Objectives To explore the efficacy of plasma exchange (PE) therapy in refractory idiopathic inflammatory myopathy (IIM) patients with positive anti-signal recognition particle (SRP) antibody. Methods Nine refractory IIM patients with positive anti-SRP antibody were enrolled, who received PE therapy at Ruijin Hospital from October 2017 to December 2020. The clinical manifestations, laboratory tests, chest CT and lower extremity MRI images before and after PE therapy were compared. The treatment response was evaluated by the 2016 ACR/EULAR myositis response criteria. Results A total of 88.9% (8/9) of subjects had achieved improvement by 3 weeks after PE therapy, with 55.6% (5/9) minimal improvement and 33.3% (3/9) moderate improvement. There were statistically significant improvements between baseline and after PE therapy at 3 weeks on the core set measures: physician global activity, patient global activity, HAQ, manual muscle testing (MMT), extramuscular disease activity, and muscle enzymes activity including creatine kinase (CK), lactate dehydrogenase (LDH), aspartate transaminase (AST), except for alanine transaminase (ALT). Moreover, the chest CT showed regression of ground glass opacities and irregular linear opacities after PE therapy in four patients with interstitial lung disease. The MRI images of lower extremity in four patients showed reduction of muscle oedema after the therapy. Conclusion PE therapy is effective for refractory IIM patients with positive anti-SRP antibody. It should be considered as an alternative treatment for those patients who are resistant to the combined therapy of glucocorticoids and immunosuppressive agents.

中文翻译：

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抗信号识别粒子抗体血浆置换治疗难治性炎症性肌病：病例系列

目的探讨血浆置换（PE）治疗抗信号识别粒子（SRP）抗体阳性的难治性特发性炎症性肌病（IIM）患者的疗效。方法 选取2017年10月至2020年12月在瑞金医院接受PE治疗的9例抗SRP抗体阳性的难治性IIM患者，比较PE治疗前后的临床表现、实验室检查、胸部CT及下肢MRI影像。治疗反应通过 2016 ACR/EULAR 肌炎反应标准进行评估。结果共有88.9% (8/9) 的受试者在PE 治疗后3 周内获得改善，其中55.6% (5/9) 最小改善和33.3% (3/9) 中等改善。在基线和 PE 治疗后 3 周的核心测量指标之间有统计学上的显着改善：医生整体活动、患者整体活动、HAQ、手动肌肉测试 (MMT)、肌肉外疾病活动和包括肌酸激酶 (CK) 在内的肌肉酶活动)、乳酸脱氢酶 (LDH)、天冬氨酸转氨酶 (AST)，丙氨酸转氨酶 (ALT) 除外。此外，4 名间质性肺病患者的胸部 CT 显示，PE 治疗后磨玻璃影和不规则线状影消退。4 例患者下肢 MRI 图像显示治疗后肌肉水肿减轻。结论 PE治疗对抗SRP抗体阳性的难治性IIM患者有效。