Innate Immune Mechanisms and TLRs in Bacterial Ligand-Induced Arteritis

描述（由申请人提供）：介导炎症性血管疾病的细胞和分子机制尚不清楚。我们之前的工作主要集中在通过toll样受体（TLRs）的先天免疫信号在动脉粥样硬化和动脉炎等炎症性疾病中的作用。我们报道了注射干酪乳杆菌的细胞壁提取物（LCCWE）通过TLR2-和myd88依赖的机制引起小鼠冠状动脉炎，但密切相关的副干酪乳杆菌的细胞壁提取物不会引起冠状动脉炎。在这项工作的基础上，我们最近的初步研究表明，LCCWE不会在缺乏T细胞和B细胞的RAG1-/-小鼠中诱导冠状动脉炎，但会在仅缺乏B细胞的小鼠中诱导病变。这些重要的发现现在暗示了适应性免疫机制（特别是T细胞）和先天免疫机制（TLR信号和树突状细胞[dc]）在lccwe诱导的免疫动脉炎机制中的作用。在这里，我们提出研究阐明细胞和分子免疫机制有助于细菌抗原诱导的小鼠冠状动脉炎。结合现有已发表的数据和我们最近的初步研究，我们提出了具有3个特定目的的研究，以验证涉及先天性和适应性免疫的动脉炎扩展模型的假设，其中主要涉及TLR-2和myd88依赖性DC和T细胞激活。目的1将在体内确定dc是否参与lccwe诱导的冠状动脉炎，并评估dc中TLR信号如何影响病理发展。我们将量化不同时间冠状动脉部位的成熟dc，并使用已建立的转基因小鼠模型（CD11c- DTR-GFP Tg+小鼠），通过在注射LCCWE之前消耗dc来测试dc是否对冠状动脉的发展至关重要。我们将测试仅在CD11c+ dc中表达MyD88的转基因小鼠（MyD88-null背景）是否会发生lccwe诱导的冠状动脉炎。Aim 2将测试造血细胞、非造血细胞或两者中TLR2和/或myd88依赖性信号是否对细菌抗原诱导的免疫动脉炎的发展至关重要。我们将只在骨髓来源的细胞或动物的其他部位创造和测试表达TLR2或MyD88的嵌合体。目的3将研究T细胞和T细胞亚群在lccwe诱导的冠状动脉炎模型中使用各种KO小鼠的作用。意义：这些研究应该为各种形式的免疫介导的动脉炎的细胞和分子基础提供创新的机制见解，包括川崎病儿童冠状动脉炎。

DESCRIPTION (provided by applicant): Cellular and molecular mechanisms mediating inflammatory vascular diseases are not well understood. Our previous work has centered on the role of innate immune signaling via Toll-like receptors (TLRs) in inflammatory diseases such as atherosclerosis and arteritis. We reported that injection of cell wall extracts from L. casei (LCCWE) cause coronary arteritis in mice via a TLR2- and MyD88-dependent mechanism, but cell wall extracts from the closely related species L. paracasei do not. Building on this work, our recent preliminary studies now indicate that LCCWE does not induce coronary arteritis in RAG1-/- mice, which lack both T cells and B cells, but does induce lesions in mice that lack only B cells. These important findings now implicate adaptive immune mechanisms (particularly T cells) in addition to innate immune mechanisms (TLR signaling and dendritic cells [DCs]) in the mechanism of LCCWE-induced immune arteritis. Here we propose studies to elucidate cellular and molecular immune mechanisms contributing to bacterial antigen-induced coronary arteritis in mice. Combining available published data with our recent preliminary studies, we propose studies with 3 Specific Aims to test the hypothesis for an expanded model of arteritis that involves both innate and adaptive immunity, that centrally involves both TLR-2 and MyD88-dependent DC and T cell activation. Aim 1 will determine whether DCs participate in LCCWE-induced coronary arteritis in vivo and will evaluate how TLR signaling in DCs affects development of the pathology. We will quantify mature DCs at sites of coronary arteritis at different times and test whether DCs are essential for development of coronary arteritis by depleting DCs prior to injection of LCCWE using an established transgenic mouse model that produces temporary depletion of CD11c+ DCs (CD11c- DTR-GFP Tg+ mice). We will test whether transgenic mice expressing MyD88 only in CD11c+ DCs (in MyD88-null background) develop LCCWE-induced coronary arteritis. Aim 2 will test whether TLR2- and/or MyD88-dependent signaling in hematopoietic cells, in non-hematopoietic cells, or both are essential for development of bacterial antigen-induced immune arteritis. We will create and test chimeras that express TLR2 or MyD88 only in bone marrow-derived cells or only in the rest of the animal. Aim 3 will examine the role of the T cells and T cell subsets in LCCWE-induced coronary arteritis model using various KO mice. Significance: These studies should provide innovative mechanistic insights into the cellular and molecular underpinnings of various forms of immune-mediated arteritis, including the coronary arteritis seen in children with Kawasaki Disease. PUBLIC HEALTH RELEVANCE: Innate immune responses play a role in Bacterial cell wall extract-induced coronary arteritis in a mouse model. Kawasaki Disease is a vasculitis involving children and results in over 20% incidence of developing coronary arteritis and aneurysms. The role of bacterial infections in vasculitis and immune arteritis and the molecular mechanisms involved in this process are not well-understood. The major goal of this application is to understand the molecular mechanisms and the role of innate and adaptive immunity that explain exactly how certain bacterial infections can lead to immune vasculitis and coronary arteritis using a mouse model. The successful completion of the proposed studies may allow us to develop novel treatment or preventive approaches to infection-mediated development of vasculitis and immune arteritis.