Effects of postnatal hydrocortisone on cytokine profile in extremely preterm infants

BACKGROUND: Systemic hydrocortisone administration has been widely used in preterm infants who are at 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.

METHODS: This is a retrospective study of 29 extremely preterm infants born at <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. The cytokine levels between the early and late phases were compared between infants who received postnatal hydrocortisone and those who did not.

RESULTS: 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. The percentage of BPD was higher in the steroid group than in the non-steroid group (P = 0.008). The ratio of IL-6 for the late-to-early phase was significantly lower in the steroid group than in the non-steroid group (P = 0.04). The concentration of the other cytokines remained unchanged between the phases.

CONCLUSIONS: Although the postnatal hydrocortisone treatment provided for respiratory deterioration did not prevent the BPD development, hydrocortisone treatment might suppress IL-6 overproduction in extremely preterm infants.