Hemodynamics of Cerebral Arteriovenous Malformations

描述（由申请方提供）：脑动静脉畸形（bAVM）患者存在颅内出血（ICH）风险。大约20%的患者由于侵入性治疗的过度风险而没有得到治疗，并且未破裂病变的治疗已经成为有争议的。没有治疗bAVM的特定药物疗法。我们已经开发了新的成年发病小鼠模型，使用激活素样激酶（Alk 1）和内皮糖蛋白（Eng）的纯合条件性缺失，bAVM（遗传性出血性毛细血管扩张症）的家族形式的致病基因。这些模型具有模拟人类bAVM关键方面的表型。目标1和2将解决这两个基因的功能丧失如何导致基本相同的人类bAVM表型，目前尚不清楚，而目标3将开发急需的bAVM治疗方法。目的1研究Alk 1或Eng基因功能的丧失如何改变对血管壁结构完整性至关重要的信号传导。对于Aim 1a（体外）和im 1b（体内），首要假设是：（1）ALK 1或ENG缺失伴VEGF刺激导致脑微血管内皮细胞中Notch配体、Delta样配体-4（DLL 4）表达减少;（2）DLL 4减少导致血小板源性生长因子-B（PDGFB）信号传导缺陷;（3）因此，壁细胞募集受损。目标2关注基因功能丧失的细胞位点。我们假设Alk 1或Eng-deficient骨髓（BM）衍生的内皮细胞（EC）和/或巨噬细胞（Mo）足以诱导发育异常（bAVM表型）。我们将测试BM衍生的EC（Aim 2a）或BM衍生的Mo（Aim 2b）是否足以诱导发育异常。在Aim 2c中，我们将测试两种细胞类型之间的协同作用，在Aim 2d中，我们将使用Notch信号传导（Mo中的Notch 1或EC中的Dll 4）的细胞特异性过表达来挽救Alk 1或Eng缺失的影响。目标3将提供一种有前途的药物的临床前数据，该药物部分基于我们在目标1中的假设而选择。我们的数据表明，沙利度胺降低异型增生的严重程度和稳定血管壁。由于沙利度胺众所周知的副作用，我们将测试来那度胺，一种新的，毒性较小的类似物。在目标3a中，我们假设来那度胺优于沙利度胺上级。在目标3b中，我们将通过在我们的Alk 1缺失模型中构建剂量-抑制曲线来确定来那度胺的疗效。在目标3c中，为了确保更广泛的适用性，我们将使用接近最大有效剂量在Eng缺失模型中测试来那度胺。这些临床前数据可用于支持早期临床试验。拟议的工作将支持继续努力阐明bAVM发病机制和改善bAVM患者的护理。

DESCRIPTION (provided by applicant): Brain arteriovenous malformation (bAVM) patients are at risk of intracranial hemorrhage (ICH). Roughly 20% of patients are not offered treatment because of excessive risk of invasive therapy, and treatment of unruptured lesions has become controversial. There are no specific medical therapies to treat bAVMs. We have developed novel adult-onset mouse models using homozygous conditional deletion of Activin-like kinase (Alk1) and Endoglin (Eng), the causative genes for a familial form of bAVM (Hereditary Hemorrhagic Telangiectasia). The models have phenotypes mimicking key aspects of human bAVM. Aims 1 and 2 will address how loss of function of these two genes results in essentially the same human bAVM phenotype, which is not currently understood, while Aim 3 will develop much-needed therapy for bAVM. Aim 1 examines how loss of Alk1 or Eng gene function alters signaling that is crucial for structural integrity of the vascular wall. For Aim 1a (in vitro) and im 1b (in vivo), the overarching hypothesis is that: (1) ALK1 or ENG deletion with VEGF stimulation leads to reduced expression of the Notch ligand, Delta-like ligand-4 (DLL4), in brain microvascular endothelial cells; (2) decreased DLL4 results in deficient platelet-derived growth factor-B (PDGFB) signaling; (3) consequently, mural cell recruitment is impaired. Aim 2 focuses on the cellular loci where the loss of gene function acts. We hypothesize that Alk1 or Eng-deficient bone marrow (BM)-derived endothelial cells (EC) and/or macrophages (Mo) are sufficient to induce dysplasia (bAVM phenotype). We will test whether BM-derived EC (Aim 2a) or BM-derived Mo (Aim 2b) are sufficient to induce dysplasia. In Aim 2c, we will test for synergism between the two cells types, and in Aim 2d, we will use cell-specific overexpression of Notch signaling (Notch1 in Mo or Dll4 in EC) to rescue the effects of Alk1 or Eng deletion. Aim 3 will provide pre-clinical data on one promising drug that was selected, in part, based on our hypotheses in Aim 1. Our data suggest that thalidomide decreases the severity of dysplasia and stabilizes the vascular wall. Because of thalidomide's well-known adverse effect profile, we will test lenalidomide, a new, less toxic analogue. In Aim 3a, we hypothesize that lenalidomide is superior to thalidomide. In Aim 3b, we will determine efficacy of lenalidomide by constructing dose-inhibitory curves in our Alk1 deletion model. In Aim 3c, to insure broader applicability, we will test lenalidomide in our Eng deletion model using a near-maximally effective dose. These pre-clinical data can be used to support early-phase clinical trials. The proposed work will underpin continued efforts to elucidate the mechanisms of bAVM pathogenesis and improve care for bAVM patients.