Enhancement by Tumor Necrosis Factor Alpha of Dengue Virus-Induced Endothelial Cell Production of Reactive Nitrogen and Oxygen Species Is Key to Hemorrhage Development

Abstract

Hemorrhage is a severe manifestation of dengue disease. Virus strain and host immune response have been implicated as the risk factors for hemorrhage development. To delineate the complex interplay between the virus and the host, we established a dengue hemorrhage model in immune-competent mice. Mice inoculated intradermally with dengue virus develop hemorrhage within 3 days. In the present study, we showed by the presence of NS1 antigen and viral nuclei acid that dengue virus actively infects the endothelium at 12 h and 24 h after inoculation. Temporal studies showed that beginning at day 2, there was macrophage infiltration into the vicinity of the endothelium, increased tumor necrosis factor alpha (TNF-␣) production, and endothelial cell apoptosis in the tissues. In the meantime, endothelial cells in the hemorrhage tissues expressed inducible nitric oxide synthase (iNOS) and nitrotyrosine. In vitro studies showed that primary mouse and human endothelial cells were productively infected by dengue virus. Infection by dengue virus induced endothelial cell production of reactive nitrogen and oxygen species and apoptotic cell death, which was greatly enhanced by TNF-␣. N G -Nitro-L-arginine methyl ester and N-acetyl cysteine reversed the effects of dengue virus and TNF-␣ on endothelial cells. Importantly, hemorrhage development and the severity of hemorrhage were greatly reduced in mice lacking iNOS or p47 phox or treatment with oxidase inhibitor, pointing to the critical roles of reactive nitrogen and oxygen species in dengue hemorrhage.

Type I Interferon Signals in Macrophages and Dendritic Cells Control Dengue Virus Infection: Implications for a New Mouse Model To Test Dengue Vaccines

“…Interestingly, sustained IFN-␥ levels have been suggested to play a protective role in a human challenge model for dengue virus infection (42). On the other hand, the IFNAR Ϫ/Ϫ mice, which would all have gone on to die from their infection, had significantly more TNF-␣ in their sera than CD11c-Cre ϩ/Ϫ IFNAR fl/fl mice, confirming previous findings that higher levels of TNF-␣ are associated with disease severity (41,43). We also measured serum levels of the murine IL-8 homologue CXCL1/KC, IFN-␣, and IP-10.…”

“…Surprisingly, the viral titers in blood and organs were also generally similar in groups of mice that would have been significantly more likely to recover from infection ( mice. In humans, the factors determining dengue disease severity are undefined, but cytokines are presumed to be important (38)(39)(40)(41), and many studies have described increases in inflammatory and regulatory cytokines during DENV infection (33). We therefore asked whether there was any correlation between the levels of specific cytokines in sera at day 3 p.i.…”

Dengue Virus Infection of Mast Cells Triggers Endothelial Cell Activation

“…Additionally, coculture of peripheral blood mononuclear cells promotes changes in dengue virusinfected HUVECs, including decreased vascular endothelial cadherin expression and increased permeability (14). Finally, TNF has been shown to enhance dengue-induced NO and reactive oxygen species effects on endothelial cell damage and hemorrhage in a mouse model of dengue virus infection (50). The results of the present study add mast cells and mast cellderived TNF to the select group of cell mediators of dengueinduced endothelial cell perturbation.…”

Clinical Features of and Risk Factors for Rhabdomyolysis Among Adult Patients with Dengue Virus Infection

“…TNF-α is a proinflammatory cytokine involved in systemic inflammation, and it is associated with increased disease severity. 42 Additionally, IL-6 has both proand anti-inflammatory effects and contributes to the regulation of TNF-α levels. 43 Also, IL-6 is released by the skeletal muscle fibers in response to muscle contraction or muscle injury.…”