Identifying polyamine dependent mechanisms in pneumococcal pneumonia

肺炎链球菌的血清型变异性、基因组可塑性和不断增加的抗生素耐药性，对设计干预策略以应对这一全球公共卫生问题提出了相当大的挑战。由于现有疫苗并不是对所有血清型都有效，因此有必要确定并确定有效免疫肺炎球菌的新候选疫苗的特征。多胺是 肺炎球菌生长和致病所必需的无处不在的小阳离子分子。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。我们的初步结果表明，多胺转运受损导致小鼠肺炎模型的减轻。然而，导致这种衰减的病原体-宿主相互作用尚不清楚。我们的中央 假设肺炎链球菌多胺转运受损导致肺炎球菌肺炎的减弱是由于毒力因子基因表达减少和/或对宿主天然免疫反应的抵抗力降低。我们将通过以下具体目标来检验这一假设。具体目标：1-通过比较肺炎链球菌野生型和ApotABCD肺炎链球菌(一种多胺转运操纵子基因缺失的菌株)在小鼠模型中的基因表达，鉴定多胺反应性肺炎球菌的基因和途径 2-利用蛋白质组学方法，通过检测抗菌蛋白、急性期蛋白、巨噬细胞和中性粒细胞吞噬巨噬细胞的吞噬功能以及宿主信号通路和功能(包括Toll样受体信号)的表达，确定宿主对多胺缺乏肺炎球菌的先天免疫反应。成功完成拟议的研究将确定肺炎球菌对多胺转运的反应分子机制以及特定的宿主先天免疫反应。 项目结果将阐明多胺在一般传染病中的作用，为今后设计新的疫苗或疗法确定独特的细胞内和细胞外目标。

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.