Molecular Mechanism Of Interleukin-27Expression And Epigenetic Modification Induced By Influenza A Virus

Detection of cytokine production and the function during the influenza A virus infection, especially the cytokines expression levels in the patients serum are emphasized in the research of host immune response to influenza virus infection. Protein microarray technology provides a high-throughput platform for efficient profiling of protein expression. We investigated the expression levels of507immune-related proteins in the serum of patients infected by influenza A virus H3N2using an antibody array and validated these findings by infecting peripheral blood mononuclear cells (PBMCs) with A/HongKong/498/97(H3N2) in vitro. Then we used selective inhibitor of proinflammatory factor cyclooxygenase-2(COX-2) NS-398to identify those immunomodulatory proteins regulated by the proinflammatory factor. In patients serum, the expression level of138proteins changed greater than two-fold in response to viral infection, including102that were upregulated and36that were downregulated.106proteins were confirmed in PBMCs infected by H3N2. Of the106proteins involved in the immune response to influenza virus infection,48were regulated by COX-2. Our findings identify the host cytokines whose expression levels change in response to influenza virus infection and those involved in the proinflammatory factor COX-2-mediated inflammatory cascade.Protein antibody array results indicate that IL-27, which belongs to the IL-12family of cytokines, is elevated in the serum of patients infected with influenza A virus (IAV). Here, we show that the expression of IL-27was significantly upregulated in A549human lung epithelial cells and human PBMCs infected with IAV. Additionally, IAV triggered IL-27expression through protein kinase A (PKA) and CREB signaling, which was mediated by cyclooxygenase-2-derived prostaglandin E2(PGE2). IL-27inhibited IAV replication by STAT1and STAT2phosphorylation and activated anti-viral factor protein kinase R (PKR) expression and phosphorylation. Clinical analysis showed that IL-27levels were significantly elevated in a cohort of patients infected with IAV compared to healthy individuals and that circulating IL-27levels were tightly and positively correlated with PEG2levels. These results indicate that IL-27expression is one host immune factor produced in response to IAV infection and that elevated IL-27levels inhibit viral replication.We previously reported that epigenetic modification was involved in influenza A virus (IAV) inducing interleukin-32(IL-32) expression. During the IAV infection, DNA methyltransferase3B (DNMT3B) expression was downregulated. But the mechanism is unknown. In this study, we show that downregulation of DNMT3B depends on DNMT3B’s interaction with non-structural protein1(NS1) of IAV. Interaction between NS1and DNMT3B changes the localization of DNMT3B from nucleus to cytosol and inhibits DNMT3B activities or expression. Additionally, the localization change of DNMT3B depends on the nuclear export signals (NES) of NS1. Compared with the wild type IAV, virus with NS1NES mutation barely leads induction of DNMT3B translocation, decrease of DNMT3B activities and proinflammatory cytokines expression. These results indicate that the interaction between DNMT3B and NS1protein of IAV, which leads DNMT3B translocation and decrease of DNMT3B activities, is a host immune response to IAV infection.