Abstract W MP47: Roles of Macrophage PPARγ on Intracranial Aneurysmal Rupture
Background and Purpose: Peroxisome proliferator-activated receptor gamma (PPARγ) plays a role in regulating not only lipid and glucose metabolism but also atherosclerosis and inflammation which are associated with intracranial aneurysmal rupture. It has been suggested that PPARγ is present in various kinds of cell types including macrophages which we reported to contribute to intracranial aneurysm formation. In addition, macrophage PPARγ regulates inflammatory cytokines negatively. Therefore we hypothesized that macrophage PPARγ is protective against intracranial aneurysmal rupture. We tested this hypothesis by using our own established mouse model of intracranial aneurysm.
Methods: Intracranial aneurysms were induced in male mice using a combination of a single injection of elastase into the cerebrospinal fluid and the deoxycorticosterone acetate (DOCA) salt hypertension. Six days after aneurysm induction, we started 2-week treatment with vehicle or PPARγ agonist (pioglitazone:PGZ) or clodronate liposome. PPARγ antagonist (GW9662) was added to PGZ treatment. We induced aneurysms to macrophage-specific PPARγ knockout mice and treated them with vehicle or PGZ with the same protocol mentioned above. Aneurysmal rupture was detected by neurological symptoms and confirmed by the presence of intracranial aneurysms with subarachnoid hemorrhage.
Results: Both PGZ and depletion of macrophage by clodronate liposome reduced the incidence of ruptured aneurysms and rupture rate. PGZ treatment decreased the inflammatory cytokines that were increased in cerebral arteries of mice with aneurysm induction compared to mice without aneurysm induction. To examine whether the macrophage PPARγ is associated with intracranial aneurysmal rupture, we administered PGZ to macrophage-specific PPARγ knock out mice. PGZ did not have protective effect against aneurysmal rupture in macrophage-specific PPARγ knock out mice although it exerted protective effects in wild type mice.
Conclusion: PPARγ activation is protective against intracranial aneurysmal rupture by suppressing inflammatory cytokines and macrophage PPARγ is associated with this protective effects.
Author Disclosures: M. Korai: None. K. Shimada: None. H. Furukawa: None. K. Wada: None. Y. Wei: None. Y. Tada: None. A. Kuwabara: None. F. Shikata: None. K.T. Kitazato: None. S. Nagahiro: None. T. Hashimoto: None.
- © 2015 by American Heart Association, Inc.