The Contribution of Ribonuclease 7 to Urinary Tract Anitbacterial Defense

摘要 尿路感染（UTIs），包括肾盂肾炎，是最常见和最严重的感染遇到 在临床实践中。目前还没有有效的治疗方案来预防UTI。需要新的战略来增强 宿主防御以预防UTI并最小化UTI相关的发病率。越来越多的证据来自我们的实验室 和其他研究表明，抗菌肽（AMP）是先天免疫反应的重要组成部分， 泌尿道感染。我们的研究小组已经确定核糖核酸酶7（RNase 7）是一种有效的， 高丰度的人AMP，保护尿路上皮免受尿路致病性大肠杆菌的侵害。大肠杆菌（UPEC）。我们公布的数据表明 RNase 7是开发为UTI治疗剂理想AMP，因为：（A）它具有有效的抗菌活性;（B）它 在泌尿道中高度丰富;（C）它由UPEC靶向的细胞类型产生;（D）它具有最小的 毒性我们的新数据表明，RNase 7诱导保护UPEC的尿路上皮，而抑制RNase 7， 生产使其易受病原体的影响。总之，这些发现为我们的中心假设提供了强有力的支持 RNase 7是维持尿液无菌性和预防UTI的生物学必需品。目前对RNase的认识 7对先天防御的影响在体内是有限的，因为它的表达在实验室小鼠中不存在，并且仅限于 高等脊椎动物和人类。为了填补这一关键的知识空白，我们开发了两种新的人源化RNase 7小鼠， 模型这些模型将用于完成本申请的总体目标，即进一步研究 RNase 7对尿不育的重要贡献。为了检验我们的中心假设，我们将评估细胞特异性 使用新型Rosa 26敲入小鼠，RNA酶7表达影响体内UTI风险（Aim 1）。在目标2中，我们将研究 使用一种新的人源化转基因小鼠调节RNase 7表达的分子机制， RNase 7在其自身启动子的控制下。在目标3中，我们将评估人类遗传多态性如何影响 RNase 7表达和抗微生物活性。完成拟议目标将进一步确定必要的 RNase 7对尿液不育的贡献，并可能为开发RNase 7作为一种新的治疗方法提供基础， 改善UTI结果。考虑到UTI的临床影响，在一个新出现的抗生素耐药性尿路病原体的时代， 确定开发RNase 7作为新UTI疗法的机制可能对公共卫生有重大益处。

ABSTRACT Urinary tract infections (UTIs), including pyelonephritis, are among the most common and serious infections encountered in clinical practice. No proven treatment options exist to prevent UTI. New strategies are needed to augment the ability of host defenses to prevent UTI and minimize UTI-associated morbidity. A growing body of evidence, from our laboratory and others suggests that antimicrobial peptides (AMP), an essential component of the innate immune response, protect the urinary tract from invasive bacterial infection. Our research team has identified Ribonuclease 7 (RNase 7) as a potent and highly abundant human AMP that shields the urothelium from uropathogenic E. coli (UPEC). Our published data suggest that RNase 7 is an ideal AMP to develop as a UTI therapeutic because: (A) it has potent antibacterial activity; (B) it is highly abundant in the urinary tract; (C) it is produced by cell types that are targeted by UPEC; and (D) it has minimal toxicity. Our emerging data suggest that RNase 7 induction shields the urothelium from UPEC, while suppressed RNase 7 production renders it susceptible to pathogens. Together, these findings provide strong support to our central hypothesis that RNase 7 is biologically necessary to maintain urine sterility and prevent UTI. Our current understanding of RNase 7's effects on innate defenses is limited in vivo because its expression is absent in the laboratory mouse and restricted to higher order vertebrates and humans. To fill this key knowledge gap, we developed two novel humanized RNase 7 mouse models. These models will be used to complete our overall objective of this application, which is to further investigate the essential contributions of RNase 7 to urine sterility. To test our central hypothesis, we will evaluate how cell-specific RNase 7 expression impacts UTI risk in vivo using a novel Rosa26 knock-in mouse (Aim 1). In Aim 2, we will investigate the molecular mechanisms that regulate RNase 7 expression using a novel humanized transgenic mouse that expresses RNase 7 under the control of its own promoter. In Aim 3, we will evaluate how human genetic polymorphisms affect RNase 7 expression and antimicrobial activity. Completion of the proposed Aims will further define the necessary contributions of RNase 7 to urine sterility and may provide the foundation to develop RNase 7 as a novel therapeutic that improves UTI outcomes. Given the clinical impact of UTI, in an era of emerging antibiotic resistant uropathogens, identifying mechanisms to develop RNase 7 as a new UTI therapy may have significant benefits to public health.