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消除威胁，同时保留自身组织。这种区分发生在T细胞受体（TCR）对靶细胞表面肽/MHC分子复合物的识别水平上。胸腺细胞自肽/MHC分子（自配体）识别产生的信号决定了谱系承诺和TCR库的选择。然而，自配体相互作用在外周成熟T细胞中的作用是有争议的。具体来说，自配体的存在如何影响体内淋巴细胞功能和迁移行为尚不清楚。直到最近，这样的决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）中的细胞间动力学。这种强大的成像工具的一个应用例子是发现炎症趋化因子在结内诱导原发性免疫反应期间多细胞合作的协调中所起的作用。在目前的研究中，我们建议提供直接的、高分辨率的数据，通过循环淋巴结中的成熟淋巴细胞来解决自身配体监测的影响。我们还计划进行一系列研究，旨在描述各种自我配体表达细胞在幼稚淋巴细胞和其他特化细胞（如调节性T细胞）的免疫监视中的相对贡献。这将通过利用我们实验室最先进的双光子激光扫描显微镜，结合经典免疫学技术和小鼠骨髓嵌合体操作来完成。这一努力的成功将提供新的见解，了解自身配体如何促进体内整体淋巴细胞的行为和功能，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过程中遇到的同源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，将有助于未来探究导致自我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。

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.