Real-time Measurement of Self-antigen Recognition by Lymphocytes In Vivo

描述（由申请人提供）：我们的免疫系统的工作是识别外来入侵者，并在保护自身组织的同时消除威胁。这种区分发生在靶细胞表面上的肽/MHC分子复合物的T细胞受体（TCR）识别水平。由发育中的胸腺细胞识别自身肽/MHC分子（自身配体）产生的信号决定TCR库的谱系定型和选择。然而，自身配体相互作用在外周成熟T细胞中的作用存在争议。具体而言，自身配体的存在如何影响淋巴细胞的功能和迁移行为在体内仍然不清楚。直到最近，这种确定主要来自间接的实验证据。然而，在双光子激光扫描显微镜的帮助下，研究人员现在可以开始了解完整组织微环境（如淋巴结）内的细胞间动力学。这个强大的成像工具的效用的一个例子是炎症趋化因子在原发性免疫应答的结内诱导期间在多细胞合作的编排中发挥的作用的揭示8。在目前的研究中，我们建议提供直接的，高分辨率的数据，解决自身配体的监督淋巴结中的循环成熟淋巴细胞的影响。我们还计划进行一系列的研究，旨在描绘各种自身配体表达细胞的相对贡献，在免疫监视幼稚淋巴细胞以及其他专门的细胞，如调节性T细胞。这将通过利用我们自己实验室中最先进的双光子激光扫描显微镜，结合经典的免疫学技术和小鼠骨髓嵌合体操作来实现。这一努力的成功将为自身配体如何促进体内整体淋巴细胞行为和功能提供新的见解，并将为详细了解自身肽/MHC相互作用如何塑造T细胞群体对感染和疫苗接种期间遇到的关联抗原的反应奠定基础。对组织微环境中错综复杂的细胞通讯的详细了解将使未来能够探究导致自身耐受失调状态发展的体内细胞机制，如自身免疫，癌症和慢性感染。 公共卫生相关性：在胸腺教育过程中，识别阳性选择性自身配体在T淋巴细胞的发育中起着至关重要的作用。然而，这种自身肽抗原识别在外周成熟T淋巴细胞中的作用是有争议的。本研究旨在探讨自身肽抗原在次级淋巴器官中T淋巴细胞体内行为中的作用。我们的目标是提供高分辨率的数据，解决自身配体相互作用的影响，并寻求各种基质和免疫细胞亚群的相对贡献，影响幼稚和调节T淋巴细胞在体内的迁移行为。拟议的研究将为正确理解自身肽/MHC相互作用如何塑造这些T细胞群体对感染和疫苗接种期间所见同源抗原的反应奠定基础。该项目的成功实施也将为自身免疫发展、诱导肿瘤耐受和维持稳态免疫反应的潜在机制提供新的见解。

DESCRIPTION (provided by applicant): The job of our immune system is to recognize foreign invaders and to eliminate the threat while sparing self-tissues. Such discrimination occurs at the level of T cell receptor (TCR) recognition of peptide/MHC molecular complexes on target cell surfaces. Signals arising from recognition of self-peptide/MHC molecules (self-ligands) by developing thymocytes determine lineage commitment and selection of the TCR repertoire. However, the role of self-ligand interaction in peripheral mature T cells is controversial. Specifically, how the presence of self-ligands influences lymphocyte function and migratory behavior in vivo remains unclear. Until recently, such determination largely comes from indirect experimental evidence. With the aid of 2-photon laser scanning microscopy, however, investigators can now begin to understand intercellular dynamics within an intact tissue microenvironment such as the lymph node. An example of the utility of this powerful imaging tool is the uncovering of the role inflammatory chemokines play in the orchestration of multi-cellular cooperation during the intranodal induction of a primary immune response8. In the current study, we propose to provide direct, high-resolution data addressing the impact of self-ligand surveillance by circulating mature lymphocytes in the lymph nodes. We also plan to undertake a series of studies aimed to delineate the relative contribution of various self-ligand-expressing cells during immune surveillance by naive lymphocytes as well as other specialized cells such as regulatory T cells. This will be accomplished by utilizing the state-of-the-art 2-photon laser scanning microscopy available in our own laboratory, combined with classical immunological techniques and mouse bone marrow chimera manipulations. Success in this endeavor will provide new insights into how self-ligands contribute to the global lymphocyte behavior and function in vivo, and will set the stage for a detailed understanding of how self-peptide/MHC interactions shape the responses of the T cell populations against cognate antigens encountered during infection and vaccination. A detailed understanding of the intricate and complex cellular communication in the tissue microenvironment will allow future inquiries into the in vivo cellular mechanisms that lead to the development of dysregulated state of self-tolerance, such as autoimmunity, cancer and chronic infection. PUBLIC HEALTH RELEVANCE: Recognition of positive-selecting self-ligands plays a crucial role in developing T lymphocytes during thymic education. However, the role of such self-peptide antigen recognition in the periphery for mature T lymphocytes is controversial. The current study seeks to investigate the role self-peptide antigens play in the in vivo behavior of T lymphocytes in secondary lymphoid organs. We aim to provide high-resolution data addressing the impact of self-ligand interactions, and to seek the relative contribution of various stromal and immune cellular subsets in affecting the migratory behavior of naive and regulatory T lymphocytes in vivo. The proposed studies will set the stage for proper understanding of how self-peptide/MHC interactions shape the responses of these T cell populations against cognate antigens seen during infection and vaccination. Successful execution of this project will also provide new insights into potential mechanisms underlying the development of autoimmunity, induction of tumor tolerance and maintenance of homeostatic immune responses.