FIG. 2.

Density distribution of common lung cell lineages. (A) Fractionated cells from sham or 2-day bleomycin-treated mice were subjected to flow cytometry and average percent of cells (±SEM) per fraction are presented. P-value representations shown: normal font—differences in the proportion of protein-expressing cells isolated between fractions from the homeostatic lung; bold font—differences in the proportion of protein-expressing cells between fractions postbleomycin treatment, and italics—overall differences in the proportion of protein-expressing cells between pre- and postbleomycin treatment regardless of fraction. No statistically significant differences were observed in the proportion of CD45-, CD31-, and EpCAM-positive cells between the density fractions in the homeostatic lung. In contrast, cells positive for c-KIT and CD49f were more prevalent in the lower fractions, while SCA-1 expressing cells equilibrated largely in the intermediate fractions. At day 2 following bleomycin treatment, only CD45-positive cells showed significant differences among the fractions equilibrating at the highest density (n≥7; P=0.01). (B) Representative western blots depicting levels of protein expression per fraction (n≥4). The fibroblastic, smooth muscle, α1-actin (ACTA1) protein signal is highest in fractions 3 and 4 (P<0.01 by densitometry). Levels of the epithelial (pro-) surfactant protein-C (SFTPC) and secretoglobin family 1A member 1 (SCGB1A1) protein bands are statistically significant between the fractions (P<0.001 for both). Levels of the AT1 epithelial protein, aquaporin-5 (AQP5) are highest in the lighter fractions (P<0.001). Bands representing levels of the endothelial CD31 protein and β-actin are also shown.