Delineating the importance of intracellular tissue occupation by Uropathogenic E.

描述(申请人提供)：尿路感染(UTI)是最常见的细菌感染之一，占巨大的发病率和医疗费用。多达60%的女性在一生中将经历尿路感染，其中25%至40%的女性因抗拒抗生素治疗而频繁复发。超过80%的社区获得性尿路感染和50%的医院尿路感染是由尿路致病性大肠埃希菌(UPEC)引起的。UTI的发病机制是复杂的，UPEC能够在膀胱和肾脏内定植多个壁龛。UPEC利用表面表达的细胞外细胞器1型菌毛附着、侵袭和复制膀胱上皮中终末分化的浅表小面CLL。UPEC逃离胞内空泡，在细胞质中复制成被称为细胞内细菌群落(IBCs)的大的生物膜样团块。在这种环境中，UPEC迅速复制，并受到保护，不受先天性免疫反应的影响，也不受排尿的清除。此外，IBCs内的UPEC对抗生素治疗具有抵抗力，否则抗生素治疗对肉汤培养中生长的微生物有效。在小鼠模型中，IBCs的形成是膀胱细菌定植的关键，在反复发生尿路感染的妇女的尿液中也检测到IBCs。了解UPEC侵袭和细胞内复制能力的发病机制，对于确定预防膀胱侵袭和持久性的新疗法的靶点至关重要。最近的数据表明，在实验中将细菌接种到小鼠尿路后的第一个24小时内，IBCs的形成构成了一个强大的种群瓶颈，限制了细菌多样性的发展到感染的后期阶段。此外，在同一时间段内，诱导强大的免疫反应使小鼠容易经历持续性菌尿和慢性膀胱炎。这一建议探索了一种假设，即在急性感染期间占据细胞内的生态位直接导致免疫反应，从而使宿主容易出现持续性菌尿和复发性/慢性膀胱炎。利用一种具有良好特征的UTI小鼠模型，将确定急性UTI期间戏剧性瓶颈的分子机制，急性致病事件与UTI长期结局之间的直接关系，以及顺序膀胱接种对感染的影响。本研究的目的是调查急性尿路感染发病机制中影响感染结局的关键事件。这项研究的完成将有助于确定发病机制中的关键事件，可以通过新的治疗方法来针对这些事件来限制尿路感染的发病率。

DESCRIPTION (provided by applicant): Urinary tract infections (UTIs) are among the most common bacterial infections, accounting for tremendous morbidity and healthcare costs. Up to 60% of women will experience a UTI in her lifetime, with between 25 and 40% of these women suffering frequent recurrences, recalcitrant to antibiotic therapy. More than 80% of community acquired and 50% of nosocomial UTIs are caused by uropathogenic E. coli (UPEC). The pathogenesis of UTI is complex with UPEC capable of colonizing multiple niches within the bladder and the kidneys. UPEC utilize surface expressed extracellular organelles known as type 1 pili to attach to, invade, and replicate within the terminally differentiated superficial facet clls in the bladder epithelium. UPEC escape the endocytic vacuole and replicate in cytoplasm into large biofilm-like masses called intracellular bacterial communities (IBCs). Within this environment, UPEC replicate rapidly and are protected from elements of the innate immune response as well as clearance by micturition. Furthermore, UPEC within IBCs are resistant to antibiotic therapy that is otherwise effective against the organisms grown in broth culture. Formation of IBCs is essential for bacterial colonization of the bladder in mouse models, and IBCs have been detected in urine from women suffering recurrent UTI. Understanding the pathogenesis of UPEC with regard to its ability to invade and replicate intracellularly is paramount to identifying targets for novel therapeutics that prevent bladder invasion and persistence. Recent data suggests that the formation of IBCs within the first 24 hours after experimental inoculation of bacteria into the murine urinary tract constitutes a robust population bottleneck restricting bacterial diversity progressing to later stages of infection. Furthermore, during this same time period, the induction of a robust immune response predisposes mice to experience persistent bacteriuria and chronic cystitis. This proposal explores the hypothesis that occupation of an intracellular niche during acute infection directly leads to an immune response predisposing the host to persistent bacteriuria and recurrent/chronic cystitis. Utilizing a well- characterized murine model of UTI, the molecular mechanisms accounting for the dramatic bottleneck during acute UTI, the direct relationship between acute pathogenic events and long-term UTI outcome, and the impact of sequential bladder inoculation on infection will be determined. The objectives of this research are to investigate the key events during acute UTI pathogenesis that impact infection outcome. Completion of this research will help to identify key events in pathogenesis that can be targeted with novel therapeutics to limit the morbidity of UTI.