2.2. BLM-Induced PF Model and Animal Treatment

Mice were randomly divided into the following groups using the table of random numbers: (i) the control group: intratracheal saline plus saline intraperitoneal, (ii) BLM group: intratracheal injection of BLM (1.5 mg/kg, in 50 μL saline, Nippon Kayaku, Japan) plus an intraperitoneal injection of saline, and (iii) BLM + TPPU group: intratracheal BLM plus TPPU intraperitoneally (1 mg/kg/day). All treatment was under sodium pentobarbital (80 mg/kg) anesthesia. Each group includes at least 6 mice. TPPU dissolved in 0.1% ethanol was administered to mice daily from the 7^th to the 21^st day after BLM injection. Mice were humanely euthanized by sodium pentobarbital anesthesia on the 21^st day. The lungs and bronchoalveolar lavage fluid (BALF) were collected. Bodyweight was recorded throughout the experiment.