Evidence of unexpected oxidative stress in airways of adolescents born very pre-term

Prematurity and its main respiratory complication, bronchopulmonary dysplasia (BPD), are potentially associated with lifelong respiratory morbidities and/or lung function abnormalities. The mechanisms behind these long-term respiratory problems are still unclear. We assessed airway oxidative stress in adolescents born very pre-term (<= 32 gestational weeks) by measuring 8-isoprostane concentration in exhaled breath condensate (EBC). In addition, the study protocol included spirometry and measurement of exhaled nitric oxide fraction (FeNO). The study groups included 34 ex-pre-term adolescents with BPD, 18 ex-pre-term adolescents without BPD and 34 healthy controls born at term. Regardless of a history of BPD, the ex-premature adolescents had higher EBC 8-isoprostane levels (median (interquartile range) BPD 9.5 (7.3-12.2) pg.mL(-1); pre-term non-BPD 10 (8.1-16) pg-mL(-1)) than the controls (3.2 (1.9-6.5) pg.mL(-1)) (p<0.001). Forced expiratory volume in 1 s was lower in the BPD group (mean +/- SD Z-score -2.1 +/- 1.58) than in the pre-term non-BPD individuals (-1.13 +/- 1.15), who showed in turn significantly lower values than the controls (0.18 +/- 0.83; p<0.001). FeNO was similar in the three groups (p=0.55). Our data show that, after premature birth, evidence of oxidative stress in the airways may be detected into adolescence, suggesting that long-term respiratory abnormalities after pre-term birth may be associated with an ongoing airway disease and not just a stabilised structural lung damage.