Epitopic targets of the monoclonal auto-antibody repertoire in autoimmune encephalitis

抗NMDAR脑炎是几年前才发现的，已成为脑炎最常见的原因之一，也是新发精神病的重要鉴别诊断，特征与幻觉、紧张症、意识水平改变、癫痫发作、呼吸不足、运动障碍和自主功能障碍有关。针对NMDAR的自身抗体通过导致受体内化和突触功能障碍而直接致病。最近，我们可以通过单细胞扩增、测序和克隆记忆B细胞和浆细胞的全长免疫球蛋白重链和轻链基因，从脑炎患者的脑脊液中产生人NMDAR自身抗体。克隆的NMDAR自身抗体迅速成为组织学和电生理学分析以及高分辨率显微镜的宝贵工具。令人惊讶的是，这些患者大脑中的大多数抗体分泌细胞产生了针对其他表位的抗体，尽管这些表位仅限于大脑，如星形胶质细胞、轴突纤维束、海马神经束或颗粒细胞、内皮或脉络丛。对目标蛋白的初步鉴定表明，它们与神经元功能、神经退行性变和自身免疫的关键角色结合。通过这种方式，这些额外的自身抗体可能具有类似的致病性，并可能通过干扰离子通道或受体功能而导致疾病的不同临床症状。因此，目前的建议旨在利用免疫沉淀和质谱法鉴定脑炎患者脑脊液自身抗体库的靶蛋白。此外，这些发现还将与相关形式的脑部炎症和健康对照组进行比较。这项研究的数据将有助于理解自身免疫和神经精神障碍之间的因果关系，并可能确定治疗此类疾病的新靶点。

Discovered only a few years ago, anti-NMDA receptor (NMDAR) encephalitis has become one of the most commonly identified causes of encephalitis and an important differential diagnosis for new-onset psychosis, characteristically associated with hallucinations, catatonia, altered levels of consciousness, seizures, hypoventilation, dyskinesia, and autonomic dysfunction. Auto-antibodies against the NMDAR are directly pathogenic by causing receptor internalization and synaptic dysfunction. We could recently generate monoclonal human NMDAR auto-antibodies from the cerebrospinal fluid of patients with this encephalitis by single-cell amplification, sequencing and cloning of full-length immunoglobulin heavy and light chain genes from memory B cells and plasma cells. The monoclonal NMDAR autoantibodies have quickly become invaluable tools for histological and electrophysiological assays and for high-resolution microscopy. Surprisingly, the majority of antibody-secreting cells in the brain of these patients produced antibodies against other, although brain-restricted, epitopes, such as astrocytes, axonal fiber tracts, hippocampal neuropil or granule cells, endothelium or choroid plexus. First identifications of target proteins suggest that they bind to key players of neuronal function, neurodegeneration and autoimmunity. In this way these additional auto-antibodies might be similarly pathogenic and can contribute to the variable clinical symptoms of the disease, potentially by interfering with ion channel or receptor function. Thus, the current proposal aims at the identification of the target proteins of the human cerebrospinal fluid auto-antibody repertoire in patients with encephalitis using immunoprecipitation and mass spectrometry. In addition, the findings will be compared to related forms of brain inflammation and to healthy controls. Data from this study will help to understand the causal relationship between autoimmunity and neuropsychiatric disorders, and potentially identify novel targets for the treatment of such conditions.