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

描述（由申请人提供）：神经病变和共济失调是乳糜泻或麸质敏感患者中最常见和最衰弱的肠外并发症。这些神经系统缺陷被认为是免疫介导的，可能是由分子模仿驱动的。然而，到目前为止，尚未发现推定的神经靶抗原。在初步研究中，我们发现小麦麦胶蛋白抗体免疫染色神经系统中的神经元。通过免疫印迹、免疫亲和层析、二维凝胶电泳和纳米lc /MS/MS技术，我们鉴定了交叉反应性自身抗原为突触素I，一种参与神经递质释放的中枢和周围神经系统蛋白。表位定位显示，主要的免疫反应位点位于突触蛋白I的功能重要的C结构域，已知该结构域介导蛋白质与突触囊泡的相互作用。此外，亲和纯化的人IgG和IgA抗麦胶蛋白抗体也被发现与突触蛋白I交叉反应。我们的假设是，在一些乳糜泻患者中，抗麦胶蛋白抗体反应与突触蛋白I交叉反应，免疫反应性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变。提出以下具体目标来解决我们的假设：i)确定抗体对突触素i的反应性是否与乳糜泻神经病变或共济失调有关。2)确定特异性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相关。3)绘制人抗体靶向synapsin I的表位，确定对某些表位的反应性是否与神经系统疾病或特定综合征的发生有关。拟议的研究有望阐明中枢和外周神经系统缺陷如何与麸质敏感性相关。它们也可能为相关周围神经病变或小脑性共济失调的诊断提供有用的标志物，并为检查针对受影响个体的自身免疫机制的治疗效果提供依据。

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.