Targeting intramural von Willebrand factor (VWF) to improve vasomotor function, enhance brain parenchymal clearance, & delay development of cerebral amyloid angiopathy (CAA) in conditions of amyloid

总结。 脑血管系统对抗体和其他溶质从脑间质液(ISF)中的清除起着至关重要的作用。这个 下面的建议研究了von Willebrand因子(Vwf)在软脑膜壁中的病理作用。 动脉和小动脉，特别关注其损害脑血管功能和血管介导性疾病的可能性 淀粉样变性条件下的清除。VWF仅在血管内皮细胞和血小板中表达，并被广泛 因其在止血和血栓形成中的作用而被公认。血管中细胞外VWF的存在通常是 仅限于管腔内皮细胞表面和直接的内皮下基质。然而，在某些病理状态下， VWF存在于血管壁内(即壁内VWF)，在那里它促进了平滑肌的增殖和壁 变厚了。重要的是，我们和其他人已经证明，VWF的缺失可以深刻地防止这种血管重构。我们的 初步数据现在将室壁内VWF的作用扩展到AD和CAA。我们展示了VWF的存在 在人类AD和CAA患者的大脑动脉和小动脉的平滑肌区内 小鼠淀粉样变性模型的软脑膜动脉(LMA)。我们进一步表明，抗体多肽促进增加 VWF在人脑内皮细胞中的表达，支持淀粉样变性在VWF积聚中的贡献作用 脉管壁。基于这些发现，我们提出了总体假设，即Ab对基底侧向的增加有贡献 血管内皮细胞释放VWF，触发血管平滑肌增殖和随后的管壁增厚并伴有狭窄 软脑膜动脉和皮质小动脉。我们还建议，校内VWF的后果包括 脑血管功能障碍、抗体肽脑清除障碍和脑血管病变的加速 (CAA)和相关的功能后果。我们建议进行研究以a)定义内壁VWF的机制 导致病理性LMA重塑和抗体清除受损，以及b)评估减少壁内的新策略 VWF可减轻淀粉样变性的血管相关病理。在目标1中，我们将检验如下假设： 基底外侧血管内皮细胞释放VWF增加，从而触发血管平滑肌增殖和随后的壁 增厚，LMA和皮质小动脉变窄。我们将结合人类细胞培养研究和 选择性脑血管内皮细胞VWF基因敲除后TgAPP小鼠模型的活体研究。在目标2中，我们将测试 假设脑内皮细胞VWF的减少将通过改善跨内皮细胞而导致抗体清除增加 和血管旁清除机制。我们将评估不同药物对脑内皮细胞中VWF的选择性抑制作用 TgAPP小鼠ISF血流量和抗体清除的成分在目标3中，我们将检验大脑击倒的假设 内皮VWF可预防或稳定血管运动功能障碍，减少血管驱动的病理改变 淀粉样变性。在这项概念验证研究中，我们将使用行为测试，即体内脑血管测量 功能和脑组织学分析，以确定VWF基因敲除在TgAPP小鼠模型中的有益效果。如果 如果成功，这些研究将确定位于血管壁内的VWF的病理作用，从而提供 淀粉样变性条件下靶向治疗壁内vwf的初步实验支持。

SUMMARY. The brain vasculature contributes to the vital clearance of Ab and other solutes from brain interstitial fluid (ISF). The following proposal examines the pathological role of von Willebrand factor (VWF) within the wall of leptomeningeal arteries and arterioles, with particular focus on its potential to impair cerebrovascular function and vascular-mediated clearance in conditions of amyloidosis. VWF is expressed exclusively in endothelial cells and platelets and is widely recognized for its role in hemostasis and thrombosis. The presence of extracellular VWF in blood vessels is normally confined to the luminal endothelial surface and immediate sub-endothelial matrix. However, in certain pathological states, VWF can be found within the vascular wall (i.e. intramural VWF) where it promotes smooth muscle proliferation and wall thickening. Importantly, we and others have shown that VWF deletion profoundly prevents this vascular remodeling. Our preliminary data now expand the role of intramural VWF to conditions of AD and CAA. We show the presence of VWF within the smooth muscle region of cerebral arteries and arterioles from human AD and CAA patients and in leptomeningeal arteries (LMA) from mouse models of amyloidosis. We further show that Ab peptides promote increased VWF expression in human brain endothelial cells, supporting a contributory role for amyloidosis in VWF accumulation in the vessel wall. Based on these findings, we propose the overall hypothesis that Ab contributes to increased basolateral endothelial release of VWF, where it triggers smooth muscle proliferation and subsequent wall thickening with narrowing of leptomeningeal arteries and cortical arterioles. We further propose that the consequences of intramural VWF include cerebrovascular dysfunction, impaired brain clearance of Ab peptides, and the acceleration of cerebral artery angiopathy (CAA) and related functional consequences. We propose studies to a) define the mechanisms by which intramural VWF leads to pathological LMA remodeling and impaired Ab clearance and b) evaluate the novel strategy of reducing intramural VWF to mitigate vascular-related pathology in amyloidosis. In Aim 1, we will test the hypothesis that Ab contributes to increased basolateral endothelial release of VWF, where it triggers smooth muscle proliferation and subsequent wall thickening with narrowing of LMAs and cortical arterioles. We will use a combination of human cell culture studies and in vivo studies in TgAPP mouse models following selective VWF knockdown in brain endothelium. In Aim 2, we will test the hypothesis that reduction of brain endothelial VWF will result in increased Ab clearance by improving transendothelial and paravascular clearance mechanisms. We will evaluate selective knockdown of VWF in brain endothelium on different components of ISF flow and Ab clearance in TgAPP mice. In Aim 3, we will test the hypothesis that knockdown of brain endothelial VWF will prevent or stabilize vasomotor dysfunction and reduce vascular-driven pathology in conditions of amyloidosis. For this proof-of-concept study, we will employ behavior testing, in vivo measures of cerebrovascular function, and brain histological analyses to determine the beneficial effect of VWF knockdown in TgAPP mouse models. If successful, these studies will establish the pathological role of VWF located within the vascular wall and thus provide the initial experimental support for therapeutically targeting intramural VWF in conditions of amyloidosis.