Mechanisms underlying adhesion and colonization in pneumococcal keratitis

项目摘要/摘要 肺炎链球菌是世界范围内导致角膜炎的主要细菌之一，可导致显著的 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， 抗生素不能减少与肺炎链球菌相关的宿主和细菌介导的损害。 角膜炎。我们的发现有力地表明，肺炎链球菌的外多糖囊被认为是一种 这种生物的主要毒力因子，阻碍细菌附着在角膜表面。初步 数据显示，当细菌附着在角膜上皮细胞上时，产生的包膜明显减少，这 建议调整囊膜以适应角膜壁龛。因此，我们的中心假设是S。 肺炎杆菌适应于下调囊膜中角膜细胞的存在，从而使附着和 持久力增强。我们将通过比较胶囊中的细菌数量来验证我们的假设 黏附于角膜细胞和角膜表面的细菌不黏附。然后我们将确定 通过优先基因筛选对角膜附着和定植所必需的基因 在体外和体内进行突变，然后通过靶向突变的功能分析进行验证。长的- 这项研究的目的是确定和描述抑制角膜中细菌包膜的因素。 并促进依恋导致角膜炎。了解管理和殖民的过程将有助于 推动保护角膜的新疗法的发展。

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.