Background: Clara cell secretory protein (CCSP) is an anti-inflammatory mediator, but its role in neonatal lung adaptation and diseases is uncertain. Objective: To characterize postnatal changes in serum CCSP in relation to gestation, respiratory disease (RDS) and bronchopulmonary dysplasia (BPD) in comparison with other anti-inflammatory cytokines (IL-4, -10 and -13). Methods: Blood was collected from 76 infants (26 of 23–29 weeks’ gestation, 33 of 30–36 weeks’ gestation and 17 term infants) at birth (preterm cord blood); on admission; at 12, 24 and 48 h; and on days 3–4 and 7 of life. CCSP was assayed by ELISA and cytokines by Bio-Plex. Results: Median serum CCSP in extremely and moderately preterm infants rose from a baseline of 13.6 and 15.9 to 33.4 ng/ml (p = 0.04) and 59.8 ng/ml (p = 0.03) at 12 h of age, respectively. CCSP levels were highest in term infants (80.7 ng/ml at 12 h). CCSP then decreased to 22.5 ng/ml on days 3–4 (p = 0.001). CCSP of 37 RDS infants fell to a lower baseline on days 4 and 7 than that of the 22 non-RDS preterms. The 8 infants who developed BPD had persistently low serum CCSP (12.7 ng/ml at 12 h). In contrast, early postnatal changes were not seen in IL-4, -10 and -13 levels, but low IL-10 and -13 levels were found on day 7 in BPD infants. Conclusions: Serum CCSP levels were characterized by an early postnatal surge. This apparent gestation-influenced surge may represent an initiation of a protective cascade against postnatal lung injury during extrauterine adaptation.

Plasma S100A12 is low in infants with RDS, possibly because of gestationally related differences in neutrophil response or to the effects of antenatal corticosteroids. It is therefore not a useful marker of BPD development.