Association between prostaglandin E receptor subtype EP4 overexpression and unstable phenotype in atherosclerotic plaques in human.
OBJECTIVE
We recently demonstrated that inducible cyclooxygenase/PGE synthase-1 (COX-2/mPGES-1) are overexpressed in symptomatic plaques in association with PGE2-dependent metalloproteinase (matrix metalloproteinase [MMP]) biosynthesis and plaque rupture. However, it is not known which of the 4 PGE2 receptors (EP1-4) mediates macrophage metalloproteinase generation. The aim of this study was to characterize EP1-4 expression in plaques from symptomatic and asymptomatic patients undergoing carotid endarterectomy and correlate it with the extent of inflammatory infiltration, COX-2/mPGES-1 and MMP expression and clinical features of patients' presentation.


RESULTS
Plaques were analyzed for COX-2, mPGES-1, EP1-4, MMP-2, and MMP-9 by immunohistochemistry, reverse-transcription polymerase chain reaction and Western blot; zymography was used to detect MMP activity. We observed strong EP4 immunoreactivity, only very weak staining for EP2, and no expression of EP1 and EP3 in atherosclerotic plaques. EP4 was more abundant in MMP-rich symptomatic lesions, whereas EP2 was no different between symptomatic and asymptomatic plaques. Finally, MMP induction by PGE2 in vitro was inhibited by the EP4 antagonist L-161 982, but not by its inactive analog L-161 983 or by the EP2 antagonist AH6809.


CONCLUSIONS
This study shows that EP4 overexpression is associated with enhanced inflammatory reaction in atherosclerotic plaques. This effect might contribute to plaque destabilization by inducing culprit metalloproteinase expression.
Cipollone
Francesco
F
Atherosclerosis Prevention Center, G.d'Annunzio University of Chieti, Chieti, Italy. fcipollone@unich.it
Fazia
Maria Luigia
ML
Iezzi
Annalisa
A
Cuccurullo
Chiara
C
De Cesare
Domenico
D
Ucchino
Sante
S
Spigonardo
Francesco
F
Marchetti
Antonio
A
Buttitta
Fiamma
F
Paloscia
Leonardo
L
Mascellanti
Marco
M
Cuccurullo
Franco
F
Mezzetti
Andrea
A
D000368:Aged; D002340:Carotid Artery Diseases / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000201:enzymology / Q000276:immunology; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D010641:Phenotype; D000071876:Prostaglandin-E Synthases; D018078:Receptors, Prostaglandin E / Q000235:genetics* / Q000378:metabolism; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D015398:Signal Transduction / Q000276:immunology; D020521:Stroke / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014657:Vasculitis / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism
C545635:PTGER1 protein, human; C545644:PTGER2 protein, human; C545647:PTGER3 protein, human; C545650:PTGER4 protein, human; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D051546:Cyclooxygenase 2; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases