Fig. 1

Peptidase activity of cysteine cathepsins after bleomycin administration to wild type and cathepsin B-deficient mice. Mice (C57BL/6 strain) were challenged with BLM (7.5 mg/kg for day 1; 3 mg/kg for day 14) or saline solution by intranasal instillation and sacrificed after 1 and 14 days [19]. Lung homogenates and BALF were prepared as described earlier by Gasse et al. ([19]) and Kasabova et al. ([8]). a Lung homogenates and (b) BALF were incubated in the activity buffer (0.1 M sodium acetate pH 5.5, 2 mM DTT, 2 mM EDTA, 0.01 % Brij35) for 5 min. at 30 °C. The overall cathepsin activity was measured toward Z-FR-AMC (50 μM, λ_exc = 350 nm and λ_em = 460 nm) at day 1 (D1) and day 14 (D14) (Gemini spectrofluorimeter, Molecular Devices). White bars: endopeptidase cathepsin activity. Grey bars: control experiments. Samples were preincubated in the presence of CA-074 (10 μM) for 30 min prior to measuring the peptidase activity. Data are expressed as mean values ± SEM. **p < 0.05 (Kruskall and Wallis non-parametric test) (WT NaCl, n = 5; WT BLM, n = 6; CatB^-/- NaCl, n = 5; CatB^-/- BLM, n = 8)