Acute phase serum amyloid A protein increases high density lipoprotein binding to human peripheral blood mononuclear cells and an endothelial cell line.
Serum Amyloid A (SAA) is an acute-phase protein secreted mainly by hepatocytes and is largely associated with high-density lipoprotein (HDL) in plasma. It has been suggested that SAA alters HDL binding to the cell surface and that this in turn changes HDL-mediated cholesterol delivery to cells. Incorporation of SAA into HDL at concentrations equivalent to those found physiologically in moderate inflammation mediated a 1.5-fold increase in the binding of HDL to adherent peripheral blood mononuclear cells but had no effect on binding of the lipoprotein to the monocyte cell lines, U937 or THP-1. SAA incorporation also increased binding to an endothelial cell line, EA.hy.926. Hepatoma cells (HuH-7) showed no change in specific binding of the SAA-enriched HDL particle compared to normal HDL. These results suggest that a specific receptor for HDL-bound SAA is found on differentiated human macrophages and an endothelial cell line, which may have functional significance in lipid metabolism or other macrophage responses during inflammation.
Hayat
S
S
Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, UK.
Raynes
J G
JG
D000210:Acute-Phase Reaction; D002460:Cell Line; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism*; D000685:Serum Amyloid A Protein / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D020298:U937 Cells
D008075:Lipoproteins, HDL; D000685:Serum Amyloid A Protein