Fig. 1

Impaired pulmonary vascular development in BPD model mice, with increased IRF4 and decreased FOXP3 protein levels and number of Tregs. A BPD model simulated using hyperoxia exposure, and mouse lung tissues taken at 7 d and 14 d after air or hyperoxia exposure, respectively. B HE staining to observe the morphology of mouse lung tissues (× 400; scale bar, 50 μm). Black arrows refer to thickened alveolar septa, red arrows refer to fused and enlarged alveolar lumina. C IHC of PECAM-1 level in mouse lung tissues (× 400; scale bar, 50 μm). D Western blot of VEGFA, Ang-1, FOXP3, and IRF4 protein levels in mouse lung tissue. E Flow cytometry to detect the number of Tregs and the expression of IRF4 and FOXP3 in the lung tissues of the mice. F Pearson correlation analysis to derive a positive correlation between the number of Tregs and the level of PECAM-1 (r = 0.730). Data are expressed as mean ± SD. n = 6. Significant differences are indicated by *p < 0.05