S. aureus virulence factor expression during kidney abscess formation

项目摘要 抗生素耐药细菌感染正变得越来越普遍，葡萄球菌 特别是金黄色葡萄球菌感染具有很高的抗生素耐药性，这促使人们研究替代抗生素。 治疗策略。S.金黄色葡萄球菌疫苗已经开发出来，但迄今为止，所有疫苗在临床试验中都失败了， 由于S.金黄色葡萄球菌钝化免疫系统并阻断保护性免疫反应。S.金黄色 产生许多促进疾病的毒力因子，包括一个毒素库，直接针对 杀死宿主免疫细胞。几个S。金黄色葡萄球菌毒素特异性结合人类细胞，并且在 小鼠，使得难以剖析毒素在疾病过程中的具体作用。很少有模型能够 研究了S.金黄色葡萄球菌群落，它们产生的毒素，以及它们的人类细胞目标。 S.金黄色葡萄球菌在人类宿主中引起广泛的疾病表现，从皮肤和软组织 感染到菌血症和全身扩散到深部组织。当S.金黄色葡萄球菌进入血液， 细菌被困在肝脏，然后扩散到肾脏，形成称为脓肿的大病变。 脓肿包含一个紧密聚集的细菌的中心核心， 嗜中性粒细胞和巨噬细胞的外层。因为抗生素很难渗透到阴道， 它们可以在药物治疗后持续存在，并且可能是负责复发性 感染.更好地了解这些结构中细菌之间的相互作用， 与周围宿主细胞的相互作用，将是至关重要的，在发展未来的治疗，以更有效地 消除这些结构。 该建议将利用荧光转录报告基因来确定时空表达。 S.金黄色葡萄球菌毒素的表达在肾脏内的表达，也将在体外开发一种 系统研究宿主内病原体相互作用。我们假设，直接互动与 中性粒细胞和来自巨噬细胞的可扩散抗菌剂促进毒力因子的表达 特别是在女性生殖器的边缘。我们将利用荧光报告菌株， 免疫荧光显微镜检查，以确定毒素表达模式是否在 在我们的小鼠模型中肾脓肿形成，并确定这是否是由中性粒细胞的存在决定的 和巨噬细胞。我们还将使用3D琼脂糖液滴开发脓肿形成的体外模型， 包封细菌并将宿主细胞粘附到液滴表面。在这个模型中，我们将可视化动态 在存在和不存在小鼠和人原代吞噬细胞的情况下， 活体成像荧光显微术。建立这些系统来研究S.金黄色空间图案 宿主-病原体相互作用将使我们能够发现关键的S。aureus漏洞，这可能是 开发出更有效的治疗方法来对抗这种重要的人类病原体。

PROJECT SUMMARY Antibiotic-resistant bacterial infections are becoming increasingly more prevalent, and Staphylococcus aureus infections in particular have high rates of antibiotic resistance, prompting research into alternative treatment strategies. S. aureus vaccines have been developed, but all have failed in clinical trials to date, likely due to the ability of S. aureus to blunt the immune system and block protective immune responses. S. aureus produces many virulence factors that promote disease, including an arsenal of toxins, which directly target and kill host immune cells. Several S. aureus toxins specifically bind to human cells, and are not active in the mouse, rendering it difficult to dissect the specific role of toxins in the disease process. Few models exist to study interactions between S. aureus communities, the toxins they produce, and their human cell targets. S. aureus causes a wide range of disease manifestations in the human host, from skin and soft tissue infections to bacteremia and systemic spread to deep tissues. When S. aureus enters the bloodstream, bacteria are trapped in the liver, and then spread to the kidney to form large lesions called abscesses. Abscesses contain a central core of tightly clustered bacteria, with concentric layers of necrotic and live neutrophils, and an outer layer of macrophages. Because it is difficult to penetrate abscesses with antibiotics, they can persist follow drug treatment, and may represent one of the reservoirs responsible for recurrent infections. Better understanding of the interactions between bacteria within these structures, and the interactions with surrounding host cells, will be critical in developing future therapeutics to more efficiently eliminate these structures. This proposal will utilize fluorescent transcriptional reporters to determine the spatiotemporal expression patterns of S. aureus toxin expression within kidney abscesses, and will also develop an in vitro system to study host-pathogen interactions within abscesses. We hypothesize that direct interactions with neutrophils, and diffusible antimicrobials from macrophages, promotes expression of virulence factors specifically at the periphery of abscesses. We will utilize fluorescent reporter strains and immunofluorescence microscopy to determine whether toxin expression patterns change over the course of kidney abscess formation in our mouse model, and determine if this is dictated by the presence of neutrophils and macrophages. We will also develop an in vitro model of abscess formation using 3D agarose droplets to encapsulate bacteria and adhere host cells to the droplet surface. In this model, we will visualize the dynamics of virulence factor expression in the presence and absence of mouse and human primary phagocytes using live imaging fluorescence microscopy. Establishing these robust systems to study S. aureus spatial patterning and host-pathogen interactions will enable us to uncover key S. aureus vulnerabilities, which could be exploited to generate more efficacious treatments against this important human pathogen.