Figure 6.

TBXA2R signaling regulates bleomycin (Bleo)–induced fibrosis, even when started 7 and 14 days after injury. (A) Experimental schema showing the timing of ifetroban (Ifet) start and date of sacrifice for panels. The top two lines correspond to B–D in this figure and the bottom line to E–K. (B–D) Wild-type mice were treated with intratracheal Bleo (0.04 U) or vehicle (Veh), with or without Ifet (25 mg/kg/day). Ifet treatment (Ifet[tr]) was delivered from Day 7 to Day 21 after Bleo. Ifet prevention (Ifet[pr]) was started 3 days before Bleo treatment and continued to Day 21. (B) Representative Masson’s trichrome–stained lung sections. (C) Morphometric evaluation of lung fibrosis using these lung sections. (D) Hydroxyproline content in right upper lobe. *P < 0.05 by Wilcoxon signed rank test. (E) Change in weight after Bleo treatment. Data are presented as mean ± SEM. Significance was determined using ANOVA with repeated measures. (F) Representative Masson’s trichrome–stained lung sections from wild-type mice at 28 days after treatment with intratracheal Bleo or Veh with or without Ifet treatment begun at Day 14. (G) Morphometric evaluation of lung fibrosis on lung sections. Data are presented as mean ± SEM. (H) Hydroxyproline content quantified from the right upper lobe. Data are presented as mean ± SEM. *P = 0.05 by Wilcoxon signed rank test. (I) Western blot for Timp-1 (tissue inhibitor of metalloproteinase-1), phospho-Smad2/3, and total Smad2/3 in lung tissue. (J) Densitometry for Timp-1. *P < 0.05 by Wilcoxon signed rank test. (K) Densitometry for total and phospho-Smad2/3 (n = 5 per group). *P < 0.05 by Wilcoxon signed rank test. Error bars denote SEM. BW = body weight; P-Smad2/3 = phospho-Smad2/3; rt = right; TBXA2R = thromboxane–prostanoid receptor; T-Smad2/3 = total Smad2/3.