Ischemia-reperfusion injury in transplantation: novel cytoprotection strategies

描述(由申请人提供)：对供体器官的缺血/再灌注损伤(IRI)大大增强了移植物的免疫原性，并增加了急性和慢性同种异体移植排斥反应的发生率。IRI越严重的移植物，其长期存活率也明显较差。因此，IRI仍然是当今移植的主要障碍，但目前还没有移植后IRI的标准治疗方法。因此，在当前的移植时代，迫切需要研究开发新的策略来减弱IRI的影响。我们的总体假设是移植物中的IRI激活了移植物来源的树突状细胞(ADDC)，ADDC成为天然免疫和同种异体免疫之间的关键纽带，最终增强了移植物的同种异体。ADDC是最强大的抗原提呈细胞。我们实验室使用各种转基因模型的大量初步数据导致了新的观察结果，即预防这种损伤可以降低缺血器官的免疫原性，促进植入。该项目的主要目标是：1)研究IRI通过增加ADDC的同种异体免疫原性来增强移植物的免疫原性的机制；2)寻找新的保护策略以减少IRI，最终目标是促进同种异体移植物的长期接受性。在目标1中，我们将研究IRI激活ADDC的机制，将先天免疫和同种异体免疫联系起来。我们将使用Treg和同种异体反应性转基因小鼠来研究缺血/抗缺血策略是否以及如何影响Tregs与同种异体反应性T细胞的产生。在AIM 2中，我们将探讨缺血诱导的TLR2/TLR4激活导致DC同种异体刺激能力和运输特性增加的机制。我们将确定NFkB上游、TLR4和TLR2下游的缺血树突状细胞中的关键信号分子，特别是MyD88和TRIF。对缺血树突状细胞的细胞因子表达谱、同种异体刺激能力和趋化因子依赖的体外和体内转运模式进行评估。器官短缺已成为阻碍全球器官移植成功的主要障碍，促使临床医生扩大他们接受边缘器官的标准，因为边缘器官更容易受到IRI的影响。我们提出的全面研究将为IRI诱导的先天免疫和同种异体免疫激活的病理生理学提供高度创新的数据和见解。这项研究将确定新的治疗目标，并在捐赠者管理领域提出新的战略和创新，以减轻IRI的有害影响，这是当前移植时代迫切需要的。我们认为，这项研究在丰富的初步数据、创新的方法、复杂的模型以及调查人员的承诺和专业知识的支持下，具备实现所述目标的所有必要要素。这项建议的发现可以很容易地转化为临床实践，并对减轻临床移植中IRI的负担有重大影响。 公共卫生相关性：本项目旨在研究缺血再灌注损伤(IRI)增强器官免疫原性的机制。我们还致力于寻找新的保护策略，以最大限度地减少移植后的IRI，最终降低同种异体移植物的免疫原性，促进长期的同种异体移植物接受。

DESCRIPTION (provided by applicant): Ischemia/reperfusion injury (IRI) to donor organs substantially enhances the immunogenicity of grafts and increases the rate of acute and chronic allograft rejection. Grafts with more severe IRI also have significantly worse long-term survival. Thus, IRI remains the major obstacle in transplantation today, but there are currently no standard treatments for IRI post-transplantation. Therefore, studies which lead to the development of novel strategies to attenuate the effects of IRI are much needed in the current era of transplantation. Our overall hypothesis is that IRI in the graft activates allograft derived dendritic cells (ADDC) which become the critical link between the innate immunity and alloimmunity, ultimately enhancing the allogenicity of the graft. ADDC are the most potent antigen-presenting cells. Extensive preliminary data from our laboratory using various transgenic models have led to the novel observation that preventing this injury could diminish the immunogenicity of ischemic organs and promote engraftment. The overarching goals of this project are: 1) to investigate the mechanisms by which IRI enhances the immunogenicity of allografts by increasing the allogenicity of ADDC, and 2) to identify novel protective strategies to minimize IRI, with the ultimate goal of promoting long-term allograft acceptance. In AIM 1, we will examine the mechanisms by which activated ADDC by IRI link innate and alloimmunity. We will employ T reg and alloreactive transgenic mice to study whether and how the ischemia/anti-ischemic strategy affects the generation of T regs vs. alloreactive T cells. In AIM 2, we will explore the mechanisms by which ischemia-induced TLR2/TLR4 activation results in higher DC allostimulatory capacity and trafficking properties. We will identify the key signaling molecules in ischemic DC upstream of NFkB and downstream of TLR4 and TLR2, with particular focus on MyD88 and TRIF. Ischemic DC will be evaluated for their cytokine elaboration profiles, allostimulatory capacity, and chemokine dependent in vitro and in vivo trafficking patterns. The organ shortage has become a major obstacle hampering the success of organ transplantation worldwide, prompting clinicians to expand their criteria for the acceptance of marginal organs, which are more susceptible to IRI. Our proposed comprehensive studies will provide highly innovative data and insights into the pathophysiology of IRI-induced activation of innate and alloimmunity. This research will identify novel therapeutic targets and set forth novel strategies and innovations in the areas of donor management to attenuate the deleterious effects of IRI which are urgently needed in the current era of transplantation. We believe that this research, supported by the wealth of preliminary data, innovative approaches, sophisticated models and the commitment and expertise of the investigators, has all the necessary elements to achieve the stated goals. The findings from this proposal could be easily translated into clinical practice and have a significant impact on reducing the burden of IRI in clinical transplantation. PUBLIC HEALTH RELEVANCE: This project seeks to investigate the mechanisms by which ischemia reperfusion injury (IRI) enhances the immunogenicity of organs. We also aim to identify novel protective strategies to minimize IRI after transplantation, ultimately reducing the immunogenicity of allografts and promoting long-term allograft acceptance.