Fig. 4.

Bleomycin-treated mice have increased periostin expression and protein production in vivo. Mice were injected intratracheally with 0.025 U of bleomycin or 50 μl of saline (controls). Lungs were harvested 3, 7, 14, and 21 days after bleomycin or saline treatment. RNA was isolated from lungs and converted to cDNA, and real-time PCR was performed using periostin and GAPDH primers. A: periostin expression in lungs increased dramatically by 3 days after bleomycin treatment but remained elevated up to 21 days later (n = 4 per group). *P < 0.05. B and C: lungs were also harvested for fluorescence microscopy at 14 days after bleomycin treatment. Images are representative of 3 sections examined per group. B: normal saline control lung with minimal periostin staining (green) and α-smooth muscle actin [α-SMA (red)] localized to myocytes around vessels only. Nuclei stained blue with 4′,6-diaminido-2-phenylindole. C: bleomycin-treated lung with increased periostin staining and increased α-SMA staining in interstitium.