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Smooth Muscle Peroxisome Proliferator-Activated Receptor γ Plays a Critical Role in Formation and Rupture of Cerebral Aneurysms in Mice In Vivo
Journal article   Peer reviewed

Smooth Muscle Peroxisome Proliferator-Activated Receptor γ Plays a Critical Role in Formation and Rupture of Cerebral Aneurysms in Mice In Vivo

David M Hasan, Robert M Starke, He Gu, Katina Wilson, Yi Chu, Nohra Chalouhi, Donald D Heistad, Frank M Faraci and Curt D Sigmund
Hypertension (Dallas, Tex. 1979), Vol.66(1), pp.211-220
07/2015
DOI: 10.1161/HYPERTENSIONAHA.115.05332
PMCID: PMC4465866
PMID: 25916724

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Abstract

Vascular inflammation plays a critical role in the pathogenesis of cerebral aneurysms. Peroxisome proliferator-activated receptor γ (PPARγ) protects against vascular inflammation and atherosclerosis, whereas dominant-negative mutations in PPARγ promote atherosclerosis and vascular dysfunction. We tested the role of PPARγ in aneurysm formation and rupture. Aneurysms were induced with a combination of systemic infusion of angiotensin-II and local injection of elastase in (1) mice that received the PPARγ antagonist GW9662 or the PPARγ agonist pioglitazone, (2) mice carrying dominant-negative PPARγ mutations in endothelial or smooth muscle cells, and (3) mice that received the Cullin inhibitor MLN4924. Incidence of aneurysm formation, rupture, and mortality was quantified. Cerebral arteries were analyzed for expression of Cullin3, Kelch-like ECH-associated protein 1, nuclear factor (erythroid-derived 2)-like 2, NAD(P)H dehydrogenase (quinone)1 (NQO1), and inflammatory marker mRNAs. Neither pioglitazone nor GW9662 altered the incidence of aneurysm formation. GW9662 significantly increased the incidence of aneurysm rupture, whereas pioglitazone tended to decrease the incidence of rupture. Dominant-negative endothelial-specific PPARγ did not alter the incidence of aneurysm formation or rupture. In contrast, dominant-negative smooth muscle-specific PPARγ resulted in an increase in aneurysm formation (P<0.05) and rupture (P=0.05). Dominant-negative smooth muscle-specific PPARγ, but not dominant-negative endothelial-specific PPARγ, resulted in significant decreases in expression of genes encoding Cullin3, Kelch-like ECH-associated protein 1, and nuclear factor (erythroid-derived 2)-like 2, along with significant increases in tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-X-C motif) ligand 1, CD68, matrix metalloproteinase-3, -9, and -13. MLN4924 did not alter incidence of aneurysm formation, but increased the incidence of rupture (P<0.05). In summary, endogenous PPARγ, specifically smooth muscle PPARγ, plays an important role in protecting from formation and rupture of experimental cerebral aneurysms in mice.
 Up-Regulation Vasculitis - metabolism Muscle, Smooth, Vascular - metabolism Vasculitis - pathology Vasculitis - complications Subarachnoid Hemorrhage - prevention & control Vasculitis - genetics Aneurysm, Ruptured - physiopathology Genes, Dominant Hypertension - chemically induced PPAR gamma - deficiency Inflammation Mediators - metabolism Pancreatic Elastase - toxicity Angiotensin II - toxicity Thiazolidinediones - pharmacology Anilides - toxicity Myocytes, Smooth Muscle - metabolism PPAR gamma - genetics Intracranial Aneurysm - genetics Gene Expression Regulation - physiology Mice, Transgenic Organ Specificity Muscle, Smooth, Vascular - pathology PPAR gamma - physiology Animals PPAR gamma - antagonists & inhibitors Cerebral Arteries - metabolism Endothelium, Vascular - metabolism Anilides - pharmacology PPAR gamma - agonists Hypertension - complications Subarachnoid Hemorrhage - etiology Mice Mutation Intracranial Aneurysm - physiopathology Aneurysm, Ruptured - genetics Intracranial Aneurysm - chemically induced

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