Rheumatology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Ann Rheum Dis. 2021 May;80(5):617-625. doi: 10.1136/annrheumdis-2020-217470. Epub 2020 Dec 4.
Systemic juvenile idiopathic arthritis (SJIA) confers high risk for macrophage activation syndrome (MAS), a life-threatening cytokine storm driven by interferon (IFN)-γ. SJIA monocytes display IFN-γ hyper-responsiveness, but the molecular basis of this remains unclear. The objective of this study is to identify circulating monocyte and bone marrow macrophage (BMM) polarisation phenotypes in SJIA including molecular features contributing to IFN response.
Bulk RNA-seq was performed on peripheral blood monocytes (n=26 SJIA patients) and single cell (sc) RNA-seq was performed on BMM (n=1). Cultured macrophages were used to define consequences of tripartite motif containing 8 (TRIM8) knockdown on IFN-γ signalling.
Bulk RNA-seq of SJIA monocytes revealed marked transcriptional changes in patients with elevated ferritin levels. We identified substantial overlap with multiple polarisation states but little evidence of IFN-induced signature. Interestingly, among the most highly upregulated genes was TRIM8, a positive regulator of IFN-γ signalling. In contrast to PBMC from SJIA patients without MAS, scRNA-seq of BMM from a patient with SJIA and MAS identified distinct subpopulations of BMM with altered transcriptomes, including upregulated IFN-γ response pathways. These BMM also showed significantly increased expression of TRIM8. In vitro knockdown of TRIM8 in macrophages significantly reduced IFN-γ responsiveness.
Macrophages with an 'IFN-γ response' phenotype and TRIM8 overexpression were expanded in the bone marrow from an MAS patient. TRIM8 is also upregulated in SJIA monocytes, and augments macrophage IFN-γ response in vitro, providing both a candidate molecular mechanism and potential therapeutic target for monocyte hyper-responsiveness to IFNγ in cytokine storms including MAS.
全身性幼年特发性关节炎（SJIA）会增加巨噬细胞活化综合征（MAS）的风险，MAS 是一种由干扰素（IFN）-γ驱动的危及生命的细胞因子风暴。SJIA 单核细胞表现出 IFN-γ超反应性，但这一现象的分子基础尚不清楚。本研究的目的是鉴定 SJIA 中循环单核细胞和骨髓巨噬细胞（BMM）的极化表型，包括对 IFN 反应有贡献的分子特征。
对 26 例 SJIA 患者的外周血单核细胞（n=26 例 SJIA 患者）进行了批量 RNA-seq，对 1 例单细胞（sc）RNA-seq 进行了 BMM（n=1）。培养的巨噬细胞用于定义三结构域蛋白 8（TRIM8）敲低对 IFN-γ信号的影响。
SJIA 单核细胞的批量 RNA-seq 显示，铁蛋白水平升高的患者存在明显的转录变化。我们发现与多种极化状态有很大的重叠，但几乎没有 IFN 诱导特征的证据。有趣的是，上调最明显的基因之一是 TRIM8，它是 IFN-γ信号的正调节剂。与没有 MAS 的 SJIA 患者的 PBMC 相比，来自 SJIA 合并 MAS 患者的 BMM 的 scRNA-seq 鉴定了具有改变的转录组的 BMM 的不同亚群，包括上调的 IFN-γ反应途径。这些 BMM 也表现出 TRIM8 的表达显著增加。体外敲低巨噬细胞中的 TRIM8 可显著降低 IFN-γ反应性。
MAS 患者骨髓中的“IFN-γ 反应”表型和 TRIM8 过表达的巨噬细胞扩增。TRIM8 在 SJIA 单核细胞中也上调，并在体外增强巨噬细胞对 IFN-γ的反应，为细胞因子风暴（包括 MAS）中单核细胞对 IFNγ的过度反应提供了候选分子机制和潜在的治疗靶点。
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