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

 描述(由申请人提供)：针对肿瘤自身抗原的疫苗需要更深入地了解外周免疫耐受的机制。人们对CD4T调节细胞(Treg)诱导耐受的了解很多，但对癌症中未明确的独特CD8T细胞的抑制研究较少。对未定义的CD8 T细胞如何抑制对肿瘤自身抗原的免疫以及它们表达哪些定义标记的了解存在差距，这是阻碍癌症疫苗开发进展的障碍。这一空白代表着一个重要的问题，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。我们这个项目的目标和目标将克服这一障碍，首先，确定一个独特的CD8T细胞亚群用来抑制对肿瘤自身抗原TP(D52)的免疫的机制(S)，第二通过定义这些独特的抑制因子CD8T细胞上的新表型标记，这些独特的抑制物是通过接种D52模拟的过表达的肿瘤自身蛋白而产生的。我们的假设是，一个独特的CD8T细胞亚群是由D52疫苗诱导的，并积极参与抑制对这种过度表达的肿瘤自身肿瘤抗原的免疫。这一假设是根据我们实验室提供的初步数据提出的。这项拟议研究的基本原理是，在小鼠癌症模型中接种针对小鼠D52肿瘤自身蛋白(MD52)的疫苗以防止肿瘤生长会导致部分肿瘤免疫，这需要产生mD52特异性的CD4和CD8IFN-分泌T细胞。然而，CD8T细胞中仅分泌IL-10的一种独特的亚群也被CD4Tregs诱导，并可能在抑制肿瘤免疫中发挥作用。在强大的初步数据的指导下，这一假说将通过追求两个具体目标来验证：1)确定mD52疫苗诱导的CD8IL-10T细胞的功能；2)确定mD52疫苗诱导的CD8IL-10T细胞的定义标志(S)。在第一个目标下，我们将从mD52免疫的小鼠中分离CD8、IL-10 T细胞，并分析其免疫抑制机制。在第二个目标中，用于明确这些独特的CD8 IL-10 T细胞特征的基于细胞的标记将被确定为将D52疫苗接种策略转化为临床联合疗法的关键步骤。这项建议是创新的，因为它集中在CD8T细胞的一个独特的子集，通过接种疫苗来对抗一种研究不足的、相关地过度表达的肿瘤自身癌抗原，该抗原在各种癌症中都是共同的。我们为成功开展这项工作做好了准备，因为我们共同发现了D52并展示了它作为疫苗的潜力。这项拟议的研究具有重要意义，因为它有望纵向推进和扩大人们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，这些挑战没有被其他充分研究的免疫调节过程解决。这些结果应该支持开发更有效的疫苗，以对抗除D52之外的其他共享的、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.