IDO & phenotypic switching of VSMC in transplant vasculopathy

描述（由申请方提供）：移植血管病（TV）是一种慢性血管疾病，特征为由平滑肌样细胞（SMLC）和相关基质组成的同心内膜过度扩张。与可以用最先进的免疫抑制方案有效预防和治疗的急性移植排斥不同，目前还没有批准的医学干预来预防甚至延迟TV的发展。我们的初步数据首次揭示了SMLC的过度增殖/合成和凋亡受损是内膜过度扩张可能发展的细胞基础。值得注意的是，我们观察到来自内皮细胞（EC）的吲哚胺-2，3-双加氧酶（IDO）具有通过上调vSMC分化特异性基因转录来下调SMLC增殖/合成的潜力，并直接消除SMLC的抗凋亡特性。在补充的体内实验中，我们发现移植物内皮是内源性IDO诱导的主要位点，并且缺乏该基因的供体器官（而不是受体动物）更容易受到TV病变的影响。根据这些新的数据，我们假设内皮源性IDO指导SMLC向更静止和分化状态的反向表型转换，并且移植EC中这种酶的特异性过表达阻断TV中的血管重塑。为了检验这一中心假设，我们已经开发了许多独特的动物模型和方法，其包括心脏或肺TV的小鼠模型和能够在移植物内皮内持久表达人IDO（hIDO）转基因的基于睡美人（SB）的非病毒基因整合策略。在具体目标1中，我们将确定内皮IDO对SMLC促增殖/合成特性的影响。在具体目标2中，我们将确定内皮IDO对SMLC抗凋亡特性的影响。在这些研究中，将探索IDO诱导SMLC表型转换背后的可能分子机制。在具体目标3中，我们将研究增强的内皮IDO在实验性TV的发展和逆转中的作用。在这项研究中，内皮IDO对移植物中功能性和结构性血管重塑的可能有益作用将分别通过回声和组织学研究来评估。该项目产生的结果可能为预防和治疗这种毁灭性疾病开辟新的途径，特别是考虑到基于SB的非病毒方法已经进入临床试验。

DESCRIPTION (provided by applicant): Transplant vasculopathy (TV) is a chronic vascular disease characterized by concentric intimal overexpansion composed of smooth muscle-like cells (SMLCs) and associated matrix. Unlike acute transplant rejection that can be effectively prevented and treated with the state-of-the-art immunosuppression regiments, at present there is no approved medical intervention to prevent or even delay the development of TV. Our preliminary data, for the first time, revealed that excessive proliferation/synthesis and impaired apoptosis of SMLCs is a cellular basis by which intimal overexpansion may develop. Remarkably, we observed that indoleamine-2,3-dioxygenase (IDO) derived from endothelial cells (ECs) has the potential to down-regulate SMLC proliferation/synthesis via upregulation of vSMC differentiation-specific gene transcription, and directly abolish the anti-apoptotic property of SMLCs. In complementary in vivo experiments, we found that graft endothelium is the primary site for endogenous IDO induction, and that donor organs (but not recipient animals) lacking this gene are more susceptible to TV lesions. In light of these novel data, we hypothesize that endothelium-derived IDO directs a reverse phenotypic switch of SMLC towards a more quiescent and differentiated state, and that specific overexpression of this enzyme in graft ECs blocks vascular remodeling in TV. To test this central hypothesis, we have developed a number of unique animal models and approaches, which include mouse models of heart or pulmonary TV and the Sleeping- Beauty (SB)-based nonviral gene integrating strategy capable of long-lasting human IDO (hIDO) transgene expression within graft endothelium. In Specific Aim 1, we will determine the effect of endothelial IDO on SMLC pro-proliferative/synthetic properties. In Specific Aim 2, we will determine the effect of endothelial IDO on SMLC anti-apoptotic properties. In these studies, the possible molecular mechanism(s) behind IDO-induced phenotypic switch of SMLCs will be explored. In Specific Aim 3, we will examine the role of enhanced endothelial IDO in the development and reversal of experimental TV. In this study, the possible beneficial effect of endothelial IDO on functional and structural vascular remodeling in graft will be assessed by echo and histological studies, respectively. Results generated from this project may open a new avenue for the prevention and treatment of this devastating disease, especially given that the SB-based nonviral approach is already advancing into clinical trials.