Immune reactivity to synapsin in the neuropathy and ataxia of celiac disease

描述(申请人提供)：神经病和共济失调是乳糜泻或面筋过敏症患者最常见和最令人衰弱的肠外并发症。这些神经缺陷被认为是由免疫调节的，可能是由分子模仿驱动的。然而，到目前为止，还没有鉴定出可能的神经靶抗原。在初步研究中，我们发现小麦醇溶蛋白抗体对神经系统中的神经元进行免疫染色。利用免疫印迹、免疫亲和层析、双向凝胶电泳法和纳米LC/MS/MS技术，我们鉴定了交叉反应的自身抗原为突触素I，这是一种参与神经递质释放的中枢和外周神经系统蛋白。表位定位显示主要的免疫反应部位位于突触素I的C区，它是已知的介导蛋白与突触小泡相互作用的蛋白。此外，还发现亲和纯化的人抗醇溶蛋白抗体与突触素I发生交叉反应。我们的假设是，在一些乳糜泻患者中，抗醇溶蛋白抗体反应与突触素I发生交叉反应，免疫反应与乳糜泻的神经功能缺陷有关，如小脑性共济失调或周围神经病。为了解决我们的假设，我们提出了以下具体目标：i)确定突触素I的抗体反应性与腹腔神经病或共济失调之间是否存在关联。2)确定特定抗体同型或亲和力是否与神经系统疾病或特定表型的存在有关。3)绘制以人类抗体为靶点的突触素I的表位(S)，确定与某些表位的反应是否与神经系统疾病或特定综合征的发生有关。这项拟议的研究有望阐明中枢和外周神经系统缺陷可能与面筋敏感性有关。它们也可能为诊断相关的周围神经病或小脑性共济失调提供一个有用的标记物，并为检查针对受影响个体的自身免疫机制的治疗的有效性提供了理论基础。

DESCRIPTION (provided by applicant): Neuropathy and ataxia are among the most common and debilitating extraintestinal complications occurring in patients with celiac disease or gluten sensitivity. These neurologic deficits are believed to be immune mediated, possibly driven by molecular mimicry. However, until now, no putative neural target antigen had been identified. In preliminary studies, we found that antibodies to wheat gliadin immunostain neurons in the nervous system. Using immunoblotting, immunoaffinity chromatography, 2- dimensional gel electrophoresis, and nano-LC/MS/MS techniques, we identified the cross-reactive autoantigen as synapsin I, a central and peripheral nervous system protein involved in neurotransmitter release. Epitope mapping revealed the major immunoreactive sites to be located in the functionally important C domain of synapsin I, which is known to mediate the interaction of the protein with synaptic vesicles. In addition, affinity purified human IgG and IgA anti-gliadin antibodies were also found to cross- react with synapsin I. Our hypothesis is that in some patients with celiac disease, the anti-gliadin antibody response cross-reacts with synapsin I and that the immune reactivity is associated with neurologic deficits in celiac disease, such as cerebellar ataxia or peripheral neuropathy. The following specific aims are proposed to address our hypothesis: i) To determine whether there is an association between antibody reactivity to synapsin I and celiac neuropathy or ataxia. 2) To determine whether specific antibody isotype or affinity is associated with the presence of neurological disease or particular phenotypes. 3) To map the epitope(s) of synapsin I targeted by human antibodies, determining whether reactivity against certain epitopes is associated with the occurrence of neurologic disease or a particular syndrome. The proposed studies are expected to shed light on how central and peripheral nervous system deficits may be associated with gluten sensitivity. They may also serve to provide a useful marker for the diagnosis of the associated peripheral neuropathy or cerebellar ataxia, and offer a rationale for examining the efficacy of therapies that target autoimmune mechanisms in affected individuals.