Brown Michael G, Huang Yan Y, Marshall Jean S, King Christine A, Hoskin David W, Anderson Robert
Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada.
J Leukoc Biol. 2009 Jan;85(1):71-80. doi: 10.1189/jlb.0308167. Epub 2008 Sep 22.
Severe forms of dengue virus disease, known as dengue hemorrhagic fever and dengue shock syndrome, result from an aberrant immune response involving antibody-dependent enhancement of infection, thrombocytopenia, and a loss of vascular integrity, culminating in hemorrhage, shock, and in some cases, death. Several studies have indicated that dengue virus infection results in the induction of apoptosis of certain cells believed to be contributory players in dengue pathogenesis. However, none have specifically examined the role of antibody enhancement in the context of induction of apoptosis. Here, we show that antibody-enhanced dengue virus infection of the FcR-bearing mast cell/basophil KU812 cell line results in a massive induction of apoptosis. Confocal microscopy and flow cytometry indicate two distinct subpopulations consisting of productively infected cells and apoptotic-uninfected bystanders. Apoptosis was found to be caspase-dependent, involving global caspase activation and cleavage of poly-ADP-ribose polymerase (PARP) and D4-guanosine diphosphate dissociation inhibitor (D4-GDI). Additional FcR-bearing cells, including K562, U937, and human mast cell 1 (HMC-1), were analyzed for apoptosis induction following infection. Although all cells displayed high susceptibility to antibody-enhanced dengue virus infection, only cells of a mast cell phenotype (KU812 and HMC-1) were found to undergo apoptosis. Dengue-induced apoptosis of KU812 cells was shown to require antibody-enhanced dengue virus infection by blockade of FcgammaRII. Transfection of KU812 cells with L-SIGN/DC-SIGNR was able to overcome the requirement for antibody enhancement with regard to dengue virus infection and apoptosis.
严重的登革病毒疾病形式，即登革出血热和登革休克综合征，是由异常免疫反应引起的，这种反应涉及感染的抗体依赖性增强、血小板减少以及血管完整性丧失，最终导致出血、休克，在某些情况下还会导致死亡。多项研究表明，登革病毒感染会导致某些细胞发生凋亡，这些细胞被认为是登革热发病机制中的重要参与者。然而，尚无研究专门探讨抗体增强在凋亡诱导背景下的作用。在此，我们表明，携带FcR的肥大细胞/嗜碱性粒细胞KU812细胞系经抗体增强的登革病毒感染会导致大量细胞凋亡。共聚焦显微镜和流式细胞术显示出两个不同的亚群，分别由有效感染的细胞和凋亡的未感染旁观者组成。发现凋亡是半胱天冬酶依赖性的，涉及全局半胱天冬酶激活以及聚ADP核糖聚合酶（PARP）和D4-鸟苷二磷酸解离抑制剂（D4-GDI）的裂解。对包括K562、U937和人肥大细胞1（HMC-1）在内的其他携带FcR的细胞进行了感染后凋亡诱导分析。尽管所有细胞对抗体增强的登革病毒感染均表现出高度敏感性，但仅发现肥大细胞表型的细胞（KU812和HMC-1）会发生凋亡。通过阻断FcγRII表明，KU812细胞的登革热诱导凋亡需要抗体增强的登革病毒感染。用L-SIGN/DC-SIGNR转染KU812细胞能够克服登革病毒感染和凋亡对抗体增强的需求。
