Identifying polyamine dependent mechanisms in pneumococcal pneumonia

血清型变异性、基因组可塑性和耐药性增加。肺炎，对设计针对这一全球公共卫生问题的干预策略提出了相当大的挑战。需要鉴定和表征用于针对肺炎球菌的有效免疫的新型疫苗候选物，因为可用的疫苗不是针对所有血清型都有效。多胺是 肺炎球菌生长和毒力所必需的普遍存在的小阳离子分子。因此，细胞内多胺水平受到严格调控，从而使多胺转运机制成为研究发病机制和免疫反应的一个非常有吸引力的焦点。我们的初步研究结果表明，受损的多胺转运导致小鼠模型肺炎的衰减。然而，病原体-宿主的相互作用，负责这种减毒的特点还有待确定。我们的中央 假设肺炎球菌多胺转运受损导致肺炎球菌肺炎的减毒是由于毒力因子基因表达降低和/或对宿主先天免疫应答的抗性降低。我们将通过以下具体目标来检验这一假设。具体目的：1-通过比较野生型和ApotABCD S的基因表达来鉴定多胺应答性肺炎球菌基因和途径。pneumoniae（一种多胺转运操纵子基因缺失的菌株）在小鼠模型中的作用 肺炎; 2-使用蛋白质组学，通过测量抗微生物蛋白、急性期蛋白、巨噬细胞和嗜中性粒细胞的调理吞噬作用以及宿主信号传导途径和功能（包括Toll样受体信号传导）的表达，确定宿主对多胺缺陷型肺炎球菌的先天免疫应答。这些研究的成功完成将确定肺炎球菌对多胺转运的分子机制以及特异性宿主先天免疫应答。 项目结果将阐明多胺在感染性疾病中的作用，以确定独特的细胞内和细胞外靶点，用于未来新疫苗或治疗方法的设计。

Serotype variability, genomic plasticity and increasing antibiotic resistance of S. pneumoniae, pose considerable challenges for designing intervention strategies for this global public health concern. There is a need for the identification as well as characterization of novel vaccine candidates for effective immunization against pneumococcus, as the available vaccines are not effective against all serotypes. Polyamines are ubiquitous small cationic molecules necessary for pneumococcal growth and virulence. Therefore, intracellular polyamine levels are tightly regulated, thus making polyamine transport mechanisms a highly attractive focus for investigation on pathogenesis and immune responses. Our preliminary results indicate that impaired polyamine transport causes attenuation of pneumonia in mouse models. However, the pathogen-host interactions responsible for this attenuation are yet to be characterized. Our central hypothesis is that attenuation in pneumococcal pneumonia by impaired pneumococcal polyamine transport is due to the reduced virulence factor gene expression and/or reduced resistance to host innate immune responses. We will test this hypothesis by conducting the following specific aims. Specific aims: 1-identify polyamine responsive pneumococcal genes and pathways by comparing gene expression of wild type and ApotABCD S. pneumoniae (a strain with genetic deletion of polyamine transport operon) in a mouse model of pneumonia ; 2-determine the host innate immune responses to polyamine deficient pneumococcus by measuring the expression of antimicrobial proteins, acute phase proteins, opsonophagocytosis by macrophages and neutrophils, and host signaling pathways and functions including Toll-like receptor signaling, using proteomics. Successful completion ofthe proposed studies will identify the pneumococcal molecular mechanisms responsive to polyamine transport as well as specific host innate immune responses. Project results will shed light on the role of polyamines in infectious diseases in general for the identification of unique intra and extracellular targets for design of novel vaccines or therapeutics in future.