TNF and infection: In particular, infection of human endothelial cells with DENV resulted in transcriptional up-regulation and secretion of various cytokines, including interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF)-α [24]–[28], which are also highly upregulated in the sera of patients with DHF and may contribute to increased endothelial cell permeability [27], [29].