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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Thematic review series: The Immune System and Atherogenesis. Cytokine regulation of macrophage functions in atherogenesis
TL;DR: The numerous cytokines that have been detected in atherosclerosis, combined with the expression of large numbers of cytokine receptors on macrophages, are consistent with this axis being an important contributor to lesion development.
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Distinct scavenger receptor expression and function in the human CD14+/CD16+monocyte subset
Georg Draude,Philipp von Hundelshausen,Marion Frankenberger,H. W. Löms Ziegler-Heitbrock,Christian Weber +4 more
TL;DR: The subset of CD14+/CD16+monocytes shows distinct ScR function and expression, possibly reflecting a preactivation by cytokines with a predilection for specific inflammatory or vascular conditions, e.g., atherogenesis.
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Transcriptional Inhibition by Interleukin-6 of the Class A Macrophage Scavenger Receptor in Macrophages Derived From Human Peripheral Monocytes and the THP-1 Monocytic Cell Line
Hai Sun Liao,Akiyo Matsumoto,Hiroshige Itakura,Takefumi Doi,Makoto Honda,Tatsuhiko Kodama,Yong Jian Geng +6 more
TL;DR: Exposure to IL-6 may inhibit expression of the class A MSR in differentiated macrophages at transcriptional levels, which suggests that this cytokine may modulate foam cell formation during atherogenesis.
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Role of Activin-A and Follistatin in Foam Cell Formation of THP-1 Macrophages
Koichi Kozaki,Masahiro Akishita,Masato Eto,Masao Yoshizumi,Kenji Toba,Satoshi Inoue,Michiro Ishikawa,Masayoshi Hashimoto,Tatsuhiko Kodama,Nobuhiro Yamada,Hajime Orimo,Yasuyoshi Ouchi +11 more
TL;DR: In this article, the authors examined the roles of activin-A and follistatin in macrophage foam cell formation in the early stage of atherosclerosis and found that the effect of activation on cell association and degradation was dose dependent, and the effect was blocked by concomitant addition of Follistatin.
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Specific Interaction of Oxidized Low-Density Lipoprotein With Macrophage-Derived Foam Cells Isolated From Rabbit Atherosclerotic Lesions
TL;DR: The induction of scavenger receptors for OxLDL on macrophage-derived foam cells during the development of atherosclerosis, as described in this study, may facilitate the lipid accumulation in macrophages derived foam cells, as observed in advanced atherosclerotic lesions.
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