Microsomal prostaglandin E synthase-1 deletion suppresses oxidative stress and angiotensin II-induced abdominal aortic aneurysm formation.
BACKGROUND
Microsomal prostaglandin (PG) E(2) synthase-1 (mPGES-1) catalyzes isomerization of the cyclooxygenase product PGH(2) into PGE(2). Deletion of mPGES-1 modulates experimentally evoked pain and inflammation and retards atherogenesis. The role of mPGES-1 in abdominal aortic aneurysm is unknown.


RESULTS
The impact of mPGES-1 deletion on formation of angiotensin II-induced abdominal aortic aneurysm was studied in mice lacking low-density lipoprotein receptor (LDLR(-/-)). Male mice deficient in both mPGES-1 and LDLR (mPGES-1(-/-) LDLR(-/-)) and littermate LDLR(-/-) mice were initiated on a high-fat diet at 6 months of age, followed 1 week later by continuous infusion of angiotensin II (1 microg/kg per minute) for an additional 4 weeks. Angiotensin II infusion upregulated aortic expression of cyclooxygenase-2 and mPGES-1, increased aortic macrophage recruitment and vascular nitrotyrosine staining (which reflects local oxidative stress), and augmented urinary excretion of the isoprostane 8,12-iso-iPF(2alpha)-VI (which reflects lipid peroxidation in vivo) and the major metabolite of PGE(2) (PGE-M). Deletion of mPGES-1 decreased both the incidence (87.5% versus 27.3%; P=0.02) and the severity of abdominal aortic aneurysm and depressed the aortic and systemic indices of oxidative stress. Deletion of mPGES-1 also depressed urinary PGE-M, whereas it augmented excretion of PGD(2) and PGI(2) metabolites, reflecting rediversion of the accumulated PGH(2) substrate in the double knockouts.


CONCLUSIONS
Deletion of mPGES-1 protects against abdominal aortic aneurysm formation induced by angiotensin II in hyperlipidemic mice, coincident with a reduction in oxidative stress. The potential efficacy of selective inhibition of mPGES-1 in preventing or retarding aneurysm formation warrants further investigation.
Wang
Miao
M
Institute for Translational Medicine and Therapeutics, 153 Johnson Pavilion, University of Pennsylvania, 3620 Hamilton Walk, Philadelphia, PA 19104, USA.
Lee
Eric
E
Song
Wenliang
W
Ricciotti
Emanuela
E
Rader
Daniel J
DJ
Lawson
John A
JA
Puré
Ellen
E
FitzGerald
Garret A
GA
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D017544:Aortic Aneurysm, Abdominal / Q000139:chemically induced / Q000517:prevention & control*; D006949:Hyperlipidemias / Q000150:complications; D019746:Intramolecular Oxidoreductases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018384:Oxidative Stress / Q000187:drug effects; D000071876:Prostaglandin-E Synthases; D011453:Prostaglandins / Q000378:metabolism; D011973:Receptors, LDL / Q000172:deficiency / Q000235:genetics; D015854:Up-Regulation
D011453:Prostaglandins; D011973:Receptors, LDL; D000804:Angiotensin II; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; C000605865:Ptges protein, mouse