Defining the role of Serratia marcescens nuclease in infection process

项目摘要 细菌耐药性的出现，特别是在医院环境中，代表着下一个 医疗保健领域的巨大挑战。粘质沙雷氏菌，革兰氏阴性杆菌 对几种抗生素的固有耐药性，可导致严重后果的感染 影响到多个身体部位。这种细菌还与腹膜并发症有关。 肾衰竭患者的透析(PD)。重要的是，沙雷氏菌相关性腹膜炎 伴中性粒细胞大量渗入的不分辩率最高 在由革兰氏阴性细菌引起的导致帕金森病患者死亡的发作中， 或拔除导尿管并转移至血液透析。我们对S.的理解取得了进展。 粘菌感染由于缺乏可靠的临床前模型而受到阻碍，这代表了一种 在这一领域取得进展的关键障碍。目前对该组织使用的策略的了解 定植于哺乳动物宿主并逃避免疫反应的机会性病原体不是 到目前为止，只发现了少数几个致病因子。已知粘质链霉菌 分泌一系列水解酶，包括糖非特异性核酸内切酶；然而， 这种酶在感染过程中的生物学作用尚未得到评估。在这项提案中，我们 寻求建立一种研究粘质葡萄球菌动态传播的小鼠模型 并检验一种假设，即粘质链球菌胞外酶 核酸酶在细菌逃逸中性粒细胞胞外陷阱(Net)中起着关键作用 利基市场。在目标1中，我们将描述以下传播的生物发光粘质链霉菌 利用活体成像进行腹膜内感染的研究。在目标2中，我们将首先评估粘质链霉菌 中性粒细胞样细胞培养中降解Net的胞外核酸酶潜力 感染研究，以确定该酶在体内的生物学作用。这项提议将会取得进展 对沙雷氏菌致病机制的最新了解，并为细菌的策略提供洞察 以避免中性粒细胞介导的清除。总之，我们的实验将为 未来对其他产生核酸酶的病原菌的研究。

Project Summary The emergence of bacterial drug resistance, especially in hospital settings, represents the next great challenge in healthcare. Serratia marcescens, the Gram-negative bacterial pathogen with intrinsic resistance to several classes of antibiotics, can cause infections with severe outcomes affecting multiple body sites. This bacterium is also associated with complications of peritoneal dialysis (PD) in patients with kidney failure. Importantly, Serratia-associated peritonitis accompanied by massive neutrophil infiltration was shown to have the highest nonresolution rate among episodes caused by Gram-negative bacteria, leading either to the death of the PD patient, or catheter removal and transfer to hemodialysis. The progress in our understanding of S. marcescens infections is hampered by the lack of reliable preclinical model, which represents a critical barrier to progress in the field. The current knowledge of strategies used by this opportunistic pathogen to colonize the mammalian host and to evade the immune response is not complete, and only a handful of virulence factors were identified to date. S. marcescens is known to secrete an array of hydrolytic enzymes, including sugar non-specific endonuclease; however, the biological role of this enzyme during infection has not been evaluated. In this proposal, we seek to establish a murine model to study the S. marcescens dynamic spread during intraperitoneal infection and to test a hypothesis that an extracellular S. marcescens enzyme nuclease plays a key role in bacterial escape from neutrophil extracellular traps (NETs) in this niche. In Aim 1 we will characterize the bioluminescent S. marcescens spread following intraperitoneal infection using in vivo imaging. In Aim 2 we will first evaluate the S. marcescens extracellular nuclease potential to degrade NETs in cultures of neutrophil-like cells, followed by infection study to determine the biological role of this enzyme in vivo. This proposal will advance current understanding of Serratia pathogenesis and provide insight into the bacterium’s strategy to avoid neutrophil-mediated clearance. Altogether, our experiments will establish a blueprint for future studies of other nuclease-producing pathogenic bacteria.