Effects of Postnatal Hydrocortisone Treatment on Cytokine Profile in Preterm Infants at Risk of Bronchopulmonary Dysplasia

Abstract Systemic hydrocortisone administration has been widely used in preterm infants who are at a risk of bronchopulmonary dysplasia (BPD). However, the effects of hydrocortisone on cytokine profiles have not been examined. We aimed to investigate the effects of postnatal hydrocortisone treatment on serum cytokine levels in extremely preterm infants at risk for BPD. In 29 extremely preterm infants (born at less than 28 weeks of gestational age), we obtained serum from blood samples collected during an early phase (5–20 days) and a late phase (28‒60 days) after birth. We measured the levels of proinflammatory cytokines (tumor necrosis factors α and β, interleukin [IL]-1β, and IL-6), T-helper (Th) 1 cytokines (interferon-γ, IL-2, and IL-12p70), Th2 cytokines (IL-4, IL-5, and IL-10), Th17 cytokine IL-17A, and chemokine IL-8. We found that serum IL-6 and IL-8 levels were significantly higher during the early phase than during the late phase (both P = 0.03). Other cytokines concentrations did not change between the phases. Thirteen infants (45%) received systemic hydrocortisone treatment at a median age of 15 days (IQR 10.0–21.5) after birth due to respiratory deterioration, after which the serum IL-6 levels significantly decreased (P = 0.04). Median duration of treatment was 16.0 (IQR 8.0–34.5) days. Conclusion: Extremely preterm infants show high serum IL-6 and IL-8 levels in the early phase of life. Moreover, postnatal systemic hydrocortisone treatment might suppress IL-6 overproduction.