Phagosomal Signals Shape Inflammatory Responses to B. Burgdorferi

吞噬体信号塑造对伯氏疏螺旋体的炎症反应

• 批准号: 8186600
• 负责人: Juan C Salazar
• 金额: $ 43.7万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8186600
• 关键词: Adult; Anti-Inflammatory Agents; Anti-inflammatory; Area; Bacteria; Binding; Bone Marrow; Borrelia; Borrelia burgdorferi; CD14 gene; Castor Bean Tick; Cell surface; Cells; Child; Clinical; Communicable Diseases; Complex; Deer; Disease; Elements; Event; Exotoxins; Generations; Genes; Genetic Transcription; Goals; Growth; Human; IRAK1 gene; Immune; Immune response; In Vitro; Inflammatory; Inflammatory Response; Interferon Type I; Interferons; Knockout Mice; Laboratories; Life; Ligands; Lipoproteins; Lyme Disease; Mediating; Membrane; Modeling; Mus; Nature; Order Spirochaetales; Orthologous Gene; Patients; Phagocytosis; Phagolysosome; Phagosomes; Population; Process; Production; Progress Reports; Reporting; Research; Research Personnel; Role; Shapes; Signal Pathway; Signal Transduction; Signs and Symptoms; Staging; Structure; Surface; System; TLR1 gene; TLR2 gene; TLR8 gene; Tail; Techniques; Ticks; Tissues; Toll-Like Receptor 1; United States; Validation; base; cytokine; extracellular; in vivo; insight; macrophage; monocyte; novel; pathogen; receptor; research study; response; vector

DESCRIPTION (provided by applicant): Lyme disease (LD) is a tick-borne, multi-system, infectious disorder caused by the extracellular spirochetal bacterium Borrelia burgdorferi (Bb). Since Bb lacks exotoxins or known bacterial secretory system, it is widely believed that the inflammatory manifestations of the disease result from the host's innate and co-evolving adaptive immune responses to the bacterium. Monocytes and macrophages are considered to be critical cellular elements of the innate immune response to the spirochete. For more than a decade, Bb-mediated cell activation was thought to occur chiefly as a result of the interactions of the spirochete's abundant outer membrane-associated lipoproteins with CD14 and Toll-like receptors (TLR) 1/2 on the surface of these cells. We now have extensive evidence that phagocytosis of live spirochetes by human monocytes and murine macrophages generates a more intense and far broader inflammatory response than can be attributed to lipoprotein-mediated, cell surface TLR1/2 activation. Phagocytosis of intact Bb also induced transcription of interferon-2 (IFN-2) and type I interferon-stimulated genes (ISGs), independently of TLR2. Recent evidence from the investigator's laboratory provides substantial evidence the TLR2-independent signaling events elicited by Bb in human monocytes are MyD88-dependent and occur via TLR8. On the basis of our collective findings we now propose a new model of Bb-induced monocyte activation, which emphasizes the importance of phagocytosis and the cooperative role of TLR2 and TLR8 signaling. In this model, binding of Bb to the monocyte/macrophage cell surface, through a yet to be characterized phagocytic receptor, is followed by a broad sequence of immune signaling events which mechanistically can only be integrated following internalization of the bacterium and formation of the phagolysosome. The validation of the phagosomal signaling model, the centerpiece of our research strategy, will significantly enhance our understanding for how the bacterium triggers the inflammatory processes that under actual disease conditions cause tissue damage and/or that promote bacterial clearance. To accomplish our goals and examine mechanistic aspects of the proposed model, we have formulated the following Specific aims. In Aim 1 we will use a ex vivo stimulation technique to characterize in detail the mechanisms by which phagocytosis of Bb elicits activation and TLR1/2 and TLR8 dependent inflammatory signals in human monocytes. In Aim 2, we will examine key elements of the phagosomal signaling model in Bb-infected human and murine macrophages. The use a large repertoire of available knockout mice will allow us to define mechanistically how Bb is sensed and triggers immune responses in these cells. In Aim 3 we will characterize MyD88 dependent and independent responses to Borrelia burgdorferi both in vitro and in vivo using human monocytes and macrophages obtained from children and adults with known congenital deficiencies in components of the MyD88 signaling pathway (IRAK-4 and MyD88 deficient). PUBLIC HEALTH RELEVANCE: Lyme disease (LD) is a tick-borne infectious disorder caused by the spirochetal bacteria Borrelia burgdorferi (Bb), which has continued to increase in endemic areas and has spread geographically, paralleling the distribution of its primary vector, Ixodes ricinus complex, and the explosive growth in the white-tailed deer population. To study the inflammatory responses to the LD spirochete, the investigator will use a powerful stimulation model that allows a very complete characterization for how the bacterium activates human immune cells and in parallel experiments takes advantage of the large repertoire of available knockout mice to study these responses. Using this combined translational-experimental approach, in this application the investigator will validate key elements of a proposed new model of spirochetal recognition, where the phagosome is a central platform for recognition of diverse borrelial ligands and which involves a cooperative interaction between TLR2 and TLR8 in pro- and anti-inflammatory cytokine responses, and TLR8 in IRF-7 mediated induction of IFN-2.

