An Intracellular Niche for Borrelia burgdorferi

伯氏疏螺旋体的细胞内生态位

基本信息

批准号：
8300386
负责人：
JON T SKARE
金额：
$ 18.31万
依托单位：
TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-03-07 至 2014-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8300386
关键词：
Address Affect Animals Antibiotics Antibodies Area Arthritis Arthropods Bacteria Blood Circulation Borrelia Borrelia burgdorferi Cardiac Case Study Cells Complement Connective Tissue Coupled Data Dermal Disease Endothelial Cells Environment Exanthema Experimental Models Exploratory/Developmental Grant Fibroblasts Fibronectins Goals Health Human Image Immune Immune response In Vitro Individual Infection Infectious Agent Integrin Binding Integrins Interferons Interleukin-10 Interleukin-12 Interleukin-6 Invaded Investigation Locales Location Lyme Disease Lymphatic Mammals Mediating Metric Molecular Morbidity - disease rate Mus Natural Immunity Neurologic Order Spirochaetales Pathogenesis Pathology Patients Public Health Publications Reagent Research Resistance Risk SU 6656 Serum Site Staging Sterilization Study Section System Testing United States Work design erythema migrans experience extracellular flu in vivo inhibitor/antagonist interest killings kinase inhibitor novel novel strategies pathogen prevent response src-Family Kinases trafficking uptake

项目摘要

DESCRIPTION (provided by applicant): Lyme disease, caused by the spirochetal bacterium Borrelia burgdorferi, is the leading arthropodborne infection in the United States and causes significant morbidity in endemic areas. If untreated B. burgdorferi can persistently infect individuals even though the host mounts a potent adaptive immune response such that antibodies obtained from infected patients or experimentally infected animals effectively kills in vitro cultivated B. burgdorferi. In addition, a robust cell-mediated proinflammatory response is observed that induces IL-6, IL-12 and IFN-??and inhibits IL-10. Furthermore, the spirochete can resist complement killing demonstrating that this important component of the innate immune response is not sufficient to eliminate B. burgdorferi infection. The observation that B. burgdorferi persists in such a hostile environment indicates that the spirochete is adept at evading the host immune response via mechanisms that have not been completely elucidated. One possibility is that B. burgdorferi invades host cells and survives at low levels. Recently we have determined that B. burgdorferi invade both immortalized and, more importantly, primary cells (both fibroblasts and endothelial cells) and persist as viable cells in o-culture. In addition we have preliminary data suggesting that the ability to invade host cells involves both integrin binding and Src kinase activity. In this application we propose to further characterize the internalization of B. burgdorferi and track the fate of B. burgdorferi within thes infected cells to determine how they affect the localized host response following infection. To accomplish this we will use both in vitro correlates of invasion and intracellular survival as well as in vivo imaging of experimentally infected mice as readouts for our studies. Specifically, we propose to: (1) Characterize the invasion of Borrelia burgdorferi into primary fibroblasts. The working hypothesis here is that B. burgdorferi exploits invasion as an additional mechanism to avoid host clearance. Our preliminary studies demonstrate that B. burgdorferi invasion is not dependent on host fibronectin, but does involve ?1 integrins other than ?5?1. In this Aim we will identify the ??subunit that pairs with ?1 to promote invasion and will also evaluate how B. burgdorferi traffics within these cells; and (2) Determine if invasion is required for B. burgdorferi persistence in vivo. Our working hypothesis is that invasion contributes to persistence by providing an immunoprotected niche for B. burgdorferi. Since Src kinases are required for borrelial internalization in vitro, we will determine whether Src kinase inhibitors aler the infectivity potential of B. burgdorferi in vivo. In addition to standard cultivation and molecuar approaches, novel in vivo imaging will be employed to assess how the inhibitor affects colonization. The overall goal of these studies is to determine the extent in which an intracellula locale contributes to borrelial persistence. PUBLIC HEALTH RELEVANCE: Borrelia burgdorferi, the etiologic agent of Lyme disease, is the most common arthropod-borne infectious agent in the United States, and, as such, represents an important Public Health issue. The studies described in this application are designed to address how B. burgdorferi is able to persist effectively in infected mammals despite effective innate immune killing mechanisms and a potent adaptive immune response directed against this pathogen. The hypothesis being tested herein is that B. burgdorferi is capable of low-level intracellular survival in non-immune cells as an additional strategy to prevent borrelial host clearance.

描述（由申请人提供）：莱姆病由螺旋体细菌伯氏疏螺旋体引起，是美国主要的节肢动物传播感染，在流行地区造成显着的发病率。如果未经治疗，即使宿主产生有效的适应性免疫反应，从感染患者或实验感染动物获得的抗体也能有效杀死体外培养的伯氏疏螺旋体，伯氏疏螺旋体仍能持续感染个体。此外，还观察到强烈的细胞介导的促炎反应，其诱导IL-6、IL-12和IFN-γ并抑制IL-10。此外，螺旋体可以抵抗补体杀伤，表明先天免疫反应的这一重要组成部分不足以消除伯氏疏螺旋体感染。伯氏疏螺旋体在如此恶劣的环境中持续存在的观察表明，螺旋体善于通过尚未完全阐明的机制逃避宿主免疫反应。一种可能性是伯氏疏螺旋体侵入宿主细胞并以低水平存活。最近，我们确定伯氏疏螺旋体侵入永生化细胞，更重要的是，侵入原代细胞（成纤维细胞和内皮细胞），并在o培养中作为活细胞持续存在。此外，我们有初步数据表明，入侵宿主细胞的能力涉及整合素结合和 Src 激酶活性。在本申请中，我们建议进一步表征伯氏疏螺旋体的内化，并追踪伯氏疏螺旋体在这些感染细胞内的命运，以确定它们如何影响感染后的局部宿主反应。为了实现这一目标，我们还将使用入侵和细胞内存活的体外相关性作为实验感染小鼠的体内成像作为我们研究的读数。具体来说，我们建议：（1）描述伯氏疏螺旋体侵入初级成纤维细胞的特征。这里的工作假设是伯氏疏螺旋体利用入侵作为避免宿主清除的额外机制。我们的初步研究表明，伯氏疏螺旋体入侵不依赖于宿主纤连蛋白，但确实涉及除 5?1 以外的 1 整联蛋白。在这个目标中，我们将鉴定与 ?1 配对以促进入侵的 ??亚基，并将评估伯氏疏螺旋体如何在这些细胞内运输； (2)确定入侵是否是伯氏疏螺旋体在体内持久存在所必需的。我们的工作假设是，入侵通过为伯氏疏螺旋体提供免疫保护的生态位来促进持久性。由于体外疏螺旋体内化需要 Src 激酶，因此我们将确定 Src 激酶抑制剂是否会增强伯氏疏螺旋体体内的感染潜力。除了标准培养和分子方法外，还将采用新颖的体内成像来评估抑制剂如何影响定植。这些研究的总体目标是确定细胞内区域对疏螺旋体持续存在的影响程度。公共卫生相关性：伯氏疏螺旋体是莱姆病的病原体，是美国最常见的节肢动物传播的传染源，因此代表了一个重要的公共卫生问题。本申请中描述的研究旨在解决伯氏疏螺旋体如何能够在受感染的哺乳动物中有效地持续存在，尽管有有效的先天免疫杀伤机制和针对该病原体的有效适应性免疫反应。本文测试的假设是，伯氏疏螺旋体能够在非免疫细胞中进行低水平的细胞内存活，作为防止疏螺旋体宿主清除的额外策略。