Mechanisms underlying adhesion and colonization in pneumococcal keratitis

项目概要/摘要 肺炎链球菌是全球角膜炎的主要细菌病因之一， 视力丧失治疗的主要手段仍然是抗生素;然而，细菌并不总是敏感的， 抗生素不能减少宿主和细菌介导的与S.肺炎 角膜炎。我们的研究结果有力地表明，S。肺炎，被认为是 该微生物的主要毒力因子，阻止细菌附着于角膜表面。初步 数据显示，当细菌粘附于角膜上皮细胞时， 提示它们调节囊膜以适应角膜小生境。因此，我们的中心假设是S。 肺炎杆菌适应于在角膜细胞存在下下调囊膜， 持久性增强。我们将测试我们的假设，通过比较胶囊数量的细菌， 粘附于角膜细胞和角膜表面不粘附的细菌。然后我们将确定 通过对以下基因文库进行优先化遗传筛选， 体外和体内突变体，然后用靶向突变的功能分析进行验证。很长的- 本研究的长期目标是确定和表征抑制角膜中细菌囊的因素 并促进附着而引起角膜炎。了解监管和殖民化的过程将有助于 在推动新疗法的发展，以保护角膜。

Project Summary/Abstract Streptococcus pneumoniae is one of the top bacterial causes of keratitis worldwide and can lead to significant vision loss. The mainstay of therapy continues to be antibiotics; however, bacteria are not always susceptible, and antibiotics are unable to reduce the host- and bacterium-mediated damage associated with S. pneumoniae keratitis. Our findings strongly indicate that the outer polysaccharide capsule of S. pneumoniae, considered a major virulence factor of this organism, impedes attachment of the bacteria to the corneal surface. Preliminary data show that the bacteria produce markedly less capsule when adhered to corneal epithelial cells, which suggest that they regulate capsule to adapt to the corneal niche. Therefore, our central hypothesis is that S. pneumoniae adapts to down-regulate capsule in the present of corneal cells so that attachment and persistence are increased. We will test our hypothesis by comparing capsule quantities of bacteria that are adherent to corneal cells and the corneal surface to bacteria that are not adherent. We will then determine the genes that are necessary for corneal attachment and colonization by a prioritized genetic screen of a library of mutants in vitro and in vivo, followed by validation with functional analyses with targeted mutations. The long- term goals of this study are to identify and characterize the factors that repress bacterial capsule in the cornea and promote attachment to cause keratitis. Understanding the processes of regulation and colonization will aid in driving development of novel therapies to preserve the cornea.