Role of Endogenous Toll-Like Receptor Ligands in Allospecific T Cell Activation

描述(由申请者提供)：这份临床科学家发展指导奖(K08)的申请书建议对先天免疫系统的内源性激活剂在同种异体特异性T细胞激活中的作用进行彻底的研究。候选人是一名免疫学家和移植外科医生，他的长期目标是防止因免疫排斥而导致的移植器官损失。这项提议将实现发展奖的教育目标，促进将申请者的知识基础扩大到需要在这些新领域进行指导的新的调查路线。协助这一赠款提案的导师的专业知识对于顺利完成该奖项的教育使命以及执行跨越这些领域的拟议研究计划都是至关重要的。托马斯·科夫曼医学博士将提供炎症和小鼠移植模型方面的专业知识；保罗·诺布尔医学博士将提供糖生物学方面的专业知识，并拥有研究内源性天然免疫激动剂的丰富经验；约翰·奥尔森医学博士将为平衡外科和研究职业提供重要的指导。此外，应聘者将参加本申请表中概述的严格的职业发展计划，这将有助于确保该应聘者成功过渡到独立研究人员。 项目摘要：随着Toll样受体(TLRs)的发现，人们越来越认识到先天免疫途径在调节适应性免疫反应中的关键作用。现在人们认识到，来自组织损伤的内源性分子可以作为TLR的配体。在移植过程中，供体器官受到许多潜在的无菌组织损伤，包括：供体脑死亡、缺血时间延长、再灌注损伤、手术创伤和免疫损伤。重要的是，这些因素中的每一个都与移植物排斥反应的风险增加有关。然而，移植物损伤如何具体导致移植物排斥反应尚不清楚。根据初步数据，这项工作假设硫酸乙酰肝素(HS)，一种在损伤过程中释放的细胞外基质多糖，作为一种损伤相关分子模式(DAMP)分子，激活TLR4，并能促进同种异体特异性T细胞激活。这项拟议的工作将：1)确定HS激活同种异体特异性T细胞的分子途径；2)确定在小鼠心脏移植模型中HS血清水平的调节如何影响移植物排斥反应的动力学；3)确定热和移植物先天免疫反应在同种异体特异性T细胞激活中的作用。这项拟议的工作具有创新性，因为它系统地研究了无菌组织损伤背景下的一种新的免疫刺激途径，该途径对移植器官如何保存、移植排斥反应的检测以及移植排斥反应的潜在治疗具有重要意义。该方法使用新的转基因小鼠模型来研究供体和受体对先天免疫刺激的贡献，以及具有直接和间接同种异体特异性的T细胞亚群的激活。 项目相关性：拟议的工作直接关系到了解组织损伤激活免疫的基本机制，以及开发减轻这些反应的治疗方法，以改善器官移植的结果。

DESCRIPTION (provided by applicant): This application for a Mentored Clinical Scientist Development Award (K08) proposes a thorough investigation into the role of endogenous activators of the innate immune system in allospecific T cell activation. The candidate is an immunologist and transplant surgeon whose long-term goal is to prevent loss of transplanted organs due to immune rejection. This proposal will fulfill the educational objective of the development award by facilitating the expansion of the applicant's knowledge base into novel lines of inquiry requiring mentorship in these new areas. The expertise of the mentors assisting in this grant proposal will be essential to the successful completion of both the educational mission of the award as well as the performance of the proposed research plan that spans these areas. Thomas Coffman, MD will provide expertise in inflammation and mouse models of transplantation; Paul Noble, MD will provide expertise in glycobiology and has extensive experience investigating endogenous innate immune agonists; John Olson, MD, PhD will provide critical mentorship on balancing careers in surgery and research. Additionally, the candidate will participate in a rigorous career development plan as outlined in this application that will be instrumental in ensuring the successful transition of this candidate to being an independent researcher. PROJECT SUMMARY: With the discovery of Toll-like receptors (TLRs) there has been an increased appreciation of the critical role of innate immune pathways in regulating adaptive immune responses. It is now recognized that endogenous molecules derived from tissue injury can serve as TLR ligands. In the setting of transplantation, donor organs are subjected to many potential sources of sterile tissue injury, including: donor brain death, prolonged ischemia time, reperfusion injury, surgical trauma, and immunological injury. Importantly, each of these factors is associated with increased risk of graft rejection. How graft injury specifically contributes to graft rejection, however, is unknown. Based on preliminary data, this work hypothesizes that heparan sulfate (HS), an extracellular matrix polysaccharide released during injury, acts as a damage-associated molecular pattern (DAMP) molecule that activates TLR4 and can promote allospecific T cell activation. The proposed work will: 1) define the molecular pathways by which HS activates allospecific T cells, 2) determine how modulation of HS serum levels in a murine cardiac transplantation model affects the kinetics of graft rejection, and 3) define the role of hot and graft innate immune responses in allospecific T cell activation. This proposed work is innovative, in that it systematically investigates a new pathway of immune stimulation in the setting of sterile tissue injury that has implications for how organ grafts are preserved for transplantation, the detection of graft rejection, and the potential treatment of graft rejection. he approach uses novel transgenic mouse models to investigate donor and recipient contributions to innate immune stimulation and the activation of T cell subsets with direct and indirect allospecificity. PROJECT RELEVANCE: The proposed work is directly relevant to understanding fundamental mechanisms of immune activation by tissue injury and to developing therapeutic approaches for mitigating these responses in order to improve outcomes in organ transplantation.