Ontogenetic niche of B cells at the CNS borders in homeostasis, aging and autoimmunity

项目总结 B细胞在神经系统自身免疫性疾病中起着重要的致病作用，如多发性硬化症(MS) 以及神经精神性系统性红斑狼疮(NP-SLE)，这是SLE最致残的表现之一。 B细胞在中枢神经系统(CNS)自身免疫中的相关性被治疗性研究强调 单抗介导的B细胞去除在MS中的疗效自身反应性B细胞是如何产生和渗入中枢的 仍然是个谜。中枢神经系统包裹在三层膜内：软脑膜、蛛网膜和硬脑膜。在两人之间 蛛网膜和软脑膜位于蛛网膜下腔，其中含有脑脊液，其中含有各种免疫。 细胞，包括B细胞。在神经炎症期间，血液淋巴细胞渗入脑膜以形成局部。 体液和/或细胞反应。因此，脑膜B细胞被认为完全来自于系统性 发行量。然而，我们最近发现，在年轻成年小鼠中，脑膜B细胞主要来自骨骼 颅骨的骨髓，称为头盖骨，通过特殊的血管通道。相比之下，在衰老过程中， 年龄相关的B细胞(ABC)从外周迁移到硬脑膜，在那里它们可能分化为Ig-B细胞。 分泌浆细胞。我们假设脑膜B细胞来源于头盖骨并在局部分化 对CNS-Ag具有耐受性。相比之下，来自外周的B细胞并不受 当CNS-Ag相遇时，局部抗原环境可能分化为自身反应性浆细胞。在目标1中，我们将 探讨稳定状态下脑膜B细胞对局部抗原的耐受机制。初步数据 提示B细胞发育过程中的自身抗原经历会导致脑膜B细胞耗竭。同时，我们 将在遇到外来抗原时检查脑膜B细胞的激活情况。最后，我们将调查 硬脑膜B细胞发育的微环境，重点是硬脑膜成纤维细胞产生的CXCL12。在目标2中，我们 将研究SWAP-70/DEF6双重敲除中脑膜B细胞和浆细胞的自身反应性 (DKO)狼疮模型。初步数据显示，DKO小鼠的脑膜中有浆母细胞积聚。我们 将比较B细胞和浆细胞的转录图谱和B细胞受体(BCR)谱系 硬脑膜和脾以确定系统B细胞克隆是否均匀分布在淋巴器官和 脑膜，或中枢神经系统环境是否招募了进一步分化为浆细胞的特定克隆。在……里面 同时，DKO小鼠将接受行为改变和中枢神经系统病理检查。我们还将确定 在DKO小鼠硬脑膜中最大限度扩增BCR克隆并产生单抗以确定 自身抗原的特异性。在目标3中，我们将获得人类硬脑膜免疫的单细胞转录图谱。 从尸检标本中分离出的细胞，填补了我们对人类脑膜知识的一个关键空白。总体而言，这 该提案将促进我们对中枢神经系统中的B细胞以及促进神经炎症的机制的理解。 为了实现这一点，我们将利用Colonna实验室的互补专业知识，该实验室研究 神经炎症，以及研究人类和小鼠模型自身免疫的佩尼斯实验室。

PROJECT SUMMARY B cells have an important pathogenic role in neurological autoimmune disorders, such as multiple sclerosis (MS) and neuropsychiatric systemic lupus erythematosus (NP-SLE), one of the most disabling manifestations of SLE. The relevance of B cells in central nervous system (CNS) autoimmunity is underscored by the therapeutic efficacy of mAb-mediated B cell depletion in MS. How autoreactive B cells are generated and infiltrate the CNS remains enigmatical. The CNS is enclosed within three membranes: pia, arachnoid, and dura. Between the arachnoid and pia lies the subarachnoid space, which contains cerebrospinal fluid that harbors assorted immune cells, including B cells. During neuroinflammation, blood lymphocytes infiltrate the meninges to mount local humoral and/or cellular responses. Thus, meningeal B cells are thought to exclusively derive from the systemic circulation. However, we recently showed that in young adult mice meningeal B cells mainly derive from the bone marrow of cranial flat bones, known as calvaria, through special vascular channels. During aging, in contrast, age-associated-B cells (ABC) migrate from the periphery into the dura, where they may differentiate into Ig- secreting plasma cells. We hypothesize that meningeal B cells that derive from calvaria and differentiate locally are tolerant to CNS-Ag. By contrast, B cells that originate from the periphery and hence are not educated by the local antigenic milieu, may differentiate into autoreactive plasma cells upon CNS-Ag encounter. In Aim 1, we will investigate mechanisms of meningeal B cell tolerance to local antigens under steady-state. Preliminary data suggest that self-Ag experience during B cell development induces meningeal B cell depletion. Alongside, we will examine meningeal B cell activation upon foreign Ag encounter. Finally, we will investigate the impact of the microenvironment in dura B cell development, focusing on CXCL12 produced by dura fibroblasts. In Aim 2, we will investigate autoreactivity of meningeal B cells and plasma cells in the SWAP-70/DEF6 double knock-out (DKO) model of lupus. Preliminary data show accumulation of plasmablasts in the meninges of DKO mice. We will compare the transcriptional profiles and B cell receptor (BCR) repertoires of B cells and plasma cells from the dura and spleen to determine whether systemic B cells clones disseminate equally in lymphoid organs and meninges, or whether the CNS environment recruits specific clones that further differentiate into plasma cells. In parallel, DKO mice will be examined for behavioral alterations and CNS pathology. We will also identify the utmost expanded BCR clones in the dura of DKO mice and generate monoclonal antibodies to ascertain specificity for autoantigens. In Aim 3, we will obtain a single-cell transcriptomic profile of human dura immune cells isolated from autoptic specimens, filling a critical gap in our knowledge of human meninges. Overall, this proposal will advance our understanding of B cells in the CNS and mechanisms that promote neuroinflammation. To achieve this, we will leverage the complementary expertise of the Colonna lab, which studies neuroinflammation, and the Pernis lab, which studies autoimmunity in both humans and mouse models.