Bleomycin-induced skin fibrosis mouse model

IRF7 knockout (KO) mice congenic on the C57BL/6J background were acquired from Riken Japan (Tokyo, Japan). Female C57BL/6J wild-type mice aged 8 weeks were purchased from Jackson Laboratory (Bar Harbor, Maine, USA). Mice were housed in autoclaved cages and fed sterile food and water. Bleomycin (0.02 units/day) (Teva Parenteral Medicines, Irvine, California, USA) dissolved in phosphate-buffered saline (PBS) or PBS alone was administered by subcutaneous injection to the back skin of mice aged 8 weeks 6 days per week daily for 4 weeks. On day 7 or 28, mice were sacrificed and lesional skin was harvested for hydroxyproline, total RNA, histology and immunohistochemistry.