[PDF][PDF] Legionella-infected macrophages engage the alveolar epithelium to metabolically reprogram myeloid cells and promote antibacterial inflammation

X Liu, MA Boyer, AM Holmgren, S Shin - Cell host & microbe, 2020 - cell.com
X Liu, MA Boyer, AM Holmgren, S Shin
Cell host & microbe, 2020cell.com
Alveolar macrophages are among the first immune cells that respond to inhaled pathogens.
However, numerous pathogens block macrophage-intrinsic immune responses, making it
unclear how robust antimicrobial responses are generated. The intracellular bacterium
Legionella pneumophila inhibits host translation, thereby impairing cytokine production by
infected macrophages. Nevertheless, Legionella-infected macrophages induce an
interleukin-1 (IL-1)-dependent inflammatory cytokine response by recruited monocytes and …
Summary
Alveolar macrophages are among the first immune cells that respond to inhaled pathogens. However, numerous pathogens block macrophage-intrinsic immune responses, making it unclear how robust antimicrobial responses are generated. The intracellular bacterium Legionella pneumophila inhibits host translation, thereby impairing cytokine production by infected macrophages. Nevertheless, Legionella-infected macrophages induce an interleukin-1 (IL-1)-dependent inflammatory cytokine response by recruited monocytes and other cells that controls infection. How IL-1 directs these cells to produce inflammatory cytokines is unknown. Here, we show that collaboration with the alveolar epithelium is critical for controlling infection. IL-1 induces the alveolar epithelium to produce granulocyte-macrophage colony-stimulating factor (GM-CSF). Intriguingly, GM-CSF signaling amplifies inflammatory cytokine production in recruited monocytes by enhancing Toll-like receptor (TLR)-induced glycolysis. Our findings reveal that alveolar macrophages engage alveolar epithelial signals to metabolically reprogram monocytes for antibacterial inflammation.
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