Tracheal aspirate gene expression in preterm newborns and development of bronchopulmonary dysplasia.

Background:  Bronchopulmonary dysplasia (BPD) occurs in association with prenatal conditions predisposing infants to inflammation and remodeling of the premature lungs. Because of the lack of useful biomarkers for BPD, the gene expression of tracheal aspirate fluid (TAF) cells in premature infants was analyzed. Methods:  Of 148 consecutive patients, 26 preterm infants (gestational age <34 weeks) were enrolled, who underwent assisted ventilation at birth for respiratory failure. Patients with congenital disorders were excluded. Half of these infants developed BPD. Interleukin (IL)-10, interferon (IFN)-γ, transforming growth factor (TGF)-β1, and platelet-derived growth factor (PDGF)-B mRNA of TAF cells were quantified on real-time polymerase chain reaction. Results:  IL-10 (P < 0.01) and IFN-γ (P= 0.03) but not TGF-β1 or PDGF-B mRNA levels at birth were higher in BPD than in non-BPD infants. IL-10 expression differentiated BPD with the highest sensitivity (92%) and specificity (77%). IL-10 levels correlated with TGF-β1 (P= 0.03) and IFN-γ (P= 0.01), but not with PDGF-B levels. When BPD infants were classified according to comorbidity (group 1, six patients who suffered respiratory distress syndrome [RDS] but not chorioamnionitis [CAM]; group 2, five patients who had CAM but not RDS), PDGF-B levels were higher in group 2 (P= 0.01). High IL-10 expression was selected as a risk factor for BPD in infants who had CAM but not RDS (P= 0.01), although prolonged oxygen therapy was the most sensitive indicator for BPD (P < 0.01) on multivariate analysis. Conclusions:  High IL-10 expression in TAF cells at birth could predict the evolution of BPD, but with less impact than oxygen requirement. PDGF might play a different role in the inflammatory process of premature lungs.