University of Michigan, Ann Arbor.
Arthritis Rheumatol. 2018 Jan;70(1):98-108. doi: 10.1002/art.40338. Epub 2017 Dec 15.
EZH2 is an epigenetic regulator that mediates H3K27 trimethylation (H3K27me3) and modulates DNA methylation. The aim of this study was to characterize the role of EZH2 in CD4+ T cells in the pathogenesis of systemic lupus erythematosus.
EZH2 expression levels were determined in CD4+ T cells isolated from lupus patients and healthy controls. The epigenetic effects of EZH2 overexpression in CD4+ T cells were evaluated using a genome-wide DNA methylation approach. Gene expression profiles and microRNAs (miRNAs) were assessed by quantitative polymerase chain reaction, while protein expression was examined by Western blotting. A cell adhesion assay was used to assess adhesion of CD4+ T cells to human microvascular endothelial cells.
EZH2 and H3K27me3 levels were increased in CD4+ T cells from lupus patients compared to healthy controls. T cell production of EZH2 was down-regulated in the presence of miR-26a and miR-101, and levels of both miRNAs were reduced in lupus CD4+ T cells. Overexpression of EZH2 induced in CD4+ T cells resulted in significant DNA methylation changes. Genes involved in leukocyte adhesion and migration, including F11R (which encodes junctional adhesion molecule A [JAM-A]), became hypomethylated in CD4+ T cells when EZH2 was overexpressed. Overexpression of EZH2 resulted in increases in JAM-A expression and CD4+ T cell adhesion. Preincubation of EZH2-transfected CD4+ T cells with neutralizing antibodies against JAM-A significantly blunted cell adhesion. Similarly, CD4+ T cells from lupus patients overexpressed JAM-A and adhered significantly more to endothelial cells than to T cells from healthy controls. Blocking JAM-A or EZH2 significantly reduced the capacity of lupus CD4+ T cells to adhere to endothelial cells.
The results of this study identify a novel role of EZH2 in T cell adhesion mediated by epigenetic remodeling and up-regulation of JAM-A. Blockade of EZH2 or JAM-A might have therapeutic potential by acting to reduce T cell adhesion, migration, and extravasation in patients with lupus.
EZH2 是一种表观遗传调节剂，可介导 H3K27 三甲基化（H3K27me3）并调节 DNA 甲基化。本研究旨在探讨 EZH2 在 CD4+T 细胞中在系统性红斑狼疮发病机制中的作用。
测定从狼疮患者和健康对照者分离的 CD4+T 细胞中的 EZH2 表达水平。通过全基因组 DNA 甲基化方法评估 EZH2 过表达对 CD4+T 细胞的表观遗传效应。通过定量聚合酶链反应评估基因表达谱和 microRNAs（miRNAs），通过 Western 印迹法检测蛋白表达。使用细胞黏附实验评估 CD4+T 细胞与人微血管内皮细胞的黏附。
与健康对照者相比，狼疮患者的 CD4+T 细胞中 EZH2 和 H3K27me3 水平升高。在存在 miR-26a 和 miR-101 的情况下，T 细胞中 EZH2 的产生被下调，而狼疮 CD4+T 细胞中的这两种 miRNA 水平均降低。CD4+T 细胞中 EZH2 的过表达导致显著的 DNA 甲基化变化。参与白细胞黏附和迁移的基因，包括 F11R（编码连接黏附分子 A [JAM-A]），在 CD4+T 细胞中 EZH2 过表达时变得低甲基化。EZH2 的过表达导致 JAM-A 表达增加和 CD4+T 细胞黏附增加。用中和抗体预先孵育转染 EZH2 的 CD4+T 细胞可显著减弱细胞黏附。同样，狼疮患者的 CD4+T 细胞过度表达 JAM-A，与健康对照者的 T 细胞相比，其对内皮细胞的黏附明显增加。阻断 JAM-A 或 EZH2 可显著降低狼疮 CD4+T 细胞黏附内皮细胞的能力。
本研究确定了 EZH2 在通过表观遗传重塑和 JAM-A 上调介导的 T 细胞黏附中的新作用。通过减少狼疮患者的 T 细胞黏附、迁移和渗出，阻断 EZH2 或 JAM-A 可能具有治疗潜力。
