Stratification and Monitoring of Juvenile Idiopathic Arthritis Patients by Synovial Proteome Analysis

Juvenile idiopathic arthritis (JIA) comprises a poorly understood group of chronic, childhood onset, autoimmune diseases with variable clinical outcomes. We investigated whether profiling of the synovial fluid (SF) proteome by a fluorescent dye based, two-dimensional gel (DIGE) approach could distinguish patients in whom inflammation extends to affect a large number of joints, early in the disease process. SF samples from 22 JIA patients were analyzed: 10 with oligoarticular arthritis, 5 extended oligoarticular and 7 polyarticular disease. SF samples were labeled with Cy dyes and separated by two-dimensional electrophoresis. Multivariate analyses were used to isolate a panel of proteins which distinguish patient subgroups. Proteins were identified using MALDI-TOF mass spectrometry with expression further verified by Western immunoblotting and immunohistochemistry. Hierarchical clustering based on the expression levels of a set of 40 proteins segregated the extended oligoarticular from the oligoarticular patients (p < 0.05). Expression patterns of the isolated protein panel have also been observed over time, as disease spreads to multiple joints. The data indicates that synovial fluid proteome profiles could be used to stratify patients based on risk of disease extension. These protein profiles may also assist in monitoring therapeutic responses over time and help predict joint damage.

幼年特发性关节炎（Juvenile idiopathic arthritis, JIA）是一类病因尚未明确的慢性儿童起病自身免疫性疾病，其临床转归存在显著异质性。本研究旨在探讨采用基于荧光染料的双向凝胶电泳（two-dimensional gel, DIGE）技术分析滑液（synovial fluid, SF）蛋白质组，是否可在疾病早期区分炎症累及大量关节的患者。本研究共纳入22例JIA患者的滑液样本，其中少关节型关节炎10例、扩展性少关节型关节炎5例、多关节型关节炎7例。滑液样本经Cy染料标记后，通过二维电泳完成分离；采用多变量分析筛选出可区分不同患者亚组的蛋白质组。通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF mass spectrometry）鉴定所得蛋白质，并通过蛋白质免疫印迹与免疫组织化学实验进一步验证其表达水平。基于40种蛋白质表达水平的层次聚类分析显示，扩展性少关节型患者与少关节型患者可被显著区分（P<0.05）。研究还观察到，随疾病进展累及多关节时，筛选得到的蛋白质组表达模式会发生相应动态变化。本研究数据表明，滑液蛋白质组谱可用于基于疾病扩展风险的患者分层；此类蛋白质谱还有助于动态监测治疗应答，并预测关节损伤风险。