Investigating the impact of collagenase in Clostridioides difficile pathogenesis

项目摘要 艰难梭菌是腹泻相关性腹泻的主要原因，有超过223，000例感染，几乎所有的感染都是由梭菌引起的。 在美国每年有13,000人死亡，10亿美元的医疗费用。C.艰难感染开始 当感染性孢子被摄入并在胃肠道（GI）中萌发产生营养体时， 导致疾病的细胞。为了建立感染，C.艰难梭菌必须定殖于人类结肠， 然而，允许C.很难成功地定殖在肠道中的细菌仍然在很大程度上是未知的。 已知水解酶如胶原酶和明胶酶帮助多种病原体降解， 通过促进渗透到宿主组织中，在人体内的不同小生境中定殖， 传播毒素，并增加病原体使用的营养物质的可用性。这些酶使 胶原蛋白及其衍生物明胶的降解是哺乳动物组织中普遍存在的成分 （包括胃肠道组织）。我推测C.艰难的是殖民化 这些因子允许这种细菌降解宿主胶原蛋白和明胶， 活动改善C。艰难的肠道定植和在肠道中的持久性增加毒力。的 本申请的总体目的是鉴定什么酶负责胶原溶解， C.艰难菌株，以及这些活动如何影响发病机制和宿主。 为了验证这一假设，并在追求的总体目标，我决心完成以下具体 目标：目标1。确定U32肽酶CD 0703和CD 1228在胶原和明胶降解中的作用。 目标2.检测胶原酶/明胶酶在C.艰难的发病机制和定植 宿主的肠道这些目标的完成将确定负责水解活动的酶 在C. difficile，并确定这些水解活性在C.艰难感染 阐明这些可能为预防或治疗C。艰难感染

PROJECT SUMMARY Clostridioides difficile is the leading cause of antibiotic-associated diarrhea, with over 223,000 infections, almost 13,000 deaths, and 1 billion dollars in healthcare cost in the United States every year. C. difficile infection starts when infectious spores are ingested and germinate in the gastrointestinal (GI) tract to produce the vegetative cells that cause the disease. In order to establish an infection, C. difficile must colonize the human colon, however, the factors that allow C. difficile to successfully colonize the intestine remain largely unknown. Hydrolytic enzymes such as collagenases and gelatinases have been known to help multiple pathogens to colonize distinct niches within the human body by facilitating penetration into host tissues, contributing to the dissemination of toxins, and increasing the availability of nutrients for the pathogen to use. These enzymes allow the degradation of collagen and its derivative gelatin, which are ubiquitous components of mammalian tissues (including gastrointestinal tissue). I hypothesize that the collagenase enzymes in C. difficile are colonization factors that allow this bacterium to degrade host collagen and gelatin, and that these hydrolytic activities improve C. difficile intestinal colonization and persistence in the gut to increase virulence. The overall objective of this application is to identify what enzyme(s) are responsible for the collagenolytic and gelatinolytic activities observed in C. difficile strains, and how these activities impact pathogenesis and the host. To test this hypothesis, and in pursuit of the overall goal, I am determined to complete the following Specific Aims: Aim 1. Determine the role of U32 peptidases CD0703 and CD1228 in collagen and gelatin degradation. Aim 2. Examine the role of the collagenase/gelatinase in C. difficile pathogenesis and colonization of the host intestine. The completion of these aims will identify the enzyme(s) responsible for the hydrolytic activities observed in C. difficile and determine the contribution of these hydrolytic activities during C. difficile infection. Elucidating these could provide novel targets for prevention or treatment of C. difficile infection.