Antifibrotic activity of a FIEL1 small molecule inhibitor in vivo. (A) C57BL/6J mice were treated i.t. with bleomycin (0.05 U). 10 d later, compound BC-1485 was given to mice through the drinking water with an estimated dose of 2 or 10 mg/kg/d. Mice were euthanized 10 d later, and lungs were lavaged with saline, harvested, and then homogenized. (B and C) Lavage proteins and total cell count were measured. Data represent mean values ± SEM (n = 6–9 mice per group; *, P < 0.05 compared with Vehicle, Student’s t test). (D) Lavage cells were also processed for Wright-Giemsa stain; lavage macrophages, neutrophils, and lymphocytes were counted and graphed. Data represent mean values ± SEM (n = 6–9 mice per group; *, P < 0.05 compared with Vehicle, Student’s t test). (E) Survival studies of mice that were given bleomycin and BC-compound treatments. Mice were carefully monitored over time; moribund, preterminal animals were immediately euthanized and recorded as deceased. Kaplan-Meier survival curves were generated using SPSS software (n = 12–16 mice per group; *, P < 0.05 compared with Vehicle, Log-rank test P < 0.05). Vehicle, n = 16, BC-1485 (2 mg/kg/d); n = 12, BC-1485 (10 mg/kg/d); n = 12. (F) Hydroxyproline content was measured in lungs from 10 d after bleomycin challenge. Data represent mean values ± SEM (n = 6–9 mice per group; *, P < 0.05 compared with Vehicle, Student’s t test). (G) H&E and Trichrome staining were performed on lung samples from A. Bar, 100 µm. (H) Collagen percent quantification from Trichrome staining. Data represent mean values ± SEM (n = 6–9 mice per group; *, P < 0.05 compared with Vehicle, Student’s t test). (I) Mice lungs were isolated and assayed for PIAS4 and FIEL1 immunoblotting.