Increased Production of Interleukin-8 in Primary Human Monocytes and in Human Epithelial and Endothelial Cell Lines after Dengue Virus Challenge

Abstract

The more severe form of dengue virus infection, dengue hemorrhagic fever, is characterized by plasma leakage and derangements in hemostasis. As elevated interleukin-8 (IL-8) levels have been observed in sera from patients with more severe disease manifestations, a study was initiated to look at the effect of dengue virus infection in vitro on proinflammatory cytokine secretion and expression. A significant increase in IL-8 levels in the culture supernatant of primary human monocytes infected with dengue 2 virus (D2V) New Guinea C (NGC) was found by enzyme-linked immunosorbent assay. Additionally, by reverse transcriptase PCR, the mRNA was also augmented. Among the proinflammatory cytokines and their mRNAs measured (IL-6, IL-1␤, IL-8, and tumor necrosis factor alpha), IL-8 showed the greatest change following D2V infection. Similarly, two cell lines, 293T (a human epithelial cell line) and ECV304 (an endothelial cell line), were permissive to D2V NGC and responded to the infection by increasing the synthesis of IL-8. Nuclear factor kappa B (NF-B) and nuclear factor IL-6 (NFIL-6) are primary mediators of IL-8 expression. We studied the transcriptional regulation of IL-8 in the ECV304 and 293T cell lines and found that the induction of IL-8 gene expression involved the activation of NF-B (P ‫؍‬ 0.001) and, to a lesser extent, the activation of NFIL-6 in ECV304 cells only. We next observed by the chromatin immunoprecipitation procedure in vivo acetylation of core histones bound to the IL-8 promoter after D2V infection. IL-8 produced by infected monocytes and also IL-8 that may be produced by endothelial or other epithelial cells is associated with the hyperacetylation of histones bound to the IL-8 promoter in addition to the activation of transcription by NF-B. We hypothesize that the overall increase in IL-8 synthesis observed in this in vitro study may play a role in the pathogenesis of the plasma leakage seen in dengue hemorrhagic fever and dengue shock syndrome.

Peripheral blood mononuclear cells increase the permeability of dengue virus-infected endothelial cells in association with downregulation of vascular endothelial cadherin

“…Dengue viruses can replicate in monocyte-derived macrophages and monocyte-like cell lines (Kurane et al, 1990;O'Sullivan & Killen, 1994) and induce cytokines (Bosch et al, 2002;Espina et al, 2003) and cytotoxic factors (Mukerjee et al, 1995;Shaio et al, 1995). Culture fluids from dengue virus-infected peripheral blood monocytes activated endothelial cells, as measured by upregulation of cell adhesion molecules (Anderson et al, 1997), and increased the permeability of endothelial cells in vitro (Carr et al, 2003).…”

“…Endothelial cells can be infected with dengue virus in vitro (Bunyaratvej et al, 1997;Huang et al, 2003;Killen & O'Sullivan, 1993). Dengue virus infection induces cytokine production (Avirutnan et al, 1998;Bosch et al, 2002) and alters the expression of adhesion molecules on endothelial cells (Krishnamurti et al, 2002). Although endothelial cells are not massively infected, there is evidence of dengue virus infection of endothelial cells in vivo (Gubler & Zaki, 1998;Hall et al, 1991;Jessie et al, 2004).…”

IL8 release, tight junction and cytoskeleton dynamic reorganization conducive to permeability increase are induced by dengue virus infection of microvascular endothelial monolayers

“…In these in vitro models it has been shown that the viral E protein binds to the endothelial cell surface in the absence of Fc receptors (Chen et al, 1996) and that infected cells produce high levels of IL8 as well as IL6 (Bosch et al, 2002;Huang et al, 2000). E protein also binds to other cell lines such as Vero, Chinese hamster ovary and glia (Chen et al, 1996).…”

“…Virus entry is suspected as viral RNA has been detected in brain microvascular endothelial cells from a fatal case of DHF (Ramos et al, 1998). Interleukin (IL) 8 and other cytokines have been proposed as inducers of alterations in endothelial function, because elevated levels of cytokines have been found in serum and pleural fluid of patients with DHF and in dengue virus-infected human primary monocytes (Raghupathy et al, 1998;Bosch et al, 2002).…”

“…Analysis of dengue virus-endothelium interaction has been approached using human endothelial cells from primary cultures of umbilical cord (HUVEC) or cell lines derived from it (Andrews et al, 1978;Chen et al, 1996;Bosch et al, 2002). In these in vitro models it has been shown that the viral E protein binds to the endothelial cell surface in the absence of Fc receptors (Chen et al, 1996) and that infected cells produce high levels of IL8 as well as IL6 (Bosch et al, 2002;Huang et al, 2000).…”