Adipocyte-derived plasma protein, adiponectin, suppresses lipid accumulation and class A scavenger receptor expression in human monocyte-derived macrophages

• Published in: Circulation (New York, N.Y.) N.Y.), 2001-02, Vol.103 (8), p.1057-1063
• Main Authors: OUCHI, Noriyuki, KIHARA, Shinji, HOTTA, Kikuko, MURAGUCHI, Masahiro, OHMOTO, Yasukazu, YAMASHITA, Shizuya, FUNAHASHI, Tohru, MATSUZAWA, Yuji, ARITA, Yukio, NISHIDA, Makoto, MATSUYAMA, Akifumi, OKAMOTO, Yoshihisa, ISHIGAMI, Masato, KURIYAMA, Hiroshi, KISHIDA, Ken, NISHIZAWA, Hitoshi
• Format: Article
• Language: English
• Subjects: Adipocytes - chemistry; Adiponectin; Apolipoproteins E - genetics; Apolipoproteins E - metabolism; Atherosclerosis (general aspects, experimental research); Biological and medical sciences; Blood and lymphatic vessels; Blood Proteins - pharmacology; Cardiology. Vascular system; CD36 Antigens - metabolism; Cell Differentiation - drug effects; Cells, Cultured; Cholesterol Esters - metabolism; Foam Cells - cytology; Foam Cells - drug effects; Humans; Intercellular Signaling Peptides and Proteins; Lipid Metabolism; Lipoprotein Lipase - genetics; Lipoprotein Lipase - metabolism; Lipoproteins, LDL - metabolism; Macrophages - drug effects; Macrophages - metabolism; Medical sciences; Monocytes - cytology; Peptide Fragments - genetics; Peptide Fragments - metabolism; Proteins - pharmacology; Receptors, Immunologic - biosynthesis; Receptors, Scavenger; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Scavenger Receptors, Class A
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.cir.103.8.1057

Excessive lipid accumulation in macrophages plays an important role in the development of atherosclerosis. Recently, we discovered an adipocyte-specific plasma protein, adiponectin, that is decreased in patients with coronary artery disease. We previously demonstrated that adiponectin acts as a modulator for proinflammatory stimuli and inhibits monocyte adhesion to endothelial cells. The present study investigated the effects of adiponectin on lipid accumulation in human monocyte-derived macrophages. Human monocytes were differentiated into macrophages by incubation in human type AB serum for 7 days, and the effects of adiponectin were investigated at different time intervals. Treatment with physiological concentrations of adiponectin reduced intracellular cholesteryl ester content, as determined using the enzymatic, fluorometric method. The adiponectin-treated macrophages contained fewer lipid droplets stained by oil red O. Adiponectin suppressed the expression of the class A macrophage scavenger receptor (MSR) at both mRNA and protein levels by Northern and immunoblot analyses, respectively, without affecting the expression of CD36, which was quantified by flow cytometry. Adiponectin reduced the class A MSR promoter activity, as measured by luciferase reporter assay. Adiponectin treatment dose-dependently decreased class A MSR ligand binding and uptake activities. The mRNA level of lipoprotein lipase as a marker of macrophage differentiation was decreased by adiponectin treatment, but that of apolipoprotein E was not altered. Adiponectin was detected around macrophages in the human injured aorta by immunohistochemistry. The adipocyte-derived plasma protein adiponectin suppressed macrophage-to-foam cell transformation, suggesting that adiponectin may act as a modulator for macrophage-to-foam cell transformation.