Modulation of Human Cells by Virulent Francisella tularensis

有毒土拉弗朗西斯菌对人体细胞的调节

• 批准号: 8556006
• 负责人: Catharine Bosio
• 金额: $ 43.19万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8556006
• 关键词: Aerosols; Anti-Inflammatory Agents; Anti-inflammatory; Autoimmune Diseases; Bacteria; Beryllium; Biological; Breathing; Cell physiology; Cells; Dendritic Cells; Development; Disease; Elements; Francisella; Francisella tularensis; Genes; Genetic Transcription; Goals; Human; Immune response; Immune system; Immunosuppression; In Vitro; Individual; Infection; Inflammation; Inflammatory; Inflammatory Response; Interferon-beta; Interferons; Interleukin-12; Invaded; Laboratories; Left; Lipids; Malignant Neoplasms; Mediating; Membrane; Molecular; Mus; Natural Immunity; Pathway interactions; Play; Production; Regulation; Research; Role; Route; Secondary to; Signal Pathway; Signal Transduction; Stimulus; Structure; Surface; Symptoms; Time; Tularemia; Tumor Necrosis Factor-alpha; USSR; United States; Virulent; adaptive immunity; cytokine; extracellular; human TNF protein; interleukin-12 subunit p40; microbial; mortality; new therapeutic target; novel therapeutics; novel vaccines; pathogen; prevent; response; restoration; transmission process; vector; weapons

Summary: Francisella tularensis, the causative agent for tularemia, can infect humans by a number of routes, including vector-borne transmission. However, it is inhalation of the bacterium, and the resulting pneumonic tularemia, that represents the most dangerous form of disease. This is due to the short incubation time (3-5 days), non-specific symptoms, and a high mortality rate (greater than 80%) in untreated individuals. Furthermore, F. tularensis has been weaponized by both the United States and the former Soviet Union making it a viable candidate for use as a biological weapon. Despite over 80 years of research on F. tularensis around the world, very little is understood about the dynamic interaction of this bacterium with the host, especially following aerosol infection. My laboratory has established that, similarly to murine cells, human dendritic cells are acutely susceptible to infection with F. tularensis, but fail to produce pro-inflammatory cytokines or undergo maturation. Further, virulent F. tularensis actively interferes with the ability of human DC to respond to secondary stimuli. Understanding the mechanism by which F. tularensis actively suppresses DC function is a central directive of my laboratory. We are tackling this directive in two different ways. First, we are analyzing the role Francisella lipids play in mediating anti-inflammatory responses. Structures present on the surface of bacteria are the first components encountered by the host cell. Thus, it is possible that, in the context of F. tularensis infections, these structures contribute to the early, rapid suppression of human dendritic cells. Bacterial lipids represent one such structure. Preliminary evidence in our lab suggests that lipids associated with the outer membrane of F. tularensis can potently suppress inflammatory responses in human dendritic cells. We are currently identifying the specific lipid(s) responsible for this suppression and the mechanism by which they interfere with human dendritic cell functions. Second, we are exploring the intracellular host pathways modulated by F. tularensis, which negatively regulates human dendritic cells through multiple pathways. For example, if the replication of extracellular bacteria is restricted, the ability of human dendritic cells to produce TNF-alpha in response to other microbial stimuli is restored. However, a similar restoration of IL-12 production is not observed. We have demonstrated that rapid induction of IFN-beta by F. tularensis potently suppresses production of IL-12 in human dendritic cells. We are currently dissecting the specific pathways and molecular mechanisms by which IFN-beta modulates host responses in F. tularensis infected human dendritic cells. In addition to aiding in the development of novel vaccines and therapeutics, identification of bacterial products capable of negatively regulating specific host pathways (while leaving others intact) may provide new targets for therapeutics directed against cancer and autoimmune diseases. Recent evidence suggests that there is a crossover of our two specific aims in that lipids derived from F. tularensis interact with specific signaling transduction and transcription elements required for Type IFN signaling. These elements are also involved regulation of IL-12p40 transcription. My laboratory is continuing to identify the specific signaling pathways manipulated by F. tularensis and the bacterial components required for this interference.

摘要：图拉氏方济氏菌是图拉热病的病原体，可通过多种途径感染人类，包括通过媒介传播。然而，吸入细菌和由此导致的肺炎图拉热症是最危险的疾病形式。这是由于未经治疗的患者的潜伏期短(3-5天)、非特异性症状以及高死亡率(大于80%)。此外，美国和前苏联都已将其武器化，使其成为用作生物武器的可行候选者。尽管世界各地对图拉氏杆菌进行了80多年的研究，但人们对这种细菌与宿主的动态相互作用知之甚少，特别是在气溶胶感染之后。 我的实验室已经证实，与小鼠细胞类似，人类树突状细胞对图拉氏杆菌感染非常敏感，但不能产生促炎细胞因子或经历成熟。此外，毒力较强的图拉氏杆菌能有效干扰人类DC对二次刺激的反应能力。了解图拉氏杆菌主动抑制DC功能的机制是我的实验室的中心指示。我们正在以两种不同的方式处理这一指令。 首先，我们正在分析弗朗西塞氏菌脂类在调节抗炎反应中所起的作用。细菌表面的结构是宿主细胞遇到的第一组分。因此，在图拉氏丝虫感染的背景下，这些结构可能有助于早期、快速地抑制人类树突状细胞。细菌脂类就是这样一种结构。我们实验室的初步证据表明，与图拉氏丝虫外膜相关的脂类可以有效地抑制人树突状细胞的炎症反应。我们目前正在确定导致这种抑制的特定脂质(S)，以及它们干扰人类树突状细胞功能的机制。 其次，我们正在探索图拉氏F菌调控的细胞内宿主途径，它通过多条途径负向调节人类树突状细胞。例如，如果细胞外细菌的复制受到限制，人类树突状细胞产生肿瘤坏死因子-α的能力就会恢复，以应对其他微生物的刺激。然而，没有观察到类似的IL-12产生的恢复。我们已经证明，图拉氏杆菌快速诱导干扰素-β可以有效地抑制人树突状细胞中IL-12的产生。我们目前正在剖析干扰素-β在感染图拉氏丝虫的人树突状细胞中调节宿主反应的具体途径和分子机制。除了帮助开发新的疫苗和治疗方法外，识别能够负调控特定宿主途径(同时保持其他途径不变)的细菌产品可能为针对癌症和自身免疫性疾病的治疗提供新的靶点。 最近的证据表明，我们的两个特定目标是交叉的，因为来自图拉夫酵母的脂类与特定的信号转导和类型干扰素信号所需的转录元件相互作用。这些元件也参与了IL-12p40转录的调控。我的实验室正在继续鉴定图拉氏丝孢子菌操纵的特定信号通路以及这种干扰所需的细菌成分。