Phenotypic alteration by dengue virus serotype 2 delays neutrophil apoptosis and stimulates the release of prosurvival secretome with immunomodulatory functions

Abstract

Neutrophils are the most abundant granuloytes, are phenotypically heterogeneous, and exert detrimental or protective roles during antiviral response. Dengue virus has been reported to activate neutrophils. However, the effect of the dengue virus on the neutrophil phenotypes, survival, and release of inflammatory secretome is yet to be understood. Herein, we investigated the effect of dengue virus serotype 2 (DV-2) on effector functions of naïve neutrophils and studied the impact of its secretome on different immune cells. We found that DV-2 activates purified human neutrophils and causes a significant shift toward the CD16bright/CD62Ldim subtype in a multiplicity of infection and time-dependent manner. These phenotypically altered neutrophils show delayed apoptosis through nuclear factor κB and PI3K pathways and have decreased phagocytic capacity. Treatment of neutrophils with myeloperoxidase and PAD4 inhibitor before DV-2 incubation significantly reduced DV-2-induced double-stranded DNA release, suggesting that myeloperoxidase and PAD4 were involved at early stages for the neutrophil activation and double-stranded DNA release. We also report that DV-2-stimulated neutrophil secretome had a significant effect on viral infection, platelet activation, and naïve neutrophil survival via binding of tumor necrosis factor α to tumor necrosis factor receptor 1/2 receptors. Furthermore, incubation of endothelial cells with the DV-2-stimulated neutrophil secretome potentially inhibits proliferation and wound healing capacity and induces endothelial cell death, which can contribute to endothelial barrier dysfunction. In conclusion, the neutrophil-DV-2 interaction modulates the phenotype of neutrophils and the release of prosurvival and antiviral secretome that may act as a double-edged sword during dengue pathogenesis.

Keywords: NETosis; apoptosis; dengue virus; endothelial dysfunction; neutrophil phenotypes; platelet activation.