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

描述（由申请人提供）：本指导临床科学家发展奖（K 08）申请提出了对先天免疫系统内源性激活剂在同种特异性T细胞激活中的作用进行彻底研究。候选人是一名免疫学家和移植外科医生，其长期目标是防止由于免疫排斥而导致的移植器官损失。这项建议将通过促进申请人的知识基础扩展到需要在这些新领域进行指导的新的调查领域，实现发展奖的教育目标。导师的专业知识，协助这项赠款提案将是必不可少的成功完成两个教育使命的奖项，以及拟议的研究计划，跨越这些领域的表现。医学博士托马斯科夫曼将提供炎症和移植小鼠模型方面的专业知识;医学博士保罗·诺布尔将提供糖生物学方面的专业知识，并在研究内源性先天免疫激动剂方面拥有丰富的经验;医学博士约翰·奥尔森将提供关于平衡手术和研究职业生涯的重要指导。此外，候选人将参加本申请中概述的严格的职业发展计划，这将有助于确保该候选人成功过渡到独立研究员。 项目概要：随着Toll样受体（TLR）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应答中的关键作用。现在认识到，来源于组织损伤的内源性分子可以充当TLR配体。在移植的背景下，供体器官经受许多潜在的无菌组织损伤来源，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排斥反应的风险增加有关。然而，移植物损伤具体如何导致移植物排斥尚不清楚。基于初步数据，这项工作假设硫酸乙酰肝素（HS），细胞外基质多糖在损伤过程中释放，作为损伤相关的分子模式（DAMP）分子，激活TLR 4，可以促进同种异体特异性T细胞活化。拟议的工作将：1）确定HS活化同种特异性T细胞的分子途径，2）确定在鼠心脏移植模型中HS血清水平的调节如何影响移植物排斥的动力学，和3）确定热和移植物先天免疫应答在同种特异性T细胞活化中的作用。这项拟议的工作是创新的，因为它系统地研究了在无菌组织损伤的情况下免疫刺激的新途径，该途径对器官移植物如何保存用于移植、移植物排斥反应的检测以及移植物排斥反应的潜在治疗具有影响。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直接和间接同种异体特异性T细胞亚群的激活。 项目相关性：拟议的工作是直接相关的理解组织损伤的免疫激活的基本机制，并开发治疗方法，以减轻这些反应，以改善器官移植的结果。 项目叙述：该项目的总体目标是了解器官移植损伤可以激活移植受体的免疫系统并使受体更容易排斥移植物的机制。激活特定的免疫细胞传感器，称为Toll样受体，似乎在这个过程中是至关重要的，我们将确定硫酸乙酰肝素，一种已知在损伤期间由组织释放的硫酸多糖，如何通过这些传感器激活免疫系统。了解器官移植损伤如何激活免疫系统是很重要的，因为它将阐明旨在改善移植受者结果的治疗目标。

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. PROJECT NARRATIVE: The overall goal of this project is to understand the mechanism by which injury to organ grafts can activate the immune system of transplant recipients and render recipients more prone to rejecting their grafts. Activation of particular immune cell sensors, termed Toll-like receptors, seems to be critical in this process, and we will determine how heparan sulfate, a sulfated polysaccharide known to be released by tissues during injury, activates the immune system via these sensors. Understanding how injury to the organ graft can activate the immune system is important because it will illuminate targets for therapies aimed at improving the outcomes of transplant recipients.