Fine specificity of antibodies against AQP4: Epitope mapping reveals intracellular epitopes
Fine specificity of antibodies against AQP4: Epitope mapping reveals intracellular epitopes
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DOI：
10.1016/j.jaut.2011.01.004
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发表时间：
2011-05-01
影响因子：
12.8
通讯作者：
Tzioufas, A. G.
中科院分区：
文献类型：
--
作者：
Kampylafka, E. I.;Routsias, J. G.;Tzioufas, A. G.
水通道蛋白 4 (AQP4) 自身抗体是视神经脊髓炎 (NMO)（德维奇综合征）的标志物和致病因素。我们的目的是鉴定 AQP4 蛋白的 B 细胞抗原线性表位并研究与其他分子的相似性。为此，我们筛选了 21 名抗 AQP4 抗体阳性患者（研究组）、23 名无神经系统受累的 SLE 和 23 名 pSS 患者（疾病对照）以及 28 名健康个体（正常对照）的血清。合成了 11 种肽，涵盖 AQP4 分子的整个胞内和胞外结构域，并通过 ELISA 筛选所有血清中的抗肽抗体。通过同源抑制测定评估特异性。 NMO 阳性血清对跨序列 aal-22 (AQPpep1)（42.9% 的患者）、aa88-113 (AQPpep4) (33%) 和 aa252-275 (AQPpep8) (23.8%) 的 3 种不同肽表现出反应性。所有表位均位于 AQP4 的细胞内结构域中。同源抑制率范围为71.1%至84.3%。在 AQPpep8' aa257-271（AQPpep8 aa252-275 的 15 聚体肽部分）和 Tax1-HTLV-1 结合蛋白 (TAX1BP1)（与人类 T 淋巴细胞病毒 1 (HTLV-1) 复制相关的宿主蛋白）的 aa219-233 结构域之间观察到 73% 的序列同源性。在 26.3% (N = 5) 和 31.6% (N = 6) 的 NMO 阳性血清中检测到针对 AQP4 和 TAX1BP1 15 聚体肽的抗体（r(s) = 0.81，P < 0.0001）。健康对照不与这些肽发生反应，而同源和交叉抑制测定证实了结合特异性。 AQP4 的第一个表位作图表明，很大一部分抗 AQP4 抗体靶向位于通道细胞内结构域的线性表位。其中一个表位与 TAX1BP1 蛋白的一部分表现出高度相似性。 (C) 2011 Elsevier Ltd. 保留所有权利。
The autoantibody to aquaporin-4 (AQP4) is a marker and a pathogenetic factor in Neuromyelitis Optica (NMO) (Devic's syndrome). Our aim was to identify B-cell antigenic linear epitopes of the AQP4 protein and investigate similarities with other molecules. To this end, we screened sera from 21 patients positive for anti-AQP4 antibodies (study group), from 23 SLE and 23 pSS patients without neurologic involvement (disease controls) and from 28 healthy individuals (normal controls). Eleven peptides, spanning the entire intracellular and extracellular domains of the AQP4 molecule, were synthesized, and all sera were screened for anti-peptide antibodies by ELISA. Specificity was evaluated by homologous inhibition assays. NMO positive sera exhibited reactivity against 3 different peptides spanning the sequences aal-22 (AQPpep1) (42.9% of patients), aa88-113 (AQPpep4) (33%) and aa252-275 (AQPpep8) (23.8%). All epitopes were localized in the intracellular domains of AQP4. Homologous inhibition rates were ranging from 71.1% to 84.3%. A 73% sequence homology was observed between AQPpep8' aa257-271, a 15-mer peptide part of the AQPpep8 aa252-275, and the aa219-233 domain of the Tax1-HTLV-1 binding protein (TAX1BP1), a host protein associated with replication of the Human T-Lymphotropic Virus 1 (HTLV-1). Antibodies against the AQP4 and the TAX1BP1 15-mer peptides were detected in 26.3% (N = 5) and 31.6% (N = 6) of NMO positive sera (r(s) = 0.81, P < 0.0001). Healthy controls did not react with these peptides, while homologous and cross-inhibition assays confirmed binding specificity. This first epitope mapping for AQP4 reveals that a significant proportion of anti-AQP4 antibodies target linear epitopes localized in the intracellular domains of the channel. One of the epitopes displays high similarity with a portion of TAX1BP1 protein. (C) 2011 Elsevier Ltd. All rights reserved.