AUTOIMMUNITY TO CALCIUM CHANNELS IN LAMBERT EATON SYNDRO

Lambert-Eaton肌无力综合征（LES）的自身免疫反应被认为是由肿瘤，特别是小细胞肺癌（SCLC）的存在引发的。神经肌肉连接处（NMJ）的突触前钙通道是IS患者抗体的靶点，因此有理由认为SCLC细胞中假定的自身抗原具有与人类NMJ中发现的P/ o型Ca2+通道相同的分子特征。目前的建议旨在验证一个中心假设：SCLc细胞表达omega-agatoxin wa敏感P/ q型电压依赖性Ca2+通道（VDCCs），其在该疾病中充当初级免疫原；这些通道启动并维持LBS患者的自身免疫反应，由此产生的自身抗体与NMJ的靶抗原发生破坏性交叉反应。该提案的长期目标有两个方面：1)鉴定在LS中启动和维持致病抗体产生的一级和二级自身抗原；2)确定它们在本病周围运动和自主神经系统功能障碍临床表现中的致病作用。本研究将追求四个特定目标：[1]确定LS自身抗体对vdcs亚型的特异性；利用稳定转染的人胚胎肾（HBK293）细胞系和爪蟾卵母细胞中表达的克隆α 1 Ca2+通道亚单位电流测定LBS IgG的交叉反应性；建立兰伯特-巴顿综合征（EALES）的实验性自身免疫动物模型并进行表征；探讨被动转移LES小鼠NMJs中P/ q型Ca2+通道与突触结合蛋白功能障碍的关系。

The autoimmune response in the Lambert-Eaton myasthenic syndrome (LES), is thought to be triggered by the presence of a tumor, particularly small-cell lung cancer (SCLC). Presynaptic calcium channels at the neuromuscular junction (NMJ) are the target of the antibodies in IS patients, thus it is reasonable to assume that the putative autoantigens in SCLC cells possess the same molecular characteristics as the P/O-type Ca2+ channels found at the human NMJ. The current proposal is aimed at verifying a central hypothesis: SCLc cells express omega-agatoxin WA-sensitive P/Q-type voltage-dependent Ca2+ channels (VDCCs), which act as the primary immunogen in this disease; these channels initiate and maintain LBS patient's autoimmune response and the autoantibodies so produced then destructively cross-react with the target antigens at the NMJ. The long term objective of this proposal is two-fold: 1) to identify the primary and secondary autoantigens that initiate and maintain the production of pathogenic antibodies in LS; and 2) to determine their pathogenic role in clinical manifestation of the peripheral motor and autonomic nervous system dysfunctions characterizing this disease. This study will pursue four Specific Aims: [1] To determine the specificity of LS autoantibodies for subtypes of VDCCs; [2] To determine the cross-reactivity of LBS IgG using cloned alpha1 Ca2+ channel subunit currents expressed in stably transfected human embryonic kidney (HBK293) cell lines and Xenopus oocytes; [3] To develop and characterize an experimental autoimmune animal model of the Lambert-Baton syndrome (EALES); and [4] To determine P/Q-type Ca2+ channel vs. synaptotagmin dysfunction at the NMJs of mice with passively transferred LES.