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: 8745527
• 负责人: Catharine Bosio
• 金额: $ 50.16万
• 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/8745527
• 关键词: Aerosols; Anti-Inflammatory Agents; Anti-inflammatory; Attenuated; Bacteria; Biological; Breathing; Carbohydrates; Cell physiology; Cells; Cover-up; Data; Defect; Dendritic Cells; Development; Disease; Francisella; Francisella tularensis; Goals; Human; Immune response; Immune system; Immunosuppression; Immunosuppressive Agents; Individual; Infection; Inflammatory; Inflammatory Response; Invaded; Laboratories; Lipids; Mediating; Membrane; Microbe; Mus; Natural Immunity; O Antigens; Play; Proteins; Publishing; Research; Role; Route; Secondary to; Sentinel; Signal Pathway; Signal Transduction; Stimulus; Structure; Surface; Symptoms; Time; Tularemia; USSR; United States; Virulence; Virulent; adaptive immunity; capsule; carbohydrate structure; cell killing; cytokine; macrophage; mortality; mutant; novel therapeutics; novel vaccines; pathogen; prevent; programs; receptor; response; 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 and macrophages 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 and macrophages to respond to secondary stimuli. Understanding the mechanism by which F. tularensis actively suppresses DC and macrophage 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. We recently published that lipids isolated from virulent, but not attenuated F. tularensis, potently suppress inflammatory responses in human dendritic cells and macrophages. Further, we identified the specific signal transduction proteins modulated by Francisella lipids. 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 role of carbohydrates associated with the outer surface of F. tularensis in directing immunosuppressive programs in human cells. The major outer surface carbohydrate structure of F. tularensis is the O-Antigen (O-Ag) associated with LPS. Typically O-Ag is thought to simply cover up proteins present on the bacterial surface that could stimulate an inflammatory response. However, we have preliminary data which demonstrates that the O-Ag directly inhibits pro-inflammatory responses in human cells. Utilizing mutants with specific defects in O-Ag synthesis, we are currently identifying the specific receptors and host signaling pathways modulated by F. tularensis O-Ag to initiate an anti-inflammatory program.

摘要：土拉热弗朗西斯菌是土拉菌病的病原体，可通过多种途径感染人类，包括媒介传播。然而，吸入细菌和由此产生的肺炎土拉菌病是最危险的疾病形式。这是由于潜伏期短（3-5天），非特异性症状，以及未经治疗的个体的高死亡率（大于80%）。此外，F.美国和前苏联都已将土拉热病毒武器化，使其成为一种可行的生物武器。尽管对F.尽管土拉热菌在世界各地流行，但人们对这种细菌与宿主的动态相互作用，特别是在气溶胶感染后的相互作用知之甚少。 我的实验室已经证实，与鼠细胞类似，人类树突状细胞和巨噬细胞对F.土拉热，但不能产生促炎细胞因子或经历成熟。 此外，毒力F.土拉菌主动干扰人DC和巨噬细胞对次级刺激的反应能力。了解F.土拉菌主动抑制DC和巨噬细胞功能是我实验室的中心指令。 我们正在以两种不同的方式处理该指令。 首先，我们分析弗朗西斯菌脂质在介导抗炎反应中的作用。 存在于细菌表面的结构是宿主细胞遇到的第一个成分。 因此，在F.在土拉热感染中，这些结构有助于人类树突细胞的早期快速抑制。 细菌脂质就是这样一种结构。我们最近发表了从强毒而非减毒的F.土拉菌，有效地抑制人类树突细胞和巨噬细胞中的炎症反应。此外，我们确定了特定的信号转导蛋白调节弗朗西斯菌脂质。 我们目前正在确定负责这种抑制的特定脂质以及它们干扰人类树突状细胞功能的机制。 其次，我们正在探索与F外表面相关的碳水化合物的作用。土拉菌在指导人类细胞中的免疫抑制程序中的作用。 F.的主要外表面糖结构。土拉热是与LPS相关的O-抗原（O-Ag）。 通常，O-Ag被认为只是掩盖了存在于细菌表面的蛋白质，这些蛋白质可能刺激炎症反应。 然而，我们有初步的数据表明，O-Ag直接抑制人类细胞中的促炎反应。 利用O-Ag合成中具有特定缺陷的突变体，我们目前正在鉴定由F.土拉菌O-Ag启动抗炎程序