Reliability of antinuclear matrix protein 2 antibody assays in idiopathic inflammatory myopathies is dependent on target protein properties
Reliability of antinuclear matrix protein 2 antibody assays in idiopathic inflammatory myopathies is dependent on target protein properties
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DOI：
10.1111/1346-8138.16295
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发表时间：
2021-12-29
影响因子：
3.1
通讯作者：
Okiyama, Naoko
中科院分区：
文献类型：
--
作者：
Ichimura, Yuki;Konishi, Risa;Okiyama, Naoko
由于其简单性，线印迹测定（LB）目前用于检测特发性炎症性肌病（IIM）患者的肌炎特异性自身抗体（MSA）；然而，该测定的敏感性和特异性较低。本研究的目的是评估商业 LB 在检测抗核基质蛋白 2 (NXP2) 抗体中的准确性。纳入了 77 份来自 IIM 患者的血清样本，其中使用 K562 细胞裂解物通过免疫沉淀和蛋白质印迹 (IP-WB) 检测了抗 NXP2 抗体。使用昆虫细胞产生的重组人NXP2全蛋白（rNXP2）对所有样品进行LB和IP-WB评估，并比较每种测定的阳性率。 32 个样本 (41.6%) 通过 LB 检测显示假阴性，其中 11 个样本通过使用 rNXP2 的 IP-WB 检测结果呈阴性。与使用 rNXP2 的 IP-WB 呈阳性但 LB 呈阴性的样品相比，LB 和使用 rNXP2 的 IP-WB 均呈阳性结果的样品中使用细胞裂解物的 IP-WB 的相对强度显着更高。使用 rNXP2 进行 LB 和 IP-WB 检测均呈阴性结果的 11 个样本中的 3 个显示出高抗体滴度。此外，在重组和天然 NXP2 蛋白之间观察到转录后 SUMO 化的差异。总之，LB 对抗 NXP2 抗体的检测灵敏度较低，抗 NXP2 抗体滴度低时这种效应会加剧。此外，抗体对具有不同转录后修饰的重组和天然NXP2蛋白的反应性似乎存在差异。
A line blotting assay (LB) is currently used to detect myositis-specific autoantibodies (MSAs) in patients with idiopathic inflammatory myopathies (IIMs), because of its simplicity; however, the sensitivity and specificity of this assay is low. The aim of this study is to evaluate the accuracy of the commercial LB in detection of antinuclear matrix protein 2 (NXP2) antibody. Seventy-seven serum samples from patients with IIMs, in which anti-NXP2 antibodies were detected through immunoprecipitation and western blotting (IP-WB) using K562 cell lysate, were enrolled. All samples were assessed by LB and IP-WB using recombinant human NXP2 whole protein (rNXP2) produced by insect cells, and the positive rates of each assay were compared. Thirty-two samples (41.6%) showed false-negativity by LB, which includes 11 samples with negative results by IP-WB using rNXP2. Relative intensities of IP-WB using cell lysate were significantly higher in the samples with positive results by both LB and IP-WB using rNXP2, compared to samples with positive by IP-WB using rNXP2 but negative by LB. Three of 11 samples with negative results by both LB and IP-WB using rNXP2 revealed high antibody titers. Further, differences in post-transcriptional SUMOylation were observed between recombinant and natural NXP2 proteins. In conclusion, the LB showed low sensitivity for detection of anti-NXP2 antibody, an effect exacerbated at low titers of anti-NXP2 antibodies. Moreover, there appears to be differences in the reactivities of antibodies to recombinant and natural NXP2 proteins with different post-transcriptional modifications.