[Effect of hyperoxia and TGF-β1 on epithelial-mesenchymal transition of type II alveolar epithelial cells].

Aim: To investigate the effect of hyperoxia and TGF-β1 on epithelial-mesenchymal transition (EMT)of type II alveolar epithelial cells (AEC-II) of mice.

Methods: AEC-II cells (MLE-12 lines) were randomly divided into following groups: air exposure group, hyperoxia exposure group, air exposure combined with TGF-β1 treatment group, hyperoxia exposure combined with TGF-β1 treatment group. The morphological changes of cells in each group were observed at 6, 12, 24, 48 hours. The protein and mRNA expressions of AECII specific marker lung surfactant protein B(SP-B)and fibroblast specific marker fibroblast specific protein (FSP1)were detected by double-labeled immunofluorescence and real time-PCR at the same time point, respectively.

Results: Along with the time of exposure to hyperoxia and TGF-β1, AECIIcells gradually changed from pebble-like shape to spindle shape, and showed some fibroblast appearances. Synchronously, the protein expression of SP-B in AECII cells decreased, whereas the expression of FSP1 increased. The co-expressed were observed at 24 hours. Comparing with that of the air exposure group, the mRNA expression of SP-B in the hyperoxia exposure group, air exposure combined with TGF-β1 treatment group, hyperoxia exposure combined with TGF-β1 treatment group decreased significantly, whereas the mRNA expression of FSP1 increased significantly at 24 hours and 48 hours (P<0.01).

Conclusion: Hyperoxia and TGF-β1 can induce EMT of type II alveolar epithelial cells in a time-dependent manner.