Structural and transcriptomic response to antenatal corticosteroids in an Erk3-null mouse model of respiratory distress.

 
TitleStructural and transcriptomic response to antenatal corticosteroids in an Erk3-null mouse model of respiratory distress.
Publication TypeJournal Article
Year of Publication2016
AuthorsPew, BK, Harris, RA, Sbrana, E, Guaman, MCuevas, Shope, C, Chen, R, Meloche, S, Aagaard, K
JournalAm J Obstet Gynecol
Volume215
Issue3
Pagination384.e1-384.e89
Date Published2016 Sep
ISSN1097-6868
Abstract

BACKGROUND: Neonatal respiratory distress syndrome in preterm infants is a leading cause of neonatal death. Pulmonary insufficiency-related infant mortality rates have improved with antenatal glucocorticoid treatment and neonatal surfactant replacement. However, the mechanism of glucocorticoid-promoted fetal lung maturation is not understood fully, despite decades of clinical use. We previously have shown that genetic deletion of Erk3 in mice results in growth restriction, cyanosis, and early neonatal lethality because of pulmonary immaturity and respiratory distress. Recently, we demonstrated that the addition of postnatal surfactant administration to antenatal dexamethasone treatment resulted in enhanced survival of neonatal Erk3-null mice.

OBJECTIVE: To better understand the molecular underpinnings of corticosteroid-mediated lung maturation, we used high-throughput transcriptomic and high-resolution morphologic analysis of the murine fetal lung. We sought to examine the alterations in fetal lung structure and function that are associated with neonatal respiratory distress and antenatal glucocorticoid treatment.

STUDY DESIGN: Dexamethasone (0.4 mg/kg) or saline solution was administered to pregnant dams on embryonic days 16.5 and 17.5. Fetal lungs were collected and analyzed by microCT and RNA-seq for differential gene expression and pathway interactions with genotype and treatment. Results from transcriptomic analysis guided further investigation of candidate genes with the use of immunostaining in murine and human fetal lung tissue.

RESULTS: Erk3(-/-) mice exhibited atelectasis with decreased overall porosity and saccular space relative to wild type, which was ameliorated by glucocorticoid treatment. Of 596 differentially expressed genes (q

CONCLUSION: Characterization of whole transcriptome gene expression revealed glucocorticoid-mediated regulation of corticotropin-releasing hormone and surfactant protein B via Erk3-independent and -dependent mechanisms, respectively. We demonstrated for the first time the expression and temporal regulation of corticotropin-releasing hormone protein in midtrimester human fetal lung. This unique model allows the effects of corticosteroids on fetal pulmonary morphologic condition to be distinguished from functional gene pathway regulation. These findings implicate Erk3 as a potentially important molecular mediator of antenatal glucocorticoid action in promoting surfactant protein production in the preterm neonatal lung and expanding our understanding of key mechanisms of clinical therapy to improve neonatal survival.

DOI10.1016/j.ajog.2016.04.043
Alternate JournalAm. J. Obstet. Gynecol.
PubMed ID27143398
PubMed Central IDPMC5003661
Grant ListDP2 OD001500 / OD / NIH HHS / United States
R01 DK089201 / DK / NIDDK NIH HHS / United States