Cytosolic 5′-nucleotidase 1A autoimmunity in sporadic inclusion body myositis
Cytosolic 5′-nucleotidase 1A autoimmunity in sporadic inclusion body myositis
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DOI：
10.1002/ana.23840
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发表时间：
2013-03-01
影响因子：
11.2
通讯作者：
Greenberg, Steven A.
中科院分区：
文献类型：
--
作者：
Larman, H. Benjamin;Salajegheh, Mohammad;Greenberg, Steven A.
目的我们先前在散发性包涵体肌炎(IBM)中发现了一种抗43 kDa肌肉自身抗原的循环自身抗体，并证明了IBM诊断血液测试的可行性。在这里，我们试图确定这种IBM自身抗体的分子靶点，了解IBM自身免疫与肌肉退变之间的关系，并建立一种具有高诊断准确性的IBM血液检测方法。方法用质谱仪和人工合成的人血多肽对IBM血样进行筛选。对200例患者的血浆和血清样本进行免疫印迹分析，结果与临床特征相关。对30例肌肉活检标本进行免疫组织化学和免疫印迹检测。对19例患者的DNA进行外显子组或全基因组测序。结果质谱学和413,611人源多肽文库的筛选均证实胞液5-核苷酸酶1A(cN1A；NT5C1A)可能是43 kDa的IBM自身抗原，并用重组cN1A蛋白进行斑点印迹和Western印迹分析。抗cN1A自身抗体中反应性诊断IBM的敏感性为70%，特异性为92%；高反应性诊断IBM的敏感性为34%，特异性为98%。确定了1~3个主要的cN1a免疫优势表位。免疫组织化学染色显示，cN1a在IBM肌肉的核周区和有边框的空泡中聚集，定位于肌核变性区域。针对cN1A的自身抗体在肌肉疾病中很常见，而且对IBM具有高度特异性，可能在IBM的自身免疫和肌肉变性的双重过程之间提供联系。血液诊断试验是可行的，并应提高IBM的早期和可靠诊断。《安·神经》2013年；73：408418
Objective We previously identified a circulating autoantibody against a 43 kDa muscle autoantigen in sporadic inclusion body myositis (IBM) and demonstrated the feasibility of an IBM diagnostic blood test. Here, we sought to identify the molecular target of this IBM autoantibody, understand the relationship between IBM autoimmunity and muscle degeneration, and develop an IBM blood test with high diagnostic accuracy. Methods IBM blood samples were screened using mass spectrometry and a synthetic human peptidome. Plasma and serum samples (N=200 patients) underwent immunoblotting assays, and results were correlated to clinical features. Muscle biopsy samples (n=30) were examined by immunohistochemistry and immunoblotting. Exome or whole genome sequencing was performed on DNA from 19 patients. Results Both mass spectrometry and screening of a 413,611 human peptide library spanning the entire human proteome identified cytosolic 5-nucleotidase 1A (cN1A; NT5C1A) as the likely 43 kDa IBM autoantigen, which was then confirmed in dot blot and Western blot assays using recombinant cN1A protein. Moderate reactivity of anti-cN1A autoantibodies was 70% sensitive and 92% specific, and high reactivity was 34% sensitive and 98% specific for the diagnosis of IBM. One to 3 major cN1A immunodominant epitopes were identified. cN1A reactivity by immunohistochemistry accumulated in perinuclear regions and rimmed vacuoles in IBM muscle, localizing to areas of myonuclear degeneration. Interpretation Autoantibodies against cN1A are common in and highly specific to IBM among muscle diseases, and may provide a link between IBM's dual processes of autoimmunity and myodegeneration. Blood diagnostic testing is feasible and should improve early and reliable diagnosis of IBM. Ann Neurol 2013;73:408418