Graft extracellular vesicles as promoters of anti-donor immunity in cardiac and skin transplantation

总结 针对同种异体移植物的先天性和适应性免疫反应是移植成功的主要障碍。 心脏移植是选定的儿童和成人终末期心力衰竭患者的最佳选择， 然而，尽管免疫抑制疗法、条件反射、免疫抑制剂和免疫抑制剂的使用， 养生和医疗护理。重要的是，目前使用的干预措施不是针对捐助者的，因此可能 导致感染和癌症的风险增加。需要更深入地了解异体识别的基础 用于开发新的供体特异性疗法来治疗移植物排斥，从而最大限度地减少有害的副作用。 最近的研究已经挑战了移植物中抗供体免疫的启动或重新激活的教条， 引流的次级淋巴组织（SLT）主要依赖于供体的Ag呈递细胞（APC）， 移植物越来越多的证据和我们的初步研究表明，心脏和非血管化皮肤移植， 释放携带供体Ag的细胞外囊泡（EV），所述供体Ag运输至SLT，在SLT处移植物EV刺激供体Ag。 反应性B细胞和T细胞。尽管在过去的5年中，关于移植物EV在 抗供体免疫的激发及其作为移植生物标志物的潜在用途，体内机制 移植物EV与移植物引流PLT中受体的免疫细胞相互作用并促进抗供体免疫 仍然在很大程度上未知。 EV家族包括具有不同生物起源、大小和组成的囊泡，包括 外来体和微泡。尽管越来越多的证据表明，电动汽车代表了一种机制， 细胞水平转移蛋白质，mRNA，非编码RNA和脂质，EV在体内的功能仍然是一个复杂的过程。 谜。因此，我们建议在体内研究移植物EV启动或重新激活的机制， 在移植物引流SLTs中，导致同种异体移植物排斥的先天性和适应性免疫反应。我们将 在小鼠心脏和非血管化皮肤同种异体移植实验模型中分析这些机制。 我们假设“移植物EV构成了一个无细胞平台，通过多种机制启动 或重新激活接受者的SLT中的抗供体免疫应答”。本申请将调查 这些机制在原位和体内使用小鼠中的移植模型和人源化小鼠中的翻译模型， 小鼠我们将在以下目标中检验我们的假设：目标1将研究移植物EV的起源及其在移植物中的表达。 目的2将分析移植物EV产生的机制， SLT中的抗供体B细胞免疫，Aim 3将分析移植物EV如何在SLT中引发抗供体T细胞免疫 以及它与人体移植的相关性。我们的长期目标是了解移植物EV如何在 为开发基于EV的疗法和具有临床意义的疾病标志物提供新的基础 移植和免疫介导的疾病。

SUMMARY The innate and adaptive immune response against allografts is the main impediment to successful transplantation. Heart transplantation is the best option for selected pediatric and adult patients with end-stage heart failure, however, the threat of rejection remains high, despite improvements in immunosuppressive therapies, conditioning regimens and medical care. Importantly, currently used interventions are not donor-specific and therefore may cause increased risk of infections and cancer. A deeper understanding of the basis of allo-recognition is needed for the development of novel donor-specific therapies to treat graft rejection minimizing the harmful side effects. Recent studies have challenged the dogma that initiation or re-activation of anti-donor immunity in graft- draining secondary lymphoid tissues (SLTs) depends mainly on donor Ag-presenting cells (APCs) mobilized from the grafts. Increasing evidence and our preliminary studies indicate that heart and non-vascularized skin allografts release extracellular vesicles (EVs) carrying donor-Ag that traffic to the SLTs where the graft EVs stimulate donor- reactive B cells and T cells. Despite increasing information during the past 5 years on the role of graft EVs on elicitation of anti-donor immunity and their potential use as biomarkers in transplantation, the mechanisms in vivo by which graft EVs interact with recipient’s immune cells in graft-draining SLTs and promote anti-donor immunity remain largely unknown. The family of EVs encompasses vesicles with different biogenesis, size and composition that includes exosomes and microvesicles. Although growing evidence indicates that EVs represent a mechanism by which cells horizontally transfer proteins, mRNAs, non-coding RNAs and lipids, the function of EVs in vivo remains an enigma. Therefore, we propose to investigate the mechanisms in vivo by which graft EVs initiate or re-activate in graft-draining SLTs, the innate and adaptive immune responses that lead to rejection of allografts. We will analyze these mechanisms in mouse experimental models of cardiac and non-vascularized skin allografts. We hypothesize that “graft EVs constitute a cell-free platform that by multiple mechanisms initiates or re-activates the anti-donor immune response in the recipient’s SLTs”. This application will investigate these mechanisms in situ and in vivo using transplant models in mice and a translational model in humanized mice. We will test our hypothesis in the following aims: Aim 1 will investigate the origin of graft EVs and their effects on recipient APCs in graft-draining SLTs, Aim 2 will analyze the mechanisms by which graft EVs generate anti-donor B cell immunity in SLTs and Aim 3 will analyze how graft EVs elicit anti-donor T cell immunity in SLTs and its relevance to transplantation in humans. Our long-term goal is to understand how graft EVs function in vivo to provide new grounds for development of EV-based therapies and disease markers of clinical relevance to transplantation and immune-mediated disorders.