PARP inhibitor and Redox Catalyst Conjugate for Traumatic Brain Injury

描述(由申请人提供)：Radikal Treeutics(RTX)正在开发一种新的双功能药物(R-503)，它可以阻断导致创伤性脑损伤(TBI)的两条主要病理生理途径。R-503既是1)核DNA修复酶多聚(ADP-核糖)聚合酶(PARP)的有效抑制剂(IC50=20 nm)，也是基于二氢硫酸盐(DHL)的氧化还原催化剂，它是超氧化物歧化酶模拟物、过氧化氢酶模拟物和过氧亚硝酸盐分解催化剂。上述两个功能部分的共价连接形成单一的治疗剂，有望同时并共同定位地阻断脑损伤的氧化剂和PARP途径。在脑外伤的实验模型和临床环境中，这两条通路与脑外伤发病机制的相关性已经得到了很好的证实。目前在脑外伤患者中证实的PARP过度激活会消耗其底物(NAD+)，从而耗尽ATP储备，引发能量衰竭、细胞内稳态丧失、神经元坏死和脑梗塞。PARP活化与脑损伤的相关性不仅表现在脑损伤的起始阶段，而且在脑损伤的恢复期也表现突出：最近的数据表明，PARP的激活通过刺激小胶质细胞和上调核因子：B介导的转录，阻断了对脑损伤(神经发生)的恢复反应，而核因子：B介导的转录在炎性细胞因子、趋化因子、黏附分子和炎症介质(包括基质金属蛋白酶)的表达中起着核心作用。尽管PARP激活在脑损伤的起始期和恢复期具有明显的中枢作用，但在氧化还原介导的损伤中，显然还有其他不依赖于PARP的下游效应因子。因此，单独抑制PARP所提供的临床益处水平不太可能足够强大。因此，我们假设，从脑损伤中更全面地恢复将需要：1)消除上游氧化和亚硝化氧化还原应激，以及2)抑制下游PARP活性。我们将通过比较R-503、DHL(氧化还原催化剂)、INO-1001(单功能PARP抑制剂)、DHL和INO-1001的组合以及假损伤组的治疗，在大鼠遭受明确的皮质挫伤伤的TBI实验模型中验证这一假设。将采用复苏模式，即在皮质挫伤后2小时引入治疗药物，并持续2周。神经行为监测将包括在第14天评估运动任务(平衡木、横梁行走、Morris水迷宫)，并在死后分析脑组织的形态和生化证据，以观察氧化还原和炎症损伤，表现为组织学评分、脂质过氧化水平、蛋白质亚硝化、PARP激活、细胞凋亡以及TNF-1、MIP-11、核核因子-1的浓度。证实RTX的双功能方法比单一功能的PARP抑制剂和氧化还原催化剂具有独特的治疗优势，它们的结合将为R-503继续作为一流的创伤性脑损伤复苏和复苏药物开发提供依据。 公共卫生相关性：细胞损伤反应的诱导对严重头部创伤后的最终神经学结果起着重要作用。目前，还没有得到批准的治疗措施来阻止皮质挫伤后触发的炎症和细胞死亡程序。我们正在开发一种针对这种疾病的基本机制的新药，并将在临床相关的动物模型中测试这种药物。

DESCRIPTION (provided by applicant): Radikal Therapeutics (RTX) is developing a novel bifunctional agent (R-503) that blocks two principal pathophysiolgoical pathways that contribute to traumatic brain injury (TBI). R-503 is both 1) a potent inhibitor of the nuclear DNA repair enzyme poly(ADP-ribose) polymeras ("PARP") (IC50=20 nM), and 2) a dihydrolipoate ("DHL")-based redox catalyst that is a superoxide dismutase mimetic, a catalase mimetic, and a peroxynitrite decomposition catalyst. The covalent linkage of both of the above functional moieties to form a single therapeutic agent is expected to create simultaneous and co-localized interruption of both the oxidant and PARP pathways of injury in TBI. The relevance of both pathways to the pathogenesis of TBI has been well established in experimental models of TBI and in the clinical setting. Overactivation of PARP, now confirmed in patients with TBI, consumes its substrate (NAD+), thereby depleting ATP stores and provoking energetic failure, loss of cellular homeostasis, neuronal necrosis, and brain infarction. The relevance of PARP activation to TBI is not merely in the initiation of brain injury, but also figures prominently in the recovery phase: Recent data indicate that PARP activation blocks the restorative response to TBI (neurogenesis) via its stimulation of microglial cells and its upregulation of NF-:B mediated transcription, which plays a central role in the expression of inflammatory cytokines, chemokines, adhesion molecules and inflammatory mediators, including matrix metalloproteases. Despite the apparent centrality of PARP activation to the initiation and recovery phases of TBI, there are clearly additional PARP-independent downstream effectors of redox-mediated injury. Accordingly, the level of clinical benefit afforded by stand-alone PARP inhibition is not likely to be sufficiently robust. Accordingly, we hypothesize that more comprehensive recovery from TBI wil require both: 1) the elimination of upstream oxidative and nitrosative redox stress, and 2) inhibition of downstream PARP activity. We will seek to confirm this hypothesis in an experimental model of TBI in which rats are subjected to a well- defined cortical contusion trauma, by comparing treatment with R-503, DHL (a redox catalyst), INO-1001 (a monofunctional PARP inhibitor), a combination of DHL and INO-1001, and a sham injury group. A resuscitation paradigm will be employed, whereby therapeutic agents will be introduced 2 h after cortical contusion and continued for 2 weeks. Neurobehavioral monitoring will include assessment of motor tasks (beam balance, beam walking, Morris water maze) on day 14, and post-mortem analysis of brain tissue for morphologic and biochemical evidence of redox and inflammatory injury, as manifested by histology score, levels of lipid peroxidation, protein nitrosation, PARP activation, apoptosis, and concentrations of TNF-1, MIP- 11, nuclear NF-: . Confirmation that RTX's bifunctional approach confers unique therapeutic superiority over a monofunctional PARP inhibitor and redox catalyst, and their combination, would provide justification for the continued development of R-503 as a first-in-class agent for emergent resuscitation and recovery of TBI. PUBLIC HEALTH RELEVANCE: The induction of cellular injury responses contributes importantly to the ultimate neurological outcome after severe head trauma. At present, there are no approved therapeutic measures that arrest inflammation and cell death programs that are triggered after cortical contusion. We are developing a novel drug that targets the basic mechanisms of this condition and will test this agent in a clinically-relevant animal model.