Inflammatory imbalance in the development of bronchopulmonary dysplasia.

AbstractIntroduction: Current evidence suggests that the lungs of infants with the debilitating disorder, bronchopulmonary dysplasia (BPD), react to the challenges of extra-uterine adaptation with inappropriately aggressive inflammation. The reasons for this are not entirely clear and this study hypothesizes that a deficiency of interleukin (IL)-10, a potent anti-inflammatory mediator, leads to the functional and architectural changes characteristic of BPD. Aim: To characterize the behaviour of IL-10 and neutrophil apoptosis in the tracheal fluids (TF) of infants at risk of developing BPD.Method: TF from intubated infants of varying gestations at the Royal Hospital for Women, Randwick was spun and ILs 8, 10 and 16 were measured in the supernatant. The residual pellets of white cells were used to determine differential white cell counts and neutrophil apoptosis.Results: None of the 20 TF specimens from the extremely premature infants with BPD (n=11) had detectable IL-10, compared to 14/20(70%) of the specimens from preterm infants without BPD (n=20) and to 5/19 (26%) of the specimens from term infants (n=19). BPD infants also had a significantly lower number of apoptotic neutrophils during the 1st week of life. Premature infants with TF IL-10 &gt5pg/ml did not develop BPD. Levels of IL-8, a neutrophil chemotaxin, and white cell counts, while not differing significantly between the groups, increased considerably towards the end of the first week of life in the BPD group. IL-16, a chemotaxin for inflammatory CD4+ cells, was also detected in more BPD than non-BPD specimens (BPD: 16/46 (35%) v 1/30 (0.3%) non-BPD preterm and 2/7 (28%) term TF specimens).Conclusions: Extremely premature infants prone to BPD have decreased pulmonary anti-inflammatory activity as demonstrated by decreased IL-10 and apoptotic neutrophils in tracheal fluids. The lack of a counter-regulatory response to the inflammatory processes that are an inevitable consequence of extra-uterine adaptation may therefore place the extremely premature newborn infant at a considerable risk of developing BPD