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。在IS患者中，神经肌肉接头(NMJ)的突触前钙通道是抗体的靶点，因此有理由认为SCLC细胞中的可能自身抗原具有与人类NMJ中发现的P/O型钙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敏感的P/Q型电压依赖性钙通道(VDCC)，它是LBS患者的主要免疫原；这些通道启动和维持LBS患者的自身免疫反应，由此产生的自身抗体然后与NMJ的靶抗原发生破坏性交叉反应。这项建议的长期目标有两个：1)确定在LS中启动和维持致病抗体产生的初级和次级自身抗原；2)确定它们在以这种疾病为特征的外周运动和自主神经功能障碍的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自身抗体针对VDCC亚型的特异性；[2]通过克隆在稳定转染的人胚胎肾脏(HBK293)细胞系和非洲爪哇卵母细胞中表达的α1钙通道亚单位电流，来确定LBS IgG的交叉反应性；[3)建立并鉴定Lambert-Baton综合征(EALS)的实验性自身免疫动物模型；以及[4]确定P/Q型钙通道与突触素功能障碍在被动转移LES小鼠NMJs中的作用。

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.