Department of Rheumatology and Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin Second Road, Shanghai, 200025, China.
BMC Med. 2023 Dec 20;21(1):507. doi: 10.1186/s12916-023-03231-9.
Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disease characterized by innate immune system activation, with a high risk for macrophage activation syndrome (MAS). MAS development is associated with monocyte/macrophage activation and cytokine storm. Monocytes consist of three different subsets, classical monocytes (CMs, CD14CD16 -), intermediate monocytes (IMs, CD14CD16 +), and non-classical monocytes (NCMs, CD14CD16 +), each has distinct roles in inflammatory regulation. However, the frequencies and regulatory mechanism of monocyte subsets in AOSD patients have not been identified.
We performed flow cytometry, RNA sequencing, phagocytosis analysis, and enzyme-linked immunosorbent assay to evaluate monocyte subsets, cell functions, and potential biomarkers. The effect of neutrophil extracellular traps (NETs) on monocytes was determined by evaluating mRNA levels of DNA sensors, surface CD16 expression, and inflammasome pathway activation.
Higher proportions of intermediate monocytes (IMs) were identified in active AOSD patients. IMs displayed higher expression of CD80, CD86, HLA-DR, and CD163 than CMs and NCMs. CD163 upregulation was noted on AOSD IMs, accompanied by increased phagocytic activity and elevated cytokine/chemokine production, including IL-1β, IL-6, CCL8, and CXCL10. The frequencies of IMs were correlated with disease activity and higher in AOSD patients with MAS (AOSD-MAS). CCL8 and CXCL10 were highly expressed in RNA sequencing of monocytes from AOSD-MAS patients and plasma CXCL10 level could serve as a potential biomarker for AOSD-MAS. Moreover, DNA-sensing pathway was activated in monocytes from AOSD-MAS patients. Stimulation with NETs derived from AOSD induced DNA sensor expression, the expansion of IMs, and inflammasome pathway activation. These effects can be abrogated by DNase I treatment.
Our results demonstrated that the proportions of IMs were elevated in AOSD and associated with MAS. The DNA component in NETs from AOSD plays an important role in the formation of IMs, shedding new light for the therapeutic target.
成人Still 病（AOSD）是一种以固有免疫系统激活为特征的全身性自身炎症性疾病，其发生巨噬细胞活化综合征（MAS）的风险较高。MAS 的发展与单核细胞/巨噬细胞的激活和细胞因子风暴有关。单核细胞由三个不同的亚群组成，经典单核细胞（CMs，CD14CD16-）、中间单核细胞（IMs，CD14CD16+）和非经典单核细胞（NCMs，CD14CD16+），每个亚群在炎症调节中都有不同的作用。然而，AOSD 患者单核细胞亚群的频率和调节机制尚未确定。
我们通过流式细胞术、RNA 测序、吞噬分析和酶联免疫吸附试验来评估单核细胞亚群、细胞功能和潜在的生物标志物。通过评估 DNA 传感器的 mRNA 水平、表面 CD16 表达和炎症小体途径的激活来确定中性粒细胞胞外陷阱（NETs）对单核细胞的影响。
在活动期 AOSD 患者中发现中间单核细胞（IMs）的比例较高。与 CMs 和 NCMs 相比，IMs 表达更高水平的 CD80、CD86、HLA-DR 和 CD163。在 AOSD IMs 上观察到 CD163 的上调，伴随着吞噬活性的增加和细胞因子/趋化因子的产生增加，包括 IL-1β、IL-6、CCL8 和 CXCL10。IMs 的频率与疾病活动度相关，且在 AOSD-MAS 患者中更高。在 AOSD-MAS 患者的单核细胞 RNA 测序和血浆 CXCL10 水平中，CCL8 和 CXCL10 高表达，可作为 AOSD-MAS 的潜在生物标志物。此外，AOSD-MAS 患者的单核细胞中 DNA 感知途径被激活。来自 AOSD-MAS 的 NETs 刺激诱导 DNA 传感器表达、IMs 的扩增和炎症小体途径的激活。这些作用可以通过 DNA 酶 I 处理来消除。
我们的研究结果表明，AOSD 患者中 IMs 的比例升高，与 MAS 相关。AOSD 中 NETs 的 DNA 成分在 IMs 的形成中起重要作用，为治疗靶点提供了新的思路。
