Figure 4. Tissue damage after P. aeruginosa chronic airways infection in IL-17a^−/−, IL-17ra^−/− and congenic wt mice.

Two groups of minimum five IL-17a^−/−, IL-17ra^−/− and congenic wt C57Bl/6 mice were infected with 1 to 2 × 10⁶ CFU/lung of the P. aeruginosa strain AA43 embedded in agar beads and analyzed 28 days post-infection. Ctrl mice were treated with sterile agar-beads. (A) Sections of airway from mice infected with AA43 were stained with VEG for elastic fibers, according to the standard procedure. Scale bars: 25 μm. Scoring of elastin preservation was performed on slices stained with VEG (B). Levels of pro-MMP-9 (C) and TGF-β₁ (D) were measured by ELISA and Bioplex respectively in lung homogenates after 28 days of chronic lung infection. Values represent the mean ± SEM. The data are pooled from at least two independent experiments (n = 3–10). Statistical significance is indicated: *p < 0.05, **p < 0.01, ***p < 0.001.