Viral kinetics are associated with changes in cytokines and chemokines in serum and target organs of SSM-CVB3-infected macaques

Dabie bandavirus infection induces macrophagic pyroptosis and this process is attenuated by platelets

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne infection with a high mortality rate in humans, which is caused by Dabie bandavirus (DBV), formerly known as SFTS virus. Clinical manifestations of SFTS are characterized by high fever, thrombocytopenia, leukopenia, hemorrhage, gastrointestinal symptoms, myalgia and local lymph node enlargement with up to 30% case fatality rates in human. Macrophage depletion in secondary lymphoid organs have important roles in the pathogenic process of fatal SFTS, but its exact cell death mechanism remains largely unknown. Here, we showed for the first time that DBV infection induced macrophagic pyroptosis, as evidenced by swollen cells, pore-forming structures, accumulation of gasdermin D N-terminal (GSDMD-NT) as well as the release of lactate dehydrogenase (LDH) and IL-1β in human macrophages. In addition to the upregulation of pyronecrosis genes, the expressions of pyroptosis-related proteins (GSDMD, caspase-1 and IL-1β) were also elevated. To be noted, platelets were found to play a protective role in DBV-derived pyroptosis. Transcriptome analysis and in vitro studies demonstrated that platelets significantly reduced the gene expressions and protein production of pro-pyroptotic markers and inflammatory cytokines in macrophages, whereas platelets conferred a propagation advantage for DBV. Collectively, this study demonstrates a novel mechanism by which DBV invasion triggers pyroptosis as a host defense to remove replication niches in human macrophages and platelets provide an additional layer to reduce cellular death. These findings may have important implications to the pathogenesis of lethal DBV, and provide new ideas for developing novel therapeutics to combat its infection.

Berberine impairs coxsackievirus B3-induced myocarditis through the inhibition of virus replication and host pro-inflammatory response

Berberine (BBR), an isoquinoline alkaloid isolated from Rhizoma coptidis, is reported to possess antiviral activity. Our previous study has shown that BBR alleviates coxsackievirus B3 (CVB3) replication in HeLa cells. However, the anti-CVB3 activity of BBR is still unclear in vivo. In this study, we explored the effect of BBR on CVB3-induced viral myocarditis in mice. These results demonstrated the beneficial effect of BBR on alleviating CVB3-induced myocarditis in vivo, which sheds new light on the utility of BBR as a therapeutic strategy against CVB3-induced viral myocarditis.

Beta interferon regulation of glucose metabolism is PI3K/Akt dependent and important for antiviral activity against coxsackievirus B3

An effective type I interferon (IFN)-mediated immune response requires the rapid expression of antiviral proteins that are necessary to inhibit viral replication and virus spread. We provide evidence that IFN-β regulates metabolic events important for the induction of a rapid antiviral response: IFN-β decreases the phosphorylation of AMP-activated protein kinase (AMPK), coincident with an increase in intracellular ATP. Our studies reveal a biphasic IFN-β-inducible uptake of glucose by cells, mediated by phosphatidylinositol 3-kinase (PI3K)/Akt, and IFN-β-inducible regulation of GLUT4 translocation to the cell surface. Additionally, we provide evidence that IFN-β-regulated glycolytic metabolism is important for the acute induction of an antiviral response during infection with coxsackievirus B3 (CVB3). Last, we demonstrate that the antidiabetic drug metformin enhances the antiviral potency of IFN-β against CVB3 both in vitro and in vivo. Taken together, these findings highlight an important role for IFN-β in modulating glucose metabolism during a virus infection and suggest that the use of metformin in combination with IFN-β during acute virus infection may result in enhanced antiviral responses.

IMPORTANCE

Type I interferons (IFN) are critical effectors of an antiviral response. These studies describe for the first time a role for IFN-β in regulating metabolism--glucose uptake and ATP production--to meet the energy requirements of a robust cellular antiviral response. Our data suggest that IFN-β regulates glucose metabolism mediated by signaling effectors similarly to activation by insulin. Interference with IFN-β-inducible glucose metabolism diminishes the antiviral response, whereas treatment with metformin, a drug that increases insulin sensitivity, enhances the antiviral potency of IFN-β.

Inhibition of IL-2 inducible T-cell kinase alleviates T-cell activation and murine myocardial inflammation associated with CVB3 infection

BACKGROUND

Coxsackievirus B3 (CVB3) infection causes myocarditis, pancreatitis, and aseptic meningitis. Targeting antigen-specific T cell reactions might be a promising way to alleviate the inflammatory response induced by CVB3 infection. IL-2-inducible T-cell kinase (ITK), a member of Tec kinase family expressed mainly in T cells, plays an important role in the activation of T cells. The role of ITK in viral myocarditis induced by CVB3 has not been documented.

METHODOLOGY

In this study, we inhibited the ITK expression in Jurkat cells, primary human peripheral blood mononuclear cells (PBMC), and mouse splenocytes by ITK-specific siRNA. The inhibition efficiently suppressed cell proliferation (P<0.05) and T-cell related cytokine secretion (P<0.05). In order to inhibit ITK in vivo, the pGCSIL plasmid containing short hairpin RNAs targeting ITK was constructed and transduced into mice infected with CVB3. ITK-inhibited mice showed reduced cell proliferation (3, 5, and 7 days post-challenge, P<0.05) as well as CD4+ and CD8+ T cells (5 days post-challenge, P<0.05). The altered production of inflammatory cytokines alleviated pathologic heart damage and improved mice survival rate (P<0.05).

CONCLUSION

ITK played an important role in the T cell development and represented a new target for the modulation of T-cell-mediated inflammatory response by CVB3 infection.