title: Delayed activation of PPARgamma by LPS and IFN-gamma attenuates the oxidative burst in macrophages.
abstract: 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.
authors.affiliation: Department of Medicine IV-Experimental Division, University of Erlangen-Nürnberg, Faculty of Medicine, 91054 Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Von Knethen A
authors.forename: B
authors.initials: B
authors.lastname: Brüne
mesh_terms: 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
chemical_list: 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