Fig. 9.

Increased lung cell apoptosis induced during MV-O₂ is suppressed in elafin-expressing mice. A: summary data (means and SD) showing increased terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling (TUNEL)-positive nuclear staining, an index of apoptosis, in lungs of 6-day-old wild-type mice after MV-O₂ for 36 h, compared with unventilated controls that breathed 40% O₂ for 36 h. Lungs of elafin-expressing mice also exhibited increased TUNEL stain after MV-O₂ for 36 h compared with unventilated controls, but the magnitude of the increase was significantly less than it was in wild-type mice. TUNEL stain was assessed by quantitative image analysis of 12 ×400 fields/animal. B: representative images of lung tissue sections (×400) showing TUNEL-stained nuclei (arrows, brown stain) in distal lungs of wild-type (top) and elafin-expressing (bottom) mice after MV-O₂ for 36 h. C: immunoblots for cleaved caspase-3, showing suppression of apoptosis in elafin-expressing mice, compared with wild-type mice, after MV-O₂ for 24 h. *Significant difference between groups, P < 0.05. Values are means and SD; n = 4–6/group for (A), n = 4–5/group for (C).