Investigating the impact of collagenase in Clostridioides difficile pathogenesis

项目总结 艰难梭状芽胞杆菌是抗生素相关性腹泻的主要原因，有超过22.3万人感染，几乎 美国每年有1.3万人死亡，10亿美元的医疗费用。艰难梭菌感染开始 当有感染性的孢子被摄取并在胃肠道(GI)中萌发时产生营养体 导致这种疾病的细胞。为了确定感染，艰难梭菌必须定植在人的结肠上， 然而，艰难梭菌能够成功定植于肠道的因素在很大程度上仍不清楚。 已知胶原酶和明胶酶等水解酶有助于多种病原体 通过促进对宿主组织的渗透，在人体内定植不同的利基，有助于 传播毒素，增加可供病原体使用的营养物质。这些酶允许 哺乳动物组织中普遍存在的胶原蛋白及其衍生明胶的降解 (包括胃肠道组织)。我推测艰难梭菌中的胶原酶是定植的 允许这种细菌降解宿主胶原蛋白和明胶的因素，以及这些水解物 活性改善艰难梭菌的肠道定植和在肠道中的持久性，以增加毒力。这个 这项应用的总体目标是确定什么酶(S)负责胶原蛋白的溶解和 艰难梭菌菌株中观察到的明胶溶解活性，以及这些活性如何影响致病机理和宿主。 为了验证这一假设，并追求总体目标，我决心完成以下具体工作 目的：目的：1.确定U32多肽酶CD0703和CD1228在胶原和明胶降解中的作用。 目的2.研究胶原酶/明胶酶在艰难梭菌致病和定植中的作用。 宿主肠道。这些目标的完成将确定负责水解酶活性的酶(S) 在艰难梭菌中观察，并确定这些水解酶活性在艰难梭菌感染过程中的贡献。 阐明这些可能为预防或治疗艰难梭菌感染提供新的靶点。

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.