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Phospholipid oxidation generates potent anti-inflammatory lipid mediators that mimic structurally related pro-resolving eicosanoids by activating Nrf2.

Bretscher P, Egger J, Shamshiev A, Trötzmüller M, Köfeler H, Carreira EM, Kopf M, Freigang S - EMBO Mol Med (2015)

Bottom Line: While the ability of OxPL to modulate biological processes is increasingly recognized, the nature of the biologically active OxPL species and the molecular mechanisms underlying their signaling remain largely unknown.Our study defines epoxycyclopentenones as potent anti-inflammatory lipid mediators that mimic the signaling of endogenous, pro-resolving prostanoids by activating the transcription factor nuclear factor E2-related factor 2 (Nrf2).Using a library of OxPL variants, we identified a synthetic OxPL derivative, which alleviated endotoxin-induced lung injury and inhibited development of pro-inflammatory T helper (Th) 1 cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Health Sciences, ETH Zurich, Zurich, Switzerland.

No MeSH data available.


Related in: MedlinePlus

Epoxycyclopentenone lipids inhibit the inflammatory response of myeloid cells via Nrf2 signalingA IL-12 production of BMDC from wild-type, Nrf2−/−, Pparg−/−, and Pparg litter mate control mice normalized to medium control (open bars). Cells were treated with the indicated lipids (filled bars) for 60 min prior TLR 7 ligation with R837 (5 μg/ml) for 18 h. Lipids were used at starting concentrations of 40 μM (POVPC, PGPC, and KOdiAPC), 40 μg/ml (OxPAPC), 20 μM (15d-PGJ2), and 1.25 μM (EC), depicted as black bars, and 2-fold serial dilutions thereof (gray bars). Data represent mean ± SEM of triplicates from one of three independent experiments.B Expression of Nrf2 target genes Hmox1 and Nqo1 in wild-type and Nrf2−/− BMDM stimulated with EC (2 μM) for 60 min. Gene expression levels are presented relative to that of untreated cells after normalization to G6pdx. Data (mean ± SEM) are representative of two independent experiments.C, D mRNA expression levels of the Nrf2 targets Gclc and Gsta3 (C) and of the pro-inflammatory cytokines IL-6 and IL-12 (D) in wild-type, PPAR-γ-deficient, and Nrf2-deficient BMDM after treatment with EC or 15d-PGJ2 for 60 min followed by LPS treatment for 3 h. Expression levels are normalized to G6pdx. Data represent mean ± SEM of triplicate cultures from one of two independent experiments.E mRNA expression of the indicated chemokines as determined by qPCR. Wild-type BMDCs were treated with EC (1 μM) or 15d-PGJ2 (20 μM) for 60 min followed by R837 stimulation (5 μg/ml) for 3 h. Expression levels are shown normalized to G6pdx. Data (mean ± SEM, n = 2) are representative of three independent experiments.Data information: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, not significant; as determined by one-way ANOVA adjusted by Dunnett's multiple comparisons test.
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fig04: Epoxycyclopentenone lipids inhibit the inflammatory response of myeloid cells via Nrf2 signalingA IL-12 production of BMDC from wild-type, Nrf2−/−, Pparg−/−, and Pparg litter mate control mice normalized to medium control (open bars). Cells were treated with the indicated lipids (filled bars) for 60 min prior TLR 7 ligation with R837 (5 μg/ml) for 18 h. Lipids were used at starting concentrations of 40 μM (POVPC, PGPC, and KOdiAPC), 40 μg/ml (OxPAPC), 20 μM (15d-PGJ2), and 1.25 μM (EC), depicted as black bars, and 2-fold serial dilutions thereof (gray bars). Data represent mean ± SEM of triplicates from one of three independent experiments.B Expression of Nrf2 target genes Hmox1 and Nqo1 in wild-type and Nrf2−/− BMDM stimulated with EC (2 μM) for 60 min. Gene expression levels are presented relative to that of untreated cells after normalization to G6pdx. Data (mean ± SEM) are representative of two independent experiments.C, D mRNA expression levels of the Nrf2 targets Gclc and Gsta3 (C) and of the pro-inflammatory cytokines IL-6 and IL-12 (D) in wild-type, PPAR-γ-deficient, and Nrf2-deficient BMDM after treatment with EC or 15d-PGJ2 for 60 min followed by LPS treatment for 3 h. Expression levels are normalized to G6pdx. Data represent mean ± SEM of triplicate cultures from one of two independent experiments.E mRNA expression of the indicated chemokines as determined by qPCR. Wild-type BMDCs were treated with EC (1 μM) or 15d-PGJ2 (20 μM) for 60 min followed by R837 stimulation (5 μg/ml) for 3 h. Expression levels are shown normalized to G6pdx. Data (mean ± SEM, n = 2) are representative of three independent experiments.Data information: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, not significant; as determined by one-way ANOVA adjusted by Dunnett's multiple comparisons test.

