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Activation of peroxisome proliferator-activated receptor γ by rosiglitazone inhibits lipopolysaccharide-induced release of high mobility group box 1.

Hwang JS, Kang ES, Ham SA, Yoo T, Lee H, Paek KS, Park C, Kim JH, Lim DS, Seo HG - Mediators Inflamm. (2012)

Bottom Line: Among the ligands of PPAR, the effect of rosiglitazone, a specific ligand for PPARγ, was superior in the inhibition of HMGB1 release induced by LPS.Notably, the administration of rosiglitazone to mice improved survival rates in an LPS-induced animal model of endotoxemia, where reduced levels of circulating HMGB1 were demonstrated.Taken together, these results suggest that PPARs play an important role in the cellular response to inflammation by inhibiting HMGB1 release.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Biotechnology, Konkuk University, Seoul, Republic of Korea.

ABSTRACT
Peroxisome proliferator-activated receptors (PPARs) are shown to modulate the pathological status of sepsis by regulating the release of high mobility group box 1 (HMGB1), a well-known late proinflammatory mediator of sepsis. Ligand-activated PPARs markedly inhibited lipopolysaccharide- (LPS) induced release of HMGB1 in RAW 264.7 cells. Among the ligands of PPAR, the effect of rosiglitazone, a specific ligand for PPARγ, was superior in the inhibition of HMGB1 release induced by LPS. This effect was observed in cells that received rosiglitazone before LPS or after LPS treatment, indicating that rosiglitazone is effective in both treatment and prevention. Ablation of PPARγ with small interfering RNA or GW9662-mediated inhibition of PPARγ abolished the effect of rosiglitazone on HMGB1 release. Furthermore, the overexpression of PPARγ markedly potentiated the inhibitory effect of rosiglitazone on HMGB1 release. In addition, rosiglitazone inhibited LPS-induced expression of Toll-like receptor 4 signal molecules, suggesting a possible mechanism by which rosiglitazone modulates HMGB1 release. Notably, the administration of rosiglitazone to mice improved survival rates in an LPS-induced animal model of endotoxemia, where reduced levels of circulating HMGB1 were demonstrated. Taken together, these results suggest that PPARs play an important role in the cellular response to inflammation by inhibiting HMGB1 release.

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Activation of PPARs by ligand inhibits LPS-induced release of HMGB1 in RAW 264.7 cells. (a) Cells were harvested and the expression levels of PPARs were detected by using Western blot with indicated antibodies, as described in Section 2. (b) Cells grown to 60% confluency were incubated with serum-free medium for 24 h and then stimulated with LPS in the presence or absence of ligands for 24 h. Equal volumes of conditioned media were subjected to Western blot analysis. Ponceau S staining was used as a loading control. (c) At the same time, total protein was extracted, fractionated by electrophoresis, and immunoblotted with the indicated antibodies. Representative blots and densitometric measurements from three independent experiments are shown. The results are expressed as the means ± S.E. (n = 3). *P < 0.01 compared to untreated group; #P < 0.01 compared to LPS-treated group.
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fig1: Activation of PPARs by ligand inhibits LPS-induced release of HMGB1 in RAW 264.7 cells. (a) Cells were harvested and the expression levels of PPARs were detected by using Western blot with indicated antibodies, as described in Section 2. (b) Cells grown to 60% confluency were incubated with serum-free medium for 24 h and then stimulated with LPS in the presence or absence of ligands for 24 h. Equal volumes of conditioned media were subjected to Western blot analysis. Ponceau S staining was used as a loading control. (c) At the same time, total protein was extracted, fractionated by electrophoresis, and immunoblotted with the indicated antibodies. Representative blots and densitometric measurements from three independent experiments are shown. The results are expressed as the means ± S.E. (n = 3). *P < 0.01 compared to untreated group; #P < 0.01 compared to LPS-treated group.

Mentions: To investigate whether PPARs exhibit biological functions in RAW 264.7 cells, constitutive expression of PPARs was examined. Expression of three PPAR isoforms was observed (Figure 1(a)), suggesting that all of the PPAR isoforms may be biologically active in RAW 264.7 cells. To determine whether the activation of PPARs by ligand affects endogenous HMGB1 endogenous expression or release, RAW 264.7 cells were treated with LPS for 24 h, and the release of HMGB1 was measured. Levels of secreted HMGB1 were significantly increased upon LPS treatment, and this increase was markedly suppressed in the presence of PPAR ligands, suggesting the involvement of PPARs in the inhibition of LPS-induced HMGB1 release (Figure 1(b)). Among the ligands for PPAR, rosiglitazone, a specific ligand for PPARγ, was superior to others in the inhibition of LPS-induced HMGB1 release. In contrast to that of secreted levels, neither LPS nor ligands of PPARs affected the expression levels of endogenous HMGB1 (Figure 1(c)). These results indicate that PPARs are involved in the regulation of LPS-induced HMGB1 release, but not in the regulation of HMGB1 expression. Under the concentrations of ligands used in these experiments, cells retained good viability within the experimental time frames used, as determined by trypan blue exclusion method (see Supplementary Figure 1 available online at doi:10.1155/2012/352807).


