Hemorrhagic manifestations occur frequently accompanying a wide range of dengue disease syndromes. Much work has focused on the contribution of immune factors to the pathogenesis of hemorrhage, but how dengue virus (DENV) participates in the pathogenic process has never been explored. Although there is no consensus that apoptosis is the basis of vascular permeability in human dengue infections, we showed in dengue hemorrhage mouse model that endothelial cell apoptosis is important to hemorrhage development in mice. To explore the molecular basis of the contribution of DENV to endothelial cell death, we show in this study that DENV protease interacts with cellular IκBα and IκBβ and cleaves them. By inducing IκBα and IκBβ cleavage and IκB kinase activation, DENV protease activates NF-κB, which results in endothelial cell death. Intradermal inoculation of DENV protease packaged in adenovirus-associated virus-9 induces endothelial cell death and dermal hemorrhage in mice. Although the H51 activity site is not involved in the interaction between DENV protease and IκB-α/β, the enzymatic activity is critical to the ability of DENV protease to induce IκBα and IκBβ cleavage and trigger hemorrhage development. Moreover, overexpression of IκBα or IκBβ protects endothelial cells from DENV-induced apoptosis. In this study, we show that DENV protease participates in the pathogenesis of dengue hemorrhage and discover IκBα and IκBβ to be the new cellular targets that are cleaved by DENV protease.
Copyright © 2014 by The American Association of Immunologists, Inc.