Mentions: Our previous results described a potent anti-inflammatory effect of OxPAPC and identified EC as principal mediator of this bioactivity. In addition, the close structural and functional similarity between EC and 15d-PGJ2 suggested both molecules induced these effects by activating similar signaling pathways. 15d-PGJ2 has been reported to interact with the nuclear hormone receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) as well as with the oxidative stress-responsive transcription factor Nrf2. Since both molecules have been implicated in the transcriptional regulation of inflammation, we next examined their contribution by assessing the anti-inflammatory activity of a series of synthetic OxPL in the respective gene-deficient BMDC (Fig4A). Whereas removal of PPAR-γ did not alter the OxPL-mediated inhibition of IL-12 production, the bioactivity of OxPAPC, EC, and 15d-PGJ2 was abrogated in the absence of Nrf2, demonstrating that EC and related OxPL signal through Nrf2 to mediate their anti-inflammatory effects. Indeed, stimulation with EC rapidly induced an Nrf2-dependent transcription of the prototypic Nrf2 targets Hmox1 and Nqo1 (Fig4B). Similar to EC, also 15d-PGJ2 triggered the expression of the Nrf2-regulated genes Gclc and Gsta3 in wild-type and PPAR-γ-deficient cells, but not in cells lacking Nrf2 (Fig4C), implying that both lipids mediated their anti-inflammatory activity via Nrf2 rather than PPAR-γ. Indeed, EC and 15d-PGJ2 inhibited the transcription of IL-6 and IL-12 genes in TLR-stimulated wild-type and PPAR-γ-deficient macrophages with comparable efficacy, while Nrf2-deficient cells remained unaffected by this treatment. Together, these results demonstrated that EC and 15d-PGJ2 inhibited pro-inflammatory cytokine responses through a shared mechanism and implicated OxPL/Nrf2 signaling in the regulation of inflammation. The anti-inflammatory effect of the Nrf2-activating prostanoids was not limited to IL-6 and IL-12 production, as both lipids virtually abolished the expression of several pro-inflammatory chemokines including CCL2, CCL3, CCL4, CCL5, and CXCL10 in TLR-stimulated BMDC (Fig4E). Notably, we observed that compared to wild-type controls, Nrf2-deficient cells generally exhibited enhanced TLR-induced cytokine and chemokine responses (Supplementary Fig S3), suggesting that Nrf2 signaling might act as a negative regulator that sets the inflammatory tone in response to endogenously generated OxPL or related prostanoid lipid mediators.


Phospholipid oxidation generates potent anti-inflammatory lipid mediators that mimic structurally related pro-resolving eicosanoids by activating Nrf2.

Bretscher P, Egger J, Shamshiev A, Trötzmüller M, Köfeler H, Carreira EM, Kopf M, Freigang S - EMBO Mol Med (2015)

