(A) C57BL/6 and fpr1–/– mice were challenged intratracheally with saline (30 μl) or bleomycin sulfate (0.007 U in 30 μl saline) and lung tissue–harvested on days 1, 5, and 21. (B) Hydroxyproline (μg/lobe) content of lung tissue on days 5 and 21. (C) Representative H&E-stained lung tissue on day 21. (D) Percentage area positive of Picrosirius red and (E) α-smooth muscle actin (αSMA) staining on day 21. Data represent the mean value of 20 randomly selected, nonoverlapping fields (original magnification, ×20). Relative gene expression of collagen type I (F), fibronectin (G), elastin (H), and MMP2 (I) in lung tissue on day 21 was assessed by qPCR. Gene expression was normalized to GAPDH as a loading control. n = 7–10 mice per group. No significant difference was seen between saline-treated C57BL/6 and fpr1–/– mice, and therefore saline-treated mice were pooled and presented as mean (red-hashed line). Data were analyzed using a Mann-Whitney U test and presented as box-and-whisker plots. *P < 0.05; **P < 0.01.