Dengue Virus Induces the Expression and Release of Endocan from Endothelial Cells by an NS1-TLR4-Dependent Mechanism.

Carlos Alonso Domínguez-Alemán,Héctor Vivanco-Cid,Andrea Isabel Torres-Zugaide,Karina Guadalupe Hernández-Flores,Luis Alberto Sánchez-Vargas,Arturo Reyes-Sandoval,Leticia Cedillo-Barrón,Ricardo Remes-Ruiz

doi:10.3390/microorganisms9061305

Carlos Alonso Domínguez-Alemán, Héctor Vivanco-Cid + Show 6 more

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https://doi.org/10.3390/microorganisms9061305

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Abstract

A common hallmark of dengue infections is the dysfunction of the vascular endothelium induced by different biological mechanisms. In this paper, we studied the role of recombinant NS1 proteins representing the four dengue serotypes, and their role in promoting the expression and release of endocan, which is a highly specific biomarker of endothelial cell activation. We evaluated mRNA expression and the levels of endocan protein in vitro following the stimulation of HUVEC and HMEC-1 cell lines with recombinant NS1 proteins. NS1 proteins increase endocan mRNA expression 48 h post-activation in both endothelial cell lines. Endocan mRNA expression levels were higher in HUVEC and HMEC-1 cells stimulated with NS1 proteins than in non-stimulated cells (p < 0.05). A two-fold to three-fold increase in endocan protein release was observed after the stimulation of HUVECs or HMEC-1 cells with NS1 proteins compared with that in non-stimulated cells (p < 0.05). The blockade of Toll-like receptor 4 (TLR-4) signaling on HMEC-1 cells with an antagonistic antibody prevented NS1-dependent endocan production. Dengue-infected patients showed elevated serum endocan levels (≥30 ng/mL) during early dengue infection. High endocan serum levels were associated with laboratory abnormalities, such as lymphopenia and thrombocytopenia, and are associated with the presence of NS1 in the serum.

Highlights

This illness is divided into two different clinical categories and a third category known as severe dengue infection, which is characterized by plasma leakage and fluid accumulation that leads to shock or respiratory distress, severe bleeding, and severe organ impairment [1,2,3]
We describe for the first time how the nonstructural protein 1 (NS1) protein in the dengue virus regulates the expression and production of endocan, which is an endothelial cell-specific molecule that has been used as an endothelial cell activation biomarker
Endocan mRNA levels in the HMEC cell line showed a marked two-fold to three-fold increase compared to negative controls 48–72 h post-activation with the recombinant NS1 proteins (Figure 1A)

Summary

Introduction

Four DENV serotypes (DENV1, DENV2, DENV3, and DENV4) circulate in tropical and subtropical areas of the globe, each of which is capable of causing a wide clinical spectrum of disease, including a mild febrile illness known as non-severe dengue. This illness is divided into two different clinical categories (with and without warning signs) and a third category known as severe dengue infection, which is characterized by plasma leakage and fluid accumulation that leads to shock or respiratory distress, severe bleeding, and severe organ impairment [1,2,3].

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