A Novel Thioredoxin Mimetic Prodrug for Prevention of Bronchopulmonary Dysplasia

描述(由申请人提供)：Radikal Treateutics(RTX)正在开发一种针对早产儿的新型药物疗法，该疗法针对硫氧还蛋白(TRX)的发育缺陷，硫氧还蛋白是一种作为细胞还原状态的中央调节蛋白。TRX在胎儿肺中的表达水平太低，无法充分对抗宫外生命的氧化还原压力，因此I在极端早产儿中相对不足。肺泡内TRX的低水平被认为是极低出生体重(VLBW)早产儿易患新生儿呼吸窘迫综合征(RDS)的主要原因。我们目前对RDS及其演变为支气管肺发育不良(BPD)的理解与肺实质内超氧化物过量所产生的损伤机制是一致的。超氧化物生成量的增加与超氧化物歧化酶和Trx等抗氧化蛋白质的发育缺陷有关，这些蛋白质在早期妊娠时数量不足。我们的创新是基于一种新的药物R-908的管理，R-908是TRX模拟物(R-901)的前药，它替代缺陷的TRX蛋白并恢复细胞内的氧化还原状态。R-901是一种富含硫醇的三肽，与天然保守的TRX基序非常相似，并显示出非凡的效力：R-901在保护培养细胞免受氧化应激方面的效力是N-乙酰半胱氨酸的450倍。在小鼠肺炎症模型中，R-901减轻了组织学损伤，减少了中性粒细胞的浸润，减轻了组织氧化，阻断了促炎细胞因子的表达和核转位，减少了抗炎细胞质蛋白I、B的降解，恢复了还原型谷胱甘肽和氧化谷胱甘肽的平衡。在急性吸入Cl2诱导的小鼠LD60氧化还原应激模型中，损伤后给予R-901可消除所有死亡率。为了克服R-901的自由硫醇基团的货架不稳定性，我们发明了一种稳定的二硫代酯 体内释放R-901的前药(R-908)。R-908现在将在一种临床相关的BPD大鼠模型中进行评估。目的#1：确定R-908在新生大鼠体内的药代动力学。我们将确定R-908及其代谢物R-901在2日龄小鼠的血浆和组织PK谱。目的#2：建立R-908减轻BPD新生大鼠高氧模型肺血管和肺泡结构的变化；2日龄大鼠处于高氧状态10天。R-908将在广泛的剂量范围内给药3周，在这个模型系统中，这段时间的特征是进行性肺纤维化、肺动脉高压(PAH)和肺泡减少。尸检肺组织将分析肺血管结构和生长、肺泡化、脂质过氧化(丙二醛)、还原型和氧化型谷胱甘肽(GSH、GSSG)、过氧亚硝酸盐(3-硝基酪氨酸)、聚腺苷二磷酸核糖(ADP-核糖)、纤维化(Mason trichrome胶原染色)、R-908和R-901水平以及促炎基因表达。心脏将接受形态计量学分析，以寻找PAH的证据(如右室肥厚所示)。

DESCRIPTION (provided by applicant): Radikal Therapeutics (RTX) is developing a novel pharmaceutical therapy for prematurity that targets a developmental deficiency in thioredoxin (Trx), a protein that serves as a central regulator of cellular reductant status. Trx is expressed t levels in the fetal lung too low to adequately counter the redox stress of extrauterine life, and i thus relatively deficient in extreme prematurity. The low level of Trx in alveoli is thought to pla a major role in the susceptibility of very low birthweight (VLBW) premature infants to neonatal respiratory distress syndrome (RDS). Our current understanding of RDS and its evolution into bronchopulmonary dysplasia (BPD) is consistent with a mechanism of injury produced by an excess of superoxide within the lung parenchyma. Compounding this increase in superoxide production is the developmental deficiency of anti-oxidant proteins, such as superoxide dismutase and Trx, that are present in insufficient quantity at an early gestational age. Our innovation is based upon the administration of a novel agent, R-908, a prodrug of a Trx mimetic (R-901) that substitutes for the deficient Trx protein and restores intracellular redox status. R-901 is a thiol-rich tripeptide closely analogous to the native conserved Trx motif and exhibits extraordinary potency: R- 901 is 450-fold more potent than N-acetyl cysteine in the protection of cultured cells from oxidant stress. In a murine ovalbumin model of pulmonary inflammation model, R-901 reduced histologic injury, diminished neutrophil infiltration, attenuated tissue oxidation, blocked pro-inflammatory cytokine expression and nuclear translocation of NF-?B, diminished the degradation of the anti-inflammatory cytoplasmic protein I?B¿, and restored the balance of reduced and oxidized forms of glutathione. In a murine LD60 model of redox stress, induced by acute Cl2 inhalation, post-insult administration of R-901 eliminated all mortality. To overcome shelf instability of the free thiol groups of R-901, we have invented a stable dithioester prodrug (R-908) that releases R-901 in vivo. R-908 will now undergo evaluation in a clinically-relevant rat pup model of BPD. Aim #1: Define the pharmacokinetics (PK) of R-908 in newborn rats. We will define the plasma and tissue PK profile of R-908, and its metabolite R-901, in 2-day old rat pups. Aim #2: Establish that R-908 attenuates changes of pulmonary vascular and alveolar structure in a hyperoxic model of BPD in neonatal rats; 2-day old rat pups will be subjected to hyperoxia for 10 days. R-908 will be administered over a broad dose range for 3 weeks, a period characterized in this model system by progressive lung fibrosis, pulmonary arterial hypertension (PAH), and hypoalveolarization. Lung tissue taken at necropsy will be analyzed for pulmonary vascular structure and growth, alveolarization, lipid peroxidation (malondialdehyde), reduced and oxidized glutathione (GSH, GSSG), peroxynitrite formation (3-nitrotyrosine), poly(ADP-ribose) formation, fibrosis (Mason Trichrome staining for collagen), R-908 and R-901 levels, and pro-inflammatory gene expression. The heart will undergo morphometric analysis for evidence of PAH (as shown by right ventricular (RV) hypertrophy).