KSHV interactions with host inflammasome components

描述：KSHV与慢性炎症相关的卡波西氏肉瘤(KS)和口腔和其他身体部位的原发渗出性B细胞淋巴瘤(PEL)有关，这些疾病发生在HIV-1感染的患者身上。炎症反应是KSHV致病的关键因素之一。KS病变以炎性细胞和细胞因子为特征。来自PEL的KS病变内皮细胞和B细胞系在潜伏状态下携带KSHV基因组的多个副本。我们的长期目标是阐明KSHV在初次感染和潜伏期间与宿主先天反应的相互作用，细胞因子的诱导途径，并确定它们在KSHV致病中的作用。我们的基本原理是，这些详细的知识对于设计治疗策略以控制KSHV感染、炎症和相关恶性肿瘤至关重要。KSHV感染细胞分泌多功能IL-1？和IL-18细胞因子进入培养上清液。将IL-1？和IL-18合成为失活的proIL-1？和proIL-18，然后用活化的caspase-1进行处理。然而，caspase-1本身是以原天冬氨酸酶-1的形式合成的，并经历了激活，导致了自动蛋白水解酶的切割。Procaspase-1的激活是由一个称为“炎症体”的分子平台介导的，该平台是由识别危险触发的传感器蛋白、接头ASC分子和proaspase-1的同型相互作用形成的。我们的研究表明，炎症体的病原体感知功能也延伸到了细胞核。在KSHV从头感染人微血管真皮内皮细胞(HMVEC-d)的过程中，γ-干扰素诱导蛋白(IFI16)与感染的内皮细胞核内的KSHV基因组共定位，并与ASC和Proaspase-1相互作用形成炎症体复合体。在潜伏感染的内皮细胞和PEL细胞中，IFI16与KSHV基因组共定位，在潜伏感染的KSHV细胞中，只有依赖于IFI16的炎症体被结构性激活。人类KS和PEL病变显示IFI16-ASC炎性小体激活。在γ1-EB病毒潜伏期I、II和III细胞中也观察到了IFI16-炎症体的组成性诱导。结合在存在IFI16-炎症体的情况下KSHV和EBV潜伏的能力，以及在潜伏感染的细胞中IFI16与KSHV和EBV基因组的关联，我们假设“IFI16参与了对细胞核中外源异体DNA的先天感知，KSHV利用IFI16来实现其潜伏”。这一假设将通过三个相互关联的创新具体目标来检验。这些研究具有重要意义，因为这样的阐明将导致设计治疗策略来控制KSHV诱导的炎症和相关的恶性肿瘤。这些还将深刻地加强当前核内先天感知的概念，并将带来新的技术和治疗方法，不仅将使KSHV研究领域受益，而且将使其他领域受益。

DESCRIPTION: KSHV is etiologically associated with chronic inflammation associated Kaposi's sarcoma (KS) and primary effusion B-cell lymphoma (PEL) in oral and other body sites that occur in HIV-1 infected patients. The inflammatory response is one of the key elements of KSHV pathogenesis. KS lesions are characterized by inflammatory cells and cytokines. The KS lesion endothelial cells and B-cell lines from PEL carry multiple copies of the KSHV genome in a latent state. Our long term goals are to elucidate KSHV's interactions with the host innate response during primary infection and latency, the pathways of cytokine induction and to define their role in KSHV pathogenesis. Our rationale is that such detailed knowledge is crucial for designing therapeutic strategies to control KSHV infection, inflammation and the associated malignancies. KSHV infected cells secrete multi-functional IL-1ß and IL-18 cytokines into the supernatants. IL-1ß and IL-18 are synthesized as inactive proIL-1ß and proIL-18 and then undergo processing by activated caspase-1. However, caspase-1 itself is synthesized as a procaspase-1 and undergoes activation leading into an auto- proteolytic cleavage. Procaspase-1 activation is mediated by a molecular platform called an "inflammasome" that is formed by homotypic interactions of a sensor protein recognizing the danger trigger, an adaptor ASC molecule, and procaspase-1. Our studies have demonstrated that the pathogen sensing functions of the inflammasome also extends into the nucleus. During de novo KSHV infection of human microvascular dermal endothelial (HMVEC-d) cells, gamma-interferon-inducible protein (IFI16) is colocalized with the KSHV genome in the infected endothelial cell nucleus, and interacted with ASC and procaspase-1 to form an inflammasome complex. IFI16 also colocalized with the KSHV genome in the nuclei of latently infected endothelial and PEL cells, and only the IFI16 dependent inflammasome is constitutively activated in KSHV latently infected cells. Human KS and PEL lesions showed evidence of IFI16-ASC inflammasome activation. Constitutive induction of the IFI16-inflammasome was also observed in γ1-EBV latency I, II and III cells. Together with the ability of KSHV and EBV latency in the presence of the IFI16-inflammasome and association of IFI16 with KSHV and EBV genome in the latently infected cells, we hypothesize that "IFI16 is involved in the innate sensing of foreign episomal DNA in the nucleus and KSHV utilizes IFI16 for its latency". This hypothesis will be tested by three innovative and interlinked specific aims. These studies are significant since such elucidation wil lead into designing therapeutic strategies to control KSHV induced inflammation and the associated malignancies. These will also profoundly enhance the current concepts of innate sensing in the nucleus and will lead into new technologies and treatments that will benefit not only the KSHV area of research but also other fields.