Decrease in Scavenger Receptor Expression in Human Monocyte–Derived Macrophages Treated With Granulocyte Macrophage Colony-Stimulating Factor
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TL;DR: Results indicate that GM-CSF can downregulate both types I and II scavenger receptor in human monocyte-derived macrophages, which might have implications for foam cell formation.
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Abstract: To determine whether scavenger receptors are susceptible to regulation by granulocyte macrophage colony-stimulating factor (GM-CSF), a macrophage-specific cytokine, human monocytes were differentiated into macrophages in the absence or presence of 20 U/mL GM-CSF. Binding, uptake, and degradation of acetylated LDL (Ac-LDL) and oxidized LDL (Ox-LDL) were measured. Treatment with GM-CSF resulted in a significant twofold to threefold decrease in the number of binding sites for Ac-LDL and Ox-LDL on the surface of macrophages without affecting the affinity of the receptor for these ligands. Competition experiments revealed that two binding sites were responsible for the recognition and uptake of Ac-LDL: one specific for Ac-LDL and one that recognized both Ac-LDL and Ox-LDL. No binding site specific for Ox-LDL could be detected in either control or GM-CSF–treated macrophages. Treatment of human monocyte–derived macrophages with GM-CSF resulted in a decrease of the Ac-LDL/Ox-LDL receptor but did not affect the binding site specific for Ac-LDL. Northern blot analysis showed that mRNA levels of both types I and II scavenger receptor were reduced in macrophages differentiated in the presence of GM-CSF. Human macrophages that were differentiated in the presence of GM-CSF accumulated ≈50% fewer cholesteryl esters. Taken together, these results indicate that GM-CSF can downregulate both types I and II scavenger receptor in human monocyte–derived macrophages, which might have implications for foam cell formation.
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Citations
Acetylated LDL Endocytosis by the Human Monocytic Mono Mac 6sr Cells Is Not Mediated by the Macrophage Type I and II Scavenger Receptors
Rupert Scheithe,Anne K. Heidenthal,Ulrich Danesch,Eva Mauthner,Gerhard Hapfelmeier,Alexander Becker,Angelika Pietsch,Peter C. Weber,N. Hrboticky +8 more
TL;DR: In this article, the binding sites of the acLDLBP were characterized on a functional and molecular basis and it was shown that the degradation of Acetylated (acLDL) increased during differentiation of Mono Mac 6sr cells with lipopolysaccharide (10 ng/mL, 72 hours) and low concentrations of phorbol 12-myristate 13-acetate (PMA; 0.1 to 1.0 n/mL).
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Binding of lipopolysaccharide and complexes of lipopolysaccharide to serum low density lipoproteins to liver macrophages
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TL;DR: It is suggested that, while binding to the Kupffer cell surface, a substantial portion of both LPS and LDL-LPS complexes share the same scavenger receptors with which, however, modified LDLs interact weakly.
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Binding of LPS and LPS--LDL complexes to rat hepatocytes.
A V Viktorov,V A Yurkiv +1 more
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