Resuscitation of smoke inhalation and burn injury with a thioredoxin mimetic

描述(申请人提供)：烟雾吸入和烧伤(SIBI)通过产生有毒的自由基和氧化剂而导致急性肺损伤(ALI)，进而， 触发整个肺实质的DNA单链断裂(SSB)。当这种基因组损伤被核DNA修复酶多聚(ADP-核糖)聚合酶(PARP)识别时，NAD被切割，产生产物多(ADP-核糖)。PARP的过度激活会耗尽NAD储存，导致氧化磷酸化的丧失和对ATP合成的干扰。在严重的情况下，高能磷酸盐(ATP)的最终耗尽会触发细胞坏死和肺泡毛细血管膜功能的丧失。为了满足这一未得到满足的临床需求和潜在的孤儿药物市场，我们正在开发一种细胞渗透性硫氧还蛋白模拟物(R-901)，这是一种富含硫醇的三肽，与天然的硫氧还蛋白(TRX)基序非常相似。R-901的体外药效分别是N-乙酰半胱氨酸(NAC)和抗坏血酸的450倍和50倍，体内药效明显高于NAC。在卵蛋白致敏和再激发所致的小鼠肺部炎症模型上，R-901的治疗作用被证明可以减轻组织学损伤，减少中性粒细胞(PMN)的渗透，减轻组织氧化，阻断促炎细胞因子的表达和核转位，减少抗炎细胞质蛋白I、B的降解，恢复还原型谷胱甘肽和氧化型谷胱甘肽的平衡。在急性氯气吸入所致严重氧化还原应激的小鼠LD100模型中，伤后给予R-901可使肺PMN渗入减少50%。这项建议的具体目的是比较R-901和NAC在绵羊SIBI-ALI联合模型中的效力。我们将进行一项前瞻性、安慰剂对照、随机、双盲的研究，在该研究中，急性SIBI诱导机械通气型美利奴绵羊呼吸功能不全。使用R-901、NAC或车辆控制的复苏将在热损伤后1小时开始，并持续48小时，这一时间点以大量呼吸衰竭为特征。我们预计R-901在以下指标上将显示出明显的优势：1)减轻肺部炎症和损伤，表现为肺湿干比、淋巴引流、脂质过氧化、气道阻塞、组织学评分、PMN浸润、ONOO-(3-硝基酪氨酸，“3-NT”)形成和多(ADP-核糖)形成；2)改善血流动力学和气道压力，表现为肺血管阻力(PVR)、平均肺动脉压(MPAP)和最大吸气压(PIP)的降低，而不影响全身血管阻力(SVR)、平均外周动脉压(MAP)和心脏指数(CI)；3)肺分流减少，表现为动脉-肺泡(AA)梯度减小和动脉血氧分压/吸入氧浓度比值(PaO2/FiO2)增加。这些好处加在一起，将证明继续开发用于治疗急性SIBI的R-901是合理的。 公共卫生相关性：吸入烟雾并伴随烧伤是导致呼吸衰竭的主要原因。目前，这种情况还没有得到批准的治疗方法，死亡率仍然很高。我们正在开发一种针对这种情况下肺损伤的基本机制的新药，并将在临床相关的大型动物创伤模型中测试这种药物。

DESCRIPTION (provided by applicant): Smoke inhalation and burn injury (SIBI) induces acute lung injury (ALI) via the generation of toxic free radical and oxidant species that, in turn, trigger DNA single strand breaks (SSB) throughout the pulmonary parenchyma. When this genomic injury is then recognized by the nuclear DNA repair enzyme poly(ADP-ribose) polymerase ("PARP"), NAD is cleaved to generate the product poly(ADP-ribose). Hyperactivation of PARP depletes NAD stores, resulting in the loss of oxidative phosphorylation and interference with ATP synthesis. In severe instances, the ultimate exhaustion of high energy phosphates (ATP) triggers cellular necrosis and the functional loss of the alveolocapillary membrane. To address this unmet clinical need and potential orphan drug market, we are developing a cell-permeable thioredoxin mimetic (R-901), a thiol-rich tripeptide that is closely analogous to the native thioredoxin (TRX) motif. R-901 exhibits in vitro potency 450- and 50-fold > than N-acetylcysteine (NAC) and ascorbic acid, respectively, and in vivo potency substantialy greater than NAC. Therapeutic administration of R-901 has been shown in a murine model of pulmonary inflammation (induced by ovalbumin sensitization and re-challenge) to reduce histologic injury, diminish neutrophil (PMN) infiltration, attenuate tissue oxidation, block pro-inflammatory cytokine expression and nuclear translocation of NF-?B, diminish the degradation of the anti-inflammatory cytoplasmic protein I?B¿, and restore the balance of reduced and oxidized forms of glutathione. In a murine LD100 model of severe redox stress induced by acute chlorine gas inhalation, post-insult administration of R-901 reduced pulmonary PMN infiltration by 50%. The Specific Aim of this proposal is to compare the potency of R-901 and NAC in an ovine model of combined SIBI-ALI. We will carry out a prospective, placebo-controlled, randomized, double-blinded, study in which respiratory insufficiency is induced in mechanically-ventilated Merino sheep by acute SIBI. Resuscitation with R-901, NAC, or vehicle control will be initiated 1 h after thermal insult and continued for 48 h, a timepoint characterized by massive respiratory failure. We expect that R-901 will demonstrate statistically significant superiority relative to NAC as noted for the following indices: 1) Reduced lung inflammation and injury, as manifested in lung wet/dry ratio, lymphatic drainage, lipid peroxidation, airway obstruction, histologic scoring, PMN infiltration, ONOO- (3-nitrotyrosine, "3-NT") formation, and poly(ADP-ribose) ("PAR") formation; 2) Improved hemodynamics and airway pressures, as revealed by reductions in pulmonary vascular resistance (PVR), mean pulmonary arterial pressure (MPAP), and peak inspiratory pressure (PIP), without impacting systemic vascular resistance (SVR), mean peripheral arterial pressure (MAP), and cardiac index (CI); and 3) Reduced pulmonary shunt, as indicated by diminished arterioalveolar (Aa) gradient and an increased ratio of arterial O2 tension to inspired O2 concentration (PaO2/FiO2). These benefits, taken together, will justify continued development of R-901 for treatment of acute SIBI. PUBLIC HEALTH RELEVANCE: Smoke inhalation with associated burn injury is a leading cause of respiratory failure. At present, there is no approved therapy for this condition and mortality remains high. We are developing a novel drug that targets the basic mechanisms of lung injury in this condition and will test this agent in a clinically-relevant large animal model f trauma.