Fig. 4

Upregulated expression of TGF-β1 protein in bronchiolar epithelial cells by intratracheal bleomycin instillation was inhibited by naphthalene-induced club cell injury. a Immunohistochemistry for TGF − β1 of lung tissues on days 1, 7, and 14. Representative image of control, naphthalene alone, bleomycin alone, and bleomycin following naphthalene were shown. b Semi-quantitative analysis of TGF-β1 expression. The intensity of immunostaining (0 = negative, 1–3 = weak, 4–6 = intense) was assessed in 20 bronchioles per each sample. Data are represented as mean ± SE of three mice each group. **P < 0.01 compared with all other groups. N = naphthalene alone; B = bleomycin alone; N + B = bleomycin following naphthalene