Cell Type-Specific Roles of TLR Signaling In Immune Responses

描述（由申请人提供）：近年来，toll样受体（TLRs）已成为先天免疫的关键识别元件，既可诱导感染部位的炎症，也可诱导适应性免疫反应。这些受体在许多组织中的三种主要类型的免疫细胞上表达，即未成熟的树突状细胞、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，我们将确定哪种类型的细胞负责介导基于tlr的免疫反应。在这些研究中，我们将利用我们在小鼠种系中设计的一个条件等位基因来表达关键的TLR信号适配器分子MyD88。在这个等位基因中，我们将loxP位点放置在myd88基因必需外显子3两侧的内含子上，结果是Cre在细胞中的表达将导致外显子3的缺失和myd88基因的失活。myd88的这个条件等位基因将与在树突状细胞（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。然后将对这些小鼠进行MyD88缺失对特定细胞类型的影响的测试：诱导效应和记忆CD4 T细胞反应（Aim 1），诱导炎症和限制两种革兰氏阳性细菌病原体，单核细胞增生李斯特菌和金黄色葡萄球菌的生长（Aim 2），以及促进对蛋白质抗原的抗体反应（Aim 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适应性免疫反应的作用。

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.