Journal of General Virology 2018 Dec;99(12):1658-1670. | https://doi.org/10.1099/jgv.0.001163
Sneha Singh, M. G. Anupriya, Ayan Modak and Easwaran Sreekumar
A transient increase in trans-endothelial cell permeability in dengue patients leads to vascular leakage and shock syndrome. Here, we analysed the molecular mechanisms that cause permeability changes in human dermal microvascular endothelial cells (HMEC-1) using a direct dengue virus (DENV) infection model or treatment with NS1, a secreted DENV non-structural protein. In HMEC-1 cells, both treatments increase permeability with a concordant increase in the secretion of angiopoietin-2 (Ang-2). There is phosphorylation and loss of the junction protein VE-Cadherin from the inter-endothelial cell junctions and phosphorylation of RhoA. Direct virus infection results in activation of Src by phosphorylation, whereas NS1 treatment alone does not lead to Src activation. Furthermore, treatment with recombinant Ang-1, a physiological antagonist of Ang-2, prevents Ang-2 release, VE-Cadherin phosphorylation and internalization, and phosphorylation of RhoA and Src, resulting in restoration of barrier function. The permeability increase could also be prevented by blocking the Ang1/2 signalling receptor, Tie-2, or using a Rho/ROCK-specific inhibitor. Dasatinib, a Src-family kinase (SFK) inhibitor that inhibits Src phosphorylation, prevents enhanced permeability induced by direct DENV infection whereas in NS1 protein-treated cells its effect is less significant. The results provide important insights on the mechanisms of increased trans-endothelial permeability in DENV infection, and suggest the therapeutic potential of using recombinant Ang-1 or targeting these key molecules to prevent vascular leakage in dengue.