Dengue Virus Infection Induced NF-kB-dependent Macrophage Migration Inhibitory Factor Production
ABSTRACT Dengue virus (DV) infection can cause mild dengue fever or severe dengue hemorrhage fever and dengue shock syndrome. Macrophage migration inhibitory factor (MIF) is a cytokine that plays an important role in the modulation of inflammatory and immune responses and serum levels of MIF are correlated with disease severity in dengue patients. However, the mechanism that induces MIFproduction during DV infection is unclear. In this study, we showed that DV infection, but not UVinactivated DV stimulation, dose-and time-dependently induced MIF secretion in human A649 epithelial cells. MIF promoter assays and RT-PCR demonstrated that MIF gene transcription was activated during DV infection. Furthermore, DV infection induced NF-κB activation, and the NF-κB inhibitors dexamethasone and curcumin inhibited DV-induced MIF production. Finally, we found that different cells have different abilities to release MIF after DV infection. Interestingly, DV infection andMIF production in the human monocytic cell line THP-1 and peripheral blood mononuclear cells increased in the presence of antibodies against DV. Taken together, these results suggest that DV infection of human cells induces NF-κB activation and MIF production, which can be increased in the presence of pre-existing antibodies.
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ABSTRACT: In this study dengue virus (DV) was found to infect primary endothelial cells derived from human umbilical cord veins (HUVEC) and alter their cytokine production. Dengue virus infection of HUVEC was confirmed by an increase in plaque-forming units in the culture supernatant and by immunofluorescence assay. HUVEC produced large amounts of interleukin (IL)-6 and IL-8 but not IL-1beta after DV infection. Both the replication of DV and the production of IL-6 and IL-8 by HUVEC after DV infection were inhibited by ribavirin, an antiviral synthetic guanosine analogue. Additionally, increased serum levels of IL-6 and IL-8 were observed in patients with dengue hemorrhagic fever but not dengue fever. Therefore, our results suggest that endothelial cells can be a target for DV infection, and that DV-induced IL-6 and IL-8 production by endothelial cells may contribute to the pathogenesis of dengue hemorrhagic fever.The American journal of tropical medicine and hygiene 63(1-2):71-5. · 2.53 Impact Factor
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ABSTRACT: Glucocorticoid hormones are important for vital functions and act to modulate inflammatory and immune responses. Yet, in contrast to other hormonal systems, no endogenous mediators have been identified that can directly counter-regulate their potent anti-inflammatory and immunosuppressive properties. Recent investigations of the protein macrophage migration inhibitory factor (MIF), which was discovered originally to be a T-lymphocyte-derived factor, have established it to be a pro-inflammatory pituitary and macrophage cytokine and a critical mediator of septic shock. Here we report the unexpected finding that low concentrations of glucocorticoids induce rather than inhibit MIF production from macrophages. MIF then acts to override glucocorticoid-mediated inhibition of cytokine secretion by lipopolysaccharide (LPS)-stimulated monocytes and to overcome glucocorticoid protection against lethal endotoxaemia. These observations identify a unique counter-regulatory system that functions to control inflammatory and immune responses.Nature 10/1995; 377(6544):68-71. · 38.60 Impact Factor
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ABSTRACT: In this study, we found that infection with flaviviruses, such as Japanese encephalitis virus (JEV) and dengue virus serotype 2 (DEN-2), leads to interferon-beta (IFN-beta) gene expression in a virus-replication- and de novo protein-synthesis-dependent manner. NF-kappaB activation is essential for IFN-beta induction in JEV- and DEN-2-infected cells. However, these two viruses seem to preferentially target different members of the interferon regulatory factor (IRF) family. The activation of constitutively expressed IRF-3, characterized by slower gel mobility, dimer formation, and nuclear translocation, is more evident in JEV-infected cells. Other members of the IRF family, such as IRF-1 and IRF-7 are also induced by DEN-2, but not by JEV infection. The upstream molecules responsible for IRF-3 and NF-kappaB activation were further studied. Evidently, a cellular RNA helicase, retinoic acid-inducible gene I (RIG-I), and a cellular kinase, phosphatidylinositol-3 kinase (PI3K), are required for flavivirus-induced IRF-3 and NF-kappaB activation, respectively. Therefore, we suggest that JEV and DEN-2 initiate the host innate immune response through a molecular mechanism involving RIG-I/IRF-3 and PI3K/NF-kappaB signaling pathways.Microbes and Infection 02/2006; 8(1):157-71. · 2.92 Impact Factor