Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Arthritis Rheumatol. 2018 Dec;70(12):2036-2045. doi: 10.1002/art.40576. Epub 2018 Oct 14.
Increasing evidence indicates that the cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) signaling pathway has a critical pathogenic role in systemic lupus erythematosus (SLE). Expression levels of the interferon (IFN)-inducible gene IFIT3 are elevated in SLE patients. However, it is still not clear how IFIT3 contributes to the pathogenesis of SLE. This study was undertaken to investigate the activation of the cGAS/STING signaling pathway in human SLE monocytes, and to determine how elevated expression of IFIT3 could contribute to overactive cGAS/STING signaling in patients with SLE.
Monocytes from SLE patients or healthy controls were examined for activity of the cGAS/STING signaling pathway and expression levels of IFIT3. Correlations between cGAS/STING signaling activity and SLE clinical features were analyzed. Gain- or loss-of-function experiments were used to determine the role of IFIT3 in cGAS/STING signaling. Coimmunoprecipitation assays were used to identify the interaction between IFIT3 and other proteins.
The cGAS/STING signaling pathway was found to have enhanced activity in monocytes from SLE patients compared to healthy controls, as indicated by the higher expression of IFNβ downstream. Levels of IFIT3 were significantly elevated in human SLE monocytes, and this was positively correlated with the activity of the cGAS/STING signaling pathway. In vitro, the expression of VACV70-induced IFNβ was reduced by knockdown of IFIT3, whereas overexpression of IFIT3 produced an opposite effect. Finally, IFIT3 was found to interact with both STING and TANK-binding kinase 1.
These findings suggest that IFIT3 is one of the genes that contributes to the overactive cGAS/STING signaling pathway in human SLE monocytes. IFIT3 may therefore serve as a novel therapeutic target for blocking the production of type I IFN and other proinflammatory cytokines by the cGAS/STING signaling pathway in patients with SLE.
越来越多的证据表明，环鸟苷酸-腺苷酸合酶/干扰素基因刺激物（cGAS/STING）信号通路在系统性红斑狼疮（SLE）中具有关键的致病作用。SLE 患者中干扰素（IFN）诱导基因 IFIT3 的表达水平升高。然而，IFIT3 如何导致 SLE 的发病机制仍不清楚。本研究旨在研究人类 SLE 单核细胞中 cGAS/STING 信号通路的激活，并确定 IFIT3 的高表达如何导致 SLE 患者中过度活跃的 cGAS/STING 信号通路。
检测 SLE 患者或健康对照者的单核细胞中 cGAS/STING 信号通路的活性和 IFIT3 的表达水平。分析 cGAS/STING 信号活性与 SLE 临床特征之间的相关性。通过增益或失活功能实验确定 IFIT3 在 cGAS/STING 信号中的作用。免疫共沉淀实验用于鉴定 IFIT3 与其他蛋白之间的相互作用。
与健康对照者相比，SLE 患者单核细胞中的 cGAS/STING 信号通路活性增强，IFNβ下游表达升高。IFIT3 在人类 SLE 单核细胞中的水平显著升高，并且与 cGAS/STING 信号通路的活性呈正相关。在体外，IFIT3 的敲低降低了 VACV70 诱导的 IFNβ的表达，而 IFIT3 的过表达则产生相反的效果。最后，发现 IFIT3 与 STING 和 TANK 结合激酶 1 相互作用。
这些发现表明 IFIT3 是导致人类 SLE 单核细胞中过度活跃的 cGAS/STING 信号通路的基因之一。因此，IFIT3 可作为阻断 cGAS/STING 信号通路产生 I 型 IFN 和其他促炎细胞因子的新型治疗靶点，用于治疗 SLE 患者。
