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: 10692137
• 负责人: Catharine Bosio
• 金额: $ 43.72万
• 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/10692137
• 关键词: Acellular Vaccines; Acute; Aerosols; Anti-Inflammatory Agents; Bacteria; Bacterial Infections; Carbohydrates; Cells; Dangerousness; Data; Defect; Dendritic Cells; Dengue Virus; Development; Disease; Francisella; Francisella tularensis; Goals; Health; Human; Immune response; Immune system; Immunosuppression; Impairment; In Vitro; Individual; Infection; Infectious Agent; Inflammation; Inflammatory; Inflammatory Response; Inhalation; Invaded; Laboratories; Legal patent; Lipid Synthesis Pathway; Lipids; Liposomes; Mediating; Membrane; Metabolic; Metabolic Pathway; Metabolism; Microbe; Mus; Natural Immunity; O Antigens; Pathogenicity; Play; Proteins; Pulmonary tularemia; Research; Role; Route; Secondary to; Sentinel; Signal Pathway; Signaling Molecule; Stimulus; Structure; Surface; Symptoms; Testing; Therapeutic; Time; Tularemia; USSR; United States; Virulence; Virulent; adaptive immunity; bioweapon; capsule; carbohydrate structure; cell killing; cytokine; in vivo; macrophage; mortality; mutant; novel; novel therapeutics; novel vaccines; pathogen; pathogenic bacteria; prevent; programs; receptor; response; transmission process; vector-borne; weapons

Francisella tularensis (FT), 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, FT 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 FT 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 FT, but fail to produce pro-inflammatory cytokines or undergo maturation. Further, virulent FT actively interferes with the ability of human DC and macrophages to respond to secondary stimuli. Understanding the mechanism by which FT actively suppresses DC and macrophage function is a central directive of my laboratory. We are tackling this directive in two different ways. Specific Aim 1: 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 FT infections, these structures contribute to the early, rapid suppression of human dendritic cells. Bacterial lipids represent one such structure. We have recently identified one of the active lipid species present in FT that inhibit inflammation. We have tested a synthetic version of this lipid and confirmed that it also impairs inflammatory responses. We have identified one of the receptors utilized by both the intact bacterium and purified lipid as well as a host signaling molecule required to promote immunosuppressive responses. Importantly, we have also demonstrated that FT lipids can limit pathogenic inflammatory responses driven by other infectious agents in vitro, including Dengue virus. We have screened FT lipids (including synthetic liposomes) for off target effects in vivo following delivery via multiple routes and have also found that they potently dampen inflammation driven by unrelated bacterial infection in vivo. We have filed a patent application for use of FT lipids as novel anti-inflammatory therapeutics. We are currently identifying the other lipids present in FT that contribute to suppression of inflammation and additional mechanisms by which they interfere with functions in human cell. We have generated a lipid mutant and identified a requirement for a specific species of FT lipid in evasion, but not suppression, of pro-inflammatory responses in human cells. Additionally, we are examining the contribution of host lipid synthesis pathways following infection with F. tularensis. Specific Aim 2: We are exploring the role of carbohydrates associated with the outer surface of FT in directing immunosuppressive programs in human cells. The major outer surface carbohydrate structure of FT is the O-Antigen (O-Ag) capsule. Typically, capsules are thought to simply cover up proteins present on the bacterial surface that could stimulate an inflammatory response. However, our data demonstrates that FT capsule directly inhibits pro-inflammatory responses in human cells. Further, we have demonstrated that capsule influences specific metabolic pathways in the host the modulate cell health and inflammatory responses. Utilizing mutants with specific defects in capsule synthesis along with purified FT capsule, we are currently identifying the specific receptors and host signaling pathways modulated by capsule to initiate an anti-inflammatory program inhuman cells.

francisella tularensis（ft）是t骨的病因，可以通过许多路线感染人类，包括矢量传播。然而，这是最危险的疾病形式的细菌和由此产生的肺炎。这是由于未经治疗的个体的短期孵育时间（3-5天），非特异性症状和高死亡率（大于80％）。此外，FT已被美国和前苏联武器化，使其成为可行的候选人作为生物武器。尽管在全球范围内进行了80多年的研究，但对这种细菌与宿主的动态相互作用的了解很少，尤其是在气溶胶感染之后。 我的实验室已经确定，与鼠细胞类似，人类树突状细胞和巨噬细胞非常容易受到FT感染，但无法产生促炎性细胞因子或经历成熟。此外，有毒的FT积极干扰人类DC和巨噬细胞对继发刺激的反应能力。了解FT积极抑制直流和巨噬细胞功能的机制是我实验室的中心指令。我们以两种不同的方式解决该指令。 具体目的1：我们正在分析弗朗西斯脂质在介导抗炎反应中的作用。细菌表面上存在的结构是宿主细胞遇到的第一个组件。因此，在FT感染的背景下，这些结构可能有助于对人树突状细胞的早期快速抑制。细菌脂质代表这样一种结构。我们最近确定了FT中存在的一种活性脂质物种，该脂质抑制了炎症。 我们已经测试了该脂质的合成版本，并确认它也损害了炎症反应。 我们已经确定了由完整细菌和纯化的脂质以及促进免疫抑制反应所需的宿主信号分子所用的一种受体。 重要的是，我们还证明了FT脂质可以限制其他在包括登革热病毒在内的其他感染剂驱动的致病性炎症反应。 我们已经筛选了FT脂质（包括合成脂质体），以通过多种途径分娩后的体内靶向效应，并且还发现它们有效地抑制了由体内无关细菌感染驱动的炎症。 我们已提出了将FT脂质用作新型抗炎疗法的专利申请。 我们目前正在识别FT中存在的其他脂质，这些脂质有助于抑制炎症以及它们干扰人类细胞功能的其他机制。我们已经产生了一种脂质突变体，并确定了对人类细胞中促炎反应的特定ft脂质物种的要求。 此外，我们正在研究感染F. tularensis后宿主脂质合成途径的贡献。 特定目标2：我们正在探索与FT外表面有关的碳水化合物在指导人类细胞中的免疫抑制程序中的作用。 FT的主要外表面碳水化合物结构是O-抗原（O-AG）胶囊。通常，胶囊被认为简单地掩盖了可能刺激炎症反应的细菌表面上存在的蛋白质。但是，我们的数据表明，FT胶囊直接抑制人类细胞中的促炎反应。此外，我们已经证明胶囊会影响宿主调节细胞健康和炎症反应中特定的代谢途径。 利用胶囊合成中具有特定缺陷的突变体以及纯化的FT胶囊，我们目前正在识别由胶囊调节的特定受体和宿主信号通路，以启动抗炎程序非人类细胞。