Expression and function of the TLRs on T cells

描述（由申请人提供）：toll样受体（TLRs）在先天免疫和适应性免疫中起着不可或缺的作用。tlr的结扎激活先天免疫系统的细胞，诱导吞噬和IFN-a、IFN-b分泌等功能。tlr结扎也作为先天免疫系统和适应性免疫系统之间的桥梁。TLR刺激dc和巨噬细胞诱导炎性细胞因子如IL-12的产生，MHC II类和共刺激配体如CD40和CD86的上调，而这些反应大多需要通过适配器信号分子MyD88传递信号。虽然tlr和MyD88在APCs中的作用已经确定，但令人惊讶的是，人们对它们在T细胞上的表达和潜在功能知之甚少。我们实验室的研究表明，几种tlr在初始CD4+CD25 T细胞激活后表达。这些tlr的连接通过MyD88激活了几种下游信号通路，包括NF- kB、p38、JNK和ERK。在功能上，这导致T细胞存活增强，并提供与次优TCR连接的共刺激。新的数据还表明，MyD88在T细胞中的体内表达可能需要对病原体弓形虫产生保护性免疫反应。我们的工作假设是，T细胞上的TLR和MyD88信号是细胞免疫反应的重要贡献者。为此，本研究计划的长期目标是确定tlr在T细胞上的表达和功能。在具体目标#1中，我们将描述控制tlr在T细胞上的表达和上调的信号，以及tlr和MyD88用来介导其作用的下游信号通路。特异性目标#2将使用来自TCR转基因小鼠的细胞，结合体外和体内过过性转移系统，对TLR和MyD88激活T细胞在诱导激活和共刺激分子、细胞因子产生或偏斜、效应/记忆分化和反应性方面的影响进行详细检查。这种方法将允许精确定义TLR刺激T细胞的作用。在具体的目标#3中，我们将询问目标#2中确定的tlr和MyD88的哪些功能在体内免疫应答中起作用。为此，我们将使用MyD88敲除小鼠和骨髓嵌合体以及过继转移系统来创建体内模型，其中只有T细胞缺乏MyD88。基于我们的初步数据，我们将使用这些模型来评估对弓形虫的反应，并将myd88缺陷小鼠回交到TCR转基因背景中，使我们能够在移植模型中追踪单个T细胞对体内异体抗原的反应。

DESCRIPTION (provided by applicant): Toll-like receptors (TLRs) play an integral role in innate and adaptive immunity. Ligation of TLRs activates cells of the innate immune system, inducing functions such as phagocytosis and IFN-a and IFN-b secretion. TLR-ligation also serves as a bridge between the innate and adaptive immune systems. TLR stimulation of DCs and macrophages induces the production of inflammatory cytokines such as IL-12, and upregulation of MHC class II and costimulatory ligands such as CD40 and CD86, and most of these responses require signals delivered through the adaptor signaling molecule MyD88. While roles for TLRs and MyD88 on APCs are well-established, surprisingly little is known about their expression and potential function on T cells. Studies from our laboratory show that several TLRs are expressed following activation of naive CD4+CD25 T cells. Ligation of these TLRs activates, via MyD88, several downstream signaling pathways, including NF- kB, p38 JNK, and ERK. Functionally, this leads to enhanced T cell survival and provides costimulation with sub-optimal TCR ligation. New data also indicates that in vivo expression of MyD88 in T cells may be required for a protective immune response to the pathogen Toxoplasma gondii. Our working hypothesis is that TLR and MyD88 signaling on T cells are important contributors to cellular immune responses. To this end, the long-term goals of this research program are to define the expression and function of TLRs on T cells. In specific aim #1 we will characterize the signals which govern the expression and upregulation of TLRs on T cells, and the downstream signaling pathways which TLRs and MyD88 use to mediate their effects. Specific aim #2 will use cells from TCR transgenic mice coupled with in vitro and in vivo adoptive transfer systems to conduct a detailed examination of the effects of TLR and MyD88 activation of T cells on induction of activation and costimulatory molecules, cytokine production or skewing, and effector/memory differentiation and responsiveness. This approach will allow for precise definition of what TLR stimulation of T cells can do. In specific aim #3 we will then ask which of the functions identified for TLRs and MyD88 in aim #2 are operative during in vivo immune responses. To do so, we will use MyD88 knockout mice and bone-marrow chimeras and adoptive transfer systems to create in vivo models in which only T cells are deficient in MyD88. Based on our preliminary data, we will use these models to assess responses to Toxoplasma gondii, and will also backcross the MyD88-deficient mice onto TCR transgenic backgrounds to enable us to track the fate of individual T cells as they respond to alloantigen in vivo in transplantation models.