KSHV interactions with host nuclear innate response components

真核生物有一系列的防御机制来识别，响应和控制 他们每天都会遇到许多病原体和有害物质。先天免疫反应是 第一道防线之一，以非特定的方式做出反应和防御。KSHV是一种 在美国和西方国家传播病原体，并在撒哈拉以南非洲的生命早期感染。在 在免疫抑制的个体中，KSHV在病因学上与炎症相关的恶性肿瘤相关 如卡波西肉瘤（KS）、原发性渗出性B细胞淋巴瘤（PEL）和多中心Castleman肉瘤 疾病（MCD）。细胞因子如IL-1β、TNF-α、IFN-γ和IL-6以及病毒基因产物被提议用于 推动KS、PEL和MCD的发展和进步。KSHV感染内皮细胞诱导 与KS/PEL/MCD病变微环境相似的炎性细胞因子和生长因子。 我们推测KSHV对先天性PRRs的持续激活可能是慢性炎症的原因之一。 在KS、PEL和MCD病变中观察到炎症。因此，我们的总体目标是定义先天免疫 对KSHV的反应，并确定其在KSHV的生物学作用。 我们已经证明，在KSHV从头感染人皮肤时， 微血管内皮细胞与KS/PEL/MCD病变微环境相同， 炎性IL-1β和IL-18细胞因子分泌到上清液中。IL-1β和IL-18前体形式经历 由活化的caspase-1处理。半胱天冬酶-1，合成为半胱天冬酶原-1，被 分子平台“炎性小体”，其由感测危险信号的传感器蛋白、适配器 分子ASC和半胱氨酸天冬氨酸蛋白酶原-1。先天反应是否识别并响应染色体外的 双环状KSHV基因组（和其他DNA病毒）在细胞核中是未知的。我们的研究首次 证明了IFI 16，一种通过未知机制参与转录的高度保守的核蛋白， 是KSHV、EBV和HSV-1基因组的先天性核传感器。后续研究显示，IFI 16 在KSHV的延迟维持中起作用。基于这些研究，我们扩展了我们原来的 假设和假设“IFI 16与细胞核中的不同蛋白质复合，以介导不同的 包括附加体DNA的先天感应的功能和KSHV利用/破坏IFI 16及其相关的 蛋白质的潜伏期”。我们令人兴奋的初步研究支持这一假设。为了验证这个假设，我们 制定了两个重点突出、相互关联的具体目标。这些研究意义重大，因为 阐明IFI 16及其相关蛋白在KSHV潜伏期细胞核中的作用将使我们能够更深入地了解KSHV的潜伏期。 了解其发病机制，这将有助于治疗操纵这一途径，以控制KSHV 感染、炎症和相关的恶性肿瘤。

Eukaryotic organisms have an array of defense mechanisms to recognize, respond and control the numerous pathogens and harmful substances that they encounter every day. The Innate immune response is one of the first lines of defense to respond and defend in a non-specific manner. KSHV is a sexually transmitted agent in the USA and Western countries, and infects early during life in sub-Saharan Africa. In immune-suppressed individuals, KSHV is etiologically associated with inflammation associated malignancies such as Kaposi’s sarcoma (KS), primary effusion B-cell lymphoma (PEL), and Multicentric Castleman’s disease (MCD). Cytokines such as IL-1β, TNF-α, IFN-γ and IL-6 as well as viral gene products are proposed to drive KS, PEL and MCD development and progression. KSHV infection of endothelial cells induces inflammatory cytokines and growth factors which are similar to the microenvironments of KS/PEL/MCD lesions. We hypothesize that constant activation of innate PRRs by KSHV could be one of the reasons for the chronic inflammation seen in KS, PEL and MCD lesions. Hence, our overall goals are to define the innate immune response against KSHV and to determine its role in KSHV’s biology. We have shown that the cytokine profiles elicited during de novo KSHV infection of human dermal microvascular endothelial cells are identical to the KS/PEL/MCD lesion microenvironments and pro- inflammatory IL-1β and IL-18 cytokines are secreted in the supernatants. IL-1β and IL-18 pro-forms undergo processing by activated caspase-1. Caspase-1, synthesized as procaspase-1, is auto-catalytically cleaved by the molecular platform “inflammasome” that is formed by a sensor protein sensing the danger signal, adaptor molecule ASC and procaspase-1. Whether innate responses recognize and respond to the extra-chromosomal ds-circular KSHV genome (and other DNA viruses) in the nuclei were not known. Our studies for the first time demonstrated that IFI16, a highly conserved nuclear protein involved in transcription by unknown mechanism, is an innate nuclear sensor of KSHV, EBV and HSV-1 genomes. Follow up studies have revealed that IFI16 plays a role in latency maintenance of KSHV. Based on these studies we have extended our original hypothesis and hypothesize that "IFI16 is in complex with different proteins in the nucleus to mediate different functions including innate sensing of episomal DNA and KSHV utilizes/subverts IFI16 and its associated proteins for its latency". Our exciting preliminary studies supports this hypothesis. To test this hypothesis, we have formulated two major focused and interlinked specific aims. These studies are significant since elucidating the role of IFI16 and its associated proteins in the nucleus in KSHV’s latency will allow a deeper understanding of its pathogenesis which will facilitate therapeutic manipulation of this pathway to control KSHV infection, inflammation and the associated malignancies.