Potential role of interleukin-1 in the development of bronchopulmonary dysplasia

Increased activities of inflammatory mediators unopposed by their inhibitors contribute to chronic lung injury and impaired healing in BPD, The deleterious effects of IL-1 beta, a cytokine involved in inflammation and host defense, are blocked by IL-1 receptor antagonist (IL-1Ra), We proposed that an imbalance of IL-1 beta and its inhibitors may contribute to the development of BPD, To determine the relative antigen concentrations of IL-1 beta and IL-1Ra and functional IL-1 activity in lung lavage of infants at risk for BPD, lung lavage was serially obtained from 1 to 28 days from 17 infants with evolving BPD, 13 infants with self-limited RDS, and 6 controls ventilated for nonpulmonary reasons, Overall, there was a high correlation between IL-1 beta antigen concentration and IL-1 activity (r = 0.82, p = 0.0001), There were no significant differences among the groups for lung lavage variables on day 1, However, in infants who developed BPD, IL-1 beta antigen concentration and IL-1 activity increased 16- and 61-fold, respectively, during the first week, IL-1Ra remained relatively unchanged during the first month, IL-1 beta/IL-1Ra antigen ratio was significantly higher on days 5 (median 0.024) and 7 (median 0.025) compared with day 1 (median 0.004), p < 0.05, These results suggest that a relative imbalance of IL-1 beta and IL-1Ra may contribute to prolonged inflammation in BPD.