Cellular FLIP Inhibits Myeloid Cell Activation by Suppressing Selective Innate Signaling.

Journal Article (Journal Article)

Cellular FLIP (c-FLIP) specifically inhibits caspase-8 and suppresses death receptor-induced apoptosis. c-FLIP has also been reported to transmit activation signals. In this study, we report a novel function of c-FLIP involving inhibition of myeloid cell activation through antagonizing the selective innate signaling pathway. We found that conditional knockout of c-FLIP in dendritic cells (DCs) led to neutrophilia and splenomegaly. Peripheral DC populations, including CD11b(+) conventional DCs (cDCs), CD8(+) cDCs, and plasmacytoid DCs, were not affected by c-FLIP deficiency. We also found that c-FLIP knockout cDCs, plasmacytoid DCs, and bone marrow-derived DCs (BMDCs) displayed enhanced production of TNF-α, IL-2, or G-CSF in response to stimulation of TLR4, TLR2, and dectin-1. Consistent with the ability of c-FLIP to inhibit the activation of p38 MAPK, the enhanced activation of c-FLIP-deficient BMDCs could be partly linked to an elevated activation of p38 MAPK after engagement of innate receptors. Increased activation was also found in c-FLIP(+/-) macrophages. Additionally, the increased activation in c-FLIP-deficient DCs was independent of caspase-8. Our results reveal a novel inhibitory role of c-FLIP in myeloid cell activation and demonstrate the unexpected anti-inflammatory activity of c-FLIP. Additionally, our observations suggest that cancer therapy targeting c-FLIP downregulation may facilitate DC activation and increase T cell immunity.

Full Text

Duke Authors

Cited Authors

  • Wu, Y-J; Wu, Y-H; Mo, S-T; Hsiao, H-W; He, Y-W; Lai, M-Z

Published Date

  • September 15, 2015

Published In

Volume / Issue

  • 195 / 6

Start / End Page

  • 2612 - 2623

PubMed ID

  • 26238491

Electronic International Standard Serial Number (EISSN)

  • 1550-6606

Digital Object Identifier (DOI)

  • 10.4049/jimmunol.1402944


  • eng

Conference Location

  • United States