Regulation of Clostridium difficile Colonization Factors

描述(申请人提供)：艰难梭菌是一种革兰氏阳性、专性厌氧菌，可引起从抗生素相关性腹泻到伪膜性结肠炎等各种疾病。近年来，艰难梭菌感染的发生率和严重性有所增加。然而，人们对致病机制的基本方面知之甚少，例如细菌附着在肠道上皮细胞的机制。因为寄主的定植是确定感染的先决条件，所以当务之急是 确定细菌附着到宿主组织的潜在机制，因为这将推动亟需的额外治疗和预防选择的发展。该项目的长期目标是了解艰难梭菌如何附着并维持肠道上皮的定植。这项建议的目的是确定鞭毛和IV型菌毛以及控制它们产生的机制如何影响艰难梭菌定植宿主组织的能力。本研究的中心假设是细菌信号分子c-di-GMP相反地调节鞭毛和IV型菌毛的生物合成，允许它们在适当的定殖阶段产生。这一假设将通过以下三个具体目标进行检验。具体目的1是确定IV型菌毛对肠道定植和毒力的影响，并由c-di-GMP调节。具体目标2是确定c-di-GMP如何调控鞭毛基因，以及调控如何影响毒力。具体目标3是确定感染期间IV型菌毛和鞭毛产生的空间和时间模式，以及协调这些表面细胞器的产生对艰难梭菌定植宿主和致病能力的重要性。这一建议代表了了解艰难梭菌疾病的一个全新的研究领域：控制艰难梭菌定植因素的细胞内信号通路。通过定义规则和 鞭毛和IV型菌毛的功能，这些研究将极大地扩展我们对 艰难梭菌控制宿主的定植，并可能揭示抑制肠道定植从而预防疾病的靶标。

DESCRIPTION (provided by applicant): Clostridium difficile is a Gram-positive, obligate anaerobe that causes diseases ranging from antibiotic- associated diarrhea to pseudomembranous colitis. In recent years, the incidence and severity of C. difficile infections has increased. Yet there is only limited knowledge of fundamental aspects of pathogenesis, such as the mechanisms used by the bacterium to attach to the intestinal epithelium. Because colonization of the host is a prerequisite for establishing an infection, it is imperative that the mechanisms underlying bacterial attachment to host tissues be defined, as this will drive the much-needed development of additional treatment and prevention options. The long-term goal of this project is to understand how C. difficile attaches to and maintains colonization of the intestinal epithelium. The objective of this proposal is to determine how flagella and Type IV pili as well as the mechanisms controlling their production, impact the ability of C. difficile to colonize host tissues. The central hypothesis of this study is that the bacterial signaling molecule c-di-GMP oppositely regulates the biosynthesis of flagella and Type IV pili, allowing their production at appropriate stages of colonization. This hypothesis will be tested with the following three specific aims. Specific aim 1 is to determine the effect of the Type IV pilus and is regulation by c-di-GMP on intestinal colonization and virulence. Specific aim 2 is to determine how flagellar genes are regulated by c-di-GMP and how regulation affects virulence. Specific aim 3 is to determine the spatial and temporal patterns of Type IV pilus and flagellum production during infection and the importance of coordinating production of these surface organelles on the ability of C. difficile to colonize the host and cause disease. This proposal represents an entirely new area of investigation toward understanding C. difficile disease: the intracellular signaling pathways controlling colonization factors of C. difficile. By defining the regulation and function of flagella and Type IV pili, these studies will significantly expand our knowledge of how C. difficile controls colonization of the host and may reveal targets for inhibition of intestinal colonization to thereby prevent disease.