Conditional knockout of macrophage PPARγ increases atherosclerosis in C57BL/6 and low-density lipoprotein receptor-deficient mice

Vladimir R. Babaev, Patricia G. Yancey, Sergey V. Ryzhov, Valentina Kon, Matthew D. Breyer, Mark A. Magnuson, Sergio Fazio, MacRae F. Linton

Research output: Contribution to journalArticle

142 Citations (Scopus)

Abstract

Objective - Peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in macrophage-derived foam cells of atherosclerotic lesions, and its expression may have a dramatic impact on atherosclerosis. Methods and Results - To investigate the contribution of macrophage PPARγ expression on atherogenesis in vivo, we generated macrophage-specific PPARγ knockout (MacPPARγKO) mice, C57BL/6 and low-density lipoprotein (LDL) receptor-deficient (LDLR-/-) mice were reconstituted with MacPPARγKO or wild-type marrow and challenged with an atherogenic diet. No differences were found in serum lipids between recipients reconstituted with MacPPARγKO and wild-type marrow. In contrast, both C57BL/6 and LDLR -/- mice transplanted with MacPPARγKO marrow had significantly larger atherosclerotic lesions than control recipients. In addition, MacPPARγKO→LDLR-/- mice had higher numbers of macrophages in atherosclerotic lesions compared with controls. Peritoneal macrophages isolated from the MacPPARγKO mice had decreased uptake of oxidized but not acetylated LDL and showed no changes in either cholesterol efflux or inflammatory cytokine expression. Macrophages from MacPPARγKO mice had increased levels of migration and CC chemokine receptor 2 (CCR2) expression compared with wild-type macrophages, Conclusion - Thus, macrophage PPARγ deficiency increases atherosclerosis under conditions of mild and severe hypercholesterolemia, indicating an antiatherogenic role for PPARγ, which may be caused, at least in part, by modulation of CCR2 expression and monocyte recruitment.

Original languageEnglish (US)
Pages (from-to)1647-1653
Number of pages7
JournalArteriosclerosis, Thrombosis, and Vascular Biology
Volume25
Issue number8
DOIs
StatePublished - Aug 2005
Externally publishedYes

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LDL Receptors
PPAR gamma
Atherosclerosis
Macrophages
Peroxisome Proliferator-Activated Receptors
CCR2 Receptors
Knockout Mice
Bone Marrow
Atherogenic Diet
Foam Cells
Peritoneal Macrophages
Hypercholesterolemia
Monocytes
Cholesterol
Cytokines

Keywords

  • ABCA1
  • Atherosclerosis
  • CCR2 expression
  • Cholesterol efflux
  • Macrophages
  • Scavenger receptor CD36

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Cite this

Conditional knockout of macrophage PPARγ increases atherosclerosis in C57BL/6 and low-density lipoprotein receptor-deficient mice. / Babaev, Vladimir R.; Yancey, Patricia G.; Ryzhov, Sergey V.; Kon, Valentina; Breyer, Matthew D.; Magnuson, Mark A.; Fazio, Sergio; Linton, MacRae F.

In: Arteriosclerosis, Thrombosis, and Vascular Biology, Vol. 25, No. 8, 08.2005, p. 1647-1653.

Research output: Contribution to journalArticle

Babaev, Vladimir R. ; Yancey, Patricia G. ; Ryzhov, Sergey V. ; Kon, Valentina ; Breyer, Matthew D. ; Magnuson, Mark A. ; Fazio, Sergio ; Linton, MacRae F. / Conditional knockout of macrophage PPARγ increases atherosclerosis in C57BL/6 and low-density lipoprotein receptor-deficient mice. In: Arteriosclerosis, Thrombosis, and Vascular Biology. 2005 ; Vol. 25, No. 8. pp. 1647-1653.
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T1 - Conditional knockout of macrophage PPARγ increases atherosclerosis in C57BL/6 and low-density lipoprotein receptor-deficient mice

AU - Babaev, Vladimir R.

AU - Yancey, Patricia G.

AU - Ryzhov, Sergey V.

AU - Kon, Valentina

AU - Breyer, Matthew D.

AU - Magnuson, Mark A.

AU - Fazio, Sergio

AU - Linton, MacRae F.

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N2 - Objective - Peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in macrophage-derived foam cells of atherosclerotic lesions, and its expression may have a dramatic impact on atherosclerosis. Methods and Results - To investigate the contribution of macrophage PPARγ expression on atherogenesis in vivo, we generated macrophage-specific PPARγ knockout (MacPPARγKO) mice, C57BL/6 and low-density lipoprotein (LDL) receptor-deficient (LDLR-/-) mice were reconstituted with MacPPARγKO or wild-type marrow and challenged with an atherogenic diet. No differences were found in serum lipids between recipients reconstituted with MacPPARγKO and wild-type marrow. In contrast, both C57BL/6 and LDLR -/- mice transplanted with MacPPARγKO marrow had significantly larger atherosclerotic lesions than control recipients. In addition, MacPPARγKO→LDLR-/- mice had higher numbers of macrophages in atherosclerotic lesions compared with controls. Peritoneal macrophages isolated from the MacPPARγKO mice had decreased uptake of oxidized but not acetylated LDL and showed no changes in either cholesterol efflux or inflammatory cytokine expression. Macrophages from MacPPARγKO mice had increased levels of migration and CC chemokine receptor 2 (CCR2) expression compared with wild-type macrophages, Conclusion - Thus, macrophage PPARγ deficiency increases atherosclerosis under conditions of mild and severe hypercholesterolemia, indicating an antiatherogenic role for PPARγ, which may be caused, at least in part, by modulation of CCR2 expression and monocyte recruitment.

AB - Objective - Peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in macrophage-derived foam cells of atherosclerotic lesions, and its expression may have a dramatic impact on atherosclerosis. Methods and Results - To investigate the contribution of macrophage PPARγ expression on atherogenesis in vivo, we generated macrophage-specific PPARγ knockout (MacPPARγKO) mice, C57BL/6 and low-density lipoprotein (LDL) receptor-deficient (LDLR-/-) mice were reconstituted with MacPPARγKO or wild-type marrow and challenged with an atherogenic diet. No differences were found in serum lipids between recipients reconstituted with MacPPARγKO and wild-type marrow. In contrast, both C57BL/6 and LDLR -/- mice transplanted with MacPPARγKO marrow had significantly larger atherosclerotic lesions than control recipients. In addition, MacPPARγKO→LDLR-/- mice had higher numbers of macrophages in atherosclerotic lesions compared with controls. Peritoneal macrophages isolated from the MacPPARγKO mice had decreased uptake of oxidized but not acetylated LDL and showed no changes in either cholesterol efflux or inflammatory cytokine expression. Macrophages from MacPPARγKO mice had increased levels of migration and CC chemokine receptor 2 (CCR2) expression compared with wild-type macrophages, Conclusion - Thus, macrophage PPARγ deficiency increases atherosclerosis under conditions of mild and severe hypercholesterolemia, indicating an antiatherogenic role for PPARγ, which may be caused, at least in part, by modulation of CCR2 expression and monocyte recruitment.

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