Fig. 2

Assessment of PPE-induced emphysema in IL-33^−/− mice. a Static lung compliance (Cst) values in WT and IL-33^−/− mice on day 21 after intratracheal instillation of PPE or saline. Mice received 2 U of PPE or saline by intratracheal instillation. Cst values were obtained as described in Materials and Methods. WT PBS: WT mice treated with PBS. IL-33^−/− PBS: IL-33^−/− mice treated with PBS. WT PPE: WT mice treated with PPE. IL-33^−/− PPE: IL-33^−/− mice treated with PPE. Data are shown as the mean ± SEM (n = 5–10 in each group). *P < 0.05 compared to WT PBS; #P < 0.05 compared to WT PPE. b Representative images of H&E-stained lung tissue (magnification: × 200) (a) WT mice treated with PBS on (i) day 7, (ii) day 14, and (iii) day 21, (b) IL-33^−/− mice treated with PBS on (i) day 7, (ii) day 14, and (iii) day 21, (c) WT mice treated with PPE on (i) day 7, (ii) day 14, and (iii) day 21, (d) IL-33^−/− mice treated with PPE on (i) day 7, (ii) day 14, and (iii) day 21. c Mean linear intercept (Lm) alveoli values. Morphometric assessment was performed on days 7, 14, and 21 after instillation. Lm values were determined as described in the “Materials and methods”. Data are shown as the mean ± SEM (n = 5–10 in each group). *P < 0.05 compared to WT PBS; **P < 0.05 compared to IL-33^−/− PBS; ^#P < 0.05 compared to WT PPE