A Novel Thioredoxin Mimetic Prodrug for Prevention of Bronchopulmonary Dysplasia

描述（由申请人提供）：Radikal Therapeutics （RTX）正在开发一种针对早产儿硫氧还蛋白（Trx）发育缺陷的新型药物治疗方法，Trx是一种作为细胞还原剂状态中央调节剂的蛋白质。Trx在胎儿肺中的表达水平过低，无法充分对抗子宫外生活的氧化还原应激，因此在极端早产中相对缺乏。肺泡中Trx的低水平被认为是极低出生体重（VLBW）早产儿对新生儿呼吸窘迫综合征（RDS）易感的主要原因。我们目前对RDS及其演变为支气管肺发育不良（BPD）的理解与肺实质内过量超氧化物产生的损伤机制一致。与超氧化物产生增加相结合的是抗氧化蛋白的发育缺陷，如超氧化物歧化酶和Trx，这些蛋白在妊娠早期数量不足。我们的创新是基于一种新型药物R-908的管理，这是一种Trx模拟物（R-901）的前药，可替代缺乏的Trx蛋白并恢复细胞内氧化还原状态。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，并表现出非凡的效力：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。在小鼠肺炎症模型卵清蛋白模型中，R-901减轻了组织损伤，减少了中性粒细胞浸润，减轻了组织氧化，阻断了促炎细胞因子的表达和NF-？B，消炎细胞质蛋白I？B¿，并恢复了还原和氧化形式的谷胱甘肽的平衡。在急性Cl2吸入引起的LD60小鼠氧化还原应激模型中，损伤后给予R-901消除了所有死亡。为了克服R-901中游离巯基的货架不稳定性，我们发明了一种稳定的二硫酯

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).