Tolerance mechanisms regulating the complete HER-2/neu CD+8 T cell repertoire

描述（由申请方提供）：本提案的主要目的是了解在非耐受化和耐受化小鼠中调节低与高亲和力肿瘤抗原特异性T细胞活化状态和功能的分子机制。鉴定这些机制是开发方法的第一步，这些方法可以更有效地激活具有一系列对癌症抗原特异性的亲和力的T细胞。针对许多病毒的免疫的成功部分是由于在健康宿主中诱导具有足够记忆T细胞区室的病毒特异性、高亲合力CD 8 + T细胞库。相反，在癌症宿主中成功接种疫苗需要绕过多种免疫耐受机制。许多已知的肿瘤抗原是过表达的组织特异性抗原。必须存在T细胞耐受机制以防止针对自身抗原的自身免疫。这些建立和维持自身耐受性的相同机制可能导致T细胞在体内缺乏有效性，这在癌症患者中经常观察到。耐受性诱导的含义是癌症特异性高亲合力T细胞群体被删除或抑制，并且癌症疫苗必须打破无反应性T细胞中的耐受性或激活低亲合力T细胞群体，所述低亲合力T细胞群体基于其弱反应性可能逃避主动耐受性诱导。直到最近，还没有了解高亲合力和低亲合力癌症特异性CD 8 + T细胞库在携带癌症的宿主中的命运的工具。自发性乳腺肿瘤的HER-2/neu转基因（neu-N）小鼠模型提供了使用天然肿瘤抗原HER-2/neu（neu）评估这一问题的机会。在接种疫苗的亲本FVB/N小鼠中，大多数CD 8 + T细胞具有高亲合力，并针对免疫显性抗原RNEU 420 -429。相比之下，在接种疫苗的neu-N小鼠中，大多数T细胞反应较弱，具有低亲合力，并且针对多个表位。为了理解调节低和高亲和力的CD 8 + T细胞的活化和功能的机制，我们开发了高和低亲和力RNEU 420 -429特异性TCR转基因小鼠。在目标1中，我们将比较和表征体内高亲合力与低亲合力RNEU 420 -429特异性CD 8 + T细胞的命运，并确定调节性T细胞（TCLs）在体内控制活化和记忆高亲合力与低亲合力T细胞功能中的作用。在目标2中，我们将评估微RNA（miRNA）作为T细胞功能的转录后调节因子在高亲合力与低亲合力RNEU 420 -429特异性CD 8 + T细胞中的作用。在目标3中，我们将评估高亲合力与低亲合力RNEU 420 -429特异性CD 8 + TCR转基因T细胞在T细胞信号传导途径中的变化。 公共卫生相关性：该提案的广泛目标是了解调节非耐受化和耐受化小鼠中低与高亲和力肿瘤抗原特异性T细胞的活化状态和功能的分子机制。具体来说，我们将评估一些机制，可能会有差异地调节低与高亲和力T细胞，包括：调节性T细胞，T细胞信号转导通路，和转录后调节。

DESCRIPTION (provided by applicant): The broad objective of this proposal is to understand the molecular mechanisms that regulate the activation status and function of low versus high avidity tumor-antigen specific T cells in non-tolerized and tolerized mice. Identification of these mechanisms is the first step toward developing approaches that can allow for more effective activation of T cells with a range of avidities specific for cancer antigens. The success of immunization against many viruses is in part due to the induction of a virus specific, high avidity CD8+ T cell repertoire with a sufficient memory T cell compartment in healthy hosts. In contrast, successful vaccination in cancer bearing hosts requires bypassing multiple mechanisms of immune tolerance. Many of the known tumor antigens are over-expressed tissue- specific antigens. Mechanisms of T cell tolerance must exist to prevent autoimmunity against self- antigens. These same mechanisms that establish and maintain self-tolerance are likely contributors to the lack of effectiveness of T cells in vivo that is often observed in cancer patients. The implications of tolerance induction are that cancer-specific high avidity T cell populations are deleted or suppressed, and that cancer vaccines must either break tolerance in anergic T cells or activate populations of low avidity T cells which, based on their weak reactivity, may escape active tolerance induction. Until recently, the tools to understand the fate of the high avidity and low avidity cancer specific CD8+ T cell repertoires in cancer bearing hosts were not available. The HER-2/neu transgenic (neu-N) mouse model of spontaneous mammary tumors provides the opportunity to evaluate this issue using a natural tumor antigen, HER-2/neu (neu). In vaccinated parental FVB/N mice, the majority of CD8+ T cells are of high avidity and directed against an immunodominant antigen, RNEU420-429. In contrast, in vaccinated neu-N mice, most T cell responses are weak, of low avidity, and directed against multiple epitopes. To understand the mechanisms that regulate the activation and function of CD8+ T cells of both low and high avidity, we have developed high and low avidity RNEU420-429-specific TCR transgenic mice. In aim 1 we will compare and characterize the fate of the high avidity versus the low avidity RNEU420-429-specific CD8+ T cells in vivo, and determine the role regulatory T cells (Tregs) play in controlling the function of activated and memory high avidity versus low avidity T cells in vivo. In aim 2, we will evaluate the role of microRNA (miRNA) as post- transcriptional regulators of T cell function in the high avidity versus low avidity RNEU420-429-specific CD8+ T cells. In aim 3, we will evaluate the high avidity versus low avidity RNEU420-429-specific CD8+ TCR transgenic T cells for changes in T cell signaling pathways. PUBLIC HEALTH RELEVANCE: The broad objective of this proposal is to understand the molecular mechanisms that regulate the activation status and function of low versus high avidity tumor-antigen specific T cells in non-tolerized and tolerized mice. Specifically, we will evaluate a number of mechanisms that may differentially regulate low versus high avidity T cells including: regulatory T cells, T cell signaling pathways, and post-transcriptional regulation.