Innate Immune Defense against Clostridium Difficile Infection

描述（由申请方提供）：艰难梭菌在肠道微生物群的抗生素介导的扰动后引起结肠炎。C.艰难梭菌导致超过50万感染， 据估计，美国每年有15，000人死亡。从污染环境中摄入感染性孢子是获得这种感染的主要途径。我们对C之间的相互作用知之甚少。艰难梭菌与正常肠道微生物群或与宿主先天免疫系统之间的相互作用。本实验室对C.艰难梭菌感染，并证明用细菌鞭毛蛋白刺激TLR-5或用瑞喹莫特刺激TLR 7/8显著增强对艰难梭菌的抗性。艰难感染我们还证实了单剂量克林霉素可延长对念珠菌的敏感性。艰难感染本项目的目标是描述先天免疫防御的特征，包括由肠道微生物植物群诱导的防御，以保护免受C。艰难感染第一个目的是表征鞭毛蛋白刺激TLR 5或瑞喹莫特刺激TLR 7/8增强对C.艰难感染我们将研究IL-22、arl碳氢化合物受体和初级和次级胆汁盐在TLR介导的抗C.艰难感染第二个目标是确定肠树突状细胞或炎症单核细胞是否有助于抵抗C。艰难感染我们将使用我们实验室产生的CCR 2报告基因和CCR 2缺失基因小鼠来确定炎症单核细胞对C.艰难性结肠炎第三个目的是确定不同抗生素治疗对肠道微生物植物群组成的影响。我们将使用Roche 454大规模平行焦磷酸测序平台来确定胃肠道中微生物的复杂性，并将植物群的变化与对C.艰难感染小鼠将用分离的肠道微生物群和对C.将测量艰难梭菌感染。这些研究将鉴定抑制C.很难我们的最终目标是确定体内保护宿主免受C.艰难梭菌感染，并发现可行的方法，如选择性TLR或细胞因子受体刺激或微生物群操纵，以重新诱导脆弱患者的这些机制。

DESCRIPTION (provided by applicant): Clostridium difficile causes colitis following antibiotic-mediated perturbation of the intestinal microbiota. C. difficile causes over 500,000 infections per year, with an estimated 15,000 deaths annually in the United States. Ingestion of infectious spores from contaminated environments represents the major route by which this infection is acquired. Very little is known about interactions between C. difficile and the normal intestinal microbiota or with the host innate immune system. Our laboratory has investigated C. difficile infection in antibiotic treated mice and demonstrated that stimulating TLR-5 with bacterial flagellin or TLR7/8 with resiquimod markedly enhances resistance to C. difficile infection. We have also demonstrated that a single dose of clindamycin results in prolonged susceptibility to C. difficile infection. The goal of this project is to characterize innate immune defenses, includig those induced by the commensal microbial flora, in protection against C. difficile infection. The first aim is to characterize the mechanism by which stimulation of TLR5 by flagellin or TLR7/8 by resiquimod enhances resistance to C. difficile infection. We will investigate the role IL22, the arl hydrocarbon receptor and primary and secondary bile salts in TLR-mediated defense against C. difficile infection. The second aim is to determine whether intestinal dendritic cells or inflammatory monocytes contribute to resistance to C. difficile infection. We will use CCR2-reporter and CCR2-depletor mice that were generated in our laboratory to determine the impact of inflammatory monocytes on the pathogenesis of C. difficile colitis. The third aim is to determine the effect of different antibiotic treatments on the composition of the intestinal microbial flora. We will use the Roche 454 massively parallel pyrosequencing platform to determine microbial complexity in the GI tract, and to correlate changes in the flora with susceptibility to C. difficile infection. Mice will be reconstituted with fractionated intestinal microbiota and resistance to C. difficile infection will be measured. These studies will identify microbial populations that inhibit germination and/or vegetative growth of C. difficile. Our ultimate goal is to identify the in vivo mechanisms protecting the host from C. difficile infection and to discover practicable approaches, such as selective TLR or cytokine receptor stimulation or microbiota manipulation, to re-induce these mechanisms in vulnerable patients.