Complement and the Clearance of Staphylococcus aureus

金黄色葡萄球菌的补体和清除

基本信息

批准号：
6653926
负责人：
KENJI Mason CUNNION
金额：
$ 10.56万
依托单位：
EASTERN VIRGINIA MEDICAL SCHOOL
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-04-01 至 2007-03-31
项目状态：
已结题

项目摘要

This research will characterize the role of complement proteins in the immune-mediated opsonophagocytosis and killing of pathogenic Staphylococcus aureus. S. aureus is a leading cause of death from infection in hospitals and is increasingly resistant to current antibiotics. For many bacteria adequate opsonization by complement proteins is critical for effectively preventing and fighting infections. Studying complement-mediated opsonization of S. aureus may provide clues to unlock new therapies against S. aureus. Encapsulated (CP+) strains, serotypes 5 and 8, cause 70% of severe S. aureus infections, however their opsonization by complement remains largely unstudied. Our preliminary in vivo and in vitro studies and in vitro studies have investigated three CP+ strains, two heavily- encapsulated strains, and one capsule-negative mutant in terms of lethality in complemented mice, C3 binding kinetics, pathways of complement activation, the nature of C3 fragments deposited and shed, the relationship between growth and C3 binding, and the effect of capsule on C3 binding. The data from these studies suggest that complement is important for surviving bacteremia with clinically relevant S. aureus serotypes. CP+ strains appear to inhibit opsonization by decreasing C3 binding, inhibiting bound C3-fragment recognition by complement receptors, and sh4edding bound C3-fragments. The global hypothesis guiding this research is that the severity of S. aur5eus infection depends on serotype dependent staphylococcal-capsule modulation of complement-mediated opsonization. In light of the preliminary data the following focused hypotheses will be tested: 1) Opsonization by complement is critical in host defense against S. aureus. 2) Capsular polysaccharide and impairs opsonphagocytosis of S. aureus by interfering with normal complement function. 3) S. aureus protects itself by degrading and shedding the major complement opsonins C3b and iC3b. 4) Anti-capsular antibodies improve the complement-mediated opsonophagocytosis and killing of S. aureus. These experiments will be performed using radiolabeled complement components, and antibodies raised against specific complement peptides. Human neutrophils will be incubated with opsonized bacteria and stained with acridine orange to measure phagocytosis and intracellular killing. In vivo experiments will be performed using complement deficient mice. Collaborating laboratories have provided special S. aureus stains and anti-S. aureus antibodies.

这项研究将表征补体蛋白质在免疫介导的调查性吞噬作用和致病性金黄色葡萄球菌的杀伤中的作用。金黄色葡萄球菌是医院感染导致死亡的主要原因，并且对当前的抗生素越来越抗性。对于许多细菌，补体蛋白质充分的调子化对于有效预防和抗击感染至关重要。研究金黄色葡萄球菌的补体介导的调子化可能会提供解锁针对金黄色葡萄球菌的新疗法的线索。封装（CP+）菌株，血清型5和8，引起70％的严重金黄色葡萄球菌感染，但是它们通过补体的调子化仍然很大程度上没有研究。我们的初步体内和体外研究以及体外研究研究了三种CP+菌株，两个重封的菌株以及一个辅助小鼠的致死性，C3结合动力学，补体激活的途径，补体激活的途径，C3片段的结合和C3的结合和C3的结合和C3的结合，在互补的小鼠中的致死性，C3结合的途径和C3的结合。这些研究的数据表明，补体对于与临床相关的金黄色葡萄球菌血清型的幸存菌血症很重要。 CP+菌株似乎通过降低C3结合，抑制补体受体抑制结合的C3碎片识别和降低结合的C3-fragments来抑制打击。指导这项研究的全球假设是，链球菌感染的严重程度取决于补体介导的调子化的依赖性血清型葡萄球菌胶囊调节。鉴于初步数据，将测试以下重点假设：1）补体的调整对于对金黄色葡萄球菌的宿主防御至关重要。 2）通过干扰正常补体功能，囊囊多糖并损害金黄色葡萄球菌的胞吐作用。 3）金黄色葡萄球菌通过降解和脱落主要补体C3B和IC3B来保护自己。 4）抗囊状抗体改善了补体介导的调查型和金黄色葡萄球菌的杀伤。这些实验将使用放射标记的补体成分以及针对特定补体肽产生的抗体进行。人类嗜中性粒细胞将与调子型细菌一起孵育，并用尖锐的橙色染色，以测量吞噬作用和细胞内杀伤。体内实验将使用补体缺乏小鼠进行。合作实验室提供了特殊的金黄色葡萄酒污渍和抗S。金黄色抗体。