Autoantibodies and glycinergic dysfunction: Pathophysiology of associated motor disorders

与甘氨酸受体自身抗体(GlyRs)相关的运动系统障碍是罕见的疾病，如僵直综合征(SPS)和进行性脑脊髓炎伴僵直和肌阵挛(PERM)。这些疾病中抑制性神经传递的减少与神经运动过度兴奋有关。虽然针对降低自身抗体水平的免疫治疗可能会改善患者的症状，但经常会观察到复发。我们需要了解抑制性突触网络的潜在病理机制，以改进治疗并制定复发预防策略。目前，在自身抗体存在的情况下，增强的GlyR内化已被描述，但其功能后果尚不清楚。这项拟议的研究项目将结合神经生物学的方法学方面与自身免疫研究和神经学，研究抑制性突触中与自身抗体相关的病理机制。我们有初步证据表明，自身抗体直接干扰GlyR功能。使用重组细胞培养系统，我们可以证明自身抗体结合导致离子通道GlyRalpha1功能降低。大多数自身抗体能识别大N端胞外区的天然表位。基于这些实验，我们计划研究自身抗体在靶向受体上的作用。这项建议将研究下列要点：(1)使用转基因细胞系和小鼠原代神经元体外鉴定自身抗体的特异性、表位图谱和配体结合的重要性(2)使用生理学读数来鉴定自身抗体对受体功能的影响(3)体外受体内化分析稳定性，(4)在被动转移后的动物模型中自体抗体的作用，(5)作为治疗选择的肽中和。

Disorders of the motor system associated with autoantibodies to glycine receptors (GlyRs) are RARE diseases such as stiff person syndrome (SPS) and progressive encephalomyelitis with rigidity and myoclonus (PERM). The reduction of inhibitory neurotransmission in these disorders is associated with neuromotor hyperexcitability. Although immunotherapy directed at reducing autoantibody levels may lead to improvement of patients symptoms, relapses are often observed. We need to understand the underlying pathomechanisms in the inhibitory synaptic network to improve therapy and to develop relapse prevention strategies. Currently, enhanced GlyR internalization has been described in the presence of autoantibodies, but the functional consequences are not known. The proposed research project will investigate the autoantibody related pathomechanisms at the inhibitory synapse, combining methodological aspects of neurobiology with autoimmune research and neurology. We have preliminary evidence that autoantibodies interfere directly with GlyR function. Using a recombinant cell cuture system, we could demonstrate that autoantibody-binding leads to decreased functionality of the ion channel GlyRalpha1. Most autoantibodies specifically recognize native epitopes in the large N-terminal extracellular domain. Based on these experiments we plan to investigate the action of autoantibodies at the targeted receptor. This proposal will investigate the following main points: (1) in vitro characterization of autoantibodies using transfected cell lines and murine primary neurons with regard to specificity, epitope mapping and importance for ligand-binding (2) influence of autoantibodies on receptor functionality using physiological readouts (3) receptor stability in in vitro internalisation assays, (4) in vivo action of autoantibodies in an animal model following passive transfer, (5) peptide neutralization as therapeutical option.