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Ceramide‐enriched secreted microvesicles as a mediator of cytotoxic synergy between TNF‐α and IFN‐γ in oligodendrocyte cell death
Author(s) -
Podbielska Maria,
Szulc Zdzislaw,
Hogan Edward,
Bielawska Alicja,
Bhat Narayan
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.715.3
Subject(s) - cytotoxic t cell , microvesicles , microbiology and biotechnology , ceramide , programmed cell death , apoptosis , cytokine , cell culture , biology , tumor necrosis factor alpha , cytotoxicity , sphingolipid , chemistry , immunology , biochemistry , microrna , in vitro , genetics , gene
A combination of TNFα and IFNγ induces cell death in several cell types including oligodendrocytes but the mechanism of their synergistic action is unclear. In this study, using a human oligodendroglioma cell line, HOG as a model, we show that secreted microvesicles (MVs) act as a paratropic mediator of synergistic cytotoxicity. Thus, TNFα and IFNγ are marginally cytotoxic individually but together induce marked cell death. MVs obtained from TNFα‐ but not IFNγ‐treated HOG cells, while mildly toxic to fresh cultures, induced extensive cell death in a fashion resembling the effect of cytokine combination when added to IFNγ‐primed target cultures. Since sphingolipids (SLs) including ceramide (Cer) form an integral part of secreted MVs, we determined the basic SL profiles of the secreted MVs as well as cytokine‐treated 'source’ cells by HPLC‐MS/MS. The treatment with the pro‐apoptotic cytokines time‐dependently increased Cer, dhCer & SM expression, in particular, of C24‐ and C24:1‐Cer species; C16‐, C24‐ and C24:1‐dhCer species; and C16‐, C24‐ and C24:1‐SM species in both intra‐ and extracellular compartments over a course of 48 hrs. That MV‐associated Cer contributes to the cytotoxic activity was supported by the observation that exogenous C6‐Cer replicated, albeit partially, the cytotoxic effect of Cer‐enriched MVs. We conclude that Cer‐laden MVs released from TNFα‐exposed cells collaterally 'spread’ the death signal to IFNγ‐primed target cells to elicit a robust synergistic cell death response.