35 - The Thioredoxin Reductase-1 Inhibitor Aurothioglucose Enhances Glutathione-dependent Antioxidant Responses in a Murine Model of Bronchopulmonary Dysplasia

Abstract

Introduction Therapeutic oxygen contributes to the development of bronchopulmonary dysplasia (BPD). The thioredoxin reductase-1 (TrxR1) inhibitor aurothioglucose (ATG) is protective in our murine BPD model. Improved lung structure in ATG-treated newborn mice was associated with enhanced nuclear factor E2-related factor 2 (Nrf2) activation. TrxR1 inhibitors also enhance glutathione (GSH) levels in models of acute lung injury. Hypothesis The present studies tested the hypothesis that ATG enhances GSH-mediated antioxidant defenses in neonatal lungs. Methods Newborn C3H/HeN mice were dosed with 25mg/kg ATG or saline (SA) i.p. within 12 h of birth and exposed to room air (RA) or hyperoxia (HO, 85% O2). Lung glutamate-cysteine ligase catalytic (Gclc) and modifier (Gclm) subunit levels were assessed by qRT-PCR. Total and oxidized GSH (GSSG) levels were determined by Tietze recycling assay. Data (n=3-6) were analyzed by 2-way ANOVA with Tukey’s post hoc. Results At 24 h, Gclm levels were not different between groups. Gclc levels were 2-fold greater in HO:ATG vs RA:SA (p=0.0456). By 72 h, independent effects of ATG and hyperoxia were detected for Gclm and Gclc. Gclm levels were 1.6-fold higher in HO:ATG vs RA:SA (p=0.0016) and Gclc levels were 2.4 fold greater in HO:ATG vs RA:SA (p=0.0182). At 72 h, total GSH was 1.3 fold greater in HO:SA (p=0.0206) and 1.7 fold greater in HO:ATG (p=0.0002) vs RA:SA. Total GSH levels in HO:ATG lungs were 1.3 fold higher than RA:ATG (p Conclusions In HO-exposed newborn pups, ATG enhanced Gclm, Gclc and lung GSH levels. Given the importance of GSH-mediated antioxidant responses in protection against HO, we speculate that enhanced de novo GSH synthesis may be a mechanism by which ATG improves lung development in our model. TrxR1 inhibitors such as ATG, which increase Nrf2-dependent responses and enhance GSH-mediated antioxidant responses, may represent a novel therapy to decrease BPD development.