Cyclopentenone Prostaglandins Induce Lymphocyte Apoptosis by Activating the Mitochondrial Apoptosis Pathway Independent of External Death Receptor Signaling

Alessio Nencioni, Kirsten Lauber, Frank Grünebach, Luk Van Parijs, Claudio Denzlinger, Sebastian Wesselborg, Peter Brossart

Research output: Contribution to journalArticlepeer-review

Abstract

15-Deoxy-Δ12,14-PGJ2 (15d-PGJ2) is a naturally occurring cyclopentenone metabolite of PGD2 that possesses both peroxisome proliferator-activated receptor γ (PPAR-γ)-dependent and PPAR-γ-independent anti-inflammatory properties. Recent studies suggest that cyclopentenone PGs may play a role in the down-regulation of inflammation-induced immune responses. In this study, we report that 15d-PGJ2 as well as synthetic PPAR-γ agonists inhibit lymphocyte proliferation. However, only 15d-PGJ2, but not the specific PPAR-γ activators, induce lymphocyte apoptosis. We found that blocking of the death receptor pathway in Fas-associated death domain -/- or caspase-8-/- Jurkat T cells has no effect on apoptosis induction by 15d-PGJ2. Conversely, overexpression of Bcl-2 or Bcl-xL completely inhibits the initiation of apoptosis, indicating that 15d-PGJ2-mediated apoptosis involves activation of the mitochondrial pathway. In line with these results, 15d-PGJ2 induces mitochondria disassemblage as demonstrated by dissipation of mitochondrial transmembrane potential (Δψm) and cytochrome c release. Both of these events are partially inhibited by the broad spectrum caspase inhibitor benzyloxycarbonil-Val-Ala-Asp-fluoromethylketone, suggesting that caspase activation may amplify the mitochondrial alterations initiated by 15d-PGJ2. We also demonstrate that 15d-PGJ2 potently stimulates reactive oxygen species production in Jurkat T cells, and Δψm loss induced by 15d-PGJ2 is prevented by the reactive oxygen species scavenger N-acetyl-L-cysteine. In conclusion, our data indicate that cyclopentenone PGs like 15d-PGJ2 may modulate immune responses even independent of PPAR-γ by activating the mitochondrial apoptosis pathway in lymphocytes in the absence of external death receptor signaling.

Original languageEnglish
Pages (from-to)5148-5156
Number of pages9
JournalJournal of Immunology
Volume171
Issue number10
Publication statusPublished - Nov 15 2003

ASJC Scopus subject areas

  • Immunology

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