Vascular leakage is a life-threatening complication of dengue virus (DENV)
infection. Previously, association between "paracellular" endothelial hyperpermeability and plasma leakage had been extensively investigated. However, whether "transcellular" endothelial leakage is involved in
dengue hemorrhagic fever (DHF) and
dengue shock syndrome (DSS) remained unknown. We thus investigated effects of DENV (serotype 2)
infection on transcellular transport of
albumin, the main oncotic
plasma protein, through human endothelial cell monolayer by Western blotting, immunofluorescence staining, fluorescence imaging, and fluorometry. The data showed that Alexa488-conjugated
bovine serum albumin (Alexa488-BSA) was detectable inside DENV2-infected cells and its level was progressively increased during 48-h post-
infection. While paracellular transport could be excluded using
FITC-conjugated
dextran, Alexa488-BSA was progressively increased and decreased in lower and upper chambers of Transwell, respectively. Pretreatment with
nystatin, an inhibitor of caveolae-dependent endocytic pathway, significantly decreased
albumin internalization into the DENV2-infected cells, whereas inhibitors of other endocytic pathways showed no significant effects. Co-localization of the internalized Alexa488-BSA and
caveolin-1 was also observed. Our findings indicate that DENV
infection enhances caveolae-mediated
albumin transcytosis through human endothelial cells that may ultimately induce plasma leakage from intravascular compartment. Further elucidation of this model in vivo may lead to effective prevention and better therapeutic outcome of DHF/DSS.