Department of Pathology, Case Western Reserve University, University Hospitals Case Medical Center, Cleveland, OH 44106, USA.
J Immunol. 2010 Apr 1;184(7):3367-76. doi: 10.4049/jimmunol.0903079. Epub 2010 Feb 24.
CpG oligodeoxynucleotides (ODNs) signal through TLR9 to induce type I IFN (IFN-alphabeta) in dendritic cells (DCs). CpG-A ODNs are more efficacious than CpG-B ODNs for induction of IFN-alphabeta. Because IFN-alphabeta may contribute to autoimmunity, it is important to identify mechanisms to inhibit induction of IFN-alphabeta. In our studies, CpG-B ODN inhibited induction of IFN-alphabeta by CpG-A ODN, whereas induction of TNF-alpha and IL-12p40 by CpG-A ODN was not affected. CpG-B inhibition of IFN-alphabeta was observed in FLT3 ligand-induced murine DCs, purified murine myeloid DCs, plasmacytoid DCs, and human PBMCs. CpG-B ODN inhibited induction of IFN-alphabeta by agonists of multiple receptors, including MyD88-dependent TLRs (CpG-A ODN signaling via TLR9, or R837 or Sendai virus signaling via TLR7) and MyD88-independent receptors (polyinosinic:polycytidylic acid signaling via TLR3 or ds break-DNA signaling via a cytosolic pathway). CpG-B ODN did not inhibit the IFN-alphabeta positive feedback loop second-wave IFN-alphabeta, because IFN-alphabeta-induced expression of IFN-alphabeta was unaffected, and CpG-B inhibition of IFN-alphabeta was manifested in IFN-alphabetaR(-/-) DCs, which lack the positive feedback mechanism. Rather, CpG-B ODN inhibited early TLR-induced first wave IFN-alpha4 and IFN-beta. Chromatin immunoprecipitation revealed that association of IFN regulatory factor 1 with the IFN-alpha4 and IFN-beta promoters was induced by CpG-A ODN but not CpG-B ODN. Moreover, CpG-A-induced association of IFN regulatory factor 1 with these promoters was inhibited by CpG-B ODN. Our studies demonstrate a novel mechanism of transcriptional regulation of first-wave IFN-alphabeta that selectively inhibits induction of IFN-alphabeta downstream of multiple receptors and may provide targets for future therapeutic inhibition of IFN-alphabeta expression in vivo.
CpG 寡脱氧核苷酸 (ODN) 通过 TLR9 信号转导诱导树突状细胞 (DC) 产生 I 型 IFN (IFN-αβ)。CpG-A ODN 比 CpG-B ODN 更有效地诱导 IFN-αβ。由于 IFN-αβ 可能有助于自身免疫，因此确定抑制 IFN-αβ 诱导的机制非常重要。在我们的研究中，CpG-B ODN 抑制了 CpG-A ODN 诱导的 IFN-αβ，而 CpG-A ODN 诱导的 TNF-α 和 IL-12p40 不受影响。在 FLT3 配体诱导的鼠源性 DC、纯化的鼠源髓样 DC、浆细胞样 DC 和人 PBMC 中均观察到 CpG-B 对 IFN-αβ 的抑制作用。CpG-B ODN 抑制了多种受体激动剂诱导的 IFN-αβ，包括 MyD88 依赖性 TLRs（CpG-A ODN 通过 TLR9 信号转导、R837 或 Sendai 病毒通过 TLR7 信号转导）和 MyD88 非依赖性受体（多聚肌苷酸：多聚胞苷酸通过 TLR3 信号转导或 ds 断裂-DNA 通过细胞质途径信号转导）。CpG-B ODN 不抑制 IFN-αβ 的正反馈环第二波 IFN-αβ，因为 IFN-αβ 诱导的 IFN-αβ 表达不受影响，并且 CpG-B 对 IFN-αβ 的抑制作用在缺乏正反馈机制的 IFN-αβR(-/-)DC 中表现出来。相反，CpG-B ODN 抑制 TLR 诱导的早期第一波 IFN-α4 和 IFN-β。染色质免疫沉淀显示，IFN 调节因子 1 与 IFN-α4 和 IFN-β 启动子的结合是由 CpG-A ODN 诱导的，但不是 CpG-B ODN。此外，CpG-B ODN 抑制了 CpG-A 诱导的 IFN 调节因子 1 与这些启动子的结合。我们的研究表明，这是一种新的转录调节机制，选择性地抑制了多种受体下游 IFN-αβ 的诱导，这可能为未来体内抑制 IFN-αβ 表达提供治疗靶点。
