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

摘要 针对同种异体移植物的先天和获得性免疫反应是移植成功的主要障碍。 心脏移植是选择患有终末期心力衰竭的儿童和成人患者的最佳选择， 然而，排斥反应的威胁仍然很高，尽管免疫抑制疗法、条件反射 养生法和医疗护理。重要的是，目前使用的干预措施不是捐赠者特有的，因此可能 会增加感染和癌症的风险。需要对同种识别的基础有更深的理解 用于开发针对供者的新疗法，以治疗移植物排斥反应，将有害副作用降至最低。 最近的研究挑战了这样一种教条，即在移植物中启动或重新激活抗供体免疫- 次级淋巴组织(SLT)的引流主要依赖于动员的供体抗原提呈细胞(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 释放携带供体抗原的细胞外小泡(EV)，这些EV运输到SLT，移植EV刺激供体- 反应性B细胞和T细胞。尽管在过去的5年里，关于移植EVS在 抗供者免疫的诱导及其作为移植生物标志物的潜在应用及其体内机制 移植物EV与受体免疫细胞在移植物引流的SLT中相互作用并促进抗供者免疫 在很大程度上仍然不为人知。 电动汽车家族包括具有不同生物发生、大小和组成的囊泡，包括 外周小体和微囊。尽管越来越多的证据表明，电动汽车代表了一种 细胞水平转运蛋白质、mRNAs、非编码RNAs和脂类，EVS在体内的功能仍然是 谜团。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。 在移植物引流的SLT中，导致同种异体移植物排斥的先天和获得性免疫反应。我们会 在小鼠心脏和非血管化皮肤移植的实验模型中分析这些机制。 我们假设“移植的电动汽车构成了一个无细胞平台，通过多种机制启动 或重新激活受者SLT中的抗供体免疫反应。此应用程序将调查 这些机制在体内和原位使用了小鼠移植模型和人源化的翻译模型 老鼠。我们将在以下目标中验证我们的假设：目标1将调查移植物EV的来源及其 在移植物引流SLT中对受体APC的影响，Aim 2将分析移植物EV产生的机制 SLT中的抗供体B细胞免疫和AIM 3将分析移植物EV如何在SLT中诱导抗供体T细胞免疫 以及它与人类移植的相关性。我们的长期目标是了解移植物电动汽车如何在 体内为开发基于EV的治疗方法和具有临床意义的疾病标志物提供新的依据 移植和免疫介导性疾病。

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.