Interleukin (IL)-1β produced by macrophages plays an important role in inflammation development. However, the underlying mechanism in epigenetic regulation of IL-1β production is not fully addressed. Though DNA methylcytosine dioxygenase ten-eleven translocation 2 (TET2) is known to be involved in the regulation of inflammatory factors by oxidizing 5-methylcytosine (5mC), the underlying molecular mechanism is largely unknown. In this study, we found that the expression of both IL-1β and TET2 is upregulated by lipopolysaccharide (LPS)-stimulated mononuclear macrophage. We then knocked down TET2 in mouse macrophagelike cell line (J774.1) and found that LPS-induced IL-1β is also downregulated. In addition, LPS-stimulated phosphorylation of the mitogen-activated protein kinase (MAPK) signaling pathway and intracellular effectors of the toll-like receptor 4 (TLR4) signaling pathway were also suppressed in TET2-knockdown cells. The methylation status in the promoter regions of myeloid differentiation primary response gene (MyD)88 and TAK1 binding protein 2 (TAB2) were estimated by bisulfite polymerase chain reaction. Compared with that of the control, the 5mC level on the TAB2 promoter is downregulated in the LPS-stimulated cells which can be reversed by TET2-knockdown. These findings altogether suggest that LPS-upregulated TET2 enhances IL-1β expression through demethylating the promoter region of TAB2, the key member of the TLR4/MAPK signaling pathway, a previously unreported molecular mechanism in TET2-regulated expression of inflammatory factors.

巨噬细胞产生的白细胞介素 (IL)-1β 在炎症发展中起重要作用。然而，IL-1β 产生的表观遗传调控的潜在机制尚未完全解决。尽管已知 DNA 甲基胞嘧啶双加氧酶 10-11 易位 2 (TET2) 通过氧化 5-甲基胞嘧啶 (5mC) 参与炎症因子的调节，但其潜在的分子机制在很大程度上是未知的。在这项研究中，我们发现 IL-1β 和 TET2 的表达都被脂多糖 (LPS) 刺激的单核巨噬细胞上调。然后我们敲低了小鼠巨噬细胞样细胞系 (J774.1) 中的 TET2，发现 LPS 诱导的 IL-1β 也被下调。此外，LPS 刺激的丝裂原活化蛋白激酶 (MAPK) 信号通路和 toll 样受体 4 (TLR4) 信号通路的细胞内效应物的磷酸化也在 TET2 敲低细胞中受到抑制。通过亚硫酸氢盐聚合酶链反应估计骨髓分化初级反应基因 (MyD)88 和 TAK1 结合蛋白 2 (TAB2) 启动子区域的甲基化状态。与对照相比，在 LPS 刺激的细胞中，TAB2 启动子上的 5mC 水平被下调，这可以通过 TET2 敲低来逆转。这些发现共同表明，LPS 上调的 TET2 通过去甲基化 TAB2 的启动子区域来增强 IL-1β 表达，TAB2 是 TLR4/MAPK 信号通路的关键成员，这是之前未报道的 TET2 调节炎症因子表达的分子机制。