Identification of novel citrullinated autoantigens of synovium in rheumatoid arthritis using a proteomic approach.
Identification of novel citrullinated autoantigens of synovium in rheumatoid arthritis using a proteomic approach.
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DOI：
10.1186/ar2085
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发表时间：
2006
影响因子：
4.9
通讯作者：
Kato, Tomohiro
中科院分区：
文献类型：
--
作者：
Matsuo, Kosuke;Xiang, Yang;Nakamura, Hiroshi;Masuko, Kayo;Yudoh, Kazuo;Noyori, Koji;Nishioka, Kusuki;Saito, Tomoyuki;Kato, Tomohiro
最近，一些瓜氨酸化自身抗原的自身抗体被报道为类风湿性关节炎(RA)的特异性抗体。然而，对瓜氨酸蛋白及其自身免疫的完整描述还知之甚少。为了了解这一特征，我们用蛋白质组学的方法检测了瓜氨酸化自身抗原，并进一步研究了瓜氨酸化在其中一种自身抗原抗原性中的意义。具体地说，我们使用五名RA患者的混合血清和抗瓜氨酸抗体，通过双向电泳和Western blotting检测了一名RA患者滑膜组织中的瓜氨酸自身抗原。在通过质谱学鉴定检测到的自身抗原后，我们通过在其中一个已鉴定的新的瓜氨酸化自身抗原上使用有或没有瓜氨酸化的重组蛋白来研究瓜氨酸化对自身抗原性的贡献。结果，我们发现了51个瓜氨酸蛋白斑点。其中30个斑点(58.8%)是自身抗原性的。在检测到的30种瓜氨酸自身抗原蛋白中，我们鉴定了13种。它们含有三个纤维蛋白原衍生物和几个新的瓜氨酸自身抗原(例如，asporin和F-肌动蛋白封顶蛋白α-1亚基[Capzα-1])。我们进一步分析了瓜氨酸化对检测到的瓜氨酸化自身抗原CAPZα-1自身抗原性的贡献。结果，抗非瓜氨酸化CAPZ-1自身抗体的频率在RA组为36.7%，在骨关节炎(OA)组为10.7%，在健康献血者为6.5%。另一方面，瓜氨酸化的CAPZα-1在RA组为53.3%，在OA组为7.1%，在健康献血者为6.5%。这表明瓜氨酸化或非瓜氨酸化的CAPZα-1的自身抗原性与RA有关。36.7%的患者对瓜氨酸化的CAPZα-1抗体效价显著高于非瓜氨酸化的CAPZα-1抗体滴度，而其他患者对瓜氨酸化和非瓜氨酸化的CAPZα-1的抗体效价几乎相同。因此，自身抗体将针对CAPZα-1的瓜氨酸相关和/或瓜氨酸无关表位(S)。总之，我们首次报道了瓜氨酸自身抗原的概况。尽管瓜氨酸化与自身抗原性密切相关，但瓜氨酸化并不总是在RA中产生自身抗原性。瓜氨酸化和非瓜氨酸化自身抗原/自身表位在类风湿关节炎中具有不同的病理作用。
Recently, autoantibodies to some citrullinated autoantigens have been reported to be specific for rheumatoid arthritis (RA). However, an entire profile of and autoimmunity of the citrullinated proteins have been poorly understood. To understand the profile, we examined citrullinated autoantigens by a proteomic approach and further investigated the significance of citrullination in antigenicity of one of the autoantigens. Specifically, we detected citrullinated autoantigens in synovial tissue of a patient with RA by two-dimensional electrophoresis and Western blotting by using pooled sera from five patients with RA and anti-citrulline antibodies. After identifying the detected autoantigens by mass spectrometry, we investigated the contribution of citrullination to autoantigenicity by using a recombinant protein with or without citrullination on one of the identified novel citrullinated autoantigens. As a result, we found 51 citrullinated protein spots. Thirty (58.8%) of these spots were autoantigenic. We identified 13 out of the 30 detected citrullinated autoantigenic proteins. They contained three fibrinogen derivatives and several novel citrullinated autoantigens (for example, asporin and F-actin capping protein α-1 subunit [CapZα-1]). We further analyzed the contribution of citrullination to autoantigenicity in one of the detected citrullinated autoantigens, CapZα-1. As a result, frequencies of autoantibodies to non-citrullinated CapZα-1 were 36.7% in the RA group tested, 10.7% in the osteoarthritis (OA) group, and 6.5% in healthy donors. On the other hand, those to citrullinated CapZα-1 were 53.3% in the RA group, 7.1% in the OA group, and 6.5% in the healthy donors. This shows that autoantigenicity of citrullinated or non-citrullinated CapZα-1 is relevant to RA. The antibody titers to the citrullinated CapZα-1 were significantly higher than those to the non-citrullinated CapZα-1 in 36.7% of patients; however, the other patients showed almost equal antibody titers to both citrullinated and non-citrullinated CapZα-1. Therefore, the autoantibodies would target citrulline-related and/or citrulline-unrelated epitope(s) of CapZα-1. In conclusion, we report a profile of citrullinated autoantigens for the first time. Even though citrullination is closely related to autoantigenicity, citrullination would not always produce autoantigenicity in RA. Citrullinated and non-citrullinated autoantigens/autoepitopes would have different pathological roles in RA.