Vaccination with the Tumor Self-Protein TP(D52) Elicits a Unique Subset of CD8+ T Cells

 描述（由申请人提供）：靶向肿瘤自身抗原的疫苗需要对外周免疫耐受机制有更深入的了解。关于CD 4 + T调节（Treg）细胞诱导耐受性已经了解很多，但与癌症中未定义的独特CD 8 + T细胞相关的抑制研究不足。关于未定义的CD 8 + T细胞如何抑制对肿瘤自身抗原的免疫以及它们表达的定义标志物的知识存在差距，这阻碍了癌症疫苗开发的进展。这一差距代表了一个重要的问题，因为在它被填补之前，开发针对肿瘤自身抗原的最佳疫苗策略可能是不可能的。本项目的目标和目的将通过以下方式克服这一障碍：首先，确定CD 8 + T细胞的独特亚群抑制对肿瘤自身抗原TP（D52）的免疫的机制，其次，通过定义这些独特抑制性CD 8 + T细胞上的新表型标记物，这些独特抑制性CD 8 + T细胞由D52模拟的过度表达肿瘤自身蛋白的疫苗接种引起。我们的假设是，一个独特的CD 8 + T细胞亚群是由D52疫苗接种引起的，并积极参与抑制对这种过度表达的肿瘤自身癌抗原的免疫。这一假设是根据我们实验室的初步数据提出的。所提出的研究的基本原理是针对鼠D52肿瘤自身蛋白（mD52）的疫苗接种以防止鼠癌症模型中的肿瘤生长，导致部分肿瘤免疫，这需要产生mD52特异性CD 4+和CD 8 + IFN-γ分泌T细胞。然而，仅分泌IL-10的独特的CD 8 + T细胞亚群也被CD 4 + T细胞诱导，并且可能在抑制肿瘤免疫中起作用。在强有力的初步数据的指导下，将通过追求两个特定目标来测试该假设：1）确定由mD52疫苗接种引起的CD 8 + IL-10+ T细胞的功能; 2）鉴定由mD52疫苗接种引起的CD 8 + IL-10+ T细胞上的定义标志物。在第一个目标下，将从mD52接种的小鼠中分离CD 8 + IL-10+ T细胞，并分析其免疫抑制机制。在第二个目标中，用于这些独特的CD 8 + IL-10+ T细胞的确定性表征的基于细胞的标志物将被鉴定为将D52疫苗接种策略临床上转化为组合疗法的关键步骤。这项提议是创新的，因为它关注的是一种独特的CD 8 + T细胞亚群，这种亚群是通过接种疫苗来对抗一种研究不足、相关过度表达的肿瘤自身癌抗原而引起的，这种抗原是多种癌症共有的。我们有能力成功开展这项工作，因为我们共同发现了D52，并证明了它作为疫苗的潜力。拟议的研究具有重要意义，因为它有望垂直推进和扩大对如何最好地克服与肿瘤自身抗原免疫耐受相关的挑战的理解，而其他研究充分的免疫调节过程没有解决这些挑战。这些结果应该支持开发更有效的疫苗，除了D52之外，还针对其他共享的、过度表达的肿瘤自身抗原。

 DESCRIPTION (provided by applicant): Vaccines that target tumor self-antigens require a deeper understanding of the mechanisms of peripheral immunologic tolerance. Much is understood about tolerance induction by CD4+ T regulatory (Treg) cells, but suppression associated with undefined unique CD8+ T cells in cancer is understudied. A gap in the knowledge of how undefined CD8+ T cells suppress immunity to tumor self-antigens and of what defining markers they express are obstacles preventing progress for cancer vaccine development. This gap represents an important problem because, until it is filled, developing the best vaccine strategy against tumor self-antigens may not be possible. Our goals and objectives for this project will overcome this obstacle by first, identifying the mechanism(s) used by a unique subset of CD8+ T cells to suppress immunity to the tumor self-antigen TP (D52), and second by defining new phenotypic markers on these unique suppressor CD8+ T cells elicited by vaccination against over expressed tumor self-proteins modeled by D52. Our hypothesis is that a unique subset of CD8+ T cells is elicited by D52-vaccination and actively participates in suppressing immunity to this overexpressed tumor self-oncoantigen. This hypothesis was formulated on the basis of preliminary data produced in our laboratory. The rationale for the proposed research is that vaccination against murine D52 tumor self-protein (mD52) to prevent tumor growth in murine models of cancer results in partial tumor immunity that requires the generation of mD52-specific CD4+ and CD8+ IFN- secreting T cells. However, a unique sub-population of CD8+ T cells that secrete IL-10 only is also elicited with CD4+Tregs and may be playing a role in suppressing tumor immunity. Guided by strong preliminary data, this hypothesis will be tested by pursuing two specific aims: 1) Determine the function of the CD8+ IL-10+ T cells elicited by mD52-vaccination; 2) Identify defining marker(s) on the CD8+ IL-10+ T cells elicited by mD52-vaccination. Under the first aim, CD8+ IL-10+ T cells will be isolated from mD52-vaccinated mice and their mechanisms of immune suppression analyzed. In the second aim, cell-based markers for definitive characterization of these unique CD8+ IL-10+ T cells will be identified as a critical step for translating D52 vaccination strategies clinically as a combination therapy. This proposal is innovative, as it focuses on a unique subset of CD8+ T cells elicited by vaccination against an understudied, relevantly overexpressed tumor self-oncoantigen shared by a wide variety of cancers. We are uniquely poised to successfully carry out this work because we co-discovered D52 and demonstrated its potential as a vaccine. The proposed research is significant as it is expected to vertically advance and expand understanding of how to best overcome challenges related to immunologic tolerance to tumor-self antigens not addressed by other well-studied processes of immune regulation. The results should support development of more effective vaccines against other shared, over expressed tumor self-antigens, in addition to D52.