ADMINISTRATION OF ANTENATAL GLUCOCORTICOIDS AND POSTNATAL SURFACTANT AMELIORATES RESPIRATORY DISTRESS SYNDROME-ASSOCIATED NEONATAL LETHALITY IN ERK3(−/−) PUPS

BACKGROUND: Respiratory distress syndrome (RDS) persists as a prevalent cause of infant morbidity and mortality. We have previously demonstrated that deletion of Erk3 results in pulmonary immaturity and neonatal lethality. Using RNA-Seq, we identified corticotrophin releasing hormone (CRH) and surfactant protein B (SFTPB) as potential molecular mediators of Erk3-dependent lung maturation. In this study, we characterized the impact of antenatal glucocorticoids and postnatal surfactant on neonatal survival of Erk3 null mice. METHODS: In a double crossover design, we administered dexamethasone (dex) or saline to pregnant dams during the saccular stage of lung development, followed by postnatal surfactant or saline via inhalation intubation. Survival was recorded, detailed lung histological analysis and staining for CRH and SFTPB protein expression was performed. RESULTS: Without treatment, Erk3 null pups die within 6 hours of birth with reduced aerated space, impaired thinning of the alveolar septa, and abundant PAS-positive glycogen stores; as described in human RDS. The administration of dex and surfactant improved RDS-associated lethality of Erk3(−/−) pups, and partially restored functional fetal lung maturation by accelerating the down-regulation of pulmonary CRH and partially rescuing production of SFTPB. CONCLUSION: These findings emphasize that Erk3 is integral to terminal differentiation of type II cells, SFTPB production, and fetal pulmonary maturity.