Adiponectin reduces lipid accumulation in macrophage foam cells.
Adiponectin is one of several, important metabolically active cytokines secreted from adipocytes. Low circulating levels of this adipokine have been associated epidemiologically with obesity, insulin resistance, type II diabetes, and cardiovascular disease. To determine if adiponectin can modulate lipid metabolism in macrophages, we expressed the adiponectin gene in human THP-1 macrophage foam cells using a lentiviral vector expression system and demonstrated that macrophages transduced with the adiponectin gene had decreased lipid accumulation compared with control macrophages transduced with the LacZ gene. Macrophages transduced with the adiponectin gene also exhibited decreased oxidized low-density lipoprotein (oxLDL) uptake and increased HDL-mediated cholesterol efflux. Additional studies suggest two potential mechanisms for the reduced lipid accumulation in these adiponectin-transduced macrophage foam cells. The first mechanism involves the PPARgamma and LXR signaling pathways which up-regulate the expression of ABCA1 and promote lipid efflux from these cells. The second mechanism involves decreased lipid uptake and increased lipid hydrolysis which may result from decreased SR-AI and increased SR-BI and HSL gene activities in the transformed macrophage foam cells. We also demonstrated that the expression of two proatherogenic cytokines, MCP-1 and TNFalpha, were decreased in the adiponectin-transduced macrophage foam cells. These results suggest that adiponectin may modulate multiple pathways of lipid metabolism in macrophages. Our studies provide new insights into potential mechanisms of adiponectin-mediated alterations in lipid metabolism and macrophage foam cell formation which may impact the development of atherosclerosis.
Tian
Ling
L
Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294-3360, United States.
Luo
Nanlan
N
Klein
Richard L
RL
Chung
B Hong
BH
Garvey
W Timothy
WT
Fu
Yuchang
Y
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D052242:Adiponectin / Q000235:genetics / Q000378:metabolism*; D050197:Atherosclerosis / Q000378:metabolism; D001692:Biological Transport; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D005487:Foam Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D052242:Adiponectin; D008055:Lipids; D008077:Lipoproteins, LDL; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein; D002784:Cholesterol