Using the MHC class I cytoplasmic tail to control tumor Ag presentation by DCs

描述（由申请方提供）：已证明利用细胞毒性T淋巴细胞（CTL）的免疫疗法可有效根除动物模型和人类癌症患者的大肿瘤负荷。由于树突状细胞（DC）是用于引发初始CD 8 + T细胞成为活化的CTL的最有效的抗原呈递细胞，所述活化的CTL以MHC I类限制的方式有效地杀死靶细胞，因此对开发用于癌症治疗的基于DC的疫苗存在广泛的兴趣。该项目的具体目标是通过利用控制MHC-I运输和DC表面表达的天然机制来产生改进的DC疫苗，以改善肿瘤抗原呈递给CD 8 + T细胞的质量和持续时间。我们的中心假设是，MHC-I胞质尾内的保守基序不仅控制MHC-I/肽复合物在细胞表面呈递的持续时间，而且还控制MHC-I通过专门的内吞交叉呈递隔室的运输。我们已经基于我们的初步结果阐明了这一假设，所述初步结果鉴定了两种功能上不同的MHC-I尾基序，所述MHC-I尾基序直接控制DC内吞运输和鼠MHC-I分子的交叉呈递功能，并且在体内产生抗病毒CTL应答中起关键作用（Lizee等人，Nature Immunology）。该提议的基本原理是利用我们对这些保守基序如何在DC中操作的知识将允许在基于人DC的癌症疫苗中改善肿瘤抗原负载和延长抗原呈递的持续时间的能力，从而改善CTL引发结果。我们计划通过关注以下三个具体目标来测试我们的中心假设并实现我们改进基于DC的癌症疫苗的总体目标：（1）确定对MHC-I胞质尾的修饰如何影响抗原特异性CTL的引发并改变DC抗原呈递的动力学。(2)使用建立的鼠模型，评估MHC-I尾修饰的DC疫苗在引发抗原特异性CTL和诱导抗肿瘤应答中的功效。(3)分析炎症介质和肿瘤源性因子如何影响DC中MHC-I尾磷酸化、细胞内运输和抗原呈递。这项工作是创新的，因为它将揭示DC用于引发最有效的抗肿瘤CTL应答的分子机制。它还将填补目前知识库中关于在Toll样受体（TLR）配体或先天免疫信号激活DC期间发生的MHC-I运输和抗原呈递的动态变化的空白。这些结果将产生重要的积极影响，因为它们将为下一代改进的DC疫苗铺平道路。它们将使得能够设计能够修饰MHC-I尾的新型治疗剂，从而潜在地允许在MHC-I抗原呈递水平上操纵免疫应答。这些研究的成功完成可能会对人类疾病治疗的其他领域产生影响，包括自身免疫，移植免疫学和病原体感染。 公共卫生相关性：癌症疫苗通过在癌症患者的血液中引发特异性细胞毒性（“杀伤”）T淋巴细胞（CTL）来发挥作用，从而破坏肿瘤。基于树突状细胞（DC）的疫苗在临床上显示出很大的前景，但我们缺乏对DC生物学的基本了解限制了这些疫苗的发展。这项资助计划利用我们对MHC I类生物学的基本知识来提高基于DC的癌症疫苗的效力，最终目标是提高患者对基于CTL的免疫治疗的反应。

DESCRIPTION (provided by applicant): Immunotherapies that utilize cytotoxic T lymphocytes (CTLs) have proven effective at eradicating large tumor burdens in both animal models and human cancer patients. Since dendritic cells (DCs) are the most potent antigen-presenting cells for priming naive CD8+ T-cells to become activated CTLs that efficiently kill target cells in an MHC class I-restricted fashion, there has been widespread interest in developing DC-based vaccines for use in cancer therapy. The specific objective of this project is to generate an improved DC vaccine by exploiting the natural mechanisms that control MHC-I trafficking and DC surface expression to improve the quality and duration of tumor antigen presentation to CD8+ T cells. It is our central hypothesis that conserved motifs within the MHC-I cytoplasmic tail control not only the duration of presentation of MHC-I/peptide complexes at the cell surface, but also MHC-I trafficking through specialized, endocytic cross-presentation compartments. We have formulated this hypothesis on the basis of our Preliminary Results identifying two functionally distinct MHC-I tail motifs that directly control DC endocytic trafficking and cross-presentation function of murine MHC-I molecules, and which play a crucial role in the generation of antiviral CTL responses in vivo (Lizee et al, Nature Immunology). The rationale for this proposal is that utilizing our knowledge of how these conserved motifs operate in DCs will allow for the ability to improve tumor antigen loading and extend duration of antigen presentation in human DC-based cancer vaccines, thus improving CTL priming outcomes. We plan to test our central hypothesis and accomplish our overall objective of improving DC-based cancer vaccines by focusing on the following three specific aims: (1) Determine how modifications to the MHC-I cytoplasmic tail impact the priming of antigen-specific CTLs and alter the dynamics of DC antigen presentation. (2) Using established murine models, assess the efficacy of MHC-I tail-modified DC vaccines in priming antigen-specific CTLs and in the induction of antitumor responses. (3) Analyze how inflammatory mediators and tumor-derived factors affect MHC-I tail phosphorylation, intracellular trafficking, and antigen presentation in DCs. The proposed work is innovative, because it will uncover the molecular mechanisms utilized by DCs to prime optimally effective antitumor CTL responses. It will also fill in gaps in the current knowledge base with regard to the dynamic changes in MHC-I trafficking and antigen presentation that occur during DC activation by toll-like receptor (TLR)-ligands or innate immune signals. Such results will have an important positive impact, because they will pave the way towards the next generation of improved, DC-based vaccines. They will enable the design of novel therapeutics capable of modifying the MHC-I tail, thus potentially allowing for manipulation of immune responses at the level of MHC-I antigen presentation. Successful completion of these studies is likely to have an impact in other areas of human disease treatment, including autoimmunity, transplant immunology, and pathogen infections. PUBLIC HEALTH RELEVANCE: Cancer vaccines work by eliciting specific cytotoxic ('killer') T lymphocytes (CTL) in the blood of cancer patients, which in turn destroy the tumor. Dendritic cell (DC)-based vaccines have shown much promise clinically, but our lack of basic understanding of DC biology has limited the development of these vaccines. This grant proposes to utilize our basic knowledge of MHC class I biology to improve the potency of DC-based based cancer vaccines, with the ultimate goal of improving patient responses to CTL-based immunotherapy.