Reduction of Brain AVM Severity through Inhibition of Pathogenic Angiogenesis

摘要 脑动静脉畸形（bAVM）病灶内血管壁结构异常， 容易破裂，造成危及生命的颅内出血和长期残疾。大脑 AVM破裂通常是不可预测的。目前还没有专门的治疗方法来预防它。 异常高水平的血管内皮生长因子（VEGF）与bAVM有关 病理生理学研究表明，VEGF信号传导的中断可防止bAVM进展。抗 VEGF抗体和酪氨酸激酶抑制剂（TKI）已用于阻断VEGF信号传导， 许多设置。然而，抗体和TKI都会对患者造成不良影响。由于bAVM 是慢性和活动性血管生成病变，需要长期VEGF抑制来抑制bAVM 发展和稳定AVM血管。抗体和TKI需要重复给药，这是昂贵的 也不方便此外，最近的研究表明TKI对小鼠皮肤AVM没有影响， 血管生成信号转导VEGF受体-2（VEGFR-2）的基因缺失可防止 过度血管生成，但不能完全逆转AVM形成。这些数据表明， VEGF血管生成作用不足以治疗某些组织中的AVM。需要更好的试剂， 预防bAVM的发展和破裂。 可溶性FMS相关酪氨酸激酶1（sFLT 1）包含VEGFR-1的细胞外结构域结合 VEGF具有高亲和力，因此通过其膜结合受体减少VEGF信号传导。 更重要的是，sFLT 1在维持正常的周细胞功能中具有直接作用。我们测试了一个 在我们的bAVM小鼠模型中，sFLT 1基因治疗策略，并已显示静脉内递送 表达sFLT 1的腺相关病毒载体降低bAVM的严重程度。然而，无处不在的 sFLT 1的表达引起一些不利影响。在这项研究中，我们希望证明sFLT 1 通过抑制VEGF信号传导和改善周细胞粘附来改善bAVM血管完整性 内皮细胞（Aim 1）。我们还将测试靶向sFLT 1表达是否降低bAVM严重程度 使用特异性感染神经元或内皮细胞的AAV载体， 与神经元特异性或脑内皮特异性启动子（Aim 2）的组合，以及是否 减少小胶质细胞/巨噬细胞浸润增强sFLT 1治疗效果（目的3）。我们还将 研究sFLT 1治疗作用在所有目标中发生的机制。的首要目标 本课题旨在开发一种安全有效的预防bAVM出血的方法。

Abstract Vessels in the nidus of brain arteriovenous malformation (bAVM) have abnormal wall structure and are prone to rupture, causing life-threatening intracranial hemorrhage and long-term disability. Brain AVM rupture is often unpredictable. There is no specific therapy for preventing it. An abnormally high level of vascular endothelial growth factor (VEGF) has been implicated in bAVM pathophysiology. Studies show that interruption of VEGF signaling prevents bAVM progression. Anti- VEGF antibodies and tyrosine kinase inhibitors (TKIs) have been used to block VEGF signaling in many settings. However, both antibodies and TKIs cause adverse effects in patients. Since bAVMs are chronic and active angiogenic lesions, long-term VEGF inhibition will be needed to inhibit bAVM progression and stabilize AVM vessels. Antibodies and TKIs need repeated dosing, which is costly and inconvenient. In addition, recent studies show that TKIs have no effect on mouse skin AVMs, and genetic deletion of the angiogenic signal-transducing VEGF receptor-2 (VEGFR-2) prevents excessive angiogenesis but does not fully revert AVM formation. These data suggest that blocking VEGF angiogenic effect is insufficient to treat AVM in certain tissues. A better reagent is needed to prevent bAVM development and rupture. Soluble FMS-related tyrosine kinase 1 (sFLT1) containing extracellular domain of VEGFR-1 binds VEGF with high affinity, and thus reduces VEGF signaling through its membrane-bound receptors. More importantly, sFLT1 has a direct role in maintaining normal pericyte function. We have tested a sFLT1 gene therapy strategy in our bAVM mouse models, and have shown that intravenous delivery of an adeno-associated viral vector expressing sFLT1 reduces bAVM severity. However, ubiquitous expression of sFLT1 caused some adverse effects. In this study, we hope to demonstrate that sFLT1 improves bAVM vessel-integrity by inhibiting VEGF signaling and improving adhesion of pericytes to endothelial cells (Aim 1). We will also test whether targeted sFLT1 expression reduces bAVM severity with minimal side effects using AAV vectors that infect neurons or endothelial cells specifically in combination with neuron specific or brain endothelial specific promoter (Aim 2), and whether reduction of microglia/macrophage infiltration enhances sFLT1 therapeutic effect (Aim 3). We will also investigate mechanisms by which sFLT1 therapeutic effects occur in all aims. The overarching goal of this project is to develop a safe and effective method to prevent bAVM hemorrhage.