China-Japan Friendship Hospital and Graduate School of Peking Union Medical College, Beijing, China.
China-Japan Friendship Hospital, Beijing, China.
Arthritis Rheumatol. 2018 Aug;70(8):1288-1297. doi: 10.1002/art.40491. Epub 2018 Jun 27.
To investigate the associations between anti-nuclear matrix protein 2 (anti-NXP-2) autoantibody levels and disease activity as well as calcinosis severity in patients with idiopathic inflammatory myopathies (IIMs).
Serum levels of anti-NXP-2 autoantibodies were determined in 709 patients with IIMs and also serially measured in the patients' sera with an in-house enzyme-linked immunosorbent assay using MORC3 recombinant protein. Patients with anti-NXP-2 autoantibodies were divided into 2 subgroups: those with and those without calcinosis. Associations of anti-NXP-2 autoantibody levels with organ-specific disease activity (using 10-cm visual analog scale [VAS] scores), serum creatine kinase (CK) levels, and calcinosis severity were investigated in cross-sectional and longitudinal analyses.
A cross-sectional analysis of 56 IIM patients with anti-NXP-2 autoantibodies (38 without calcinosis and 18 with calcinosis) showed that in patients without calcinosis, the levels of anti-NXP-2 autoantibodies were positively correlated with the physician's global assessment of disease activity and muscle VAS scores and serum CK levels, whereas no such association was found in patients with calcinosis. Results of the longitudinal study revealed strong correlations of anti-NXP-2 antibody levels with the physician's global assessment and constitutional, cutaneous, gastrointestinal, and muscle VAS scores and serum CK levels in patients without calcinosis, but in patients with calcinosis, only a moderate correlation was observed between anti-NXP-2 antibody levels and the physician's global VAS and constitutional VAS scores. Of note, in patients without calcinosis, anti-NXP-2 autoantibodies were found to disappear during periods of clinical remission, but reappeared with disease relapse. No association between anti-NXP-2 antibody levels and the severity of calcinosis was observed.
These findings indicate that anti-NXP-2 autoantibodies serve as a useful marker for disease activity in patients with IIMs, especially in the absence of calcinosis. The differential associations observed between anti-NXP-2 autoantibody levels and disease activity suggest that there may be a phenotypic difference between patients with and those without calcinosis.
探讨抗核基质蛋白 2（anti-NXP-2）自身抗体水平与特发性炎性肌病（IIM）患者疾病活动度和钙质沉着严重程度的关系。
采用酶联免疫吸附试验（ELISA）检测 709 例 IIM 患者血清中抗 NXP-2 自身抗体水平，并使用 MORC3 重组蛋白对患者血清进行连续检测。将抗 NXP-2 自身抗体阳性患者分为有钙质沉着和无钙质沉着两组。在横断面和纵向分析中，研究抗 NXP-2 自身抗体水平与器官特异性疾病活动度（使用 10cm 视觉模拟量表[VAS]评分）、血清肌酸激酶（CK）水平和钙质沉着严重程度的关系。
对 56 例抗 NXP-2 自身抗体阳性的 IIM 患者（38 例无钙质沉着，18 例有钙质沉着）进行横断面分析，结果显示无钙质沉着的患者中，抗 NXP-2 自身抗体水平与医生总体评估的疾病活动度和肌肉 VAS 评分及血清 CK 水平呈正相关，而钙质沉着的患者中则无此相关性。纵向研究结果显示，无钙质沉着的患者抗 NXP-2 抗体水平与医生总体评估、全身、皮肤、胃肠道和肌肉 VAS 评分及血清 CK 水平呈强相关，但钙质沉着的患者仅观察到抗 NXP-2 抗体水平与医生总体 VAS 和全身 VAS 评分之间存在中度相关性。值得注意的是，无钙质沉着的患者在临床缓解期抗 NXP-2 自身抗体消失，但疾病复发时再次出现。未观察到抗 NXP-2 抗体水平与钙质沉着严重程度之间存在关联。
这些发现表明，抗 NXP-2 自身抗体是 IIM 患者疾病活动度的有用标志物，尤其是在无钙质沉着的情况下。抗 NXP-2 自身抗体水平与疾病活动度之间的差异关联表明，有钙质沉着和无钙质沉着的患者之间可能存在表型差异。
