NF-E2-related factor 2 promotes atherosclerosis by effects on plasma lipoproteins and cholesterol transport that overshadow antioxidant protection.

Abstract

OBJECTIVE:

To test the hypothesis that NF-E2-related factor 2 (Nrf2) expression plays an antiatherogenic role by its vascular antioxidant and anti-inflammatory properties.

METHODS AND RESULTS:

Nrf2 is an important transcription factor that regulates the expression of phase 2 detoxifying enzymes and antioxidant genes. Its expression in vascular cells appears to be an important factor in the protection against vascular oxidative stress and inflammation. We developed Nrf2 heterozygous (HET) and homozygous knockout (KO) mice on an apolipoprotein (apo) E-null background by sequential breeding, resulting in Nrf2(-/-), apoE(-/-) (KO), Nrf2(-/+), apoE(-/-) (HET) and Nrf2(+/+), and apoE(-/-) wild-type littermates. KO mice exhibited decreased levels of antioxidant genes with evidence of increased reactive oxygen species generation compared with wild-type controls. Surprisingly, KO males exhibited 47% and 53% reductions in the degree of aortic atherosclerosis compared with HET or wild-type littermates, respectively. Decreased atherosclerosis in KO mice correlated with lower plasma total cholesterol in a sex-dependent manner. KO mice also had a decreased hepatic cholesterol content and a lower expression of lipogenic genes, suggesting that hepatic lipogenesis could be reduced. In addition, KO mice exhibited atherosclerotic plaques characterized by a lesser macrophage component and decreased foam cell formation in an in vitro lipid-loading assay. This was associated with a lower rate of cholesterol influx, mediated in part by decreased expression of the scavenger receptor CD36.

CONCLUSIONS:

Nrf2 expression unexpectedly promotes atherosclerotic lesion formation in a sex-dependent manner, most likely by a combination of systemic metabolic and local vascular effects.

• Authors: Berenice Barajas, Nam Che, Fen Yin, Amir Rowshanrad, Luz D Orozco, Ke Wei Gong, Xuping Wang, Lawrence W Castellani, Karen Reue, Aldons J Lusis, Jesus A Araujo
• Journal: Arteriosclerosis, thrombosis, and vascular biology (Arterioscler Thromb Vasc Biol) Vol. 31 Issue 1 Pg. 58-66 (Jan 2011) ISSN: 1524-4636 [Electronic] United States
• PMID: 20947826 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antioxidants
• Apolipoproteins E
• CD36 Antigens
• Lipoproteins
• NF-E2-Related Factor 2
• Nfe2l2 protein, mouse
• Reactive Oxygen Species
• Cholesterol

Topics

• Animals
• Antioxidants (metabolism)
• Aortic Diseases (etiology, genetics, metabolism, pathology, prevention & control)
• Apolipoproteins E (deficiency, genetics)
• Atherosclerosis (etiology, genetics, metabolism, pathology, prevention & control)
• Biological Transport
• CD36 Antigens (metabolism)
• Cholesterol (metabolism)
• Disease Models, Animal
• Female
• Foam Cells (metabolism)
• Gene Expression Regulation
• Lipogenesis (genetics)
• Lipoproteins (blood)
• Liver (metabolism)
• Male
• Mice
• Mice, Knockout
• NF-E2-Related Factor 2 (deficiency, genetics, metabolism)
• Reactive Oxygen Species (metabolism)
• Sex Factors