OBJECTIVETo investigate the expressions of thyroid transcription factor-1 (TTF-1), the type II alveolar epithelial cells (AECII)-specific marker, and vimentin, the fibroblast-specific marker, in the lungs of neonatal mice with bronchopulmonary dysplasia (BPD) and explore the pathogenesis of BPD.

METHODSNeonatal mice were exposed to hyperoxia to induce BPD, and pathological changes in the lung tissues were examined. At 3, 7, 14 and 21 days after the exposure, the protein and mRNA expressions of TTF-1 and vimentin were detected by double-labeled immunofluorescence assay and real-time PCR, respectively.

RESULTSCompared with the neonatal mice exposed in normal air, those with hyperoxic exposure showed developmental disorders and collagen deposition in the lung tissues. The protein expression of TTF-1 decreased while vimentin expression increased in the lung tissues, where their co-expression was observed at 14 and 21 days after the exposure. TTF-1 mRNA expression decreased markedly (P<0.05) and vimentin mRNA increased significantly in the lung tissues at 21 days after hyperoxic exposure of the mice (P<0.05).

CONCLUSIONHyperoxia-induced transition of AECII to fibroblasts may play an important role in pulmonary fibrosis in neonatal mice with BPD.