Pneumolysin, Innate and Acquired Immunity to Pneumococci

肺炎链球菌仍然是世界范围内发病率和死亡率的主要原因。肺炎球菌的两种组分被认为是造成许多有害的炎性热反应的原因，即硫醇活化的分泌毒素肺炎球菌溶血素和细胞壁的肽聚糖组分。这两种分子在上皮细胞和神经元细胞的体外研究中已显示出引起炎症变化，以及激活非活性免疫系统的单核细胞和巨噬细胞。我们实验室的初步工作支持肺炎球菌溶血素通过跨膜受体Toll样受体4（TLR 4）与肽聚糖（TLR 2配体）和/或整个肺炎球菌协同激活免疫系统的先天臂的假设。此外，我们有一些初步的数据表明，肺炎球菌溶血素激活先天免疫反应可能大大增强获得性免疫肺炎球菌以及。该项目的科学目标分为两个阶段。在第一阶段，PI将研究肺炎球菌溶血素单独使用以及与肽聚糖或整个肺炎球菌联合使用的TLR依赖性信号传导途径。将进行研究以检验肺炎球菌溶血素直接结合TLR 4的假设。这一阶段还将包括一个密集的教学部分，以补充实验室的工作。在第二阶段，PI将研究这一途径在调节疾病和获得性免疫肺炎球菌中的作用。 该项目的这一阶段将测试的假设，TLR 4介导的细胞激活肺炎球菌溶血素在肺炎球菌疾病的病理生理学中起着重要作用。将在体外（巨噬细胞）和体内（定植和疾病的鼠模型）研究携带肺炎球菌溶血素基因突变的肺炎球菌，其TLR 4信号传导能力减弱或消除。TLR 4介导的肺炎球菌溶血素应答在获得性免疫发展中的可能作用将在该提案的最终目标中进行研究。建立对肺炎球菌的先天性和获得性免疫反应之间的联系，可以更好地理解对肺炎球菌的免疫获得的机制。

Streptococcus pneumoniae remains a major cause of morbidity and mortality worldwide. Two components of pneumococci are thought to be responsible for much of the deleterious inflammatory hot response, the thiol-activated secreted toxin pneumolysin and the peptidoglycan component of the ell wall. Both of these molecules have been shown to cause inflammatory changes in vitro studies in epithelial and neuronal cells, as well as activate monocytes and macrophages of the inactive immune system. Preliminary work in our laboratory supports the hypothesis that pneumolysin activates the innate arm of the immune system through a transmembrane receptor, Toll-like receptor 4 (TLR4), in synergy with peptidoglycan (a TLR2 ligand) and/or whole pneumococci. In addition, we have some preliminary data to suggest that the activation of the innate immune response by pneumolysin may greatly augment acquired immunity to pneumococcus as well. The scientific goals of this project are divided in two phases. In the first phase, the PI will study the TLR- dependent signaling pathway of pneumolysin, alone and in combination with peptidoglycan or whole pneumococci. Studies will be done to test the hypothesis that pneumolysin binds directly to TLR4. This phase will also include an intense didactic component, to complement the work in the laboratory. In the second phase, the PI will study the role of this pathway in the modulation of disease and acquired immunity to pneumococci. This phase of the project will test the hypothesis that TLR4-mediated cellular activation by pneumolysin plays an important role in the pathophysiology of pneumococcal disease. Pneumococci carrying mutations in the pneumolysin gene, with diminished or abrogated TLR4-signaling capability, will be studied both in vitro (in macrophages) and in vivo (in murine models of colonization and disease). The possible role of TLR4-mediated response to pneumolysin in the development of acquired immunity will be studied in the final aim of the proposal. The establishment of a link between the innate and the acquired arm of the immune response to pneumococcus may provide a better understanding of the mechanisms by which immunity to pneumococcus is acquired.