- Authors: Zhang N. et al.
- Year: 2022
- Journal: Front Immunol 13 838990
- Applications: in vitro / mRNA / jetMESSENGER
- Cell type: C8-D1A [Astrocyte type I clone]
Therefore, we hypothesized that JEV RNA activates the transcription of ZBP1 and IRF7. Therefore, positive- and negative-strand JEV 3′-UTR fused partial NS5 C-terminal sequences were transcribed with a T7 transcription kit in vitro and transfected into C8-D1A cells. Meanwhile, mock-transfected and A-RNA (49)-transfected cells were used as controls. Real-time PCR detection found that compared with the control groups, 3′-UTR-transfected cells dramatically upregulated the expression of ZBP1 and IRF7 (Figure 4D). Western blotting also confirmed that positive 3′-UTR transfection significantly increased levels of the IRF7 protein (Figure 4E). JetMessenger, an RNA transfection reagent, was purchased from Polyplus (Illkirch, FRANCE).
Japanese encephalitis virus (JEV) is one of the most important members of the flavivirus family. It is a typical zoonotic pathogen that has caused substantial social and economic losses worldwide. The relation between JEV-induced immunosuppression and inflammatory responses has not been thoroughly investigated. In this study, cells infiltrating the brain tissue of JEV-infected mice were mainly identified as monocytic myeloid-derived suppressor cells (M-MDSCs), which subsequently differentiated into CD3+ macrophages. Co-culture with T cells showed that both splenic M-MDSCs and brain infiltrated M-MDSCs isolated from JEV-infected mice inhibited T cell proliferation through ARG1 and iNOS. The splenectomy model revealed that JEV-induced M-MDSCs were mainly derived from bone marrow and migrated to the spleen and central nervous system (CNS). The results of the transcriptome analysis and IRF7-deficient mice indicated that the ZBP1-IRF7 signaling pathway stimulated by JEV RNA played a central role in the induction of M-MDSCs. M-MDSCs migrated into the CNS through the chemokine CCL2/N-CCL2 derived from astrocytes and brain infiltrated M-MDSCs differentiated into CD3+ macrophages through a mechanism mediated by M-CSF, IL-6 and IFN-γ in the brain microenvironment. These findings provide evidence for the mechanism that JEV regulates the differentiation of M-MDSCs and thereby exacerbates pathogenicity, which represents a potential therapeutic target for Japanese encephalitis (JE).