title: Paradoxical Increase in Mortality and Rupture of Intracranial Aneurysms in Microsomal Prostaglandin E2 Synthase Type 1-Deficient Mice: Attenuation by Aspirin.
abstract: BACKGROUND
  Inflammation plays an important role in formation and rupture of intracranial aneurysms. Expression of microsomal prostaglandin E2 (PGE2) synthase type 1 (mPGES-1) is increased in the wall of intracranial aneurysms in humans. PGE2, a by-product of mPGES-1, is associated with inflammation and cerebrovascular dysfunction.
  
  
  OBJECTIVE
  To test the hypothesis that deletion of mPGES-1 decreases the formation and rupture of intracranial aneurysms in a murine model.
  
  
  METHODS
  Intracranial aneurysms were induced in wild-type and mPGES-1 knockout (mPGES-1 KO) mice by using a combination of deoxycorticosterone acetate-salt-induced hypertension and intracranial injection of elastase in the basal cistern. Prevalence of aneurysms, subarachnoid hemorrhage, and mortality were assessed. We also tested the effects of administration of aspirin (6 mg/kg/d) by gavage and PGE2 (1 mg/kg/d) by subcutaneous infusion.
  
  
  RESULTS
  Systolic blood pressure and prevalence of aneurysm were similar in wild-type and mPGES-1 KO mice. However, mortality and the prevalence of subarachnoid hemorrhage were markedly increased in mPGES-1 KO mice (P < .05). Bone marrow reconstitution studies suggest that mPGES-1 derived from leukocytes does not appear to increase rupture of intracranial aneurysms. Aspirin, but not PGE2, attenuated the increased mortality in mPGES-1 KO mice (P < .05).
  
  
  CONCLUSIONS
  Vascular mPGES-1 plays a protective role in blood vessels and attenuates rupture of cerebral aneurysms. In contrast to effects on abdominal aneurysms, mPGES-1 deficiency is associated with an increase in rupture of cerebral aneurysms and mortality, which are attenuated by low-dose aspirin.
authors.affiliation: *Universidad de los Andes, Bogotá, Colombia; ‡Departments of Internal Medicine, §Neurosurgery, ¶Microbiology, and ‖Pharmacology, University of Iowa, Iowa City, Iowa.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Peña Silva
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Mitchell
authors.forename: David K
authors.initials: DK
authors.lastname: Kung
authors.forename: Lecia L
authors.initials: LL
authors.lastname: Pewe
authors.forename: Manuel F
authors.initials: MF
authors.lastname: Granja
authors.forename: John T
authors.initials: JT
authors.lastname: Harty
authors.forename: Frank M
authors.initials: FM
authors.lastname: Faraci
authors.forename: Donald D
authors.initials: DD
authors.lastname: Heistad
authors.forename: David M
authors.initials: DM
authors.lastname: Hasan
mesh_terms: D017542:Aneurysm, Ruptured / Q000188:drug therapy* / Q000201:enzymology* / Q000401:mortality; D000818:Animals; D001241:Aspirin / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D002532:Intracranial Aneurysm / Q000188:drug therapy* / Q000201:enzymology* / Q000401:mortality; D019746:Intramolecular Oxidoreductases / Q000172:deficiency*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology*; D009026:Mortality / Q000639:trends; D000071876:Prostaglandin-E Synthases
chemical_list: D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; C000605865:Ptges protein, mouse; D001241:Aspirin