The regulation of myeloid cell development and mobilization during autoimmune dem

描述(申请人提供)：血液中的髓系细胞(巨噬细胞和树突状细胞)是多发性硬化症(MS)患者和实验性自身免疫性脑脊髓炎(EAE)动物炎性浸润物的主要成分。它们与导致这些疾病残疾的脱髓鞘和轴突丢失有关。然而，在自身免疫性脱髓鞘疾病中，髓系细胞是如何在外周和中枢神经系统中被调节的，我们知之甚少。我们发现，在EAE恶化之前，髓系祖细胞从骨髓中以加速的速度动员起来。新输出的Ly6ChiCD11b+单核细胞在临床前期侵入中枢神经系统，形成CD11c+MHC ClassIIhi DC，在症状期占神经炎性细胞的很大比例。在目标1中，我们将研究EAE过程中骨髓髓系细胞扩增和动员的细胞因子途径和分子机制。我们的工作假设是，在髓鞘特异性T细胞的诱导下，GM-CSF和MIP-1a刺激骨髓基质细胞产生G-CSF和CXCL1/2。这些因子反过来激活驻留的中性粒细胞分泌蛋白酶，这些酶降解趋化因子和黏附分子，对髓内壁龛中的造血祖细胞的隔离至关重要。阻断这一途径的任何步骤(例如，通过中和G-CSF或失活蛋白酶)将阻止髓系细胞的释放，并最终耗尽在复发期间提供中枢神经系统渗透细胞来源的外周单核细胞池。在目标2中，我们将研究刺激Ly6ChiCD11b+单核细胞在中枢神经系统内分化为CD11c+MHC IIhi DC的因素。我们认为中枢神经系统浸润性单核细胞由于直接与髓鞘特异性T细胞相互作用而获得髓系树突状细胞的特征。将评估候选可溶性因子(如GM-CSF和TNF)和细胞表面分子(如RANKL、CD40L和淋巴毒素)的作用。我们的研究可能为自身免疫过程中驱动致病髓系细胞动员和发展的途径提供洞察力。这一结果有望为多发性硬化症提供新的治疗靶点和与髓系细胞失调相关的生物标记物。 公共卫生相关性：尽管多发性硬化症(MS)免疫治疗的最新进展集中在自身免疫反应的T细胞成分上，但在MS及其模型-实验性自身免疫性脑脊髓炎(EAE)中，髓系细胞(包括巨噬细胞和树突状细胞)构成了大多数中枢神经系统浸润性细胞，并介导了对神经元和神经胶质的直接损伤。本研究的目的是阐明在自身免疫性脱髓鞘疾病中，髓系细胞从骨髓中动员并分化为致病效应细胞的细胞因子途径和分子机制。预计我们的结果将导致发现与多发性硬化髓系细胞失调相关的新的生物标志物和治疗靶点。

DESCRIPTION (provided by applicant): Blood borne myeloid cells (macrophages and dendritic cells) comprise a major component of the inflammatory infiltrates in patients with multiple sclerosis (MS) and animals with experimental autoimmune encephalomyelitis (EAE). They have been implicated in the demyelination and axonal loss that cause disability in these disorders. However, relatively little is known about how myeloid cells are regulated in the periphery and CNS during autoimmune demyelinating disease. We have found that myeloid progenitor cells are mobilized from the bone marrow at an accelerated rate immediately prior to EAE exacerbations. Newly exported Ly6ChiCD11b+ monocytes infiltrate the CNS during the preclinical stage and give rise to the CD11c+MHC ClassIIhi DC that constitute a significant percent of neuroinflammatory cells during the symptomatic stage. In Aim 1 we will investigate the cytokine pathways and molecular mechanisms underlying the expansion and mobilization of bone marrow myeloid cells during EAE. Our working hypothesis is that GM-CSF and MIP-1a, induced by myelin-specific T cells, stimulate bone marrow stromal cells to produce G-CSF and CXCL1/2. These factors, in turn, activate resident neutrophils to secrete proteases that degrade chemokines and adhesion molecules critical for the sequestration of hematopoietic precursor cells in intramedullary niches. Interruption of any step in this pathway (ex, by neutralizing G-CSF or by inactivating proteases) will prevent myeloid cell release and ultimately exhaust the peripheral monocyte pools that provide a source of CNS infiltrating cells during relapses. In Aim 2 we will investigate the factors that stimulate Ly6ChiCD11b+ monocytes to differentiate into CD11c+MHC Class IIhi DC within the CNS. We propose that CNS infiltrating monocytes acquire characteristics of myeloid dendritic cells consequent to direct interactions with myelin- specific T cells. The roles of candidate soluble factors (such as GM-CSF and TNF) and cell surface molecules (such as RANKL, CD40L and Lymphotoxin-¿) will be assessed. Our studies are likely to provide insights into the pathways driving the mobilization and development of pathogenic myeloid cells during autoimmunity. The results are expected to suggest novel therapeutic targets and biomarkers in MS related to myeloid cell dysregulation. PUBLIC HEALTH RELEVANCE: Although recent advancements in the immunotherapy of multiple sclerosis (MS) have focused on the T cell component of the autoimmune response, myeloid cells (including macrophages and dendritic cells) compose the majority of CNS-infiltrating cells in MS and its model, experimental autoimmune encephalomyelitis (EAE), and mediate direct damage to neurons and glia. The purpose of this proposal is to elucidate the cytokine pathways and molecular mechanisms that underlie the mobilization of myeloid cells from the bone marrow and that drive their differentiation into pathogenic effector cells during autoimmune demyelinating disease. It is anticipated that our results will lead to the discovery of novel biomarkers and therapeutic targets related to myeloid cell dysregulation in MS.