Regulatory B cells in multiple sclerosis - functional characterization and therapeutic implication

多发性硬化症（MS）是一种中枢神经系统的炎症性脱髓鞘疾病，其残疾可以急性复发或持续慢性恶化。在其发病机制中，B细胞和B细胞衍生产物可能起关键作用；在许多多发性硬化症患者中，外周B细胞表现出慢性激活和促炎分化的迹象。在脑脊液中，克隆扩增的浆细胞产生寡克隆免疫球蛋白，这仍然是一个标志性的诊断发现。此外，在最近的临床MS试验中，抗cd20介导的B细胞耗竭阻止了中枢神经系统病变的发展并减少了复发的发生。除了这些致病作用的证据外，B细胞可能在MS中发挥抗炎特性Naïve在MS患者中，B细胞与健康对照相似，是调节细胞因子的相关来源，如IL-10，其抑制其他免疫细胞的活性。在MS模型实验性自身免疫性脑脊髓炎（EAE）的急性发作中，缺乏释放调节性B细胞因子的小鼠不能恢复，而是慢性恶化。因此，B细胞在由新生中枢神经系统浸润引起的复发的发展中起着至关重要的作用，并且具有促进恢复和防止过渡到慢性进展的潜力。为了解开这个具有广泛临床意义的谜题，我们将从MS致病性B细胞特性中描述并可能描述调节性B细胞功能。首先，我们将描述MS患者中枢神经系统组织中的B细胞和浆细胞。通过我们研究所开发的一种成像技术，这些研究现在成为可能。结合转录组分析，我们将研究MS病变中的所有B细胞是否都具有统一的致病性，以及患者或中枢神经系统病变的亚型是否在致病性和调节性B细胞的程度上有所不同（目的1）。其次，我们将确定MS患者外周血亲炎性和抗炎性B细胞的相对程度是否存在差异。我们将把这种个体B细胞表型与IL-10的缺失和抗cd20治疗后促炎单核细胞功能的相对增加联系起来。从临床结果的角度和相关性来看，这些免疫学参数可能成为预测个体对抗cd20治疗反应的迫切需要的生物标志物（aim 2）。最后，我们将探讨在EAE中，B细胞是否、在何处以及如何促进恢复和控制慢性进展。为此，我们使用纯T细胞介导的EAE模型，其中抗cd20显著恶化疾病严重程度。利用该模型结合过继转移和基因修饰B细胞的跟踪，我们将研究B细胞在多大程度上可以抑制中枢神经系统炎症的内在回路，假设的进展相关性以及需要哪种B细胞特性来介导这种作用（目的3）。

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system, in which disability can occur as acute relapses or as continuous chronic deterioration. In its pathogenesis, B cells and B cell-derived products may play a key role; in many MS patients, peripheral B cells show signs of chronic activation and pro-inflammatory differentiation. In the cerebrospinal fluid, clonally expanded plasma cells produce oligoclonal immunoglobulins, which remain a hallmark diagnostic finding. Moreover, anti-CD20-mediated depletion of B cells halted development of CNS lesions and reduced occurrence of relapses in recent clinical MS trials. Besides such evidence for their pathogenic contribution, B cells may exert anti-inflammatory properties in MS. Naïve B cells, in MS patients similar to healthy controls, are a relevant source of regulatory cytokines, such as IL-10, which dampens the activity of other immune cells. Mice deficient in releasing regulatory B cell cytokines fail to recover from an acute attack in the MS model experimental autoimmune encephalomyelitis (EAE) and instead chronically deteriorate. B cells are thus crucially involved in development of relapses caused by de novo CNS infiltration, and yet convey the potential to promote recovery and to prevent transition to chronic progression. To decrypt this apparent enigma with wide-ranging clinical implications, we will functionally characterize and possibly delineate regulatory B cell function from pathogenic B cell properties in MS. At first, we will characterize B and plasma cells in CNS tissues from MS patients. These studies are now possible by an imaging technique developed at our Institute. In conjunction with transcriptome analyses, we will investigate whether all B cells in MS lesions are uniformly pathogenic, and whether subtypes of patients or CNS lesions may vary in the extent of pathogenic versus regulatory B cells (aim 1). Second, we will determine whether MS patients differ in the relative extent of peripheral pro- and anti-inflammatory B cells. We will correlate this individual B cell phenotype to the loss of IL-10 and the relative increase of pro-inflammatory monocyte function upon anti-CD20 treatment. In perspective and correlation with the clinical outcome, these immunological parameters could develop into an urgently needed biomarker predicting the individual response to anti-CD20 treatment (aim 2). Lastly, we will investigate in EAE, whether, where and how B cells promote recovery and control chronic progression. For this purpose, we are utilizing a purely T cell-mediated EAE model, in which anti-CD20 substantially deteriorates disease severity. Using this model in combination with adoptive transfer and tracking of genetically modified B cells, we will investigate to what extent B cells can dampen CNS intrinsic circuits of inflammation, the assumed correlate of progression and which B cell property is required to mediate this effect (aim 3).