Regulatory Immune Cell Networks in Cancer

描述（由申请人提供）：肿瘤抗原的表达激发适应性免疫应答，在有利的情况下，其可导致癌症患者的肿瘤排斥。然而，恶性肿瘤的几个生物学特征更频繁地导致肿瘤特异性免疫耐受的发展。这种耐受性是由多种免疫调节因子的复杂相互作用诱导和维持的。调节性T细胞（Treg）、髓源性抑制细胞以及肿瘤浸润性巨噬细胞和髓源性树突状细胞是这些调节网络中最突出的细胞成分。越来越明显的是，肿瘤微环境中Treg和髓样抗原呈递细胞（APC）之间的局部串扰对于它们对抗肿瘤效应细胞（最显著的是CD 8+细胞毒性T淋巴细胞（CTL））的免疫抑制功能至关重要。间接证据表明，Treg和骨髓APC之间的串扰以及CTL的抑制是由直接细胞-细胞接触赋予的，其允许在抗原依赖性相互作用的背景下通过可溶性因子和膜蛋白进行信息交换。然而，肿瘤环境中T细胞-APC相互作用的物理性质、动力学和化学计量学尚未探索。在该项目的前期工作中，我们已经开发了一种多光子活体显微镜方法来研究麻醉小鼠完整皮下肿瘤中肿瘤相关APC和T细胞受体（TCR）转基因肿瘤抗原特异性Treg和CTL的动态行为和细胞间信号交换。这种成像方法以亚细胞分辨率产生相互作用的T细胞和APC的3D延时电影，并将用于解决以下三个具体目标：表征肿瘤浸润性骨髓APC和Treg对肿瘤中CTL积累和功能的局部影响; 2.）测试Treg介导的CTL抑制是否表现为TCR信号转导的损伤;和3.）目的研究髓系APC与肿瘤细胞环境中CTL和Treg的相互作用。拟议的实验将产生一个全面的，机制为导向的调查的局部之间的相互作用的免疫调节细胞的髓系和淋巴系。这些信息可能会导致临床免疫调节的改进策略，不仅用于肿瘤治疗，而且用于治疗感染性，炎症性和自身免疫性疾病。公共卫生相关性：免疫疗法已成为癌症患者的一种强有力的治疗方式。为了优化其有效性并通过全身免疫激活将副作用降至最低，需要对针对肿瘤的免疫应答进行更深刻的机制理解。拟议的研究将深入了解免疫抑制细胞群的相互作用，这将提高我们合理设计癌症靶向治疗的能力。

DESCRIPTION (provided by applicant): The expression of tumor antigens elicits adaptive immune responses, which in favorable situations can lead to tumor rejection in cancer patients. However, several biological characteristics of malignant growths more frequently lead to the development of tumor-specific immunological tolerance. This tolerance is induced and maintained by the complex interplay of a multitude of immunoregulatory factors. T regulatory cells (Treg), myeloid-derived suppressor cells, as well as tumor-infiltrating macrophages and myeloid dendritic cells are among the most prominent cellular constituents of these regulatory networks. It is becoming apparent that local crosstalk between Treg and myeloid antigen-presenting cells (APC) in the tumor microenvironment is critical for their immunosuppressive function on anti-tumor effector cells, most prominently CD8+ cytotoxic T lymphocytes (CTL). Indirect evidence suggests that the crosstalk between Treg and myeloid APC, as well as the suppression of CTL is conferred by direct cell-cell contacts that allows for information exchange through soluble factors and membrane proteins in the context of antigen-dependent interactions. However, the physical nature, the kinetics, and stoichiometry of T cell-APC interactions in the tumor environment are unexplored. In preliminary work for this project, we have developed a multiphoton intravital microscopy approach to study the dynamic behavior and intercellular signal exchange of tumor-associated APC and T cell receptor (TCR) transgenic tumor-antigen-specific Treg and CTL in intact subcutaneous tumors of anesthetized mice. This imaging approach produces 3D time-lapse movies of interacting T cells and APC at subcellular resolution and will be used to address the following three specific aims: 1.) To characterize the local impact of tumor- infiltrating myeloid APC and Treg on CTL accumulation and function in tumors; 2.) To test if Treg-mediated suppression of CTL manifests itself in an impairment of TCR signal transduction; and 3.) To investigate the cellular interactions of myeloid APC with CTL and Treg in the tumor environment. The proposed experiments will generate a comprehensive, mechanism-oriented survey of the local interplay between immunoregulatory cells of the myeloid and the lymphoid lineage. This information may lead to improved strategies for clinical immunomodulation, not only for tumor therapy, but also for the treatment of infectious, inflammatory and autoimmune diseases. PUBLIC HEALTH RELEVANCE: Immunotherapy has emerged as a powerful treatment modality for cancer patients. In order to optimize its effectiveness and to minimize side effects through systemic immune activation, a more profound mechanistic understanding of immune responses against tumors is required. The proposed studies will generate insight into the interplay of immunosuppressive cell populations, which will enhance our capacity for the rational design of targeted therapies for cancer.