OBJECTIVETo study the effect of hyperoxia exposure on high mobility group protein-B1 (HMGB1) expression in neonatal mice and the role of HMGB1 in the pathogenesis of bronchopulmonary dysplasia (BPD).

METHODSC57BL/6 mice were randomly exposed to 60% O2 or air 1 day after birth. BPD was induced by 60% O2 exposure. The pulmonary tissue samples were harvested 3, 7 and 14 days after exposure. The pathologic changes of pulmonary tissues were observed by hematoxylin and eosin staining, Masson staining and radical alveolar count. The expression of HMGB1 protein in lungs was detected by immunofluorescence. The expression of HMGB1 mRNA was detected by real-time fluorescent quantitative PCR.

RESULTSIn the BPD group, the lungs developed decreased alceolar septation, swollen alveolar epithelium, stroma edema, interstitial fibrosis and developmental lag when compared with the control group. These changes became more obvious with more prolonged hyperoxia exposure. The expression of HMGB1 protein and mRNA 7 and 14 days after exposure increased significantly in the BPD group compared with that in the control group.

CONCLUSIONSHyperoxia exposure results in an increase in lung HMGB1 expression. The increased HMGB1 expression may be associated with the development of BPD.