OBJECTIVE: In vitro studies implicate that the low-density lipoprotein receptor (LDLR)-related protein (LRP) in macrophages has a pro-atherogenic potential. In the present study, we investigated the in vivo role of macrophage specific LRP in atherogenesis independent of its role in the uptake of lipoproteins. METHODS AND RESULTS: We generated macrophage-specific LRP-deficient mice on an apoE/LDLR double-deficient background. Macrophage LRP deletion did not affect plasma cholesterol and triglyceride levels, lipoprotein distribution, and blood monocyte counts. Nevertheless, macrophage LRP deficiency resulted in a 1.8-fold increase in total atherosclerotic lesion area in the aortic root of 18-week-old mice. Moreover, LRP deficiency also resulted in a relatively higher number of advanced lesions. Whereas macrophage and smooth muscle cell content did not differ between LRP-deficient mice and control littermates, a 1.7-fold increase in collagen content and 2.3-fold decrease in relative number of CD3+ T cells were observed in lesions from macrophage specific LRP-deficient mice. CONCLUSIONS: Our data demonstrate that independent of its role in lipoprotein uptake, absence of LRP in macrophages resulted in more advanced atherosclerosis and in lesions that contained more collagen and less CD3+ T cells. In contrast to previous in vitro studies, we conclude that macrophage LRP has an atheroprotective potential and may modulate the extracellular matrix in the atherosclerotic lesions.
OBJECTIVE: In vitro studies implicate that the low-density lipoprotein receptor (LDLR)-related protein (LRP) in macrophages has a pro-atherogenic potential. In the present study, we investigated the in vivo role of macrophage specific LRP in atherogenesis independent of its role in the uptake of lipoproteins. METHODS AND RESULTS: We generated macrophage-specific LRP-deficient mice on an apoE/LDLR double-deficient background. Macrophage LRP deletion did not affect plasma cholesterol and triglyceride levels, lipoprotein distribution, and blood monocyte counts. Nevertheless, macrophage LRP deficiency resulted in a 1.8-fold increase in total atherosclerotic lesion area in the aortic root of 18-week-old mice. Moreover, LRP deficiency also resulted in a relatively higher number of advanced lesions. Whereas macrophage and smooth muscle cell content did not differ between LRP-deficient mice and control littermates, a 1.7-fold increase in collagen content and 2.3-fold decrease in relative number of CD3+ T cells were observed in lesions from macrophage specific LRP-deficient mice. CONCLUSIONS: Our data demonstrate that independent of its role in lipoprotein uptake, absence of LRP in macrophages resulted in more advanced atherosclerosis and in lesions that contained more collagen and less CD3+ T cells. In contrast to previous in vitro studies, we conclude that macrophage LRP has an atheroprotective potential and may modulate the extracellular matrix in the atherosclerotic lesions.
Authors: Frank M Davis; Debra L Rateri; Anju Balakrishnan; Deborah A Howatt; Dudley K Strickland; Selen C Muratoglu; Christopher M Haggerty; Brandon K Fornwalt; Lisa A Cassis; Alan Daugherty Journal: Arterioscler Thromb Vasc Biol Date: 2014-11-13 Impact factor: 8.311
Authors: R Michael Gower; Huaizhu Wu; Greg A Foster; Sridevi Devaraj; Ishwarlal Jialal; Christie M Ballantyne; Anne A Knowlton; Scott I Simon Journal: Arterioscler Thromb Vasc Biol Date: 2010-10-28 Impact factor: 8.311
Authors: Sara M Reekmans; Thorsten Pflanzner; Philip L S M Gordts; Simone Isbert; Pascale Zimmermann; Wim Annaert; Sascha Weggen; Anton J M Roebroek; Claus U Pietrzik Journal: Cell Mol Life Sci Date: 2009-10-25 Impact factor: 9.261
Authors: Anna P Lillis; Mallary C Greenlee; Irina Mikhailenko; Salvatore V Pizzo; Andrea J Tenner; Dudley K Strickland; Suzanne S Bohlson Journal: J Immunol Date: 2008-07-01 Impact factor: 5.422