The Contribution of Ribonuclease 7 to Urinary Tract Anitbacterial Defense

摘要 尿路感染(UTI)，包括肾盂肾炎，是最常见和最严重的感染之一 在临床实践中。目前尚无已证实的治疗方案可预防尿路感染。需要新的战略来增强 宿主防御，以预防尿路感染并最大限度地减少尿路感染相关的发病率。来自我们实验室的越来越多的证据 另一些人则认为，抗菌肽(AMP)是先天性免疫反应的重要组成部分，它可以保护 尿路不受侵袭性细菌感染。我们的研究小组已经发现核糖核酸酶7(RNase7)是一种有效的 高度丰富的人AMP，保护尿路上皮免受致尿路病原性大肠杆菌(UPEC)的侵袭。我们公布的数据表明 RNase7是开发为尿路感染治疗药物的理想AMP，因为：(A)它具有强大的抗菌活性；(B)它是 在尿路中高度丰富；(C)它是由UPEC靶向的细胞类型产生的；以及(D)它含有最少的 毒性。我们新出现的数据表明，诱导RNase7保护尿路上皮免受UPEC的影响，同时抑制RNase7 生产使其容易受到病原体的影响。总之，这些发现为我们的中心假设提供了强有力的支持 RNase7是维持尿液无菌和预防尿路感染所必需的生物学特性。我们目前对核糖核酸酶的理解 7‘S对先天防御的影响在体内是有限的，因为它在实验小鼠中没有表达，而且仅限于 高等脊椎动物和人类。为了填补这一关键知识空白，我们开发了两个新型人源化RNase7小鼠 模特们。这些模型将用于完成本应用程序的总体目标，即进一步研究 核糖核酸酶7在尿液不育中的重要作用。为了检验我们的中心假设，我们将评估细胞特异性 利用一种新型的rosa26敲入小鼠(目标1)，RNase7的表达影响体内尿路感染的风险。在目标2中，我们将调查 利用一种新型人源化转基因小鼠调控RNase7表达的分子机制 RNase7在其自身启动子的控制下。在目标3中，我们将评估人类基因多态如何影响 核糖核酸酶7的表达和抗菌活性。拟议目标的完成将进一步界定必要的 RNase7在尿液不育中的作用，并可能为开发RNase7作为一种新的治疗尿性不孕症的药物提供基础 改善尿路感染结果。考虑到尿路感染的临床影响，在一个出现耐药尿路病原体的时代， 确定开发RNase7作为一种新的尿路感染疗法的机制可能对公众健康有重大好处。

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.