The NOTCH Signaling Pathway in Large Vessel Vasculitis

描述（申请人提供）：大血管性血管炎（LVV），如巨细胞性动脉炎（GCA）导致失明、中风、主动脉弓综合征、主动脉瘤、高血压和心肌功能不全。在老龄化人口中，需要LVV慢性治疗的患者数量一直在稳步上升，而治疗手段仍然严格限于大剂量皮质类固醇。近十年来，先天性免疫和适应性免疫系统在LVV免疫发病机制中的作用取得了令人兴奋的进展。然而，我们对这种疾病为什么以主动脉及其主要分支为目标，以及动脉壁上的免疫基质通讯如何引发和促进血管炎的认识还存在一个关键的空白。致病性免疫反应具有抗原诱导克隆扩增的特征，但我们最近发现，来自组织生态位中驻留细胞的共刺激信号在驱动组织损伤免疫中同样重要。GCA动脉表达丰富的NOTCH受体和配体，为细胞间通讯提供了分子平台。阻断NOTCH信号可以有效抑制血管炎。GCA患者的CD4 T细胞组成性表达NOTCH1受体，使其能够与表达血管平滑肌细胞（VSMC）和内皮细胞（EC）的NOTCH配体相互作用。该应用程序旨在揭示Notch通路如何参与免疫内皮和免疫间质通讯，以及Notch依赖的信号如何形成血管源性T细胞反应和不适应的VSMC和EC行为。该项目以一系列有利资源为基础；包括GCA患者的临床表型队列；一种新的人体动脉壁三维模型系统，它允许从具有定义细胞群的可堆叠单元组装定制血管；还有一个带有发炎动脉的人源化老鼠模型。通过与配体竞争的抗体/融合蛋白可以阻断Notch受体和配体的通路，并且通过RNAi技术可以使细胞呈现Notch信号缺陷。特异性目的1在机制水平上研究VSMC和EC上的NOTCH配体如何调节血管源性CD4 T细胞的效应功能；调节它们的生长、组织侵袭能力和细胞因子的产生。特异性Aim 2旨在鉴定可用于抑制NOTCH1表达或靶向致病性T细胞中NOTCH1依赖性生存信号的信号网络。破坏notch衍生信号的小分子抑制剂将在嵌合体模型中测试其抗血管的潜力。Specific Aim 3关注VSMC作为信号发送和接收细胞的作用，并确定NOTCH-NOTCH配体相互作用如何影响VSMC的存活、迁移、基质生成、收缩性和ROS释放。特异性目的4揭示了患者来源的CD4+NOTCH1+ T细胞调节EC功能行为的分子机制，并研究了这些T细胞如何调节EC的促炎功能、血管生成能力、EC屏障的粘附性和渗漏性。

DESCRIPTION (provided by applicant): Large vessel vasculitides (LVV), such as giant cell arteritis (GCA) cause blindness, stroke, aortic arch syndrome, aortic aneurysm, hypertension and myocardial insufficiency. In an aging population the number of patients requiring chronic management for LVV has been steadily rising, while the therapeutic armamentarium has remained strictly limited to high-dose corticosteroids. The last decade has seen exciting progress in implicating the innate and adaptive immune system in the immunopathogenesis of LVV. However, there is a critical gap in our knowledge why the disease targets the aorta and its major branches and how immuno- stromal communications in the arterial wall initiate and promote vasculitis. The pathogenic immune response has a signature of antigen-induced clonal expansion, but we have recently seen that costimulatory signals deriving from resident cells in the tissue niche are equally important in driving tissue-damaging immunity. GCA arteries express abundant levels of NOTCH receptors and ligands, providing a molecular platform for superb cell-to-cell communication. Blocking of NOTCH signaling effectively inhibits vasculitis. CD4 T cells from GCA patients constitutively express NOTCH1 receptor, enabling them to interact with NOTCH ligand expressing vascular smooth muscle cells (VSMC) and endothelial cells (EC). This application is designed to uncover how the Notch pathway participates in immuno-endothelial and immuno-stromal communications and how NOTCH- dependent signaling shapes vasculitogenic T cell responses and maladaptive VSMC and EC behavior. The project builds on a series of enabling resources; including a clinically phenotyped cohort of GCA patients; a novel 3-D model system of human arterial walls which permits assembly of custom-made vessels from stackable units populated with defined cell populations; and a humanized mouse model carrying inflamed human arteries. Access to Notch receptor and ligands can be blocked through ligand-competing antibodies/fusion proteins and cells can be rendered Notch signaling deficient by RNAi technology. Specific Aim 1 examines on a mechanistic level how NOTCH ligands on VSMC and EC regulate effector functions of vasculitogenic CD4 T cells; modulate their growth, tissue invasion capacity and cytokine production. Specific Aim 2 seeks to identify signaling networks that can be utilized to either suppress NOTCH1 expression or target NOTCH-dependent survival signals in pathogenic T cells. Small molecule inhibitors disrupting Notch-derived signals will be tested in the chimera model for their anti-vasculitic potential. Specific Aim 3 is focused on the role of VSMC as signal-sending and signal-receiving cells and determines how NOTCH-NOTCH ligand interactions affect VSMC survival, migration, matrix production, contractility and ROS release. Specific Aim 4 unravels the molecular mechanisms through which patient-derived CD4+NOTCH1+ T cells regulate the functional behavior of ECs and investigates how such T cells modulate EC proinflammatory functions, angiogenic capacity, adhesiveness and leakiness of the EC barrier.