Abstract：Objective To investigate the effect of transforming growth factor-β1 (TGF-β1) on the extracellular matrix (ECM) of lungs in premature infants with chronic lung disease (CLD). Methods Sixty premature rats were randomly assigned into a Model group of CLD and a Control group (n=30 each). CLD was induced by hyperoxia exposure. The distribution and expression of TGF-β1 and levels of type I collagen, fibronectin (FN) and hyaluronic acid (HA) from lung specimens were assayed by the immunohistochemical method and enzyme-linked immunoabsorbent technique on days 1, 3, 7, 14 and 21 of the experiment. Results In the Control group there was a slight expression of TGF-β1 in bronchial epithelial cells and vascular endothelial cells. In the Model group, the TGF-β1 expression was similar to that of the Control group on day 1 and day 3, while on day 7, the TGF-β1 expression in alveolar macrophages, alveolar epithelial cells and interstitial cells was found. Expression intensity and range were increased with the time of hyperoxia-inducement and reached a peak on the 21st day. On days 1, 3, and 7, there were no differences in the type I collagen level between the two groups. On day 14, however, it was higher in the Model group than that of the Control group (P< 0.05). This difference was more significant on day 21 (P< 0.01). Levels of FN and HA in the Model group did not differ from those of the Control group at any time point of the experiment. The level of TGF-β1 expression was postitively correlated with the type I collagen level on day 14 (r= 0.709,P< 0.01) and day 21 (r= 0.711, P< 0.01). Conclusions Over-expression of TGF-β1 may play an important role in ECM remodeling in rats with hyperoxia-induced CLD.
