Imaging the struggle for nutrient metal between host and pathogen

描述（由申请人提供）：所有细菌病原体必须在其宿主体内获得营养金属，以便定殖并引起疾病。脊椎动物已经通过进化高亲和力金属结合蛋白来利用这一要求，该蛋白在称为“营养免疫”的过程中螯合金属并防止细菌生长。为了与营养免疫竞争，细菌感知金属水平的变化，并协调基因表达的变化，使其能够适应这种环境通量。尽管已经在体外描述了响应于改变的金属水平而被激活的细菌调节回路，但是在脊椎动物感染期间细菌何时何地经历金属应激尚不清楚。此外，对营养免疫有贡献的宿主蛋白质的完整目录尚未被定义。在本申请中，我们建议通过以下方法填补这些知识空白： 多模态成像模式应用于金黄色葡萄球菌感染的鼠模型。S.选择金黄色葡萄球菌进行这些实验是因为它是美国感染的主要原因，并且我们的实验室在葡萄球菌全身感染、骨髓炎和肺炎的鼠模型中有经验。这些感染模型的多样性将提供有关营养免疫对不同部位感染的贡献的有价值的信息。 为了实现宿主与病原体之间争夺金属的全动物三维图像，将小鼠感染S。金黄色葡萄球菌，并依次进行一系列不同的成像模式。为了观察感染后整个动物发生的解剖学变化，我们将采用磁共振成像（MRI）和计算机断层扫描（CT）。为了确定感染动物体内细菌金属依赖性基因表达，我们将使用体内生物发光成像（BLI）。为了研究感染对整个动物体内蛋白质和元素丰度和分布的影响，我们将使用成像质谱法（IMS），这是我们最近在传染病研究中开创的。使用我们最近开发的计算分析工具，将从这些成像模式中获得的数据共配准到单个三维图像中。结合起来，这些数据将定义感染对金属蛋白分布和金属丰度的影响，并确定细菌如何应对这些变化。这些数据将为合理设计针对营养金属获取的疗法奠定基础。此外，由于这些实验而开发的技术将适用于可以使用动物模型研究的所有生理相关过程。

DESCRIPTION (provided by applicant): All bacterial pathogens must acquire nutrient metals within their hosts in order to colonize and cause disease. Vertebrates have taken advantage of this requirement by evolving high-affinity metal binding proteins that sequester metals and prevent bacterial growth in a process known as "nutritional immunity". To compete with nutritional immunity, bacteria sense alterations in metal levels and coordinate gene expression changes that enable adaptation to this environmental flux. Although the bacterial regulatory circuits that are activated in response to altered metal levels have been described in vitro, when and where bacteria experience metal stress during vertebrate infection is not known. In addition, the complete catalogue of host proteins that contribute to nutritional immunity has not been defined. In this application, we propose to fill these gaps in knowledge through the application of multi-modal imaging modalities to murine models of Staphylococcus aureus infection. S. aureus is chosen for these experiments because it is the leading cause of infection in the United States and our laboratory is experienced in murine models of staphylococcal systemic infection, osteomyelitis, and pneumonia. The diversity of these infection models will provide valuable information regarding the contribution of nutritional immunity to infection at a variety of distinc sites. To achieve a whole-animal three-dimensional image of the struggle for metal between host and pathogen, mice will be infected with S. aureus and sequentially subjected to a series of distinct imaging modalities. To observe anatomical changes that occur in whole animals following infection, we will employ magnetic resonance imaging (MRI) and computed tomography (CT). To define bacterial metal-dependent gene expression within infected animals we will use in vivo bioluminescence imaging (BLI). To study the impact of infection on protein and elemental abundance and distribution within whole animals, we will use imaging mass spectrometry (IMS) which we have recently pioneered for the study of infectious diseases. Data obtained from each of these imaging modalities will be co-registered into a single three-dimensional image using computational analysis tools that we have recently developed. Combined, these data will define the impact of infection on metalloprotein distribution and metal abundance and determine how bacteria respond to these changes. These data will lay the foundation for the rational design of therapeutics that target nutrient metal acquisition. In addition, the technologies developed as a result of these experiments will be applicable to all physiologically relevant processes that can be studied using animal models.