Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, L. Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland, and National Institute of Geriatrics, Rheumatology, and Rehabilitation, Warsaw, Poland.
Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, and Durham University, School of Biological and Biomedical Sciences, Durham, UK.
Arthritis Rheumatol. 2016 Jun;68(6):1493-504. doi: 10.1002/art.39602.
To investigate whether epigenetic changes can modulate monocytes to produce tissue inhibitor of metalloproteinases 1 (TIMP-1) via Fra-2 (an activator protein 1 [AP-1] family member), a novel downstream mediator that promotes fibrogenesis.
AP-1 transcription factors and TIMP-1 expression were measured in monocytes from systemic sclerosis (SSc) patients and healthy controls. Involvement of Fra-2 in the regulation of TIMP-1 following treatment with Toll-like receptor 8 (TLR-8) agonist was investigated using a luciferase activity assay and chromatin immunoprecipitation (ChIP) analysis. Expression of TIMP-1 and Fra-2 was determined in response to TLR-8 treatment and to different histone modifications, including 3'-deazaneplanocin (DZNep) and apicidin. Fibroblasts from healthy controls were cocultured with DZNep plus TLR-8-treated healthy control monocytes.
Up-regulation of Fra-2 was detected in bleomycin-challenged mice and in skin biopsy samples from SSc patients. Enhanced expression of Fra-2 and TIMP-1 was correlated in SSc monocytes (P = 0.021). The expression of Fra-1 was significantly reduced (P = 0.037) in SSc monocytes. Inhibiting AP-1 activity reduced TIMP-1 production in TLR-8-stimulated monocytes from healthy controls and SSc patients. ChIP experiments revealed binding of Fra-2 to the TIMP-1 promoter. Stimulation with DZNep plus TLR-8 enhanced Fra-2 and TIMP-1 expression in healthy control monocytes, whereas TLR-8 plus apicidin repressed Fra-2 and TIMP-1 expression. Finally, healthy control monocytes treated with DZNep plus TLR-8 induced strong production of α-smooth muscle actin in dermal fibroblasts, which was inhibited by TIMP-1-blocking antibody.
These data demonstrate a novel role of histone demethylation induced by DZNep on Fra-2-mediated TIMP-1 production by monocytes in the presence of TLR-8 agonist. This consequently orchestrates the transdifferentiation of fibroblasts, a key event in the pathogenesis of SSc.
研究表观遗传变化是否可以通过 Fra-2（激活蛋白 1 [AP-1] 家族成员）将单核细胞调节为产生组织金属蛋白酶抑制剂 1（TIMP-1），Fra-2 是一种促进纤维化的新下游介质。
测量系统性硬化症（SSc）患者和健康对照者单核细胞中的 AP-1 转录因子和 TIMP-1 表达。使用荧光素酶活性测定和染色质免疫沉淀（ChIP）分析研究 Toll 样受体 8（TLR-8）激动剂治疗后 Fra-2 对 TIMP-1 调节的作用。检测 TLR-8 处理以及不同组蛋白修饰（包括 3'-去氮胞苷（DZNep）和阿比定）对 TIMP-1 和 Fra-2 的表达。将健康对照者的成纤维细胞与 DZNep 加 TLR-8 处理的健康对照者单核细胞共培养。
在博来霉素处理的小鼠和 SSc 患者的皮肤活检样本中检测到 Fra-2 的上调。SSc 单核细胞中 Fra-2 和 TIMP-1 的表达增强呈正相关（P=0.021）。SSc 单核细胞中 Fra-1 的表达显著降低（P=0.037）。抑制 AP-1 活性可减少 TLR-8 刺激的健康对照者和 SSc 患者单核细胞中 TIMP-1 的产生。ChIP 实验显示 Fra-2 与 TIMP-1 启动子结合。用 DZNep 加 TLR-8 刺激健康对照者单核细胞可增强 Fra-2 和 TIMP-1 的表达，而 TLR-8 加阿比定则抑制 Fra-2 和 TIMP-1 的表达。最后，用 DZNep 加 TLR-8 处理的健康对照者单核细胞可诱导真皮成纤维细胞大量产生α-平滑肌肌动蛋白，该作用可被 TIMP-1 阻断抗体抑制。
这些数据表明，DZNep 诱导的组蛋白去甲基化在 TLR-8 激动剂存在下通过 Fra-2 介导的单核细胞 TIMP-1 产生中发挥新的作用。这继而协调了成纤维细胞的转分化，这是 SSc 发病机制中的一个关键事件。
