Interleukin-8 in bronchoalveolar lavage fluid of premature infants at risk of chronic lung disease

Background and Purpose: Persistence of neutrophils in the tracheal fluid of premature infants is associated with chronic lung disease (CLD). Interleukin-8 (IL-8) is a potent neutrophil chemoattractant. This study investigated whether IL-8 is increased in the bronchoalveolar lavage fluid of premature infants with different types of CLD. Methods: Forty two very low birth weight infants who required mechanical ventilation were recruited. Twenty eight of these infants developed CLD and 14 infants recovered without developing CLD. Four additional infants receiving mechanical ventilation for non-respiratory reasons were also enrolled as controls. CLD was defined as requirement for supplemental oxygen at 28 days of age and chest radiograph showing characteristic appearance. CLD was further classified into 3 subtypes: bronchopulmonary dysplasia (BPD), Wilson-Mikity syndrome (WMS) and chronic pulmonary insufficiency of prematurity (CPIP). Results: IL-8 in bronchoalveolar lavage fluid was significantly increased in the CLD group by 8 days of age compared to those who did not develop CLD (p < 0.05). For infants without CLD, IL-8 increased from 963 pg/mL on day 1 after delivery to 1463 pg/mL, on day 4, and decreased to 1000 pg/mL, on day 8. For infants with BPD, IL-8 increased from 925 pg/mL on day 1 after delivery to 2650 pg/ml, on day 8, and then gradually decreased to 1500 pg/ml., on day 28. Infants with WMS had significantly higher IL-8 from the first day after delivery (4567 pg/mL) than infants with BPD or CPIP and this difference persisted to age 28 days (2475 pg/mL). Conclusions: Persistent inflammation could be a major contributory factor in the development of CLD. The different patterns of response to inflammation in different types of CLD may have implications for the design of appropriate strategies to prevent and treat CLD.