13-Oxo-ODE is an endogenous ligand for PPARgamma in human colonic epithelial cells.
BACKGROUND
The ligand activated nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPARgamma) induces transcriptional repression of pro-inflammatory factors. Activation of PPARgamma is followed by amelioration of colitis in animal models of inflammatory bowel disease (IBD). A reduced expression of PPARgamma was found in epithelial cells of patients with ulcerative colitis. The eicosanoids 13-HODE and 15-HETE are products of 12/15-lipoxygenase (LOX) and endogenous ligands for PPARgamma. Dehydrogenation of 13-HODE by 13-HODE dehydrogenase results in formation of the 13-Oxo-ODE. Highest activity of 13-HODE dehydrogenase is found in colonic epithelial cells (CECs). We therefore investigated whether 13-Oxo-ODE is a new endogenous ligand of PPARgamma in CECs.


METHODS
LOX activity and 13-HODE dehydrogenase in CECs were investigated after stimulation with arachidonic or linoleic acid. LOX metabolites were identified by RP-18 reversed-phase HPLC. Binding of (14)C-labelled 13-Oxo-ODE was demonstrated using a His-tagged PPARgamma.


RESULTS
Stimulation of HT-29 and primary CECs homogenates with and without Ca-ionophor was followed by the formation of high amounts of the linoleic acid metabolite 13-Oxo-ODE (155 and 85 ng/ml). The decrease of IL-8 secretion from IEC was more pronounced after pre-incubation with 13-Oxo-ODE compared to the PPARgamma agonist troglitazone and higher as with the known PPARgamma ligands 13-HODE and 15-HETE. Binding assays with (14)C-labelled 13-Oxo-ODE clearly demonstrated a direct interaction.


CONCLUSIONS
High amounts of 13-Oxo-ODE can be induced in CECs by stimulation of linoleic acid metabolism. 13-Oxo-ODE binds to PPARgamma and has anti-inflammatory effects. 13-HODE dehydrogenase might be a therapeutic target in IBD.
Altmann
Reinhold
R
Department of Internal Medicine I, University of Regensburg, 93042 Regensburg, Germany.
Hausmann
Martin
M
Spöttl
Tanja
T
Gruber
Michael
M
Bull
Arthur W
AW
Menzel
Katrin
K
Vogl
Daniela
D
Herfarth
Hans
H
Schölmerich
Jürgen
J
Falk
Werner
W
Rogler
Gerhard
G
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology; D015153:Blotting, Western; D002250:Carbon Radioisotopes; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003106:Colon / Q000378:metabolism / Q000473:pathology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D019073:HT29 Cells; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D047468:Immunoprecipitation; D016209:Interleukin-8 / Q000378:metabolism; D008024:Ligands; D019787:Linoleic Acid / Q000378:metabolism / Q000494:pharmacology; D008041:Linoleic Acids / Q000494:pharmacology; D008042:Linolenic Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D015394:Molecular Structure; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D021241:Spectrometry, Mass, Electrospray Ionization; D014162:Transfection
D002250:Carbon Radioisotopes; D006893:Hydroxyeicosatetraenoic Acids; D016209:Interleukin-8; D008024:Ligands; D008041:Linoleic Acids; D008042:Linolenic Acids; D047495:PPAR gamma; D016718:Arachidonic Acid; C064441:13-oxo-9,11-octadecadienoic acid; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; C024348:13-hydroxy-9,11-octadecadienoic acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D019787:Linoleic Acid