HL Exosomes as paracrine signal mediators in cardiac allograft rejection

 描述(申请人提供)：HL-142。我们提交这项申请是为了响应最近NHLBI特别感兴趣的(TOSI)HL-142题为“外泌体作为心血管、肺和血液疾病的旁分泌信号媒介(R01)”的主题。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。尽管免疫抑制疗法取得了进展，但由于排斥反应和心脏移植物血管病变导致的移植物衰竭仍然是一种威胁。因此，需要新的治疗方法来预防和治疗心脏移植物的急性和慢性排斥反应，最大限度地减少免疫抑制药物的使用及其副作用。这需要对同种异体移植物的识别和排斥机制有更深入的了解。这项应用建议研究通过细胞外小泡(EV)，特别是外切体，在导致心脏移植排斥反应的同种异体识别机制中细胞间通信的作用。我们的初步研究表明，受体免疫系统通过供体和受体白细胞之间的细胞间通讯，通过外体样囊泡(以及可能的其他EV)识别同种异体心脏移植物的供体MHC分子。越来越多的证据表明，白细胞和其他类型的细胞转移外切体和其他携带功能蛋白、mRNAs和非编码RNA的EV，从而对靶细胞产生生物学效应。我们的应用旨在研究供体来源的EVS与心脏移植受体的白细胞之间的相互作用，以及供体EVS对受体免疫系统的影响。外切体(和其他EV)在体内的功能仍然是一个谜。我们的实验方法旨在揭示Exosome(和其他EVS)在原位和体内的作用。如果成功，该结果将为外切体在体内的生物学作用提供最早的证据之一。这一应用也将挑战目前关于受者T和B淋巴细胞识别移植器官的机制的范式。我们提出的假说是：“心脏移植后，供体外周小体(和其他EV)作为旁分泌介质，将供体MHC抗原和APC刺激信号传递给受体APC。因此，供体外体(和其他EV)参与心脏移植急、慢性排斥反应的诱导和维持。”我们将测试 在小鼠异位(腹部)心脏移植模型中，我们的假设有以下具体目的：目的1：研究供体外切体(和其他EVS)在心脏移植后T细胞异体识别中的作用；目的2：研究供体来源的EOS(和其他EVS)在激发和维持对心脏移植物的B细胞免疫中的作用。我们的长期目标是更好地了解心脏移植排斥反应的机制，目的是为基于EVS生物学的治疗和疾病标记物的开发提供新的依据。

 DESCRIPTION (provided by applicant): HL-142. We submit this application in response to the recent NHLBI topic of special interest (TOSI) HL-142 titled "Exosomes as paracrine signal mediators in cardiovascular, lung and blood disease (R01)". Cardiac transplants are the best option for selected pediatric and adult patients with end-stage heart failure. Despite advances in immunosuppressive regimens, graft failure due to rejection and cardiac allograft vasculopathy remains a threat. Therefore, there is a need of new therapies to prevent/treat acute and chronic rejection of cardiac allografts, minimizing the use of immunosuppressive drugs and its side effects. This requires a deeper understanding of the mechanisms of allograft recognition and rejection. This application proposes to investigate the role of cell-to-cell communication via extracellular vesicles (EVs), in particular exosomes, in the allorecognition mechanisms that lead to cardiac graft rejection. Our preliminary studies indicate that the recipient immune system recognizes donor MHC molecules of cardiac allografts as non-self through cell-to-cell communication between donor and recipient leukocytes via exosome-like vesicles (and likely other EVs). Growing evidence indicates that leukocytes and other cell types transfer exosomes and other EVs carrying functional proteins, mRNAs and non-coding RNAs, which exert biological effects on target cells. Our application proposes to study the interaction between donor-derived EVs and the leukocytes of cardiac graft recipients, and the effects of donor EVs on the recipient immune system. The function of exosomes (and other EVs) in vivo remains an enigma. Our experimental approached has been designed to unveil the role of exosomes (and other EVs) in situ and in vivo. If successful, the results will provide one of the first evidences f the biological role of exosomes in vivo. This application will also challenge current paradigms on the mechanism of recognition of transplanted organs by T- and B-lymphocytes of the recipient. We propose the hypothesis that "after heart transplantation, donor exosomes (and other EVs) function as paracrine mediators for passage and dissemination of donor MHC Ag and APC-stimulating signals to recipient APCs. Therefore, donor exosomes (and other EVs) are involved in elicitation and maintenance of acute and chronic rejection of cardiac transplants." We will test our hypothesis in a mouse model of heterotopic (abdomen) cardiac transplantation, in the following Specific Aims: Aim 1: Study the role of donor exosomes (and other EVs) in T-cell allo-recognition after cardiac transplantation, and Aim 2: Study the role of donor-derived exosomes (and other EVs) in elicitation and maintenance of B-cell immunity against cardiac allografts. Our long-term goal is to achieve a better understanding of the mechanisms of heart allograft rejection with the aim of providing new grounds for development of therapies and disease markers based on the biology of EVs.