Novel Mechanistic Approaches in Prevention, Treatment and Non-Invasive Assessment of Radiation Cystitis in Mice

摘要 男性和女性的盆腔器官肿瘤预计分别占新发癌症的40%和18% 根据2020年美国癌症相关死亡的诊断，分别为31%和26%， 美国癌症协会2020年癌症事实与数据将近一半的盆腔癌患者 接受放射治疗，剂量是有限的，并在几周内由于发展的潜力分次 放射性膀胱炎这是一种使人衰弱的继发性疾病，可导致尿道破裂， 炎症、神经源性逼尿肌过度活动（NDO）、出血性膀胱炎和慢性纤维化可能需要 一个Cyber。目前的治疗方法，如膀胱镜电灼，膀胱内福尔马林和高压氧 通常是无效的，并且专注于限制出血而不是泌尿系统后果。因此，有一个 迫切需要临床前模型，以更好地了解放射性膀胱炎的病理生理学，设计新颖 机械方法在其预防和治疗和非侵入性监测这些结果， 临床上可行的成像方法。在我们的小鼠模型中，膀胱要么是外部化的，要么是灌输了一种 红外线染料选择性照射（10 Gy; 1Gy= 100 rad）引起放射性膀胱炎急性期（1- 3天），特征为尿路上皮细胞（UC）凋亡和屏障功能破坏，以及慢性期 （108周）伴炎症、传入致敏、NDO，最终胶原沉积、纤维化和 膀胱壁顺应性降低。我们建议测试不同类别的治疗和 我们有很强的初步数据的造影剂：1）线粒体靶向自由基清除剂， XJB-5-131，减少抑制线粒体自噬的活性氧; 2）p75神经营养因子受体（p75 NTR） 调节剂LM 11 A-31，减少尿路上皮细胞凋亡和屏障破坏; 3）可溶性鸟苷酸环化酶 (sGC)激活剂西那西呱，以减少炎症、传入致敏和胶原沉积，治疗NDO 和纤维化;和4）膀胱内红外染料和新型造影剂混合物，钆布醇/ferumoxytol， 选择性地照射腹部内的膀胱，以增强磁共振的能力， 成像（MRI）用于膀胱壁中纤维化的非侵入性评估。LM11A-31 cinaciguat已经通过了非泌尿系统疾病的1期临床安全性试验， 放射性膀胱炎的预防和治疗的临床意义。该提案的总体目标是 更好地表征放射性膀胱炎的病理生理学，并设计临床相关的治疗方案 单独或组合使用所提出的药剂。实现这一目标的进展将通过以下方式进行监测： 去大脑或清醒（遥测）膀胱测压（CMG）记录、MRI、组织学和分子生物学 方法、线粒体自噬报告基因（mt-keima）小鼠和NADPH细胞色素b5条件性敲除小鼠 还原酶3（CyB 5 R3），其使sGC对这些细胞中的NO·无反应。

ABSTRACT Pelvic organ tumors in men and women are projected to account for 40% and 18%, respectively, of new cancers diagnosed, and 31% and 26%, respectively, of cancer related deaths in the United States in 2020, according to the American Cancer Society’s Cancer Facts & Figures 2020. While nearly half of all pelvic cancer patients receive radiation therapy, the dose is limited and fractionated over weeks due to the potential for developing radiation cystitis. This is a debilitating secondary condition that can lead to disruption of the urothelium, inflammation, neurogenic detrusor overactivity (NDO), hemorrhagic cystitis and chronic fibrosis that may require a cystectomy. Current therapies such as cystoscopic fulguration, intravesical formalin and hyperbaric oxygen are often ineffective and focus on restricting hemorrhage rather than urological consequences. Thus, there is a critical need for preclinical models to better understand the pathophysiology of radiation cystitis, design novel mechanistic approaches in its prevention and treatment and non-invasive monitoring of these outcomes using clinically viable imaging methods. In our mouse models, bladders are either externalized or instilled with an infrared dye for selective irradiation (10Gy; 1Gy=100rad) to cause radiation cystitis with an acute phase (1- 3days) characterized by urothelial cell (UC) apoptosis and disruption of barrier function, and a chronic phase (8wks) with inflammation, afferent sensitization, NDO, and eventually collagen deposition, fibrosis and decreased bladder wall compliance. We propose to test mechanistically different classes of therapeutic and contrast agents for which we have strong preliminary data: 1) Mitochondrial targeted free radical scavenger, XJB-5-131, to decrease reactive oxygen species that inhibit mitophagy; 2) p75 neurotrophin receptor (p75NTR) modulator, LM11A-31, to decrease urothelial cell apoptosis and barrier disruption; 3) soluble guanylyl cyclase (sGC) activator, cinaciguat, to decrease inflammation, afferent sensitization and collagen deposition to treat NDO and fibrosis; and 4) intravesical infrared dye and novel contrast media mixture, gadobutrol/ferumoxytol, to selectively irradiate the bladder within the abdomen and to enhance the capabilities of magnetic resonance imaging (MRI) for non-invasive assessment of fibrosis in the bladder wall, respectively. As LM11A-31 and cinaciguat have passed phase 1 clinical safety trials for non-urological pathologies, they have considerable clinical relevance in the prevention and treatment of radiation cystitis. The overall goals of the proposal are to better characterize the pathophysiology of radiation cystitis and to design clinically relevant treatment protocols utilizing the proposed agents individually or in combination. Progress toward this goal will be monitored using decerebrate or awake (telemetric) cystometrogram (CMG) recordings, MRI, histological and molecular approaches, mitophagy reporter (mt-keima) mice, and conditional knockout mice for NADPH cytochrome b5 reductase 3 (CyB5R3) in smooth muscle or nerves which renders sGC unresponsive to NO• in these cells.