The role of cytochrome bd in uropathogenic Escherichia coli pathogenesis

项目总结 生物被膜是与大多数细菌感染有关的多细胞细菌群落，几乎所有 慢性细菌感染。这些社区几乎不可能通过传统的方式根除 癌症是一种化疗方法，对人类健康构成重大威胁。生物被膜细菌分泌一种 细胞外基质(ECM)，限制吞噬细胞、补体、抗生素和其他外部物质的能力 与生物膜细菌相互作用的压力源。因此，生物被膜对抗生素和 免疫系统，通常需要生物被膜相关感染的患者接受长期的 抑制性抗生素或接受手术切除感染组织。除了抑制病毒的渗入 抗生素和免疫防御，ECM限制营养物质的扩散，如氧气，这些营养物质与 利用驻留细菌的代谢活动，在生物膜内建立氧梯度，使 生物膜内部缺氧。几项研究已经证明，氧气梯度在 有弹性的生物膜群落的发展，在生物膜中，氧气的可用性是 细菌代谢和细胞外基质成分的表达。泌尿系致病大肠杆菌的研究进展 尿路感染的主要原因(UPEC)已经证明，尽管是一种临时性的 厌氧菌，UPEC在感染过程中依靠好氧呼吸形成生物膜群落。通过我的 论文研究表明，UPEC异源表达呼吸酶，而这些酶 酶在离散的亚群中表达。尽管表达的多样性，只有表达 细胞色素BD是低氧条件下有氧呼吸所必需的一种高亲和力的喹酚氧化酶， 是UPEC发病和生物被膜形成所必需的。细胞色素BD的丢失，但不是其他喹酚氧化酶的丢失， 破坏生物膜的发育，改变细胞外基质的产生，增加对抗生素的敏感性，并损害 在小鼠感染模型中的毒力。这项提案概述了一系列实验，这些实验将定义 细胞色素BD在尿路感染发病机制中的作用及UPEC形成生物膜的能力 能够承受抗生素治疗和免疫攻击的社区。完成这项提案将 确定限制细胞色素BD缺陷的UPEC定植的瓶颈，生化确定其作用 细胞色素BD在尿路感染细胞内期的表达，并确定其机制 细胞色素BD促进耐药生物膜的形成。这些研究将产生基本的 洞察中枢代谢过程的适应如何使细菌适应不同的宿主生态位和 建立有弹性的生物被膜群落，同时也研究细胞色素BD作为潜在的药物靶点来帮助 在预防或根除与生物膜相关的感染方面。

PROJECT SUMMARY Biofilms are multicellular bacterial communities implicated in the majority of bacterial infections, and nearly all chronic bacterial infections. These communities are nearly impossible to eradicate by traditional chemotherapeutic approaches and represent a major threat to human health. Biofilm bacteria secrete an extracellular matrix (ECM) that limits the ability for phagocytes, complement, antibiotics, and other external stressors to interact with biofilm bacteria. Accordingly, biofilms are highly resistant to antibiotics and the immune system, often necessitating that patients with biofilm-associated infections receive long-term suppressive antibiotics or undergo surgery to remove infected tissues. In addition to inhibiting penetrance of antibiotics and immune defenses, the ECM limits diffusion of nutrients such as oxygen, which, in conjunction with the metabolic activity of resident bacteria, establishes oxygen gradients within biofilms that render the interior of biofilms hypoxic. Several studies have demonstrated that oxygen gradients play a critical role in the development of resilient biofilm communities, and that in biofilms oxygen availability is a central regulator of bacterial metabolism and expression of ECM components. Previous work in uropathogenic Escherichia coli (UPEC), the primary cause of urinary tract infections, has demonstrated that despite being a facultative anaerobe, UPEC relies on aerobic respiration during infection and to form biofilm communities. Through my thesis research, I have shown that UPEC heterogeneously expresses respiratory enzymes, and that these enzymes are expressed in discrete subpopulations. Despite this heterogeneity of expression, only expression of cytochrome bd, a high affinity quinol oxidase necessary for aerobic respiration under hypoxic conditions, is required for UPEC pathogenesis and biofilm formation. Loss of cytochrome bd, but not other quinol oxidases, disrupts biofilm development, alters ECM production, increases susceptibility to antibiotics, and impairs virulence in a murine model of infection. This proposal outlines a series of experiments which will define the role of cytochrome bd in urinary tract infection pathogenesis and the ability for UPEC to form biofilm communities capable of withstanding antibiotic therapy and immune assault. Completion of this proposal will identify bottlenecks that restricts colonization by cytochrome bd deficient UPEC, biochemically define the role of cytochrome bd in the intracellular phase of urinary tract infection, and define mechanisms by which cytochrome bd promotes the formation of antibiotic tolerant biofilms. These studies will yield fundamental insights into how adaptation of central metabolic processes allows bacteria to adapt to diverse host niches and establish resilient biofilm communities, while also investigating cytochrome bd as a potential drug target to aid in the prevention or eradication of biofilm-associated infection.