Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an in vivo atherosclerosis model

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Abstract

Abstract Background
Thiazolidinediones exert anti-inflammatory and anti-oxidative roles and attenuate atherosclerosis by mechanisms partially independent of their metabolizing actions. High doses of angiotensin type 1 receptor (AT1R) blocker losartan (LST) seem to promote fat cell formation by preserving PPARÎł activity.

Methods
C57BL/6J diet-induced atherosclerotic susceptible mice randomly received a normal or a high-fat high-cholesterol (HFHC) diet and were treated with rosiglitazone (RG), LST or a vehicle for 12 weeks.

Results
HFHC was associated with increased PPARÎł gene expression without an over regulation of PPARÎł responsive genes, whereas RG and LST treatments were found to maintain PPARÎł activity without resulting in increased PPARÎł gene expression. A better anti-inflammatory and antioxidant profile in mice treated with RG regarding LST was observed in spite of a similar PPARÎł preserved activity. Chromatin immunoprecipitation (ChIP) assays revealed that animals under HFHC diet treated with RG showed a significant nuclear factor erythroid 2-like 2 (Nrf2)-dependent down-regulation of the expression of the CD36 gene.

Conclusion
The PPARÎł agonist RG exerts antioxidant properties that significantly reduced Nrf-2-dependent CD-36 up-regulation in mice under HFHC diet. Because LST treatment was also associated with a preserved PPARÎł activity, our data suggests that these RG antioxidant effects are partially independent of its PPARÎł metabolizing properties.

References
  1. Ross R: Atherosclerosis--an inflammatory disease. N Engl J Med 1999, 340:115-126.
  2. Steinberg D: Low density lipoprotein oxidation and its pathobiological significance. J Biol Chem 1997, 272:20963-20966.
  3. Davignon J, Ganz P: Role of endothelial dysfunction in atherosclerosis. Circulation 2004, 109:III27-III32.
  4. Chang MY, Olin KL, Tsoi C, Wight TN, Chait A: Human monocyte-derived macrophages secrete two forms of proteoglycan-macrophage colony-stimulating factor that differ in their ability to bind low density lipoproteins. J Biol Chem 1998, 273:15985-15992.
  5. Nakashima Y, Fujii H, Sumiyoshi S, Wight TN, Sueishi K: Early human atherosclerosis: accumulation of lipid and proteoglycans in intimal thickenings followed by macrophage infiltration. Arterioscler Thromb Vasc Biol 2007, 27:1159-1165.