Vascular Remodeling in Transplant Arteriosclerosis

描述(申请人提供)：移植相关血管病变(TAV)是一种加速的动脉粥样硬化，导致带血管器官移植的慢性排斥反应，自新的免疫抑制方案问世以来，它是移植失败的主要原因。慢性排斥反应和TAV的原因可能是多因素的，包括免疫和非免疫因素，这些因素在血管壁水平整合，导致内皮细胞(EC)和平滑肌细胞(SMC)的表型转换，突出了TAV病变的发展。激活的EC促进炎症、凝血、血小板聚集和细胞侵袭，并可能导致EC凋亡，暴露内皮下基质，进一步促进血栓形成。此外，激活的EC和侵袭性白细胞产生的细胞因子和趋化因子以及内皮下基质的暴露引起SMC表型的转换。激活的SMC(I)促进炎症和增加细胞外基质的合成；(Ii)表现出新生内膜内的异常增殖和迁移；(Iii)表现出失控的细胞凋亡，最终导致慢性排斥反应的闭塞性血管病变。TAV的病理生理学最近重新被证实，移植物血管壁的损伤触发了循环中的SMC和可能的EC祖细胞从受体归巢。了解这种促动脉粥样硬化的EC/SMC表型的分子基础并防止其获得，以及阻止循环中的SMC归巢到新生内膜，对于设计预防和治疗TAV的新的治疗方法至关重要。我们已经证明A20是EC对损伤的调节性细胞保护反应的一部分。在EC中，在体外，A20具有双重的抗凋亡和抗炎功能，支持其抗动脉粥样硬化的潜力。我们还证明A20是SMC对损伤的生理反应的一部分。A20在SMC中的过表达抑制了TAV相关的NF-KB依赖基因的诱导，阻断了SMC的增殖，并意外地使新生内膜SMC对凋亡敏感。在体内，A20在长期存活的大鼠移植肾的EC和SMC中表达，并与TAV的缺失有关。此外，球囊血管成形术后，A20在大鼠颈动脉SMC中的过表达可以预防和治疗新生内膜形成，并通过增加再内皮化来促进愈合。基于这些发现，我们推测A20在EC和SMC中的表达可能有益于影响TAV。我们的目标是(I)确定A20在EC中与激活、凋亡和血管重塑相关的功能；(Ii)确定A20对SMC激活、增殖、表型和对凋亡刺激的反应的影响；这两个目标都将包括功能的丧失和获得；(Iii)建立A20在EC和SMC中的结构/功能分析；*[(Iv)利用小鼠主动脉移植模型评估A20对TAV的保护作用。体内研究将包括使用Rad进行的功能实验。介导将A20转移到主动脉移植物，或者在其血管系统中表达A20的转基因小鼠。它们还将包括使用A20基因敲除小鼠的同种异体主动脉移植进行的功能丧失实验]*。

DESCRIPTION (provided by applicant): Transplant associated vasculopathy (TAV) is an accelerated form of atherosclerosis resulting in chronic rejection of vascularized organ grafts and the major cause of graft failure since the advent of novel immunosuppressive regimen. The causes of chronic rejection and TAV are likely multifactorial including immunologic and non- immunologic factors that integrate at the level of the vascular wall leading to a phenotypic switch of endothelial (EC) and smooth muscle cells (SMC), underscoring the development of TAV lesions. Activated EC promote inflammation, coagulation, platelet aggregation and cellular invasion and may lead to EC apoptosis exposing the subendothelial matrix and further promoting thrombosis. In addition, production of cytokines and chemokines by activated EC and invasive leukocytes as well as exposure of the subendothelial matrix provoke a switch in SMC phenotype. Activated SMC (i) promote inflammation and increased synthesis of extra-cellular matrix; (ii) exhibit aberrant proliferation and migration within the neointima and (iii) demonstrate deregulated apoptosis, all culminating in the occlusive vasculopathy of chronic rejection. The pathophysiology of TAV has been recently revisited by the demonstration that injury to the vessel wall of the graft triggers homing of circulating SMC and possibly EC progenitors from the recipient. Understanding the molecular basis for, and preventing the acquisition of, this "pro-atherogenic" EC/SMC phenotype as well as halting the homing of circulating SMC to the neointima are critical for devising new therapeutic approaches for the prevention and treatment of TAV. We have shown that A20 is part of the regulatory cytoprotective response of EC to injury. In EC, in vitro, A20 has a dual anti-apoptotic and anti-inflammatory function supporting its atheroprotective potential. We also demonstrate that A20 is part of the physiologic response of SMC to injury. Overexpression of A20 in SMC inhibits the induction of NF-KB dependent genes implicated in TAV, blocks SMC proliferation and unexpectedly sensitizes neointimal SMC to apoptosis. In vivo, A20 is expressed in EC and SMC of long term surviving rat kidney allografts and is associated with the absence of TAV. In addition, overexpression of A20 in rat carotid artery SMC following balloon angioplasty prevents but also cures neointima formation and promotes healing by increasing re-endothelialization. Based on these findings, we hypothesize that expression of A20 in EC and SMC may beneficially impact TAV. Our aims are to (i) Determine the function of A20 in EC as it pertains to activation, apoptosis and vascular remodeling; (ii) Determine the effect of A20 upon SMC activation, proliferation, phenotype and response to apoptotic stimuli; both aims will include loss and gain of function studies; (iii) Establish a structure/function analysis for A20 in EC and SMC; *[(iv) Evaluate the protective function of A20 against TAV using a mouse model of aortic transplantation. In vivo studies will include gain of function experiments using rAd. mediated transfer of A20 to the aortic graft or alternatively, transgenic mice expressing A20 in their vasculature. They will also include loss of function experiments using aortic allografts from A20 knock-out mice]*.