Profile of time-dependent VEGF upregulation in human pulmonary endothelial cells, HPMEC-ST1.6R infected with DENV-1, -2, -3, and -4 viruses

Abstract

In this study, the upregulated expression level of vascular endothelial growth factor (VEGF) in a pulmonary endothelial cell line (HPMEC-ST1.6R) infected with dengue virus serotypes 1, 2, 3, and 4 (DENV-1, -2, -3 and -4), was investigated. This cell line exhibits the major constitutive and inducible endothelial cell characteristics, as well as angiogenic response. Infection by all four DENV serotypes was confirmed by an observed cytopathic effect (CPE), as well as RT-PCR (reversetranscription polymerase chain reaction) assays. As we had previously reported, the DENVinfected HPMEC-ST1.6R cells exhibited an elongated cytoplasmic morphology, possibly representing a response to VEGF and activation of angiogenesis. In this study, increase in VEGF expression level at designated time points of 0, 8, 24, 96 and 192 hours post-infection was investigated, using a microbead-based Bio-Plex immunoassay. Increased level of VEGF expression in infected-HPMEC-ST1.6R was detected at 8 hours post-infection. Interestingly, VEGF expression level began to decrease up to 96 hours post-infection, after which an upsurge of increased VEGF expression was detected at 192 hours post-infection. This profile of VEGF upregulated expression pattern associated with DENV infection appeared to be consistent among all four DENV-serotypes, and was not observed in mock-infected cells. In this study, the expression level of VEGF, a wellestablished vascular permeabilizing agent was shown to be elevated in a time-dependent manner, and exhibited a unique dual-response profile, in a DENV-infected endothelial cell. The experimental observation described here provided additional insights into potential mechanism for VEGFmediated vascular leakage associated with DENV, and support the idea that there are potential applications of anti-VEGF therapeutic interventions for prevention of severe DENV infections.

Endothelial Cells Elicit Immune-Enhancing Responses to Dengue Virus Infection

“…2 and 3, which indicate that IFN secreted by a small percentage of initially infected cells protects surrounding ECs from dengue virus spread. Some dengue virus-induced EC responses were also analyzed in LSEC-1, HMEC-1, or HPMEC-ST1.6R cell lines (9,10,41,63). Dengue virus infection of the HPMEC-ST1.6R cell line increased IL-6 and IL-8 (6 to 8 days pi) as well as vascular endothelial cell growth factor (VEGF) levels (9,10).…”

“…Some dengue virus-induced EC responses were also analyzed in LSEC-1, HMEC-1, or HPMEC-ST1.6R cell lines (9,10,41,63). Dengue virus infection of the HPMEC-ST1.6R cell line increased IL-6 and IL-8 (6 to 8 days pi) as well as vascular endothelial cell growth factor (VEGF) levels (9,10). In contrast, we found no induction of capillary permeabilizing VEGF (9,23) in primary human ECs, and 1 to 2 days after infection we detected IL-6 and IL-8 induction.…”

Dengue Virus neither Directly Mediates Hyperpermeability nor Enhances Tumor Necrosis Factor-^|^alpha;-Induced Permeability In Vitro

“…DENV infection of ECs has been proposed to contribute to this pathophysiology; however, the mechanism by which infected ECs modulate vascular (12,28,29), which is reported to be a bladder carcinoma rather than endothelial in nature (30). In addition, ECs from different tissue origins, such as LSEC-1, HMEC-1, or HPMEC-ST1.6R, which may have different characteristics, responded differently to DENV infection (9,15,31,32). In the present study, primary HUVECs isolated from normal human umbilical vein were evaluated because they are more relevant to the pathophysiology of DHF/DSS and the most commonly used model to investigate macromolecule transport (33,34).…”

Bleeding complications in dengue are not associated with significant changes in the modulators of the endothelial barrier

“…In the context of dengue, it has been demonstrated that dengue virus could down-regulate the secretion of sVEGFR-2 by endothelial cells, thus promoting an increase in microvascular permeability via excess of circulating VEGF-A [15,16]. Indeed, clinical studies have demonstrated that patients with DHF may present high levels of VEGF-A [17] and low levels of sVEGFR-2 [15,18].…”