Division of Rheumatology, Centre hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.
Division of Rheumatology, Hôpital de la Cité-de-la-Santé, Laval, Quebec, Canada.
RMD Open. 2023 Oct;9(4). doi: 10.1136/rmdopen-2023-003431.
The survival of motor neuron (SMN) complex has an essential role in the assembly of small nuclear ribonucleoproteins (RNP). Recent reports have described autoantibodies (aAbs) to the SMN complex as novel biomarkers in anti-U1RNP+ myositis patients. The aim of this study was to compare phenotypic features of anti-U1RNP+ mixed connective tissue disease (MCTD) patients with and without anti-SMN aAbs.
A retrospective MCTD cohort was studied. Addressable laser bead immunoassay was used to detect specific anti-SMN aAbs with <300 mean fluorescence intensity (MFI) as normal reference range, 300-999 MFI as low-titre and ≥1000 MFI as high-titre positivity. Comparison of clinical features between anti-SMN+ and anti-SMN- subgroups used two-tailed Fisher's exact test, and logistic regression analyses.
Sixty-six patients were included. Median age at MCTD diagnosis was 40.6 years, and duration of follow-up was 12 years. Based on the highest available titre, 39 (59%) were anti-SMN+: 10 (26%) had low titre and 29 (74%) had high titre. Anti-SMN+ patients had a higher frequency of fingertip pitting scars (anti-SMN+ 23% vs anti-SMN- 4%, p=0.04), lower gastrointestinal (GI) involvement (26% vs 4%, p=0.04), and myocarditis (16% vs 0%, p=0.04). The combined outcome of pitting scars and/or lower GI involvement and/or myositis and/or myocarditis was highest among high-titre anti-SMN+ patients: adjusted OR 7.79 (2.33 to 30.45, p=0.002).
Anti-SMN aAbs were present in 59% of our MCTD cohort. Their presence, especially at high-titres, was associated with a severe systemic sclerosis (scleroderma) phenotype including myositis, myocarditis and lower GI involvement.
运动神经元（SMN）复合物的存活在小核核糖核蛋白（RNP）的组装中起着重要作用。最近的报告描述了抗 U1RNP+肌炎患者的 SMN 复合物自身抗体（aAbs）作为新型生物标志物。本研究旨在比较抗 U1RNP+混合性结缔组织病（MCTD）患者有无抗-SMN aAbs 的表型特征。
回顾性 MCTD 队列研究。使用可寻址激光珠免疫分析检测具有<300 平均荧光强度（MFI）的特异性抗-SMN aAbs，<300 MFI 为正常参考范围，300-999 MFI 为低滴度，≥1000 MFI 为高滴度阳性。使用双侧 Fisher 确切检验和逻辑回归分析比较抗-SMN+和抗-SMN-亚组之间的临床特征。
共纳入 66 例患者。MCTD 诊断时的中位年龄为 40.6 岁，随访时间为 12 年。根据最高滴度，39 例（59%）为抗-SMN+：10 例（26%）为低滴度，29 例（74%）为高滴度。抗-SMN+患者指尖凹陷性瘢痕的发生率更高（抗-SMN+23%vs抗-SMN-4%，p=0.04），下消化道（GI）受累（抗-SMN+26%vs抗-SMN-4%，p=0.04）和心肌炎（抗-SMN+16%vs抗-SMN-0%，p=0.04）。高滴度抗-SMN+患者中凹陷性瘢痕和/或下 GI 受累和/或肌炎和/或心肌炎的联合结局最高：调整后的 OR 为 7.79（2.33 至 30.45，p=0.002）。
我们的 MCTD 队列中有 59%的患者存在抗-SMN aAbs。它们的存在，尤其是高滴度的存在，与包括肌炎、心肌炎和下 GI 受累在内的严重系统性硬化症（硬皮病）表型有关。
Zotero 插件