Recruitment of CX3CR1-GFP+ monocytes during Schistosoma mansoni infection.

描述（由申请人提供）：巨噬细胞（MF）是免疫对抗病原体、组织稳态和免疫调节所必需的。蠕虫感染、过敏反应和组织损伤可诱导巨噬细胞（AAMF）分化，AAMF在促进组织重塑、伤口修复、T辅助2 （TH2）分化和寄生虫清除等方面发挥重要作用。AAMF的分化过程和细胞前体尚不清楚。最近，两个功能不同的单核细胞亚群及其性质已经被描述；(1) Ly-6C+“炎性”单核细胞和(2)Ly6C-“常驻”单核细胞。当Ly6C-单核细胞在正常组织中聚集时，它们也被证明可以在血管中巡逻，并迅速外渗到炎症或感染组织中，以促进炎症的消退。Ly6C-细胞在CX3CR1-GFP报告小鼠中也是CX3CR1-GFPhi，并且在心肌梗死和细菌感染模型中得到了最好的表征。在这两种模型中，外渗的Ly6C-、CX3CR1-GFPhi单核细胞具有AAMF的特征，并能促进组织重塑、伤口愈合和免疫调节。我们之前已经证明，蠕虫感染可以有效地诱导AAMF的募集。其他研究表明，AAMF的募集对于保护曼索尼沙门氏菌感染小鼠免受对卵子的急性免疫病理反应至关重要。我们最近也表明，无菌组织损伤可以通过T细胞独立的先天免疫途径在没有感染的情况下诱导AAMF的募集。我们现在对mansoni感染的CX3CR1-GFP/+小鼠的肝脏肉芽肿进行了初步的流式细胞术、共聚焦显微镜和活体成像研究，表明AAMF是CX3CR1-GFPhi，可能来自于在窦状血管中巡行的Ly6C-、CX3CR1-GFPhi单核细胞。在本提案中，我们建议使用活体显微镜观察曼氏梭菌感染小鼠肝脏肉芽肿中T细胞-巨噬细胞的相互作用。具体来说，我们提出验证mansoni卵募集的AAMF从CX3CR1-GFPhi， Ly6C-单核细胞分化的假设。作为次要假设，我们提出CD4+ T细胞可能在慢性感染期间招募或维持CX3CR1-GFP+细胞进入肉芽肿分化为AAMF中发挥作用。因此，我们的具体目标是：(1)利用CX3CR1- GFP报告小鼠观察肝肉芽肿中单核细胞募集和巨噬细胞分化的动态；(2)探讨CD4+ TH2细胞在肝肉芽肿曼氏梭菌卵募集CX3CR1-GFPhi细胞中的作用。这些研究将提高我们对Th2条件下单核细胞募集和巨噬细胞分化的理解，并可能为我们提供新的介入治疗框架，以调节致病性炎症Th2反应。

DESCRIPTION (provided by applicant): Macrophages (MF) are essential for immunity against pathogens, tissue homeostasis and immune regulation. Helminth infections, allergic reactions and tissue injury can induce the differentiation of alternatively activated macrophages (AAMF), which are important in promoting tissue remodeling, wound repair, T helper 2 (TH2) differentiation and parasite clearance. The differentiation process and cellular precursors of AAMF remains poorly understood. Recently, two functionally distinct subsets of monocytes and their properties have been described; (1) Ly-6C+ "inflammatory" monocytes and (2) Ly6C- "resident" monocytes. While Ly6C- monocytes populate normal tissues, they have also been shown to patrol blood vessels and extravasate rapidly into inflamed or infected tissues to promote the resolution of inflammation. Ly6C- cells are also CX3CR1-GFPhi in a CX3CR1-GFP reporter mouse and have been best characterized in models of myocardial infarction and bacterial infection. In both models, extravasated Ly6C-, CX3CR1-GFPhi monocytes have characteristics of AAMF and can promote tissue remodeling, wound healing and immune modulation. We have previously shown that helminth infection potently induces recruitment of AAMF. Others have shown that the recruitment of AAMF is critical in protecting S. mansoni infected mice from acute immunopathology in response to the eggs. We have also recently shown that sterile tissue injury can induce recruitment of AAMF in the absence of infection, through a T cell independent innate immune pathway. We have now conducted preliminary flow cytometry, confocal microscopy and intra-vital imaging studies of the liver granulomas of S. mansoni infected CX3CR1-GFP/+ mice, which suggest that AAMF are CX3CR1-GFPhi and may arise from the Ly6C-, CX3CR1-GFPhi monocytes that are patrolling the sinusoidal vessels. In this proposal, we propose to use intra-vital microscopy to observe T cell-macrophage interactions in the liver granulomas of S. mansoni infected mice. Specifically, we propose to test the hypothesis that AAMF recruited by S. mansoni eggs differentiate from CX3CR1-GFPhi, Ly6C- monocytes. As a secondary hypothesis, we propose that CD4+ T cells may play a role in recruiting or maintaining CX3CR1-GFP+ cells into the granulomas to differentiate into AAMF during chronic infection. Therefore, our specific aims are: (1) to visualize the dynamics of monocyte recruitment and macrophage differentiation in liver granulomas using the CX3CR1- GFP reporter mice; (2) to determine the role of CD4+ TH2 cells in the recruitment of CX3CR1-GFPhi cells by S. mansoni eggs in the liver granulomas. These studies will improve our understanding of monocyte recruitment and macrophage differentiation under Th2 conditions and may provide us with a framework for new interventional therapies to regulate pathogenic inflammatory Th2 responses. PUBLIC HEALTH RELEVANCE: Macrophages activated under T helper type 2 conditions are important in wound healing, allergic reactions and parasite infections. How these cells are recruited into the tissues from monocytes in the blood is not clear. The goal of this project is to identify where these macrophages come from in order to design interventional strategies that could help regulate the inflammatory process during a type 2 response.