Mucosal Immune Defense Mechanisms of the Urinary Bladder

摘要：复杂的粘膜网络影响尿路感染(UTI)的转归。导致的尿路感染 尿路致病性大肠埃希菌(UPEC)是常见的、高度复发的，也是抗生素治疗的主要原因 为健康的成年女性准备的。因此，随着抗生素耐药性的可怕预测达到临界点，它 必须更好地了解反复发生的尿路感染(RUTI)的机制，以避免未来通常 可治疗的感染变得无法控制。20%-30%的女性在初次就诊后6个月内复发 感染。事实上，尿路感染病史是继发尿路感染的独立危险因素。老鼠模型已经表明， 一旦UPEC感染膀胱，就会发生长期的膀胱粘膜重塑，其性质是 取决于炎症和感染史，这改变了对后续感染的易感性。这 重塑，或对先前感染的“记忆”，可以包括：1)膀胱上皮通过 表观遗传重新编程；二)适应性免疫反应，有时是保护性的；三)干扰 由于口服抗生素治疗而导致的肠道微生物区系失调。原代培养的上皮干细胞 从有感染史的小鼠的膀胱中可以概括出许多重新编程的形态和基因 在恢复期的小鼠膀胱中出现了表达特征。此外，CD_4~+和CD_8~+T细胞耗竭 细胞改变了对相同菌株复发的敏感性。UPEC还与胃肠道(Git)相互作用。 微生物区系，直接受胃肠道免疫功能的影响，如细胞因子的产生 白介素22(IL-22)，调节粘蛋白的产生，并诱导抗菌因子的表达，从而 防止侵入性殖民。胃肠道微生物区系反过来又形成粘液的组成。了解如何 因此，Git微生物区系和粘膜协同工作以限制UPEC的定植是理解的关键 UPEC与东道主的关系。这项建议旨在调查以前的感染是如何导致训练有素的 通过以下方式改变后续感染的反应和结果的免疫：i)使用健壮的小鼠感染 模型以及培养的原代细胞以探索小鼠来源的细胞系之间的染色质修饰 有不同的尿路感染病史和对RUTI的易感性，特别关注编程细胞 死亡相关基因，以及肿瘤坏死因子α和环氧合酶-2(目标1)；二)探索 既往感染对膀胱粘膜获得性免疫形成的影响及其调节机制 对反复感染的易感性(目标2)；和三)通过以下方式确定微生物和粘膜免疫机制 肠粘膜限制UPEC在健康和生物失调中的定植及IL-22及其结合的作用 伙伴IL-22结合蛋白调节微生物区系和粘液的数量和质量(目标3)。优势所在 这一建议的目的是试图了解不同形式的感染记忆，这些记忆是在应对 初始感染包括：i)训练免疫；ii)获得性免疫；iii)肠道生态失调以及这些宿主如何- 病原体的相互作用会导致表观遗传印记，这容易导致未来的感染。

ABSTRACT: Complex mucosal networks impact the outcome of a urinary tract infection (UTI). UTIs caused mostly by uropathogenic E. coli (UPEC) are common, highly recurrent, and a leading cause of antibiotic therapy for otherwise healthy adult women. Thus, with dire predictions of antibiotic resistance reaching a tipping point, it is imperative to better understand the mechanisms of recurrent UTIs (rUTIs) to avoid a future where ordinarily treatable infections become unmanageable. 20-30% of women have a recurrence within 6 months of their initial infection. In fact, history of UTI is an independent risk factor for subsequent UTI. Mouse models have shown that upon UPEC infection of the bladder, a long-term remodeling of the bladder mucosa occurs, the nature of which depends upon the inflammatory and infection history, which alters susceptibility to subsequent infection. This remodeling, or “memory” of a prior infection, can include i) “trained immunity” of the bladder epithelium through epigenetic reprogramming; ii) an adaptive immune response, which is sometimes protective; and iii) disruptions of the gut microbiota due to oral antibiotic therapy leading to dysbiosis. Primary epithelial stem cells cultured from bladders of mice with a history of infection recapitulate many of the reprogrammed morphologic and gene expression features present in the convalescent mouse bladder. In addition, depletion of CD4+ and CD8+ T- cells alters susceptibility to same-strain recurrence. UPEC also interact with the gastrointestinal tract (GIT) microbiota, which is directly influenced by immune functions in the GIT, such as production of the cytokine interleukin 22 (IL-22), which regulates mucin production and induces the expression of antimicrobial factors that prevent invasive colonization. The GIT microbiota in turn shapes the composition of mucus. Understanding how the GIT microbiota and mucosa work in concert to restrict UPEC colonization is therefore key to understanding UPEC's relationship with the host. This proposal seeks to investigate how a prior infection leads to trained immunity that alters the response and outcome of subsequent infections by: i) using robust mouse infection models as well as cultured primary cells to probe chromatin modifications between cell lines derived from mice with differential UTI disease histories and susceptibilities to rUTI, with particular focus on Programmed Cell Death-associated genes, as well as tumor necrosis factor alpha and cyclooxygenase-2 (Aim 1); ii) probing how prior infection shapes the formation of adaptive immunity at the bladder mucosa and how that modulates susceptibility to recurrent infection (Aim 2); and iii) identifying microbial and mucosal immune mechanisms by which the gut mucosa restricts UPEC colonization in health and dysbiosis and the roles of IL-22 and its binding partner IL-22 binding protein in regulating the microbiota and mucus quantity and quality (Aim 3). The strength of this proposal is that it seeks to understand different forms of infection memory that develop in response to an initial infection including: i) trained immunity; ii) adaptive immunity; and iii) gut dysbiosis and how these host- pathogen interactions lead to epigenetic imprints that predispose to future infections.