Cell Type-Specific Roles of TLR Signaling In Immune Responses

描述(申请人提供)：近年来，Toll样受体(TLRs)已成为先天免疫的关键识别元件，用于在感染部位诱导炎症和诱导适应性免疫反应。这些受体表达在许多组织中的三种主要类型的免疫细胞上，即未成熟树突状细胞、组织巨噬细胞和肥大细胞，以及其他几种类型的细胞。在拟议的项目中，我们将定义哪种类型的细胞负责调节基于TLR的免疫反应。在这些研究中，我们将利用我们在小鼠胚系中为关键的TLR信号适配器分子MyD88设计的条件等位基因。在这个等位基因中，我们在MyD88基因基本外显子3的两侧内含子上放置了loxP位点，结果是Cre在细胞中的表达会导致外显子3的缺失和MyD88基因的失活。MyD88的条件等位基因将与选择性地在树突状细胞(CD11c-Cre)、巨噬细胞和中性粒细胞(LysM-Cre)或B细胞(CD19-Cre)中选择性表达Cre的转基因一起使用。然后，这些小鼠将接受特定细胞类型MyD88缺失的影响测试：诱导效应和记忆的CD4T细胞反应(目标1)，诱导炎症和限制两种革兰氏阳性细菌病原体的生长(目标2)，以及促进对蛋白质抗原的抗体反应(目标3)。这些研究将确定TLR信号在树突状细胞、巨噬细胞、肥大细胞和B细胞中诱导炎症和促进有效的适应性免疫反应中的作用。 叙述性语言概述：拟议的研究将确定组织中的哪些免疫细胞负责启动对细菌感染的各种免疫反应，包括炎症、细胞介导的免疫和特定抗体的产生。这将通过使用转基因小鼠来实现，在转基因小鼠中，关键的免疫细胞类型无法识别细菌的存在。这些研究将有助于改进疫苗接种策略，并开发新的策略来阻止炎症性疾病患者的炎症。

DESCRIPTION (provided by applicant): In recent years, Toll-like receptors (TLRs) have emerged as critical recognition elements of innate immunity, both for induction of inflammation at the site of an infection and for induction of an adaptive immune response. These receptors are expressed on the three major types of immune cells in many tissues, immature dendritic cells, tissue macrophages, and mast cells, as well as on several other types of cells. In the proposed project, we shall define which type of cell is responsible for mediating TLR-based immune responses. In these studies, we shall take advantage of a conditional allele we have engineered into the mouse germ line for the key TLR signaling adaptor molecule MyD88. In this allele, we have placed loxP sites in the introns on either side of the essential exon 3 of the myd88 gene, with the result that Cre expression in a cell will result in deletion of exon 3 and inactivation of the myd88 gene. This conditional allele of myd88 will be used together with transgenes that express Cre either selectively in dendritic cells (CD11c-Cre), selectively in macrophages and neutrophils (LysM-Cre), or selectively in B cells (CD19-Cre). These mice will then be tested for the effect of loss of MyD88 in particular cell types for: induction of effector and memory CD4 T cell responses (Aim 1), induction of inflammation and restriction of growth of two gram-positive bacterial pathogens, Listeria monocytogenes and Staphylococcus aureus (Aim 2), and for promotion of antibody responses to protein antigens (Aim 3). These studies will define the roles of TLR signaling in dendritic cells, macrophages, mast cells, and B cells for induction of inflammation and for promotion of effective adaptive immune responses. Narrative Lay Language Summary: The proposed studies will determine which immune cells in tissues are responsible for initiating various immune responses to bacterial infection, including inflammation, cell-mediated immunity, and production of specific antibodies. This will be accomplished by the use of genetically modified mice, in which key immune cell types are unable to recognize the presence of bacteria. These studies will be useful for improving vaccination strategies and for developing novel strategies to block inflammation for patients with inflammatory diseases.