Delayed activation of PPARgamma by LPS and IFN-gamma attenuates the oxidative burst in macrophages.
Desensitization of macrophages is important during the development of sepsis. It was our intention to identify mechanisms that promote macrophage deactivation upon contact with endotoxin (LPS) and interferon-gamma (IFN-gamma) in vitro. Macrophage activation was achieved with 12-O-tetradecanoylphorbol 13-acetate (TPA), and the oxidative burst (i.e., oxygen radical formation) was followed by oxidation of the redox-sensitive dyes hydroethidine and dichlorodihydrofluorescein diacetate. Prestimulation of macrophages for 15 h with a combination of LPS/IFN-gamma attenuated oxygen radical formation in response to TPA. Taking the anti-inflammatory properties of the peroxisome proliferator-activating receptorgamma (PPARgamma) into consideration, we established activation of PPARgamma in response to LPS/IFN-gamma by an electrophoretic mobility shift, supershift, and a reporter gene assay. The reporter contains a triple PPAR-responsive element (PPRE) in front of a thymidine kinase minimal promoter driving the luciferase gene. We demonstrated that PPRE decoy oligonucleotides, supplied in front of LPS/IFN-gamma, allowed a full oxidative burst to recover upon TPA addition. Furthermore, we suppressed the oxidative burst by using the PPARgamma agonists 15-deoxy-Delta12,14-prostaglandin J2, BRL 49653, or ciglitazone. No effect was observed with WY 14643, a PPARalpha agonist. We conclude that activation of PPARs, most likely PPARgamma, promotes macrophage desensitization, thus attenuating the oxidative burst. This process appears important during development of sepsis.
Von Knethen A
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Department of Medicine IV-Experimental Division, University of Erlangen-Nürnberg, Faculty of Medicine, 91054 Erlangen, Germany.
Brüne
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D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004926:Escherichia coli; D017930:Genes, Reporter; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008830:Microbodies / Q000187:drug effects / Q000502:physiology; D009000:Monocytes / Q000166:cytology* / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000502:physiology*; D011994:Recombinant Proteins; D016897:Respiratory Burst / Q000187:drug effects / Q000502:physiology*; D000077154:Rosiglitazone; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D045162:Thiazolidinediones; D014157:Transcription Factors / Q000819:agonists / Q000502:physiology*; D014162:Transfection
D007004:Hypoglycemic Agents; D008070:Lipopolysaccharides; D011743:Pyrimidines; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D013844:Thiazoles; D045162:Thiazolidinediones; D014157:Transcription Factors; D000077154:Rosiglitazone; D007371:Interferon-gamma; C006253:pirinixic acid; D008156:Luciferases; D013755:Tetradecanoylphorbol Acetate; C039671:ciglitazone; D019331:NG-Nitroarginine Methyl Ester