Expression data from infected mice bladder and kidney tissue. Mus musculus

Acute cystitis is rapidly becoming a therapeutic enigma, as antibiotic resistance is reducing the options to a minimum. Fortunately, new insights are now making it possible to explore immune response modifiers as alternatives to antibiotics. In patients with acute cystitis, infection triggers a rapid and potent inflammatory response in the bladder mucosa and clinical symptoms include pain, urgency and frequency of urination. The molecular basis of these symptoms is not well understood, but bacterial interactions with the bladder epithelium have been shown to create inflammatory cascades. This study examined how innate immune response genes influence the outcome of bladder infection and the pathogenesis of acute cystitis with a particular focus on IL-1β. C57BL/6 mice were intravesically infected with relevant uropathogenic Escherichia coli strain, CFT073. Acute cystitis in infected bladders was defined by macroscopic inspection of edema, hyperemia and purulent discharge followed by histology and immunohistochemistry, after 24 hours and seven days. Genetic determinants of transient bladder inflammation versus severe disease were subsequently identified using C57BL/6 mice with specific inflammasome gene deletions (Il1b-/-, Casp1-/-, Asc-/- and Nlrp3-/-). Using genome-wide transcriptomic analysis to characterize genes regulated by infection in the bladders of these mice, we identified acute cystitis as an IL-1β-driven, hyper-inflammatory disease. Consistent with such a role, Il1b-/- mice were protected from infection and pathology. In contrast Asc-/- and Nlrp3-/- mice developed progressive IL-1β-driven bladder inflammation and severe pathology, caused by a new, non-canonical IL-1β processing mechanism, involving the metalloproteinase MMP-7. Using IL-1β and MMP-7 as targets for immunotherapy, we succeeded in protecting susceptible Asc-/- mice against acute cystitis, confirming the potential of immunotherapy for this indication. The results reproduce important aspects of human cystitis in the murine urinary tract infection (UTI) model and provide a comprehensive molecular framework for the pathogenesis and immunotherapy of acute cystitis, one of the most common bacterial infections in man. Overall design: Mouse were infected intravesically with E. coli CFT073 and bladder and kidney samples were collected after 7 days. Isolated RNA was subjected to Affymetrix whole genome transcriptomic analysis.

急性膀胱炎正迅速成为治疗难题，抗生素耐药性正将治疗选择压缩至极低水平。值得庆幸的是，最新研究进展使得探索免疫应答调节剂作为抗生素替代方案成为可能。急性膀胱炎患者中，感染会触发膀胱黏膜产生快速且强烈的炎症应答，临床症状包括尿痛、尿急及尿频。目前此类症状的分子机制尚未完全阐明，但已有研究证实，细菌与膀胱上皮细胞的相互作用可引发炎症级联反应。本研究旨在探讨固有免疫应答基因如何影响膀胱感染的转归以及急性膀胱炎的发病机制，重点聚焦于白细胞介素-1β（IL-1β）。实验中，我们采用尿路致病性大肠杆菌CFT073菌株对C57BL/6小鼠进行膀胱内感染。分别于感染后24小时及7天，通过肉眼观察水肿、充血及脓性分泌物，并结合组织学与免疫组织化学检测，对感染膀胱的急性膀胱炎病变进行判定。随后，我们利用携带特定炎性体基因敲除（Il1b-/-、Casp1-/-、Asc-/-及Nlrp3-/-）的C57BL/6小鼠，鉴定出与短暂性膀胱炎症及重症疾病相关的遗传决定因素。通过全基因组转录组分析，对上述小鼠膀胱中受感染调控的基因进行表征，我们发现急性膀胱炎是一种由IL-1β介导的过度炎症性疾病。与该结论相符的是，Il1b-/-小鼠可免受感染及病理损伤。与之相反，Asc-/-与Nlrp3-/-小鼠则出现了进行性的IL-1β介导的膀胱炎症与严重病理损伤，这一现象由一种新发现的非经典IL-1β加工机制所介导，该机制涉及金属蛋白酶MMP-7。以IL-1β与MMP-7作为免疫治疗靶点，我们成功使易感的Asc-/-小鼠免受急性膀胱炎侵扰，证实了免疫疗法在该适应证中的应用潜力。本研究结果在小鼠尿路感染(UTI)模型中重现了人类膀胱炎的重要特征，并为急性膀胱炎——这一人类最常见的细菌性感染之一的发病机制与免疫治疗提供了全面的分子框架。整体实验设计：将大肠杆菌CFT073膀胱内感染小鼠，于感染7天后采集膀胱与肾脏样本，对分离得到的RNA进行Affymetrix全基因组转录组分析。