A novel diabetic co-infection model to study pathogen interaction during coinfection

抽象的。 人类中的几种细菌感染是多菌的，包括金黄色葡萄球菌和假单胞菌 经常从同一感染部位共培养。金黄色葡萄球菌和铜绿假单胞菌所在的两个种群 常见于糖尿病患者的皮肤和软组织感染以及囊性病变的肺部。 纤维化(CF)。与CF相关的一种常见并发症是CF相关性糖尿病(CFRD)，它与 与非糖尿病的CF患者相比，肺功能减退的速度更快，死亡率更早。最初， 本病的主要病原菌为金黄色葡萄球菌。然而，金黄色葡萄球菌最终被铜绿假单胞菌取代，成为 最主要的病原体。相反，在CFRD患者中，金黄色葡萄球菌重新出现在P。 铜绿假单胞菌和铜绿假单胞菌都是肺部感染的主要原因。因为 由于缺乏体内模型，许多实验室研究了金黄色葡萄球菌和铜绿假单胞菌之间的体外相互作用。 定义它们在CF Airways中如何相互影响的目标。然而，这些研究已经 有几个限制，因为它们不在免疫反应的上下文中，而是在条件下执行 不能准确反映感染的动态微环境。此外，体外研究不能 充分复制糖尿病感染。在这里，我们描述了一种新的小鼠联合感染模型，该模型允许我们 动态宿主环境中金黄色葡萄球菌与铜绿假单胞菌相互作用的研究 免疫系统在正常和糖尿病感染的背景下。铜绿假单胞菌不能在单细胞- 在我们的模型中感染。然而，在合并感染期间，我们观察到铜绿假单胞菌在 金黄色葡萄球菌的存在。此外，我们还观察了铜绿假单胞菌在合并感染时杀死金黄色葡萄球菌的能力。 在正常小鼠身上。相反，在糖尿病小鼠中，我们观察到金黄色葡萄球菌和P. 铜绿假单胞菌与正常小鼠比较。我们还观察到这两个物种的毒力潜力在 糖尿病合并感染，既侵袭周围组织，又扩散至周围器官。IS的目标1 该提案旨在确定金黄色葡萄球菌是如何形成混合感染微环境的，以允许P。 铜绿假单胞菌的生长以及确定铜绿假单胞菌杀死金黄色葡萄球菌的机制。我们 假设金黄色葡萄球菌产生的代谢物被铜绿假单胞菌用作生长碳源 在合并感染期间，铜绿假单胞菌随后产生有毒产品，杀死金黄色葡萄球菌。在目标2中 这一建议，我们试图确定机制，使金黄色葡萄球菌成为免疫的P。 铜绿假单胞菌以及使这两个物种在糖尿病感染中变得更具毒力的机制。 我们假设，感染环境中的过量葡萄糖允许金黄色葡萄球菌将其新陈代谢转移到 抵抗铜绿假单胞菌产生的有毒产物。此外，我们还提出葡萄糖可促进 毒力因子在两个物种中的表达导致了毒力的增强。总而言之，我们试图理解 并定义在正常和糖尿病环境中无法进行测试的复杂微生物相互作用 传统的模型。

Abstract. Several bacterial infections in humans are polymicrobial with Staphylococcus aureus and Pseudomonas frequently co-cultured from the same infection site. Two populations where S. aureus and P. aeruginosa are frequently found together are diabetic skin and soft tissue infections and in the lungs of patients with cystic fibrosis (CF). A common comorbidity associated with CF is CF-related diabetes (CFRD) that is associated with accelerated rates of pulmonary decline and earlier mortality compared to non-diabetic CF patients. Initially the dominant pathogen in CF lungs is S. aureus. However, S. auerus is eventually replaced by P. aeruginosa as the dominant pathogen. Conversely, in patients with CFRD, S. aureus re-emerges in the presence P. aeruginosa where both are responsible for a significant amount of pulmonary infections. Because of the absence of an in vivo model, many labs study interactions between S. aureus and P. aeruginosa in vitro with the goal of defining how they might interact with each other in CF airways. However, these studies have several limitations in that they are outside the context of an immune response and are performed in conditions that do not accurately reflect the dynamic infection microenvironment. Moreover, in vitro studies cannot adequately replicate diabetic infections. Here we describe a novel murine co-infection model that allows us to study the interactions between S. aureus and P. aeruginosa in a dynamic host environment with an intact immune system in the context of normal and diabetic infections. P. aeruginosa does not survive in a mono- infection in our model. However, during co-infection we observed the ability of P. aeruginosa to grow in the presence of S. aureus. Additionally, we observe the ability of P. aeruginosa to kill S. aureus during co-infection in normal mice. Conversely, in diabetic mice, we observed increased growth of both S. aureus and P. aeruginosa compared to normal mice. We also observed increased virulence potential of both species in diabetic co-infection as both invade surrounding tissues and disseminate to peripheral organs. Aim 1 of the is proposal seeks to identify how S. aureus “terraforms” the co-infection microenvironment to allow for P. aeruginosa growth as well as determine the mechanisms employed by P. aeruginosa to kill S. aureus. We hypothesize that metabolites produced by S. aureus are used by P. aeruginosa as carbon sources for growth during co-infection, and that P. aeruginosa subsequently produces toxic products that kill S. aureus. In aim 2 of this proposal we seek to identify the mechanisms that allow S. aureus to become immune to killing by P. aeruginosa as well as the mechanisms that allow both species to become more virulent in diabetic infections. We hypothesize that excess glucose in the infection environment allows S. aureus to shift its metabolism to resist the toxic products produced by P. aeruginosa. We additionally propose that glucose promotes the expression of virulence factors in both species resulting in enhanced virulence. In total, we seek to understand and define complex microbial interactions in normal and diabetic environments that cannot be tested in conventional models.