GM-CSF-mediated epithelial-immune cell crosstalk orchestrates pulmonary immunity to Aspergillus fumigatus

Aspergillus fumigatus causes life-threatening mold pneumonia in immune compromised patients, particularly in those with quantitative or qualitative defects in neutrophils. While innate immune cell crosstalk licenses neutrophil antifungal activity in the lung, the role of epithelial cells in this process is unknown. Here, we find that that surfactant protein C (SPC)-expressing lung epithelial cells integrate infection-induced IL-1 and type III interferon signaling to produce granulocyte-macrophage colony-stimulating factor (GM-CSF) preferentially at local sites of fungal infection and neutrophil influx. Using in vivo models that distinguish the role of GM-CSF during acute infection from its homeostatic function in alveolar macrophage survival and surfactant catabolism, we demonstrate that epithelial-derived GM-CSF increases the accumulation and fungicidal activity of GM-CSF-responsive neutrophils, with the latter being essential for host survival. Our findings establish SPC+ epithelial cells as a central player in regulating the quality and strength of neutrophil-dependent immunity against inhaled mold pathogens. HIGHLIGHTSO_LIGM-CSF is essential for host defense against A. fumigatus in the lung C_LIO_LIIL-1 and IFN-{lambda} promote GM-CSF production by lung epithelial cells in parallel C_LIO_LIEpithelial cell-derived GM-CSF increases neutrophil accumulation and fungal killing capacity C_LIO_LIEpithelial cells preferentially upregulate GM-CSF in local sites of inflammation C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/574062v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@708497org.highwire.dtl.DTLVardef@11106f7org.highwire.dtl.DTLVardef@e08140org.highwire.dtl.DTLVardef@1459e89_HPS_FORMAT_FIGEXP M_FIG C_FIG