Figure 4: Bleomycin-induced lung injury and fibrosis are prevented in the absence of vimentin.

Shown is the histology of mice lungs 21 days following intratracheal instillation of bleomycin or PBS. Masson trichrome (a) and Picrosirius Red (b) stains for collagen. Original magnification for overview mosaics, × 5. Enlargements were taken with a × 40 objective (scale bar, 200 μm). (c) Representative elastographs from AFM micro-indentation of lung tissue from WT and Vim^−/− animals. The colour bar indicates elastic modulus, E. The darkest red corresponds to elastic modulus values of 50 kPa and above. The data represent 256 indentations per region, with at least two regions per tissue section from at least three mice per group. (d) Collagen content in lungs from WT and Vim^−/− mice assessed by Sircol assay. (e) Mice were ventilated 21 days after intratracheal instillation of bleomycin or PBS. Shown are quasi-static compliance measurements of WT and Vim^−/− lungs. (f) Elastic modulus frequency plot obtained from live, unfixed lung tissue of saline and bleomycin-treated WT and Vim^−/− animals. Microindentation data were fit using the Hertz model to acquire the elastic modulus of regions of lung tissue. Images in a–b represent data obtained from at least three animals per group; data shown in d–e are mean±s.d. of at least five animals. **P<0.001, ***P<0.0001 relative to WT versus Vim^−/−, by one-way analysis of variance with a correction provided by the Bonferroni multiple comparisons test.