The transcriptomic profile of monocytes from patients with Sjögren's Syndrome is associated with inflammatory parameters and is mimicked by circulating mediators

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by infiltration of the exocrine glands and prominent B cell hyperactivity. Considering the key role of monocytes in promoting B cell hyperactivity, we performed RNA-sequencing analysis of CD14+ monocytes from patients with pSS, non-Sjögren's sicca (nSS), and healthy controls (HC). We demonstrated that the transcriptomic profile of pSS patients is enriched in intermediate and non-classical monocyte profiles, and confirmed the increased frequency of non-classical monocytes in pSS patients by flow-cytometry analysis. Weighted gene co-expression network analysis identified four molecular signatures in monocytes from pSS patients, functionally annotated for processes related with translation, IFN-signaling, and toll like receptor signaling. Systemic and local inflammatory features significantly correlated with the expression of these signatures. Furthermore, genes highly associated with clinical features in pSS were identified as hub-genes for each signature. Unsupervised hierarchical cluster analysis of the hub-genes identified four clusters of nSS and pSS patients, each with distinct inflammatory and transcriptomic profiles. One cluster showed a significantly higher percentage of pSS patients with higher prevalence of anti-SSA autoantibodies, interferon score, and erythrocyte sedimentation rate compared to the other clusters. Finally, we showed that the identified transcriptomic differences in pSS monocytes were induced in monocytes of healthy controls by exposure to serum of pSS patients. Representative hub-genes of all four signatures were partially inhibited by interferon-a/b receptor blockade, indicating that the circulating inflammatory mediators, including type I interferons have a significant contribution to the altered transcriptional profile of pSS-monocytes. Our study suggests that targeting key circulating inflammatory mediators, such as type I interferons, could offer new insights into the important pathways and mechanisms driving pSS, and holds promise for halting immunopathology in Sjögren's Syndrome. Overall design: RNA-sequencing of pheripheral blood isolated CD14+ monocytes from patients with primary Sjögren's syndrome (pSS; n=14) , non-Sjögren's sicca (nSS; n=8), and healthy controls (HC; n=14).

原发性干燥综合征（Primary Sjögren's syndrome, pSS）是一种以外分泌腺浸润及显著B细胞过度活化为特征的系统性自身免疫病。考虑到单核细胞在促进B细胞过度活化中的关键作用，本研究对原发性干燥综合征患者、非干燥综合征性干燥症（non-Sjögren's sicca, nSS）患者及健康对照（healthy controls, HC）的CD14阳性单核细胞（CD14+ monocytes）开展了RNA测序（RNA-sequencing）分析。本研究证实，原发性干燥综合征患者的转录组特征富集于中间型与非经典型单核细胞特征，并通过流式细胞术（flow-cytometry analysis）验证了原发性干燥综合征患者中非经典型单核细胞的频率升高。加权基因共表达网络分析（Weighted gene co-expression network analysis）从原发性干燥综合征患者的单核细胞中鉴定出4个分子特征，功能注释显示其涉及翻译过程、干扰素信号通路及Toll样受体信号通路。全身与局部炎症特征与这些分子特征的表达显著相关。此外，本研究还鉴定出与原发性干燥综合征临床特征高度相关的基因，作为各分子特征的核心基因（hub-genes）。对核心基因开展无监督层级聚类分析（unsupervised hierarchical cluster analysis）后，将非干燥综合征性干燥症及原发性干燥综合征患者划分为4个聚类群，每个聚类群均具有独特的炎症及转录组特征。其中一个聚类群的原发性干燥综合征患者占比显著更高，且相较于其余聚类群，该群患者的抗SSA自身抗体阳性率、干扰素评分及红细胞沉降率（erythrocyte sedimentation rate）均更高。本研究进一步证实，将健康对照的单核细胞暴露于原发性干燥综合征患者的血清后，可诱导出原发性干燥综合征患者单核细胞中所观察到的转录组差异。4个分子特征的代表性核心基因可部分被干扰素α/β受体阻断剂所抑制，这表明包括I型干扰素（type I interferons）在内的循环炎症介质对原发性干燥综合征单核细胞的转录组改变具有显著贡献。本研究提示，靶向关键循环炎症介质（如I型干扰素）可为阐明驱动原发性干燥综合征的重要通路及机制提供新视角，并有望为阻断干燥综合征的免疫病理进程提供潜在策略。实验设计概述：本研究对14例原发性干燥综合征患者、8例非干燥综合征性干燥症患者及14例健康对照的外周血分离CD14阳性单核细胞进行了RNA测序。