TY - JOUR
T1 - Cyclopentenone Prostaglandins Induce Lymphocyte Apoptosis by Activating the Mitochondrial Apoptosis Pathway Independent of External Death Receptor Signaling
AU - Nencioni, Alessio
AU - Lauber, Kirsten
AU - Grünebach, Frank
AU - Van Parijs, Luk
AU - Denzlinger, Claudio
AU - Wesselborg, Sebastian
AU - Brossart, Peter
PY - 2003/11/15
Y1 - 2003/11/15
N2 - 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.
AB - 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.
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M3 - Article
C2 - 14607914
AN - SCOPUS:0242412240
VL - 171
SP - 5148
EP - 5156
JO - Journal of Immunology
JF - Journal of Immunology
SN - 0022-1767
IS - 10
ER -