Tumor necrosis factor (TNF) is essential for the host defense against tuberculosis (TB). However, scarcity or excessive TNF production in macrophages can also increase susceptibility to TB. The precise mechanisms underlying how Mycobacterium tuberculosis (Mtb) induces TNF over-expression are unclear. Here, we show that Mtb infection significantly increases 5-hydroxylmethylocytosine (5hmC) levels in the TNF promoter. Luciferase reporter assays identify the precise methylated CpG sites that are essential to regulating TNF promoter activity. Infection simultaneously promotes the expression of the TET2 demethylase in macrophages. After inhibiting NF-κB or knocking down TET2, we found that TNF promoter demethylation levels is increased while Mtb-induced TNF expression decrease. Here, NF-κB binds to TET2 and mediates its recruitment to the TNF promoter to induce TNF demethylation. Finally, we show that TLR2 activation during Mtb infection promotes NF-κB translocation into the nucleus which is important for NF-κB-mediated TET2-dependent TNF promoter demethylation thus helps drive Mtb-induced TNF expression. Targeting this axis might be a novel strategy for host-directed therapy against TB.

肿瘤坏死因子 (TNF) 对于宿主防御结核病 (TB) 至关重要。然而，巨噬细胞中 TNF 的缺乏或过量也会增加对结核病的易感性。结核分枝杆菌 (Mtb)诱导TNF过度表达的确切机制尚不清楚。在这里，我们发现Mtb感染显着增加TNF启动子中的 5-羟甲基胞嘧啶 (5hmC) 水平。荧光素酶报告基因检测可准确识别对于调节TNF启动子活性至关重要的甲基化 CpG 位点。感染同时促进巨噬细胞中 TET2 去甲基酶的表达。抑制 NF-κB 或敲除 TET2 后，我们发现TNF启动子去甲基化水平增加，而Mtb诱导的TNF表达减少。此处，NF-κB 与 TET2 结合并介导其募集至TNF启动子以诱导TNF去甲基化。最后，我们发现Mtb感染期间 TLR2 的激活促进 NF-κB 易位到细胞核中，这对于 NF-κB 介导的 TET2 依赖性TNF启动子去甲基化非常重要，从而有助于驱动Mtb诱导的TNF表达。针对该轴可能是针对宿主的结核病治疗的一种新策略。