Chronic lung disease of prematurity (CLD) is associated with an inflammatory response in the preterm lung and increased levels of proinflammatory cytokines in tracheobronchial aspirate fluid (TAF).

Objectives: To determine TAF levels of transforming growth factor-β1(TGF-β1), interleukin-10, 4 and 12, cytokines possibly important in downregulating the pro-inflammatory response and/or inducing lung fibrosis in infants with developing and established CLD.

Study design: Infants with CLD (n=24) were compared with preterm infants with RDS that resolved (n=22) and postoperative infants without lung disease (n=23). TAF levels of TGF-β1, IL-10, IL-4 and IL-12 were analyzed by quantitative enzyme immunoassay (EIA).

Results: Levels of TGF-β1 were significantly higher during the first week of life in infants who developed CLD, remained high at 2 weeks and past 4 weeks of age. TAF levels of TGF-β1 did not decrease significantly in infants with CLD after treatment with steroids. Infants with CLD and RDS infants were significantly more likely to have measurable TAF levels of IL-10, compared with the postoperative infants (p<0.02 and 0.04, respectively). TAF levels of IL-4 or IL-12 were below the detection limits in all samples.

Conclusions: We have demonstrated increased levels of TGF-β1 in TAF from preterm infants who develop CLD, compared to preterms with RDS that resolved and postoperative infants. Corticosteroids did not decrease TGF-β1 in infants with CLD. This suggests an important role for TGF-β1 in the fibrotic response in the CLD lung. The levels of IL-4, IL-10 and IL-12 were not found to be related the development of CLD.