Fig. 6: LPS exposure modulates pneumonia outcome in a context-dependent manner.

a Experimental setup for adoptive transfer of LPS-trained or control donor AMs, followed by i.n. S. pneumoniae infection (in vivo challenge). Donor AMs were isolated by BAL five days after in vivo training and transferred intratracheally (i.t.) to naïve WT mice. Recipients were i.n. infected with S. pneumoniae 24 h after cell transfer. b Lung bacterial loads of recipients, determined 48 h after infection. c, d Representative histology images (c) and pneumonia score (d) of H&E-stained lung tissue 48 h after infection; scale bars: 100 µm. Graphs show means + SEM of two pooled experiments with 6–8 biological replicates each (total n = 12–16). e Experimental setup for in vivo training, followed by infection with S. pneumoniae (in vivo challenge) on day six. f Lung bacterial loads, 48 h after infection. g, h Representative histology images (g) and pneumonia score (h) of H&E-stained lung tissue, 48 h after infection; scale bars: 200 µm. Graphs show means + SD of 8–10 biological replicates. Data are representative of two independent experiments. Statistical analysis: Mann-Whitney-U test. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.