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

概括。 脑脉管系统有助于从脑间质液 (ISF) 中清除抗体和其他溶质。的 以下提案检查了软脑膜壁内血管性血友病因子 (VWF) 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的潜力 淀粉样变性情况下的清除。 VWF仅在内皮细胞和血小板中表达，广泛分布于内皮细胞和血小板中。 因其在止血和血栓形成中的作用而得到认可。血管中存在细胞外 VWF 通常是 局限于管腔内皮表面和直接内皮下基质。然而，在某些病理状态下， VWF 存在于血管壁内（即壁内 VWF），可促进平滑肌增殖和血管壁 增稠。重要的是，我们和其他人已经证明，VWF 缺失可以极大地阻止这种血管重塑。我们的 现在的初步数据将壁内 VWF 的作用扩展到 AD 和 CAA 的情况。我们展示了 VWF 的存在 在人类 AD 和 CAA 患者的脑动脉和小动脉的平滑肌区域内 来自淀粉样变性小鼠模型的软脑膜动脉（LMA）。我们进一步表明 Ab 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 积累中的贡献作用 血管壁。基于这些发现，我们提出总体假设：Ab 有助于增加基底外侧 VWF 的内皮释放，触发平滑肌增殖和随后的壁增厚和狭窄 软脑膜动脉和皮质小动脉。我们进一步提出，壁内 VWF 的后果包括 脑血管功能障碍、Ab肽脑清除率受损、加速脑动脉血管病变 （CAA）和相关的功能后果。我们建议研究 a) 定义壁内 VWF 的机制 导致病理性 LMA 重塑和抗体清除受损，b) 评估减少壁内抗体的新策略 VWF 可减轻淀粉样变性中血管相关的病理。在目标 1 中，我们将检验 Ab 有助于的假设 VWF 的基底外侧内皮释放增加，触发平滑肌增殖和随后的壁 LMAs 和皮质小动脉变窄而增厚。我们将结合人类细胞培养研究和 在脑内皮细胞中选择性敲低 VWF 后，对 TgAPP 小鼠模型进行体内研究。在目标 2 中，我们将测试 假设脑内皮 VWF 的减少将通过改善跨内皮细胞导致抗体清除率增加 和血管旁清除机制。我们将评估不同脑内皮细胞中 VWF 的选择性敲低 TgAPP 小鼠中 ISF 流量和抗体清除的组成部分。在目标 3 中，我们将检验大脑敲低的假设 内皮 VWF 将预防或稳定血管舒缩功能障碍，并减少以下情况下血管驱动的病理： 淀粉样变性。对于这项概念验证研究，我们将采用行为测试、脑血管的体内测量 功能和脑组织学分析以确定 VWF 敲低对 TgAPP 小鼠模型的有益影响。如果 如果成功的话，这些研究将确定位于血管壁内的 VWF 的病理作用，从而提供 在淀粉样变性的情况下，针对壁内 VWF 进行治疗的初步实验支持。

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.