PPARɣ Agonist Pioglitazone and Synthetic Surfactant Protein B Mimic B‐YL Prevents Hyperoxia‐Induced Lung Injury in Adult Mice

Abstract

Purpose of Study Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome (ARDS) are serious conditions and often life threatening. ALI and ARDS are characterized by acute alveolar injury, disrupted epithelial-mesenchymal signaling, oxidative stress, and surfactant dysfunction. Previously we demonstrated that perturbation in TGF-β and wingless/Int (Wnt) signaling pathways, known to be involved in perinatal lung development and hyperoxia-induced rat lung injury, was ameliorated by pioglitazone and B-YL, a novel synthetic surfactant, in neonatal rats. However, whether this approach can be extended to be effective in adult lung injury is unknown. We hypothesize that by stabilizing alveolar homeostasis, combined PPARγ agonist PGZ and oxidant resistant synthetic surfactant B-YL can be a unified approach to block hyperoxia-induced lung injury not only in neonates but also in adults. Methods Used 3 to 6 months old C57BL/6 adult mice lungs were harvested. Lung explants were placed in 15% FBS/Weymouth medium and exposed ex-vivo to 21% or 95% O2 for 24 or 72h. Treatment groups included: 1) untreated control; 2) B-YL (100 mg/kg); 3) PGZ (1 mg/kg); and 4) B-YL (100 mg/kg)+PGZ (1 mg/kg). Wnt signaling (LEF-1 and β-catenin), TGF-β signaling (Alk5 and SMAD3), and apoptosis (BAX) markers were determined by Western analysis. Inflammatory cytokines (IL6, IL1β, TNFα, and MCP1) were measured by qRT-PCR. Summary of Results Hyperoxia exposure resulted in significant increases in lung injury and apoptosis markers including the upregulation of Wnt and TGF-β pathway proteins. PGZ+ B-YL treated group showed significant amelioration of hyperoxia-induced alterations in these injury markers, including Wnt (LEF-1 and β-catenin) and TGF-β (ALK-5) pathway proteins (vs. 95% O2 control group). Similarly, hyperoxia-induced increases in IL6, IL1β, TNFα, and MCP1 were blocked in B-YL alone, as well as PGZ+B-YL treated groups. Conclusions Effectiveness of combined PGZ+B-YL in blocking hyperoxia- induced lung injury ex-vivo sets the stage to test this therapeutic approach for adult lung injury in vivo.