MAFB surrogates the glucocorticoid receptor ability to induce tolerogenesis in dendritic cells [CHIP_SEQ]

Glucocorticoids (GCs) exert potent anti-inflammatory effects in immune cells through the glucocorticoid receptor (GR). Dendritic cells (DCs), central actors for coordinating immune responses, acquire tolerogenic properties in response to GCs. Tolerogenic DCs (tolDCs) have emerged as a potential treatment for different inflammatory diseases. To date, the underlying cell type-specific regulatory mechanisms orchestrating GC-mediated acquisition of immunosuppressive properties remain poorly understood. In this study, we investigated the transcriptomic and epigenomic remodeling associated with differentiation to DCs in the presence of GCs. Our analysis demonstrates a major role of MAFB in this process, in synergy with GR. Both GR and MAFB interact with methylcytosine dioxygenase TET2 and bind to genomic loci that undergo specific demethylation in tolDCs. We also show that the role of MAFB is more extensive, binding to thousands of genomic loci in tolDCs. Finally, MAFB knockdown erases the tolerogenic properties of tolDCs and reverts the specific DNA demethylation and gene upregulation. The preeminent role of MAFB is also demonstrated in vivo for myeloid cells from synovium in rheumatoid arthritis following GC treatment. These results support that, once directly activated by GR, MAFB takes over the main roles to orchestrate the epigenomic and transcriptomic remodelling that define the tolerogenic phenotype. Overall design: GR and MAFB ChIP-seq in DCs and tolDCs differentiated from monocytes. Two biological replicates are included.

糖皮质激素（Glucocorticoids, GCs）可通过糖皮质激素受体（glucocorticoid receptor, GR）在免疫细胞中发挥强效抗炎活性。树突状细胞（Dendritic cells, DCs）作为协调免疫应答的核心细胞，可在GCs刺激下获得耐受性表型。耐受性树突状细胞（tolerogenic DCs, tolDCs）已成为多种炎症性疾病的潜在治疗候选方案。目前，调控GCs介导的免疫抑制表型获得的细胞类型特异性分子机制仍不甚明确。本研究针对GCs存在条件下DCs分化过程中的转录组与表观基因组重塑展开探究。分析结果显示，MAFB在此过程中与GR协同发挥关键作用。GR与MAFB均可与甲基胞嘧啶双加氧酶TET2相互作用，并结合tolDCs中发生特异性去甲基化的基因组位点。研究同时证实，MAFB的结合范围更为广泛，可靶向结合tolDCs中数千个基因组位点。进一步实验表明，MAFB敲低可消除tolDCs的耐受性表型，并逆转特异性DNA去甲基化与基因上调现象。在类风湿关节炎患者滑膜来源的髓系细胞中，经GCs处理后的体内实验同样可验证MAFB的核心调控功能。上述结果证实，MAFB在被GR直接激活后，可主导调控定义耐受性表型的表观基因组与转录组重塑过程。本研究的实验整体设计：对由单核细胞分化得到的DCs与tolDCs开展GR与MAFB的染色质免疫共沉淀测序（ChIP-seq），共包含2次生物学重复。