Epoxycyclopentenone lipids inhibit the inflammatory response of myeloid cells via Nrf2 signalingA IL-12 production of BMDC from wild-type, Nrf2−/−, Pparg−/−, and Pparg litter mate control mice normalized to medium control (open bars). Cells were treated with the indicated lipids (filled bars) for 60 min prior TLR 7 ligation with R837 (5 μg/ml) for 18 h. Lipids were used at starting concentrations of 40 μM (POVPC, PGPC, and KOdiAPC), 40 μg/ml (OxPAPC), 20 μM (15d-PGJ2), and 1.25 μM (EC), depicted as black bars, and 2-fold serial dilutions thereof (gray bars). Data represent mean ± SEM of triplicates from one of three independent experiments.B Expression of Nrf2 target genes Hmox1 and Nqo1 in wild-type and Nrf2−/− BMDM stimulated with EC (2 μM) for 60 min. Gene expression levels are presented relative to that of untreated cells after normalization to G6pdx. Data (mean ± SEM) are representative of two independent experiments.C, D mRNA expression levels of the Nrf2 targets Gclc and Gsta3 (C) and of the pro-inflammatory cytokines IL-6 and IL-12 (D) in wild-type, PPAR-γ-deficient, and Nrf2-deficient BMDM after treatment with EC or 15d-PGJ2 for 60 min followed by LPS treatment for 3 h. Expression levels are normalized to G6pdx. Data represent mean ± SEM of triplicate cultures from one of two independent experiments.E mRNA expression of the indicated chemokines as determined by qPCR. Wild-type BMDCs were treated with EC (1 μM) or 15d-PGJ2 (20 μM) for 60 min followed by R837 stimulation (5 μg/ml) for 3 h. Expression levels are shown normalized to G6pdx. Data (mean ± SEM, n = 2) are representative of three independent experiments.Data information: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, not significant; as determined by one-way ANOVA adjusted by Dunnett's multiple comparisons test.
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fig04: Epoxycyclopentenone lipids inhibit the inflammatory response of myeloid cells via Nrf2 signalingA IL-12 production of BMDC from wild-type, Nrf2−/−, Pparg−/−, and Pparg litter mate control mice normalized to medium control (open bars). Cells were treated with the indicated lipids (filled bars) for 60 min prior TLR 7 ligation with R837 (5 μg/ml) for 18 h. Lipids were used at starting concentrations of 40 μM (POVPC, PGPC, and KOdiAPC), 40 μg/ml (OxPAPC), 20 μM (15d-PGJ2), and 1.25 μM (EC), depicted as black bars, and 2-fold serial dilutions thereof (gray bars). Data represent mean ± SEM of triplicates from one of three independent experiments.B Expression of Nrf2 target genes Hmox1 and Nqo1 in wild-type and Nrf2−/− BMDM stimulated with EC (2 μM) for 60 min. Gene expression levels are presented relative to that of untreated cells after normalization to G6pdx. Data (mean ± SEM) are representative of two independent experiments.C, D mRNA expression levels of the Nrf2 targets Gclc and Gsta3 (C) and of the pro-inflammatory cytokines IL-6 and IL-12 (D) in wild-type, PPAR-γ-deficient, and Nrf2-deficient BMDM after treatment with EC or 15d-PGJ2 for 60 min followed by LPS treatment for 3 h. Expression levels are normalized to G6pdx. Data represent mean ± SEM of triplicate cultures from one of two independent experiments.E mRNA expression of the indicated chemokines as determined by qPCR. Wild-type BMDCs were treated with EC (1 μM) or 15d-PGJ2 (20 μM) for 60 min followed by R837 stimulation (5 μg/ml) for 3 h. Expression levels are shown normalized to G6pdx. Data (mean ± SEM, n = 2) are representative of three independent experiments.Data information: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, not significant; as determined by one-way ANOVA adjusted by Dunnett's multiple comparisons test.
Mentions: Our previous results described a potent anti-inflammatory effect of OxPAPC and identified EC as principal mediator of this bioactivity. In addition, the close structural and functional similarity between EC and 15d-PGJ2 suggested both molecules induced these effects by activating similar signaling pathways. 15d-PGJ2 has been reported to interact with the nuclear hormone receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) as well as with the oxidative stress-responsive transcription factor Nrf2. Since both molecules have been implicated in the transcriptional regulation of inflammation, we next examined their contribution by assessing the anti-inflammatory activity of a series of synthetic OxPL in the respective gene-deficient BMDC (Fig4A). Whereas removal of PPAR-γ did not alter the OxPL-mediated inhibition of IL-12 production, the bioactivity of OxPAPC, EC, and 15d-PGJ2 was abrogated in the absence of Nrf2, demonstrating that EC and related OxPL signal through Nrf2 to mediate their anti-inflammatory effects. Indeed, stimulation with EC rapidly induced an Nrf2-dependent transcription of the prototypic Nrf2 targets Hmox1 and Nqo1 (Fig4B). Similar to EC, also 15d-PGJ2 triggered the expression of the Nrf2-regulated genes Gclc and Gsta3 in wild-type and PPAR-γ-deficient cells, but not in cells lacking Nrf2 (Fig4C), implying that both lipids mediated their anti-inflammatory activity via Nrf2 rather than PPAR-γ. Indeed, EC and 15d-PGJ2 inhibited the transcription of IL-6 and IL-12 genes in TLR-stimulated wild-type and PPAR-γ-deficient macrophages with comparable efficacy, while Nrf2-deficient cells remained unaffected by this treatment. Together, these results demonstrated that EC and 15d-PGJ2 inhibited pro-inflammatory cytokine responses through a shared mechanism and implicated OxPL/Nrf2 signaling in the regulation of inflammation. The anti-inflammatory effect of the Nrf2-activating prostanoids was not limited to IL-6 and IL-12 production, as both lipids virtually abolished the expression of several pro-inflammatory chemokines including CCL2, CCL3, CCL4, CCL5, and CXCL10 in TLR-stimulated BMDC (Fig4E). Notably, we observed that compared to wild-type controls, Nrf2-deficient cells generally exhibited enhanced TLR-induced cytokine and chemokine responses (Supplementary Fig S3), suggesting that Nrf2 signaling might act as a negative regulator that sets the inflammatory tone in response to endogenously generated OxPL or related prostanoid lipid mediators.

Bottom Line: While the ability of OxPL to modulate biological processes is increasingly recognized, the nature of the biologically active OxPL species and the molecular mechanisms underlying their signaling remain largely unknown.Our study defines epoxycyclopentenones as potent anti-inflammatory lipid mediators that mimic the signaling of endogenous, pro-resolving prostanoids by activating the transcription factor nuclear factor E2-related factor 2 (Nrf2).Using a library of OxPL variants, we identified a synthetic OxPL derivative, which alleviated endotoxin-induced lung injury and inhibited development of pro-inflammatory T helper (Th) 1 cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Health Sciences, ETH Zurich, Zurich, Switzerland.

No MeSH data available.


Related in: MedlinePlus