Figure 4

Enhanced lung histopathology in IRAK-M^−/− mice early after induction of Klebsiella pneumonia. Representative lung histology of WT (A, D, G and J) and IRAK-M^−/− (B, E, H and K) mice at 3 (A-C), 6 (D-F), 24 (G-I) and 48 (J-L) h after intranasal infection with 1 × 10⁴ CFU K. pneumoniae. The lung sections are representative for 7–9 mice per group per time point. H&E staining, original magnification 20x. Inflammation scores are expressed as mean ± SEM (WT mice: black bars; IRAK-M^−/− mice: white bars n = 7–9/group). Neutrophil influx into bronchoalveolar lavage fluid (M) and myeloperoxidase (MPO) concentrations in lung homogenates (N) at 3 h to 48 h after infection with 1 × 10⁴ CFU of K. pneumoniae. Data are expressed as mean ± SEM; n = 7–9/group, *P < 0.05, **P < 0.01 as compared with WT mice.