Role of CX3CR1 in adaptive immunity during autoimmune encephalomyelitis

描述（由申请人提供）：存在于神经元和外周内皮细胞上的跨膜趋化因子fractalkine（CX 3CL 1）作为粘附分子或作为可溶性化学引诱物。CX 3CL 1通过其受体CX 3CR 1进行信号传导，CX 3CR 1在小胶质细胞、单核细胞/巨噬细胞和树突状细胞、NK细胞和T细胞中表达。值得注意的是，多发性硬化患者与健康对照组相比，外周NK细胞中CX 3CR 1的表达较低，外周血中CX 3CR 1+细胞的缺乏与疾病活动相关。然而，CX 3CR 1在抗原呈递细胞和T细胞中的作用以及它们对CNS病理学的贡献仍然是谜。这项研究背后的假设是，CX 3CR 1/CX 3CL 1调节抗原呈递细胞（APC）效应子功能，影响实验性自身免疫性脑脊髓炎（EAE）期间致病性T细胞的发展。这一假设的依据如下：1）CX 3CR 1缺陷小鼠的EAE症状更严重，CNS脱髓鞘增强，2）CX 3CR 1的缺乏与CD 115 + CD 11 c+树突细胞向CNS组织的选择性积累相关，和3）骨髓嵌合小鼠揭示骨髓中CX 3CR 1的缺乏诱导了异常，重度和慢性非缓解性EAE疾病，伴持续瘫痪。本提案的总体目标是阐明CX 3CR 1在EAE期间的功能以及它如何调节致病性CNS炎症。具体目标是：1.以确定CX 3CR 1通过调节抗原呈递和T细胞引发在EAE起始中的作用。我们将检验CX 3CR 1控制外周DC成熟影响抗原呈递和随后的外周T细胞极化的假设。我们将研究CX 3CR 1抗原运输和树突状细胞动员的作用，以及CX 3CR 1缺陷在致脑炎性T细胞产生中的作用。2.确定CX 3CR 1缺陷在EAE效应期的作用以及对神经元损伤和脱髓鞘的保护作用。我们假设骨髓中CX 3CR 1的缺失对于维持EAE脑中T细胞介导的炎症和组织损伤至关重要。我们将研究CX 3CR 1在疾病高峰期和恢复期CNS组织内致病性和调节性T细胞亚群的抑制性信号传导、激活和存活中的作用。3.旨在确定通过人CX 3CR 1 I249/M280的较弱信号传导如何在EAE期间复制Cx 3cr 1-/-小鼠的病理学。我们假设I249/M280表达细胞将表现出与CX 3CR 1缺陷细胞相当的效应子功能。我们将使用表达人变体的敲入小鼠作为低亲和力模型来研究I249/M280在CNS自身免疫过程中体内APC活化和T细胞极化中的作用。

DESCRIPTION (provided by applicant): The transmembrane chemokine fractalkine (CX3CL1) present on neurons and peripheral endothelial cells acts as an adhesion molecule or as a soluble chemoattractant. CX3CL1 signals through its receptor CX3CR1 which is expressed in microglia, monocytes/macrophages and dendritic cells, NK cells and T cells. Notably, multiple sclerosis patients revealed lower expression of CX3CR1 in peripheral NK cells when compared to healthy controls and lack of CX3CR1+ cells in peripheral blood correlated with disease activity. However, the role of CX3CR1 in antigen presenting cells and T cells, and their contribution to CNS pathology are still enigmatic. The hypothesis behind the proposed research is that CX3CR1/CX3CL1 regulates antigen presenting cell (APC) effector functions influencing the development of pathogenic T cells during experimental autoimmune encephalomyelitis (EAE). This hypothesis is based on the following: 1) EAE symptoms are more severe and CNS demyelination is enhanced CX3CR1-deficient mice, 2) absence of CX3CR1 correlated with a selective accumulation of CD115+CD11c+ dendritic cells to CNS tissues, and 3) Bone marrow chimeric mice revealed that absence of CX3CR1 in bone marrow induced an unusual, severe and chronic non-remitting EAE disease with sustained paralysis. The overall goal of this proposal is to elucidate the function of CX3CR1 during EAE and how it regulates pathogenic CNS inflammation. The specific aims are: 1. to determine the role of CX3CR1 for the initiation of EAE via modulation of antigen presentation and T cell priming. We will test the hypothesis that CX3CR1 controls peripherally DC maturation affecting antigen presentation and subsequently peripheral T cell polarization. We will investigate the role of CX3CR1 antigen trafficking and dendritic cell mobilization and effects of CX3CR1-deficiency in generation of encephalitogenic T cells. 2. To determine the role of CX3CR1 deficiency in the effector phase of EAE and protection from neuronal damage and demyelination. We hypothesize that absence of CX3CR1 in bone marrow is critical for the maintenance of T cell mediated inflammation and tissue damage in the EAE brain. We will investigate the role of CX3CR1 in inhibitory signaling, activation, and survival of pathogenic and regulatory T cell subsets within CNS tissues at peak of disease and at time of recovery. 3. To define address how weaker signaling through human CX3CR1I249/M280 replicates the pathology of Cx3cr1-/- mice during EAE. We hypothesize that I249/M280 expressing cells will exhibit effector functions comparable to CX3CR1-deficient cells. We will use knock-in mice expressing the human variant as a low affinity model to investigate the role of the I249/M280 in APC activation and T cell polarization in vivo during CNS autoimmunity.