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

描述（由申请人提供）：开发针对艾滋病毒、结核病和疟疾等慢性感染的有效疫苗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细胞类型。为了解决这些知识上的空白，我们建议鉴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，它们将发挥最大的保护作用。慢性感染还会增强Th1细胞因子（IFN3+）的产生，这与这种保护作用有关。因此，我们的中心假设是Tem亚群维持了一种保护性细胞因子程序，就像由慢性感染相关的炎症维持的Th1细胞一样。因此，该建议的目标是确定哪些CD4+记忆T细胞亚群具有保护性和存活性，哪些帮助B细胞（T滤泡辅助细胞，Tfh）或继续致力于Th1表型。这些目标将通过完成以下具体目标来实现：1)确定CD4+效应记忆T细胞亚群的保护、存活和效应功能（Th1, Tfh）； 2)确定产生IFN3的亚群及其Th1承诺的程度。第一个目标将定义保护性记忆T细胞亚群及其维持所需的因素，并将通过使用现代体内免疫技术和多参数流式细胞术，在申请人手中建立可行的体内保护，存活和细胞因子产生测定来完成。第二个目标是首先测试疟疾特异性记忆细胞Th1细胞因子谱的体外稳定性，使用我在论文中使用的相同技术，其次；研究细胞因子、细胞因子受体、转录因子和染色质统计因子的指示模式，以确定Th1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CD4+ 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。提供包括新刺激的知识，包括成功的疫苗接种方案和与保护相关的记忆T细胞类型。这种方法是创新的，因为我们有一种新的疟疾特异性T细胞转基因系统，一种精确的小鼠疟疾模型，使用的是chabaudi疟原虫；另一个原因是，这项研究的重点是效应记忆T细胞，尽管有证据表明，Tem具有更好的保护作用，但其他人却忽视了它们，转而支持中枢记忆细胞。有证据表明，通过接种疫苗产生和维持效应记忆细胞是可行的，这一接种方法得到了支持。拟议中的研究意义重大，因为其结果可直接适用于疟疾、艾滋病毒和结核病疫苗试验，并可能加速寻找针对疟疾的保护性疫苗。疟疾是人类最致命的传染病之一。

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.