Graduate Institute of Immunology, National Taiwan University College of Medicine, Taipei 100, Taiwan;
Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 100, Taiwan; and Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
J Immunol. 2014 Aug 1;193(3):1258-67. doi: 10.4049/jimmunol.1302675. Epub 2014 Jun 27.
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.
出血表现常伴随多种登革热疾病综合征发生。大量工作集中于免疫因素对出血发病机制的贡献，但登革病毒（DENV）如何参与发病过程从未被探究过。虽然普遍认为细胞凋亡是人类登革热感染中血管通透性的基础，但我们在登革热出血小鼠模型中显示，内皮细胞凋亡对小鼠出血的发生很重要。为了探究 DENV 对内皮细胞死亡的贡献的分子基础，我们在本研究中显示，DENV 蛋白酶与细胞 IκBα 和 IκBβ相互作用并将其切割。通过诱导 IκBα 和 IκBβ 的切割和 IκB 激酶的激活，DENV 蛋白酶激活 NF-κB，导致内皮细胞死亡。腺相关病毒-9 包装的 DENV 蛋白酶皮内接种会诱导小鼠内皮细胞死亡和皮肤出血。尽管 H51 活性位点不参与 DENV 蛋白酶与 IκB-α/β 的相互作用，但酶活性对于 DENV 蛋白酶诱导 IκBα 和 IκBβ 切割和引发出血发展至关重要。此外，IκBα 或 IκBβ 的过表达可保护内皮细胞免受 DENV 诱导的凋亡。在本研究中，我们显示 DENV 蛋白酶参与登革热出血的发病机制，并发现 IκBα 和 IκBβ 是 DENV 蛋白酶切割的新的细胞靶标。
