Maintenance vs Programming in Th1 Memory Cell Development in P. Chabaudi Malaria

描述（由申请人提供）：在开发用于慢性感染（如HIV、TB和疟疾）的有效疫苗方面的两个主要障碍是缺乏对维持保护性免疫的关键因素的了解，以及缺乏与保护相关的可测量的细胞类型。为了解决我们知识中的这些空白，我们建议确定慢性疟疾感染中的保护性记忆T细胞亚群，并确定它们用于生存和维持保护性细胞因子产生的机制。我们的初步数据表明，疟疾特异性T细胞分化为效应记忆细胞（Tem），如果它们暴露于慢性感染，则最有助于保护。慢性感染也会增强Th 1细胞因子（IFN 3+）的产生，与这种保护作用相关。因此，我们的中心假设是，Tem亚群维持保护性细胞因子程序，如由慢性感染相关炎症维持的定型Th 1细胞。因此，本建议的目标是确定哪些CD 4+记忆T细胞亚群是保护性的并存活，哪些帮助B细胞（T滤泡辅助细胞，Tfh）或保持致力于Th 1表型。这些目标将通过完成以下具体目标来实现：1）确定CD 4+效应记忆T细胞亚群的保护、存活和效应功能（Th 1，Tfh），和2）确定产生IFN 3的亚群及其Th 1定型程度。第一个目的将定义保护性记忆T细胞亚群和维持它们所需的因子，并将通过体内保护、存活和细胞因子产生测定来实现，所述测定已经在申请人手中建立为可行的，使用现代体内免疫学技术和多参数流式细胞术。第二个目的是首先测试疟疾特异性记忆细胞的Th 1细胞因子谱的体外稳定性，使用我在我的论文工作中使用的相同技术，其次，研究细胞因子，细胞因子受体，转录和染色质统计因子的指示模式，以确定Th 1记忆细胞在慢性感染中维持其效应功能的机制。这两个目标的结果将使我们能够定义保护性记忆CD 4 + T细胞生存所使用的刺激以及在慢性感染中保持保护性的机制。提供知识，包括用于成功的疫苗接种方案的新刺激和与保护相关的记忆T细胞类型。这种方法是创新的，因为我们有一个新的疟疾特异性T细胞转基因系统，一个准确的鼠疟疾模型，使用疟原虫chabaudi;也因为该提案侧重于效应记忆T细胞，尽管其他人忽视了它们，而支持中央记忆细胞，尽管有证据表明Tem具有更好的保护作用。这种疫苗接种方法得到了通过疫苗接种产生和维持效应记忆细胞是可行的证据的支持。这项拟议的研究意义重大，因为其结果直接适用于疟疾、艾滋病毒和结核病疫苗接种试验，并可能加速寻找疟疾的保护性疫苗，疟疾是人类最致命的感染之一。

DESCRIPTION (provided by applicant): Two major hurdles in developing effective vaccines for chronic infections such as HIV, TB and malaria are the lack of knowledge of the critical factors for maintenance of protective immunity, and the lack of a measurable cell type that correlates with protection. To address these gaps in our knowledge, we propose to identify the protective memory T cell subsets in chronic malaria infection and define the mechanisms that they use to survive and maintain protective cytokine production. Our preliminary data demonstrate that malaria- specific T cells differentiate into effector memory cells (Tem), which contribute to protection best if they are exposed to chronic infection. Chronic infection also enhances their Th1 cytokine production (IFN3+), correlating with this protection. Therefore, our central hypothesis is that Tem subsets maintain a protective cytokine program like committed Th1 cells that is maintained by the inflammation associated with chronic infection. The goals of this proposal are therefore to determine which CD4+ memory T cell subsets are protective and survive and which help B cells (T follicular helper, Tfh) or remain committed to the Th1 phenotype. These goals will be achieved by the completion of the following specific aims: 1) To determine protection, survival and effector function (Th1, Tfh) of CD4+ effector memory T cell subsets, and 2) To determine subsets producing IFN3 and their degree of Th1 commitment. The first aim will define protective memory T cell subsets and the factors required for their maintenance and will be accomplished by in vivo protection, survival and cytokine production assays already established as feasible in the applicant's hands, using modern in vivo immunological techniques and multi-parameter flow cytometry. The second aim is firstly to test the in vitro stability of the Th1 cytokine profile of malaria-specific memory cells, using the same techniques I used in my dissertation work, and secondly; to study the indicative pattern of cytokines, cytokine receptors, transcription and chromatin tatistics factors to define mechanisms utilized by Th1 memory cells for maintenance of their effector function in chronic infection. The outcomes of these two aims will allow us to define stimuli used by protective memory CD4+ T cells to survive and the mechanisms to remain protective in chronic infection. Providing knowledge including both novel stimuli to include for a successful vaccination protocol and a memory T cell- type that correlates with protection. The approach is innovative because we have a novel malaria-specific T cell transgenic system, an accurate murine malaria model, using Plasmodium chabaudi; and also because the proposal focuses on effector memory T cells, though others have disregarded them in favor of central memory cells, in spite of evidence of better protection by Tem. This approach to vaccination is supported by evidence that generating and maintaining effector memory cells by vaccination is feasible. The proposed research is significant because the outcomes are directly applicable to malaria, HIV and TB vaccination trials and may speed the search for a protective vaccine to malaria, one of the most lethal infections of mankind.