Increased periostin expression in the lungs of infants with BPD.

The lung of a full-term infants dying of a non-pulmonary cause is shown in (A). There is significant staining in the airway subepithelium, with miminal staining of the airway epithelium or alveolar walls. B–D. Staining of lung sections from three individual infants dying of BPD showed increased periostin expression, particularly in the subepithelium and fibroblastic foci. E. We also examined periostin (green) and α-smooth muscle actin (red) expression by fluorescence microscopy. Lungs of full-term infants showed periostin expression in the airway subepithelium which was distinct from the adjacent smooth muscle. F–H. Lungs of three individual infants with BPD were also examined for periostin expression. Lungs showed colocalization of periostin and α-actin in interstitial alveolar myofibroblasts (F and G, arrows, insets). Colocalization of periostin and α-actin (yellow-orange) was also found at the tips of secondary crests (H, arrow, inset). Original magnification, 200×.