Origin and diversity of pathogenic human monoclonal antibodies to the NMDA receptor

在抗NMDAR(NMDAR)脑炎中，针对NMDAR的GluN1亚单位的自身抗体会导致一种独特的神经精神综合征。我们最近从NMDAR脑炎患者的脑脊液浆细胞中克隆了第一个人类单抗GluN1自身抗体。抗体诱导的突触病理类似于患者来源的免疫球蛋白。到目前为止，尚不清楚体液自身免疫反应是如何触发的，抗体产生细胞是否在外围发育并迁移到大脑，以及个别自身抗体的致病潜力是否因亲和力成熟程度或其生物物理性质而不同。在这里，我们将通过抗体克隆和表达，在单细胞水平上比较血清和脑脊液来源的B细胞的功能，探讨NMDAR脑炎中抗体产生细胞的来源。具体地说，我们将研究单抗是否与原代神经元、人诱导多能干细胞(IPSC)和脑切片中的突触靶点发生反应。此外，我们将在小鼠模型中确定它们的亲和力及其对被动转移的致病作用。我们将进一步评估病毒感染或导致继发性自身免疫性脑炎的肿瘤是否包括抗NMDAR抗体。使用我们已建立的单细胞克隆技术，我们还旨在从其他自身免疫性脑炎亚型中识别致病抗体，如使用抗GABAB受体抗体的脑炎和抗LGI1自身抗体的脑炎。

In anti-NMDA receptor (NMDAR) encephalitis, autoantibodies against the GluN1 subunit of the NMDAR cause a distinct neuropsychiatric syndrome. We recently cloned the first human monoclonal GluN1 autoantibodies from cerebrospinal fluid plasma cells of NMDAR encephalitis patients. The antibodies induced synaptic pathology similar to patient-derived IgG. So far, it is unclear how the humoral autoimmune response is triggered, whether antibody-producing cells develop in the periphery and migrate into the brain, and whether individual autoantibodies differ in their pathogenic potential depending on the degree of affinity maturation or their biophysical properties. Here, we will investigate the origin of antibody-producing cells in NMDAR encephalitis by functional comparison of serum and cerebrospinal fluid-derived B cells at single-cell level through antibody cloning and expression. Specifically, we will investigate if the monoclonal antibodies react with synaptic targets in primary neurons, in human induced pluripotent stem cells (iPSC), and in brain sections. Furthermore, we will determine their affinity and their pathogenic effect upon passive-transfer in mouse models. We will further assess whether viral infections or tumors leading to secondary autoimmune encephalitis encompass anti-NMDAR antibody repertoires. Using our established single-cell cloning techniques, we also aim to identify disease-causing antibodies from other subtypes of autoimmune encephalitis, such as encephalitis with anti-GABAB receptor antibodies and with anti-LGI1 autoantibodies.