Spatial and temporal expression of SP-B and TGF-β1 in hyperoxia-induced neonatal rat lung injury.

Objective: Bronchopulmonary dysplasia (BPD) is a severe complication of extreme prematurity that can be caused by hyperoxia inhalation. SP-B and TGF-β have been reported to be implicated in the development of lung. This study aimed to reveal the spatial and temporal expression patterns of these two factors in an animal model of BPD.

Methods: Newborn Sprague-Dawley (SD) rats were subjected to hyperoxia conditions to establish an animal model of BPD. The levels of SP-B, TGF-β, MDA and TAOC, as well as the activations of MAPK and PI3K/AKT pathways in lung tissues were monitored during newborn rats prolonged exposure to hyperoxia.

Results: We found that hyperoxia exposure significantly induced body weight loss of SD rats. H&E staining for morphometric analyses revealed that hyperoxia arrested alveolar development or loss of alveoli, with fewer and dysmorphic capillaries. mRNA and protein levels of SP-B and TGF-β were high expressed in hyperoxic lung tissues. The concentrations of SP-B and TGF-β in bronchoalveolar lavage fluid were also increased. All these increases begin at the 3th day of hyperoxia exposure. MDA content was increased while TAOC content was decreased in response to hyperoxia. Furthermore, hyperoxia activated p38, and deactivated PI3K and AKT expression.

Conclusion: Our research demonstrated that SP-B and TGF-β1 were highly expressed in three levels: mRNA and protein levels in lung tissues, and the release of SP-B and TGF-β1 in bronchoalveolar lavage fluid, beginning at the 3th day of hyperoxia exposure.