Molecular Mechanisms of Clostridium difficile Resistance to Innate Host Defenses

描述（由申请方提供）：艰难梭菌引起一种潜在的致命性肠道疾病，其发病率和严重程度正在增加。这些感染通常是慢性的，难以根除。尽管这种微生物给公共卫生带来了巨大的负担，但人们对C。艰难梭菌逃避宿主的防御而在人的肠道内定居。为了生存，细菌必须科普宿主防御的持续攻击。这个项目的长期目标是揭示C。艰难梭菌逃避宿主的先天免疫，目的是开辟新的治疗途径。本申请的具体目标是定义机制C。艰难梭菌用于抵抗宿主产生的阳离子抗菌肽（CAMP）。这些肽在宿主先天防御中起着关键作用，防止细菌的生长和传播。初步数据表明，C.艰难梭菌可以响应并适应CAMPs的存在。我假设C.艰难梭菌已经进化出多种耐药机制，使细菌能够绕过宿主免疫反应，如CAMP，使其能够在人类肠道中定植和复制。本研究将为进一步阐明C.艰难梭菌，鉴定和表征CAMP抗性机制的调节，并确定这些机制在体内毒力和定殖中的作用。CAMP抗性将使用传统的遗传和生物化学方法，沿着新技术，如快速全基因组测序进行研究。这些目标的成功实现将阐明C. difficile感染和鉴定用于治疗疾病的潜在治疗靶点。此外，这些知识将使我们更好地理解肠道中宿主-细菌相互作用如何导致消化系统疾病。在这个建议中概述的实验将帮助我学习广泛的分子遗传学，生物化学，和动物研究技术，我以前没有使用过，也掌握使用这种重要的医院病原体的方法。最终，这项工作将为我未来的C语言研究奠定基础。艰难的发病机制，并为我过渡到一个独立的研究者的立场提供了框架。

DESCRIPTION (provided by applicant): Clostridium difficile causes a potentially fatal intestinal disease that is increasing in incidence and severity. These infections are often chronic and incredibly difficult to eradicate. Though this organism presents an enormous public health burden, little is understood about how C. difficile evades host defenses to colonize the human intestine. In order to persist, the bacteria must cope with a continuous onslaught by host defenses. The long-term goal of this project is to reveal how C. difficile evades host innate immunity with the intent of opening new avenues for treatment. The specific objective of this application is to define the mechanisms C. difficile employs to resist cationic antimicrobial peptides (CAMPs) produced by the host. These peptides play a critical role in host innate defenses, preventing the growth and spread of bacteria. Preliminary data obtained thus far indicate that C. difficile can respond and adapt to the presence of CAMPs. I hypothesize that C. difficile has evolved multiple resistance mechanisms that allow the bacterium to bypass host immune responses, such as CAMPs, allowing it to colonize and replicate in the human intestine. This proposal will identify the genetic mechanisms of CAMP resistance in C. difficile, identify and characterize the regulation of CAMP resistance mechanisms, and determine the role of these mechanisms in the virulence and colonization in vivo. CAMP resistance will be studied using traditional genetic and biochemical methods, along with new technologies, such as rapid, whole-genome sequencing. Successful completion of these aims will illuminate fundamental aspects of C. difficile infection and identify potential therapeutic targets for treatment of disease. Furthermore, this knowledge will better our understanding of how host-bacterial interactions in the intestine can lead to digestive diseases. The experiments outlined in this proposal will help me learn a wide range of molecular genetics, biochemistry, and animal research techniques I have not previously used, and also to master methods for use with this important hospital pathogen. Ultimately, this work will set the stage for my future research on C. difficile pathogenesis and provide the framework for my transition into an independent investigator position.