There is a need for biomarker to identify patients “at risk” for rheumatoid arthritis (risk-RA) and to better predict the therapeutic response and in this study we tested the hypothesis that novel native and citrullinated heterogeneous nuclear ribonucleoprotein (hnRNP)-DL autoantibodies could be possible biomarkers. Using protein macroarray and ELISA, epitope recognition against hnRNP-DL was analysed in sera from different developed RA disease and diagnosed SLE patients. Toll-like receptor (TLR) 7/9 and myeloid differentiation primary response gene 88 (MyD88)-dependency were studied in sera from murine disease models. HnRNP-DL expression in cultivated cells and synovial tissue was analysed by indirect immunofluorescence, immunoblot and immunohistochemistry. HnRNP-DL was highly expressed in stress granules, citrullinated in the rheumatoid joint and targeted by autoantibodies either as native or citrullinated proteins in patient subsets with different developed RA disease. Structural citrullination dependent epitopes (SCEs) of hnRNP-DL were detected in 58% of the SLE patients although 98% of these sera were α-CCP-2-negative. To obtain a specific citrullinated signal value, we subtracted the native antibody value from the citrullinated signal. The citrullinated/native index of autoantibodies against hnRNP-DL (CNDL-Index) was identified as a new value for an “individual window of treatment success” in early RA and for the detection of RF IgM/α-CCP-2 seronegative RA patients (24–46%). Negative CNDL-index was found in SLE patients, risk-RA and early RA cohorts such as EIRA where the majority of these patients are DAS28-responders to methotrexate (MTX) treatment (87%). High positive CNDL-values were associated with more severe RA, shared epitope and parenchymal changes in the lung. Specifically, native α-hnRNP-DL is TLR7/9-dependent, associated with pain and ROC analysis revealed an association to initial MTX or etanercept treatment response, especially in seronegative RA patients. CNDL-index defines people at risk to develop RA and the “window of treatment success” thereby closing the sensitivity gap in RA.

中文翻译：

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抗 hnRNP-DL 自身抗体的瓜氨酸/天然指数可预测 RA 患者的个体“治疗成功窗口”

需要生物标志物来识别患有类风湿关节炎（风险-RA）“有风险”的患者并更好地预测治疗反应，在这项研究中，我们测试了以下假设：新型天然和瓜氨酸异质核糖核蛋白（hnRNP）-DL自身抗体可能是可能的生物标志物。使用蛋白质宏阵列和 ELISA，分析了来自不同发展的 RA 疾病和诊断的 SLE 患者的血清中针对 hnRNP-DL 的表位识别。在小鼠疾病模型的血清中研究了 Toll 样受体 (TLR) 7/9 和骨髓分化初级反应基因 88 (MyD88) 依赖性。通过间接免疫荧光、免疫印迹和免疫组织化学分析培养细胞和滑膜组织中的HnRNP-DL表达。HnRNP-DL 在应激颗粒中高度表达，在类风湿关节中被瓜氨酸化，并且在患有不同发展的 RA 疾病的患者亚群中作为天然或瓜氨酸蛋白被自身抗体靶向。在 58% 的 SLE 患者中检测到 hnRNP-DL 的结构瓜氨酸依赖性表位 (SCE)，尽管这些血清中 98% 的血清为 α-CCP-2 阴性。为了获得特定的瓜氨酸信号值，我们从瓜氨酸信号中减去天然抗体值。抗 hnRNP-DL 自身抗体的瓜氨酸/天然指数（CNDL-指数）被确定为早期 RA 的“个体治疗成功窗口”和检测 RF IgM/α-CCP-2 血清阴性 RA 患者的新值(24–46%)。在 SLE 患者、RA 风险患者和早期 RA 队列（如 EIRA）中发现 CNDL 指数呈阴性，其中大多数患者对甲氨蝶呤 (MTX) 治疗有 DAS28 反应（87%）。高阳性 CNDL 值与更严重的 RA、共享表位和肺实质变化相关。具体来说，天然 α-hnRNP-DL 是 TLR7/9 依赖性的，与疼痛相关，ROC 分析显示与初始 MTX 或依那西普治疗反应相关，尤其是在血清阴性 RA 患者中。CNDL-指数定义了有患 RA 风险的人群和“治疗成功之窗”，从而缩小了 RA 的敏感性差距。