Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, Debrecen, Hungary.
Front Immunol. 2020 Sep 11;11:572960. doi: 10.3389/fimmu.2020.572960. eCollection 2020.
To detect replicating viruses, dendritic cells (DCs) utilize cytoplasmic retinoic acid inducible gene-(RIG) I-like receptors (RLRs), which play an essential role in the subsequent activation of antiviral immune responses. In this study, we aimed to explore the role of the mammalian target of rapamycin (mTOR) in the regulation of RLR-triggered effector functions of human monocyte-derived DCs (moDCs) and plasmacytoid DCs (pDCs). Our results show that RLR stimulation increased the phosphorylation of the mTOR complex (mTORC) 1 and mTORC2 downstream targets p70S6 kinase and Akt, respectively, and this process was prevented by the mTORC1 inhibitor rapamycin as well as the dual mTORC1/C2 kinase inhibitor AZD8055 in both DC subtypes. Furthermore, inhibition of mTOR in moDCs impaired the RLR stimulation-triggered glycolytic switch, which was reflected by the inhibition of lactate production and downregulation of key glycolytic genes. Blockade of mTOR diminished the ability of RLR-stimulated moDCs and pDCs to secret type I interferons (IFNs) and pro-inflammatory cytokines, while it did not affect the phenotype of DCs. We also found that mTOR blockade decreased the phosphorylation of Tank-binding kinase 1 (TBK1), which mediates RLR-driven cytokine production. In addition, rapamycin abrogated the ability of both DC subtypes to promote the proliferation and differentiation of IFN-y and Granzyme B producing CD8 + T cells. Interestingly, AZD8055 was much weaker in its ability to decrease the T cell proliferation capacity of DCs and was unable to inhibit the DC-triggered production of IFN-y and Granyzme B by CD8 + T cells. Here we demonstrated for the first time that mTOR positively regulates the RLR-mediated antiviral activity of human DCs. Further, we show that only selective inhibition of mTORC1 but not dual mTORC1/C2 blockade suppresses effectively the T cell stimulatory capacity of DCs that should be considered in the development of new generation mTOR inhibitors and in the improvement of DC-based vaccines.
为了检测复制病毒，树突状细胞（DC）利用细胞质视黄酸诱导基因-I 样受体（RLR），RLR 在随后的抗病毒免疫反应激活中起着至关重要的作用。在这项研究中，我们旨在探讨哺乳动物雷帕霉素靶蛋白（mTOR）在调节人类单核细胞衍生的树突状细胞（moDC）和浆细胞样树突状细胞（pDC）的 RLR 触发效应功能中的作用。我们的结果表明，RLR 刺激分别增加了 mTOR 复合物（mTORC）1 和 mTORC2 下游靶点 p70S6 激酶和 Akt 的磷酸化，这一过程可被 mTORC1 抑制剂雷帕霉素以及 mTORC1/C2 双重激酶抑制剂 AZD8055 在两种 DC 亚型中阻断。此外，在 moDC 中抑制 mTOR 会损害 RLR 刺激引发的糖酵解开关，这反映在抑制乳酸产生和下调关键糖酵解基因上。阻断 mTOR 会降低 RLR 刺激的 moDC 和 pDC 分泌 I 型干扰素（IFN）和促炎细胞因子的能力，而不影响 DC 的表型。我们还发现，mTOR 阻断会降低 Tank-binding kinase 1（TBK1）的磷酸化，TBK1 介导 RLR 驱动的细胞因子产生。此外，雷帕霉素削弱了两种 DC 亚型促进 IFN-y 和 Granzyme B 产生的 CD8+T 细胞增殖和分化的能力。有趣的是，AZD8055 降低 DC 细胞增殖能力的能力要弱得多，并且无法抑制 DC 触发的 CD8+T 细胞产生 IFN-y 和 Granyzme B。在这里，我们首次证明 mTOR 正向调节人类 DC 中的 RLR 介导的抗病毒活性。此外，我们还表明，只有选择性抑制 mTORC1 而不是双重 mTORC1/C2 阻断才能有效地抑制 DC 的 T 细胞刺激能力，这在新一代 mTOR 抑制剂的开发和基于 DC 的疫苗的改进中应加以考虑。
