The cell-interactive properties of glucosylated very-low-density and low-density lipoproteins
Turk, Z.; Skrabalo, Z.
Cellular and Molecular Biology 33(3): 345-354
1987
ISSN/ISBN: 0145-5680 PMID: 3607833 Document Number: 287177
Monolayered cultures of human skin fibroblasts and monocyte-derived macrophages were used to examine the high-affinity bindings, internalization and degradation of glucosylated 125I-very-low-density and 125I-low-density lipoproteins (g1c-VLDL and g1c-LDL) in comparison with the same native lipoproteins. Human lipoproteins were glucosylated in plasma to which glucose and protease inhibitors were added. Non-glucosylated lipoproteins were separated from the glucosylated ones by aminophenylboronic affinity chromatography. The high affinity binding of the control of glucosylated lipoproteins was determined in normal fibroblasts pre-incubated in lipoprotein-deficient serum. The binding of glucosylated lipoproteins, measured in the presence of LDL-receptor antibodies (g1c-LDL; 048 ng/mg, control: 25.4 ng/mg; g1c-VLDL: 1.6 ng/mg. control: 7.76 ng/mg), and their degradation (g1c-LDL: 80 ng/mg, control: 1200 ng/mg; g1c-VLDL: 200 ng/mg, control: 540 ng/mg) were found markedly decreased. As the results indicated that glucosylation inhibited the high-affinity binding and degradation of lipoprotein particles, experiments were conducted to establish whether or not human monocyte-derived macrophages can recognize and ingest g1c-VLDL and g1c-LDL. The amount of degraded g1c-VLDL was three times higher than the amount of control VLDL (g1c-VLDL: 83 .+-. 15 ng/mg, control: 30 .+-. 5 ng/mg), whereas the degradation of g1c-LDL was almost double compared to that of unmodified particles (g1c-LDL: 29.5 .+-. 0.9 mg/mg, control: 15.8 .+-. 1.5 ng/mg). Our findings support the concept that glucosylation elicits changes in lipoprotein metabolism. The increased recognition of glucosylated lipoproteins by macrophage cells may have an impact on tissue pathology.