Division of Rheumatology, Department of Medicine, George Washington University School of Medicine and Health Sciences, Washington, DC, USA.
Environmental Autoimmunity Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Bethesda, MD, USA.
Rheumatology (Oxford). 2021 Apr 6;60(4):1839-1849. doi: 10.1093/rheumatology/keaa429.
Myositis-specific autoantibodies have defined distinct phenotypes of patients with juvenile myositis (JIIM). We assessed the frequency and clinical significance of anti-melanoma differentiation-associated gene 5 (MDA5) autoantibody-associated JIIM in a North American registry.
Retrospective examination of the characteristics of 35 JIIM patients with anti-MDA5 autoantibodies was performed, and differences from other myositis-specific autoantibody groups were evaluated.
Anti-MDA5 autoantibodies were present in 35/453 (7.7%) of JIIM patients and associated with older age at diagnosis, and lower serum creatine kinase and aldolase levels. Patients with anti-MDA5 autoantibodies had more frequent weight loss, adenopathy, arthritis, interstitial lung disease (ILD), and less frequent falling compared with anti-transcriptional intermediary factor 1 (TIF1), anti-nuclear matrix protein 2 (NXP2) and myositis-specific autoantibody/myositis-associated autoantibody-negative patients. They had a different season of diagnosis and less frequent mechanic's hands and ILD compared with those with anti-synthetase autoantibodies. Anti-MDA5 patients received fewer medications compared with anti-TIF1, and corticosteroid treatment was shorter compared with anti-TIF1 and anti-nuclear matrix protein 2 autoantibody groups. The frequency of remission was higher in anti-MDA5 than anti-synthetase autoantibody-positive JIIM. In multivariable analyses, weight loss, arthritis and arthralgia were most strongly associated with anti-MDA5 autoantibody-positive JIIM.
Anti-MDA5 JIIM is a distinct subset, with frequent arthritis, weight loss, adenopathy and less severe myositis, and is also associated with ILD. Anti-MDA5 is distinguished from anti-synthetase autoantibody-positive JIIM by less frequent ILD, lower creatine kinase levels and differing seasons of diagnosis. Anti-MDA5 has comparable outcomes, but with the ability to discontinue steroids more rapidly and less frequent flares compared with anti-TIF1 autoantibodies, and more frequent remission compared with anti-synthetase JIIM patients.
肌炎特异性自身抗体定义了青少年皮肌炎（JIIM）患者的不同表型。我们评估了北美登记处中抗黑色素瘤分化相关基因 5（MDA5）自身抗体相关 JIIM 的频率和临床意义。
回顾性分析了 35 例抗 MDA5 自身抗体 JIIM 患者的特征，并与其他肌炎特异性自身抗体组进行了比较。
在 453 例 JIIM 患者中存在 35 例（7.7%）抗 MDA5 自身抗体，其与诊断时年龄较大、血清肌酸激酶和醛缩酶水平较低有关。与抗转录中介因子 1（TIF1）、抗核基质蛋白 2（NXP2）和肌炎特异性自身抗体/肌炎相关自身抗体阴性患者相比，抗 MDA5 自身抗体患者更频繁出现体重减轻、淋巴结病、关节炎、间质性肺病（ILD）和较少的跌倒。他们的诊断季节不同，与抗合成酶自身抗体患者相比，机械性手和ILD 的发生率较低。与抗 TIF1 相比，抗 MDA5 患者接受的药物较少，与抗 TIF1 和抗核基质蛋白 2 自身抗体组相比，皮质类固醇治疗时间更短。与抗合成酶自身抗体阳性 JIIM 相比，抗 MDA5 患者的缓解率更高。在多变量分析中，体重减轻、关节炎和关节痛与抗 MDA5 自身抗体阳性 JIIM 相关性最强。
抗 MDA5 JIIM 是一个独特的亚组，具有频繁的关节炎、体重减轻、淋巴结病和不太严重的肌炎，也与 ILD 相关。与抗合成酶自身抗体阳性 JIIM 相比，抗 MDA5 与较少的ILD、较低的肌酸激酶水平和不同的诊断季节有关。抗 MDA5 的结局相当，但与抗 TIF1 自身抗体相比，停用类固醇的速度更快，发作频率更低，与抗合成酶 JIIM 患者相比，缓解频率更高。
