Radiocontrast Nephropathy: Redox Degradation Catalyst and Nitric Oxide Donor

描述(申请人提供)：我们正在开发一种新的小分子细胞保护药物(R-100)，用于预防静脉注射放射造影剂(CM)后的造影剂诱导的肾病(CIN)。R-100是一种新型的细胞透过性氧化还原活性试剂，由两个化学部分共价融合而成：1)提供一氧化氮的有机硝基血管扩张剂，2)作为三官能团的活性氧降解催化剂的吡咯烷氮氧化物。在肾缺血/再灌注损伤(RiRi)大鼠中， 再灌流前静脉注射R-100可使再灌后6h血清肌酐、血清NGAL、组织髓过氧化物酶和组织学评分升高75-90%(p&lt；10-14)，并使内生肌酐清除率从90%降低到50%(p&lt；0.01)。在小鼠RiRi模型中，再灌流前单次注射R-100可完全消除24小时肌酐升高(p&lt；0.01)。目的#1：建立健康和糖尿病大鼠CIN模型中R-100的药效学(PD)谱，在正常水分和积极容量负荷条件下，大鼠将受到脱水、前列腺素合成酶抑制和静脉注射CM的影响。将假损伤组与CM攻击的健康大鼠进行比较，在CM给药前10分钟开始并持续48小时，用3个剂量水平的静脉注射R-100、N-乙酰半胱氨酸(NAC)或赋形剂对照组。然后在48小时后评估大鼠的肾功能(以及反映肾损伤的参数，包括向血液中释放蛋白质(NGAL、Kim-1)、促炎转录因子表达(胞浆I？B降解、核p65易位)、组织学损伤、核损伤和DNA修复(PARP激活和亚硝化应激，以多聚ADP-核糖和3-硝基酪氨酸(3-NT)组织免疫反应表示)。为了更好地对CIN风险最大的患者群体进行建模，随后将进一步评估R-100的最佳剂量，使用与之前相同的实验方法和设计，但在先前通过注射链脲佐菌素(STZ)而在2周前出现糖尿病的大鼠中进行。最后，我们将调查是否可以通过联合应用R-100和积极的容量复苏在糖尿病患者中获得进一步的益处。目的#2：建立R-100在CIN啮齿动物模型中的药代动力学(PK)我们将在与目标1相同的条件下对啮齿动物进行PK研究，以产生CIN。将生成完整的PK曲线，以确定血浆半衰期、清除量和体积分布。暴露于R-100的累积血浆浓度和肾组织中的R-100浓度将与目标1中详述的形态、免疫学和功能终点相关联，以构建药物暴露与效果之间的PD曲线。拟议的研究将为R-100的高级商业开发提供合理的基础，目的是该产品将作为接受CM注射的高危糖尿病患者的一线预防。

DESCRIPTION (provided by applicant): We are developing a novel small molecule cytoprotective drug (R-100) for the prevention of contrast- induced nephropathy (CIN) following IV radiocontrast media (CM) injection. R-100 is a novel cell- permeable redox-active agent formed from the covalent fusion of 2 chemical moieties: 1) an organic nitrovasodilator that donates nitric oxide, and 2) a pyrrolidine nitroxide that acts as a trifunctional degradation catalyst of reactive oxygen species. In rats subjected to renal ischemia/reperfusion injury (RIRI), IV administration of R-100 prior to reperfusion reduced the 6 h elevations in serum creatinine, serum NGAL, tissue myeloperoxidase, and histologic score by 75-90% (p<10-14) and restored the reduction of creatinine clearance from 90% to 50% (p<0.01). In a murine RIRI model, 24 h creatinine elevations were entirely eliminated by a single dose of R-100 prior to reperfusion (p<0.01). Aim #1: Establish the pharmacodynamic (PD) profile of R-100 in models of CIN in healthy and diabetic rodents under conditions of normal hydration and aggressive volume loading Rats will be subjected to dehydration, prostaglandin synthetase inhibition, and an IV challenge of CM. A sham injury group will be compared to treatment of CM-challenged healthy rats with 3 dose levels of IV R-100, N-acetyl-cysteine (NAC), or vehicle control initiated 10 min before CM administration and continued for 48 h. Rats will then be evaluated at 48 h for renal function (and parameters reflecting renal injury, including protein release into the blood (NGAL, KIM-1), pro-inflammatory transcription factor expression (cytoplasmic I¿B¿ degradation, nuclear p65 translocation), histologic damage, and nuclear damage and DNA repair (PARP activation and nitrosative stress as noted by poly(ADP-ribose) and 3-nitrotyrosine (3-NT) tissue immunoreactivity). In order to better model the patient population at greatest risk of CIN, the optimal dose of R-100 will then be further evaluated, using the same experimental approach and design as before, but in rats previously rendered diabetic 2 weeks earlier by injection of streptozotocin (STZ). Finally, we will investigate whether further benefit may be obtained in the diabetic setting by combining the administration of R-100 with aggressive volume resuscitation. Aim #2: Establish the pharmacokinetics (PK) of R-100 in a rodent model of CIN We will carry out PK studies in rodents exposed to the same conditions utilized to generate CIN as in Aim #1. A full PK profile will be generated, to define plasma half-life, clearance, and volume of distribution. The exposure to cumulative plasma concentrations of R-100 and the renal tissue concentration of R-100 will be correlated with the morphologic, immunologic, and functional endpoints detailed in Aim #1, in order to construct a PD profile relating drug exposure to effect. The proposed studies will provide a rational foundation for advanced commercial development of R-100, with the intent that this product will serve as first-line prophylaxis in high-risk diabeic patients undergoing CM injection.