Institute of Immunopharmacology and Immunotherapy, School of Pharmaceutical Sciences, Shandong University, Jinan, China.
PLoS One. 2011;6(12):e27931. doi: 10.1371/journal.pone.0027931. Epub 2011 Dec 8.
RNA interference (RNAi) of virus-specific genes offers the possibility of developing a new anti-hepatitis B virus (anti-HBV) therapy. Recent studies have revealed that siRNAs can induce an innate immune response in vitro and in vivo. Here, HBVx (HBx) mRNA expression and HBV replication were significantly inhibited, followed by the enhancement of expression of type I interferons (IFNs), IFN-stimulated genes (ISG15 and ISG56) and proinflammatory cytokines after HepG2.2.15 cells were transfected with chemically synthesized HBx-siRNAs. Transfection with HBx-siRNAs also significantly increased expression of dsRNA-dependent protein kinase R (PKR) in HepG2.2.15 cells, followed by activation of downstream signaling events such as eukaryotic initiation factor 2α (eIF2-α). In PKR-over-expressing HepG2.2.15 cells, HBx-siRNAs exerted more potent inhibitory effects on HBV replication and greater production of type I IFNs. By contrast, the inhibitory effect of HBx-siRNAs on HBV replication was attenuated when PKR was inhibited or silenced, demonstrating that HBx-siRNAs greatly promoted PKR activation, leading to the higher production of type I IFN. Therefore, we concluded that PKR is involved in the innate immune effects mediated by HBx-siRNAs and further contributes to HBV inhibition. The bifunctional siRNAs with both gene silencing and innate immune activation properties may represent a new potential strategy for treatment of HBV.
RNA 干扰 (RNAi) 特异性病毒基因提供了一种新的抗乙型肝炎病毒 (抗-HBV) 治疗的可能性。最近的研究表明，siRNA 可以在体外和体内诱导先天免疫反应。在这里，HBVx (HBx) mRNA 表达和 HBV 复制明显受到抑制，随后 HepG2.2.15 细胞转染化学合成的 HBx-siRNA 后，I 型干扰素 (IFN)、IFN 刺激基因 (ISG15 和 ISG56) 和促炎细胞因子的表达增强。HBx-siRNA 转染还显著增加了 HepG2.2.15 细胞中双链 RNA 依赖性蛋白激酶 R (PKR) 的表达，随后激活了下游信号事件，如真核起始因子 2α (eIF2-α)。在 PKR 过表达的 HepG2.2.15 细胞中，HBx-siRNA 对 HBV 复制的抑制作用更强，I 型 IFN 的产生也更多。相比之下，当 PKR 被抑制或沉默时，HBx-siRNA 对 HBV 复制的抑制作用减弱，表明 HBx-siRNA 大大促进了 PKR 的激活，导致 I 型 IFN 的产生增加。因此，我们得出结论，PKR 参与了 HBx-siRNA 介导的先天免疫效应，并进一步有助于 HBV 的抑制。具有基因沉默和先天免疫激活特性的双功能 siRNA 可能代表了治疗 HBV 的一种新的潜在策略。