Activation of peroxisome proliferator-activated receptor γ by rosiglitazone inhibits lipopolysaccharide-induced release of high mobility group box 1.

Hwang JS, Kang ES, Ham SA, Yoo T, Lee H, Paek KS, Park C, Kim JH, Lim DS, Seo HG - Mediators Inflamm. (2012)

Activation of PPARs by ligand inhibits LPS-induced release of HMGB1 in RAW 264.7 cells. (a) Cells were harvested and the expression levels of PPARs were detected by using Western blot with indicated antibodies, as described in Section 2. (b) Cells grown to 60% confluency were incubated with serum-free medium for 24 h and then stimulated with LPS in the presence or absence of ligands for 24 h. Equal volumes of conditioned media were subjected to Western blot analysis. Ponceau S staining was used as a loading control. (c) At the same time, total protein was extracted, fractionated by electrophoresis, and immunoblotted with the indicated antibodies. Representative blots and densitometric measurements from three independent experiments are shown. The results are expressed as the means ± S.E. (n = 3). *P < 0.01 compared to untreated group; #P < 0.01 compared to LPS-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3539392&req=5

fig1: Activation of PPARs by ligand inhibits LPS-induced release of HMGB1 in RAW 264.7 cells. (a) Cells were harvested and the expression levels of PPARs were detected by using Western blot with indicated antibodies, as described in Section 2. (b) Cells grown to 60% confluency were incubated with serum-free medium for 24 h and then stimulated with LPS in the presence or absence of ligands for 24 h. Equal volumes of conditioned media were subjected to Western blot analysis. Ponceau S staining was used as a loading control. (c) At the same time, total protein was extracted, fractionated by electrophoresis, and immunoblotted with the indicated antibodies. Representative blots and densitometric measurements from three independent experiments are shown. The results are expressed as the means ± S.E. (n = 3). *P < 0.01 compared to untreated group; #P < 0.01 compared to LPS-treated group.
Mentions: To investigate whether PPARs exhibit biological functions in RAW 264.7 cells, constitutive expression of PPARs was examined. Expression of three PPAR isoforms was observed (Figure 1(a)), suggesting that all of the PPAR isoforms may be biologically active in RAW 264.7 cells. To determine whether the activation of PPARs by ligand affects endogenous HMGB1 endogenous expression or release, RAW 264.7 cells were treated with LPS for 24 h, and the release of HMGB1 was measured. Levels of secreted HMGB1 were significantly increased upon LPS treatment, and this increase was markedly suppressed in the presence of PPAR ligands, suggesting the involvement of PPARs in the inhibition of LPS-induced HMGB1 release (Figure 1(b)). Among the ligands for PPAR, rosiglitazone, a specific ligand for PPARγ, was superior to others in the inhibition of LPS-induced HMGB1 release. In contrast to that of secreted levels, neither LPS nor ligands of PPARs affected the expression levels of endogenous HMGB1 (Figure 1(c)). These results indicate that PPARs are involved in the regulation of LPS-induced HMGB1 release, but not in the regulation of HMGB1 expression. Under the concentrations of ligands used in these experiments, cells retained good viability within the experimental time frames used, as determined by trypan blue exclusion method (see Supplementary Figure 1 available online at doi:10.1155/2012/352807).

Bottom Line: Among the ligands of PPAR, the effect of rosiglitazone, a specific ligand for PPARγ, was superior in the inhibition of HMGB1 release induced by LPS.Notably, the administration of rosiglitazone to mice improved survival rates in an LPS-induced animal model of endotoxemia, where reduced levels of circulating HMGB1 were demonstrated.Taken together, these results suggest that PPARs play an important role in the cellular response to inflammation by inhibiting HMGB1 release.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Biotechnology, Konkuk University, Seoul, Republic of Korea.

ABSTRACT
Peroxisome proliferator-activated receptors (PPARs) are shown to modulate the pathological status of sepsis by regulating the release of high mobility group box 1 (HMGB1), a well-known late proinflammatory mediator of sepsis. Ligand-activated PPARs markedly inhibited lipopolysaccharide- (LPS) induced release of HMGB1 in RAW 264.7 cells. Among the ligands of PPAR, the effect of rosiglitazone, a specific ligand for PPARγ, was superior in the inhibition of HMGB1 release induced by LPS. This effect was observed in cells that received rosiglitazone before LPS or after LPS treatment, indicating that rosiglitazone is effective in both treatment and prevention. Ablation of PPARγ with small interfering RNA or GW9662-mediated inhibition of PPARγ abolished the effect of rosiglitazone on HMGB1 release. Furthermore, the overexpression of PPARγ markedly potentiated the inhibitory effect of rosiglitazone on HMGB1 release. In addition, rosiglitazone inhibited LPS-induced expression of Toll-like receptor 4 signal molecules, suggesting a possible mechanism by which rosiglitazone modulates HMGB1 release. Notably, the administration of rosiglitazone to mice improved survival rates in an LPS-induced animal model of endotoxemia, where reduced levels of circulating HMGB1 were demonstrated. Taken together, these results suggest that PPARs play an important role in the cellular response to inflammation by inhibiting HMGB1 release.

Show MeSH
Related in: MedlinePlus