微血管病变引起的淀粉样斑块的种植。在初步工作中，我们发现微血管凝块导致在一天内形成新的淀粉样蛋白斑块（3只动物中3/3凝块，见图7）。新的斑块形成在凝固的微血管和附近的实质组织。附近直径相似但未受损的血管未显示新的淀粉样斑块。这些初步结果表明，由于单个微血管闭塞导致的血流严重减少可触发淀粉样斑块形成。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。公共卫生相关性：阿尔茨海默病（AD）是老年痴呆症的主要原因，尽管最近的一些治疗方法适度减缓了疾病的进展，但没有治愈方法。临床研究表明，血管健康是AD患者严重程度的一个重要因素，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学工具的独特组合来直接研究大脑中的微血管凝块和血管扩张如何影响AD的发展，我们的初步结果表明，微血管功能障碍可能在启动AD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。