Glucocorticoids, sodium transport mediators, and respiratory distress syndrome in preterm infants

Background Antenatal glucocorticoids (GCs) reduce respiratory distress syndrome (RDS) in preterm infants and are associated with reduced lung liquid content. Our aim was to assess whether airway gene expression of mediators of pulmonary epithelial sodium and liquid absorption, and further, respiratory morbidity, associate with cord blood GC concentrations. Methods The study included 64 infants delivered <32 weeks gestation. Cortisol and betamethasone in umbilical cord blood were quantified with liquid chromatography-tandem mass spectrometry. The total GC concentration was calculated. Gene expression of the epithelial sodium channel (ENaC), Na,K-ATPase, and serum- and GC-inducible kinase 1 at Results Concentrations of cord blood betamethasone and total GC were significantly lower in infants with RDS and correlated with mean oxygen supplementation. Expression of alpha ENaC and alpha 1- and beta 1Na,K-ATPase at <2 h correlated with betamethasone and total GC concentrations. Expression of Na,K-ATPase was lower in infants with RDS. Conclusion Enhancement of lung liquid absorption via increased expression of sodium transporters may contribute to the beneficial pulmonary effects of antenatal GCs. Impact RDS is related to lower umbilical cord blood GC concentrations and lower airway expression of sodium transporters. In addition to the timing of antenatal GC treatment, resulting concentrations may be of importance in preventing RDS. Induction of sodium transport may be a factor contributing to the pulmonary response to antenatal GCs.

Automated summary

The study found that infants with RDS had significantly lower umbilical cord blood GC concentrations, which were correlated with oxygen supplementation. Within the first 2 hours after birth, the expression of α-ENaC, α1, and β1Na,K-ATPase was correlated with cord blood betamethasone and total GC concentrations. Overall, enhancing lung liquid absorption through increased expression of sodium transporters may contribute to the beneficial effects of antenatal GCs on the lungs.