Figure 1.

Hyperoxia impairs alveolar macrophage-mediated efferocytosis, and Nrf2-deficiency worsens it in vivo. Nrf2^+/+ (WT) and Nrf2^−/− mice (n = 3 per group) were exposed to room air or hyperoxia for 48 h, and a set of hyperoxia-exposed mice were allowed to recover at room air for 72 as outlined in schema. (a) BAL from these mice was obtained, and macrophages were incubated on cover glasses with apoptotic neutrophils for 1 h. Macrophages were washed to remove unbound/non-internalized apoptotic cells and stained with Diff Quick stain. Images were captured to quantify apoptotic neutrophil binding, and internalization (indicated by red arrows). (b) Representative images of macrophages with neutrophils for each experimental condition are shown. (c) The number of apoptotic neutrophils either bound or internalized by macrophages from ~5–9 fields were quantified and expressed as % efferocytosis. Versus room air of respective genotypes, † Nrf2^−/− versus WT counterparts, § hyperoxia vs. recovery; †† p < 0.01; ****/§§§§/†††† p < 0.0001. Purple, room air group; Red, hyperoxia group; Green, hyperoxia and recovery.