Microbiology and Infectious Diseases and Eye & Vision Health, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
Cell Screen SA, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia, Australia.
J Virol. 2018 Jun 29;92(14). doi: 10.1128/JVI.00633-18. Print 2018 Jul 15.
Severe dengue virus (DENV) infection is associated with overactivity of the complement alternative pathway (AP) in patient studies. Here, the molecular changes in components of the AP during DENV infection were investigated. mRNA for factor H (FH), a major negative regulator of the AP, was significantly increased in DENV-infected endothelial cells (EC) and macrophages, but, in contrast, production of extracellular FH protein was not. This discord was not seen for the AP activator factor B (FB), with DENV induction of both FB mRNA and protein, nor was it seen with Toll-like receptor 3 or 4 stimulation of EC and macrophages, which induces both FH and FB mRNA and protein. Surface-bound and intracellular FH protein was, however, induced by DENV, but only in DENV antigen-positive cells, while in two other DENV-susceptible immortalized cell lines (ARPE-19 and human retinal endothelial cells), FH protein was induced both intracellularly and extracellularly by DENV infection. Regardless of the cell type, there was an imbalance in AP components and an increase in markers of complement AP activity associated with DENV-infected cells, with lower FH relative to FB protein, an increased ability to promote AP-mediated lytic activity, and increased deposition of complement component C3b on the surface of DENV-infected cells. For EC in particular, these changes are predicted to result in higher complement activity in the local cellular microenvironment, with the potential to induce functional changes that may result in increased vascular permeability, a hallmark of dengue disease. Dengue virus (DENV) is a significant human viral pathogen with a global medical and economic impact. DENV may cause serious and life-threatening disease, with increased vascular permeability and plasma leakage. The pathogenic mechanisms underlying these features remain unclear; however, overactivity of the complement alternative pathway has been suggested to play a role. In this study, we investigate the molecular events that may be responsible for this observed alternative pathway overactivity and provide novel findings of changes in the complement system in response to DENV infection in primary cell types that are a major target for DENV infection (macrophages) and pathogenesis (endothelial cells) Our results suggest a new dimension of cellular events that may influence endothelial cell barrier function during DENV infection that could expand strategies for developing therapeutics to prevent or control DENV-mediated vascular disease.
登革热病毒（DENV）感染与补体替代途径（AP）的过度活跃有关，在患者研究中已有报道。在此，我们研究了 DENV 感染期间 AP 成分的分子变化。在 DENV 感染的内皮细胞（EC）和巨噬细胞中，因子 H（FH）的 mRNA 显著增加，这是 AP 的主要负调节剂，但细胞外 FH 蛋白的产生则不然。这种不匹配在 AP 激活剂因子 B（FB）中并未出现，因为 DENV 诱导 FB 的 mRNA 和蛋白，TLR3 或 4 刺激 EC 和巨噬细胞也未出现这种情况，TLR3 或 4 可诱导 FH 和 FB 的 mRNA 和蛋白。然而，DENV 可诱导表面结合和细胞内 FH 蛋白，但仅在 DENV 抗原阳性细胞中，而在另外两种 DENV 易感的永生化细胞系（ARPE-19 和人视网膜内皮细胞）中，DENV 感染可同时诱导细胞内和细胞外 FH 蛋白。无论细胞类型如何，AP 成分的失衡以及与 DENV 感染细胞相关的补体 AP 活性标志物增加，FH 蛋白相对 FB 蛋白减少，促进 AP 介导的溶解活性的能力增加，以及补体成分 C3b 在 DENV 感染细胞表面的沉积增加。对于 EC 尤其如此，这些变化预计会导致局部细胞微环境中补体活性升高，有可能引起功能变化，从而导致血管通透性增加，这是登革热疾病的一个标志。登革热病毒（DENV）是一种重要的人类病毒病原体，具有全球性的医疗和经济影响。DENV 可能导致严重和危及生命的疾病，伴有血管通透性增加和血浆渗漏。这些特征的发病机制尚不清楚；然而，补体替代途径的过度活跃已被认为发挥了作用。在这项研究中，我们研究了可能导致这种观察到的替代途径过度活跃的分子事件，并提供了在 DENV 感染中补体系统变化的新发现，这些变化发生在主要的 DENV 感染靶细胞（巨噬细胞）和发病机制（内皮细胞）中。我们的结果表明，在 DENV 感染期间，内皮细胞屏障功能可能受到影响的细胞事件的新维度，这可能扩大了开发治疗方法以预防或控制 DENV 介导的血管疾病的策略。