描述（由申请人提供）：莱姆病（LD）是由细胞外螺旋细菌Borrelia burgdorferi（BB）引起的tick传播的多系统，传染病。由于BB缺乏外毒素或已知的细菌分泌系统，因此人们普遍认为该疾病的炎症表现是由于宿主的先天和共同发展对细菌的适应性免疫反应而导致的。单核细胞和巨噬细胞被认为是对螺旋体的先天免疫反应的关键细胞元素。十多年来，人们认为BB介导的细胞活化主要是由于螺旋体丰富的外膜相关脂蛋白与CD14和Toll-like受体（TLR）1/2在这些细胞表面上的相互作用。现在，我们有广泛的证据表明，人类单核细胞和鼠巨噬细胞对活螺旋体的吞噬作用产生的炎症反应比脂蛋白介导的细胞表面TLR1/2激活更为强烈，更广泛。完整BB的吞噬作用还诱导了干扰素2（IFN-2）和I型干扰素刺激的基因（ISG）的转录，独立于TLR2。研究者实验室的最新证据提供了大量证据，BB在人类单核细胞中引起的TLR2独立的信号传导事件是myd88依赖性的，并且通过TLR8发生。根据我们的集体发现，我们现在提出了一个新的BB诱导的单核细胞激活模型，该模型强调了吞噬作用的重要性以及TLR2和TLR8信号传导的合作作用。在该模型中，BB通过尚未表征的吞噬受体的结合与单核细胞/巨噬细胞表面结合，之后是一系列广泛的免疫信号事件，只有在细菌的内在化和吞噬体的形成后才能进行机理化。吞噬体信号传导模型的验证是我们研究策略的核心，将显着增强我们对细菌如何触发在实际疾病条件下造成组织损害和/或促进细菌清除率的炎症过程的理解。为了实现我们的目标并检查所提出模型的机械方面，我们已经制定了以下特定目标。在AIM 1中，我们将使用过体内刺激技术详细表征BB的吞噬作用激活，TLR1/2和TLR8依赖性炎症信号在人类单核细胞中的机制。在AIM 2中，我们将检查BB感染的人和鼠巨噬细胞中吞噬体信号传导模型的关键要素。使用大量可用的敲除小鼠的曲目将使我们能够从机械上定义BB的感觉，并触发这些细胞中的免疫反应。在AIM 3中，我们将使用人的单核细胞和巨噬细胞和巨噬细胞在MyD88信号通路（IRAK-4和MYD88 FAFE）中获得的儿童和成人（IRAK-4和MYD88的巨噬细胞）（IRAK-4和MYD88的较低）中获得的人类单核细胞和巨噬细胞（IRAK-4和MYD88的较低）中获得了对Borrelia burgdorferi的依赖和独立反应。 公共卫生相关性：莱姆病（LD）是一种由螺旋体细菌引起的tick传播感染性疾病，波雷利亚·伯格多菲利（BB）一直在流行地区增加，并在地理位置上扩散，与其主要矢量的分布，ixodes ixodes ricicinus ricinus complecter和爆炸性的人口中的爆炸性成长。为了研究对LD螺旋体的炎症反应，研究者将使用强大的刺激模型，该模型可以完全表征细菌如何激活人类免疫细胞，并且在并行实验中利用了可用的敲除小鼠的大量曲目来研究这些反应。在本应用程序中，使用这种结合的翻译实验方法，研究者将验证拟议的螺旋体识别模型的关键要素，其中吞噬体是识别多样的杂体配体的核心平台，涉及TLR2和TLR8在亲和抗炎性cilemandied cytokine cytokine和iffn的iffn inffrn ins iffrrn ins iffrrrrrrrrrrrrrrrrrrr中的合作互动。