PNPase inhibition as an effective treatment for chronic bladder pain

摘要： 慢性内脏疼痛疾病，如间质性膀胱炎/膀胱疼痛综合征（IC/BPS），是 最难治疗的疼痛类型，对治疗的反应往往可以忽略不计。IC/BPS缺乏明确的 原因，难以诊断，迄今为止，没有明确的治疗目标。重要的是，心理和 氧化应激已经显示出引发许多反应 综合征，并可能通过增强促伤害性介质的作用和促进氧化 损害慢性压力不同于急性或偶发性压力，因为它导致压力的持续升高 对动物和人类的器官功能产生负面影响的介质。慢性压力会增加 并且其本身可导致易患病个体的痛觉过敏或疼痛。更 超过一半的IC/BPS患者报告每天或持续的疼痛和尿频， 这种恶化被称为疼痛“突发”。虽然在描绘脊柱的轮廓方面取得了进展， 由于缺乏对功能性疼痛的清晰理解， 相关的共病和治疗靶点是临床医生和患者沮丧的根源。 由于IC/BPS没有有效的治疗方法，我们的研究计划致力于发现 中介IC/BPS的机制，并将这些知识应用于目标识别和验证。在这 应用程序，我们的初步目标识别和验证计划将使用两种不同的啮齿动物模型IC/BPS 包括“膀胱中心”模型（环磷酰胺-环磷酰胺）和慢性应激模型（避水 应力或WAS）模型。虽然没有可用的模型试图模拟IC/BPS的特定流行病学结果， 我们在这两种模型中的发现揭示了与人类IC/BPS的相似性，包括形态学的变化和 膀胱神经和非神经细胞的功能。在这方面，我们最新的初步实验表明， 用嘌呤类似物治疗IC/BPS动物， 减少尿损伤性嘌呤可有效降低疼痛敏感性并逆转膀胱功能障碍。 总之，我们的研究团队将使用多学科方法来验证非阿片类药物靶点， 即嘌呤核苷磷酸化酶（PNTR），用于治疗内脏疼痛病症（例如， IC/BPS）。为了实现我们的目标，在目标1中，本项目将通过评估 除了使用分子方法， 敲低PNIPs，以及在目标2中，通过测量分离的外泌体中的嘌呤来证明我们的靶标的概念 从IC/BPS和Hunner病变患者样本中提取，以评估PNTR作为内脏疼痛的贡献者的作用。 可以保护线粒体和减少氧化应激的疗法可能在疾病方面很重要 预防如果成功，这种疗法将挑战和改变目前的研究和临床实践范式。

Abstract: Chronic visceral pain disorders, such as interstitial cystitis/bladder pain syndrome (IC/BPS), are among the most difficult types of pain to treat, and response to treatment is often negligible. IC/BPS lacks a well-defined cause, is difficult to diagnose and to date, has no clear therapeutic target. Importantly, both psychological and oxidative stress have been shown to trigger a number of responses which can exacerbate such generalized pain syndromes and may do so by enhancing the effects of pro-nociceptive mediators and promoting oxidative damage. Chronic stress differs from acute or episodic stress as it leads to the persistent elevation of stress mediators that negatively impacts organ function in both animals and humans. Chronic stress increases the risk of disease/pathology and can itself result in hyperalgesia or pain in individuals predisposed to disease. More than half of patients with IC/BPS report daily or constant pain and urinary frequency, exacerbated by stressful circumstances- this exacerbation is termed a pain ‘flare’. While progress has been made to delineate the spinal circuits that gate pain signals emanating from the viscera, lack of a clear understanding of functional pain, their associated co-morbidities and a therapeutic target are a source of frustration for the clinician and patient. Because there are no effective treatments for IC/BPS, our research program is dedicated to discovering mechanisms mediating IC/BPS and applying that knowledge to target identification and validation. In this application, our plans for initial target identification and validation will use two distinct rodent models for IC/BPS which include a ‘bladder-centric’ model (cyclophosphamide-CYP) and a chronic stress model (water avoidance stress or WAS) model. While no available model attempts to mimic particular epidemiologic findings of IC/BPS patients, our findings in both models reveal similarities to human IC/BPS including changes in morphology and function of bladder neural and non-neuronal cells. In this regard, our newest preliminary experiments show that treatment of IC/BPS animals with a purine analog that increases uro-protective purines while simultaneously decreasing uro-damaging purines is effective at lowering pain sensitivity and reverses bladder dysfunction. Taken together, our research teams will use a multidisciplinary approach to validate a non-opioid-based target, namely purine nucleoside phosphorylase (PNPase), for the treatment of visceral pain disorders (e.g., IC/BPS). To achieve our objectives, in Aim 1, this project will determine validity of our target by assessing the role of PNPase in visceral pain using pharmacologic inhibitors in addition to using molecular approaches to knockdown PNPase and, in Aim 2, proof of concept for our target by measuring purines in exosomes isolated from IC/BPS and Hunner’s lesion patient samples to assess the role of PNPase as a contributor to visceral pain. Therapies that can protect mitochondria and reduce oxidative stress are likely to be important in terms of disease prevention. If successful, this therapy will challenge and shift current research and clinical practice paradigms.