Expression data from pDC infected with Aspergillus fumigatus

Plasmacytoid dendritic cells (pDCs) were initially considered as critical for innate immunity to viruses. However, our group has shown that pDCs bind to and inhibit the growth of Aspergillus fumigatus hyphae and that depletion of pDCs renders mice hypersusceptible to experimental aspergillosis. In this study, we examined pDC receptors responsible for hyphal recognition and downstream events in pDCs stimulated by A. fumigatus hyphae. Our data show that Dectin-2 but not Dectin-1 participates in hyphal recognition by pDCs and that Dectin-2 acts in cooperation with the FcR chain to trigger signaling responses. In addition, using confocal and electron microscopy we demonstrated that the interaction between pDCs and A. fumigatus induced the formation of pDC extracellular traps (pETs) containing DNA and citrullinated histone H3. Thus, these structures closely resembled those of neutrophil extracellular traps (NETs). Microarray analysis of the pDC transcriptome upon A. fumigatus infection demonstrated up-regulated expression of genes previously associated with viral infections or apoptosis. Moreover, the abundant expression of type I Interferon-encoding genes seen in CpG-stimulated pDCs was absent in the pDCs infected with A. fumigatus hyphae. Thus, human pDCs directly recognize A. fumigatus hyphae via Dectin-2. This interaction leads to formation of pET and triggers a distinct pattern of pDC gene expression.

11