Regulation of B cells in the CNS

描述(由申请人提供)：在患有脱髓鞘疾病多发性硬化症(MS)和患有嗜神经性感染的人中，抗体(Ab)的产生和中枢神经系统(CNS)中B细胞的存在被很好地记录下来。他们在多发性硬化症中的作用目前尚不清楚。然而，由于异位B细胞滤泡的形成而持续的免疫激活，以及使用抗CD20单抗利妥昔单抗治疗的MS患者减少循环B细胞的改善，意味着有害的体液反应。如果抗体与自身抗原发生交叉反应或直接以自身抗原为靶标，抗体分泌细胞(ASC)也是有害的。相比之下，在病毒感染CNS期间，鞘内体液反应与保护功能有关。本地生产的抗病毒抗体与中枢神经系统内的持续免疫控制相一致，没有明显的病理，暗示了强大的非裂解性抗病毒作用。此外， 在类风湿关节炎和MS的治疗过程中，在利妥昔单抗治疗后发生进行性多灶性白质脑病，失去对临床上看不见的持续病毒的控制的潜在危险变得明显。尽管体液免疫在不同的神经炎症环境中具有生物学意义，但中枢神经系统中抗体的产生如何持续以及哪些B细胞群和环境因素支持ASC的分化仍然缺乏特征。这项建议使用与脱髓鞘相关的急性和持续感染的嗜神经性冠状病毒模型来确定外周和中枢神经系统体液反应之间的相互作用，以支持CNS抗体的产生。总体目标是拓宽对多发性硬化症等炎症性疾病的治疗选择的洞察力，而不会引发内源性病毒的出现，以及针对急性病毒性脑炎。我们追求三个具体目标。目标1将确定外周淋巴组织来源的B细胞在补充和维持中枢神经系统内ASC方面的作用。结果将揭示CNS内的所有B细胞是否都来自生发中心，以及迁移到CNS的ASC是否在CNS内分化为长期存活的ASC。此外，还将确定非抗体产生记忆B细胞(Bmem)在中枢神经系统体液免疫中的未知作用。抗原(Ag)和CD4T细胞在促进中枢神经系统内B细胞向固有型ASC分化中的作用将分别在AIMS 2和AIMS 3中确定。方法是基于转基因小鼠的免疫，在转基因小鼠中，生发中心来源的B细胞被荧光标记以分离ASC和Bmem用于过继转移。抗体产生缺陷的受体将监测其中枢神经系统的迁移、分化和保护能力。同源抗原的影响是通过供体B细胞特异性的变化和炎性损伤来检验的。T细胞的帮助将被评估为采用CD4T细胞消融和补充的方法。这一结果将首次确定在人类自身免疫和中枢神经系统感染期间调节与B细胞相关的保护性和致病性反应的参数。

DESCRIPTION (provided by applicant): Antibody (Ab) production and the presence of B cells within the central nervous system (CNS) is well documented in humans with the demyelinating disease multiple sclerosis (MS) and those afflicted by neurotropic infections. Their role in MS is currently unclear. However, detrimental humoral responses are implied by ongoing immune activation due to ectopic B cell follicle formation, as well as improvement in MS patients treated with anti-CD20 monoclonal Ab rituximab to reduce circulating B cells. Antibody secreting cells (ASC) are also detrimental if Ab are cross-reactive with, or directly target, self antigens. By contrast, during viral CNS infections intrathecal humoral responses are associated with protective functions. Locally produced anti-viral Ab coincide with sustained immune control within the CNS without overt pathology implicating a potent non lytic anti-viral role. Furthermore, the potential danger of losing control of clinically inapparent persisting viruses became apparent by development of progressive multifocal leukoencephalopathy following rituximab treatment during therapy for rheumatoid arthritis and MS. Despite the biological significance of humoral immunity in diverse settings of neuroinflammation, how Ab production in the CNS is sustained and which B cell populations and environmental factors support differentiation of ASC remain poorly characterized. This proposal uses a neurotropic coronavirus model of acute and persistent infection associated with demyelination to define the interactions between peripheral and CNS humoral responses in supporting CNS Ab production. The overall goal is to broaden insights into treatment options for inflammatory diseases such as MS, without provoking emergence of endogenous viruses, as well as targeting acute viral encephalitis. Three Specific Aims are pursued. Aim 1 will define the contribution of peripheral lymphoid tissue derived B cells in replenishing and maintaining ASC within the CNS. Results will reveal whether all B cells within the CNS are germinal center derived, and whether ASC migrating to the CNS differentiate within the CNS to become long lived ASC. Furthermore, the unexplored role of non Ab producing memory B cells (Bmem) to CNS humoral immunity will be defined. The role of antigen (Ag) and CD4 T cells in promoting B cell differentiation to sessile ASC within the CNS will be determined in Aims 2 and 3, respectively. Approaches are based on immunization of transgenic mice in which germinal center derived B cells are marked by fluorescence to isolate ASC and Bmem for adoptive transfer. Their CNS migration, differentiation and protective capacity will be monitored in recipients defective in Ab production. The influence of cognate Ag is examined by variations in donor B cell specificities, and inflammatory insult. T cell "help" will be assessed b CD4 T cell ablation and supplementation approaches. The results will for the first time define the parameters regulating both protective and pathogenic responses associated with B cells during human autoimmunity and CNS infections.