chondroitin-sulfates and Hypercholesterolemia

Novel flower-type and three-dimensional porous nanoparticles are prepared for the isolation of low density lipoprotein (LDL). The amino-terminated dendritic mesoporous silica nanoparticles (A-DMSNs) show highly accessible central-radial pore (0.655 cm

Topics: Adsorption; Chondroitin Sulfates; Circular Dichroism; Dendrimers; Healthy Volunteers; Humans; Hypercholesterolemia; Lipoproteins, LDL; Microscopy, Electron, Transmission; Nanoparticles; Porosity; Silicon Dioxide; Surface Properties

Hypercholesterolemia is one of the factors contributing to cardiovascular problems. Erythrocytes are known to contribute its cholesterol to atherosclerotic plaque. Our earlier study showed that erythrocytes overexpress chondroitin sulphate/dermatan sulphate (CS/DS), a linear co-polymer, during diabetes which resulted in increased cytoadherence to extracellular matrix (ECM) components. This study was carried out to determine whether diet-induced hypercholesterolemia had any effect on erythrocyte CS/DS and impacted cytoadherence to ECM components. Unlike in diabetes, diet-induced hypercholesterolemia did not show quantitative changes in erythrocyte CS/DS but showed difference in proportion of un-sulphated and 4-O-sulphated disaccharides. Erythrocytes from hypercholesterolemic rats showed increased adhesion to ECM components which was abrogated to various extents when subjected to chondroitinase ABC digestion. However, isolated CS/DS chains showed a different pattern of binding to ECM components indicating that orientation of CS/DS chains could be playing a role in binding.

Topics: Animals; Cell Adhesion; Chondroitin Sulfates; Dermatan Sulfate; Diabetes Mellitus; Erythrocytes; Extracellular Matrix; Humans; Hypercholesterolemia; Rats; Structure-Activity Relationship

The interactions between serum lipoproteins isolated from rabbits fed a cholesterol-supplemented diet for six weeks, and soluble extracts of arterial neointima enriched in proteoglycans extracted from normocholesterolaemic rabbit aortas, were studied in an in vitro system. Neointimal tissues of rabbit aorta, which developed during three months following a selective endothelial injury, were excised and the areas covered or uncovered by regenerated endothelium were separated. To isolate the proteoglycan enriched fraction, both normal and injured tissue was homogenized in a sucrose solution containing protease inhibitors, centrifuged, and further fractionated by gel exclusion chromatography. The composition of the soluble extracts and each of their corresponding proteoglycan enriched fractions were analyzed in terms of protein and glycosaminoglycan content. Lipoproteins of donor animals fed an atherogenic diet were prepared by sequential ultracentrifugal flotation after density adjustment with KBr. Aliquots of electrophoretically pure lipoprotein fractions were incubated with proteoglycan enriched fraction from uninjured, denuded, or endothelium-covered neointima in the presence of Ca++ and Mg++ at 4 degrees C. The complexes formed during incubation were separated by centrifugation. The cholesterol content of the complexes was considered as an index of binding capacity. Results were expressed as micrograms of cholesterol bound per mg of glycosaminoglycan. The data reveal the higher affinity of hypercholesterolaemic lipoprotein fractions for aortic proteoglycans, as compared to normocholesterolaemic lipoproteins. In addition, when evaluating the relevance of the proteoglycan enriched fraction source, the affinity of fractions extracted from aortic neointima was found to be much higher for hypercholesterolaemic lipoproteins. These results suggest the role that proteoglycan-lipoprotein interactions could play in the event of the combined actions of endothelial injury and hypercholesterolaemia in the pathogenesis of atherosclerosis.

Topics: Animals; Aorta; Cholesterol, Dietary; Chondroitin Sulfates; Electrophoresis, Polyacrylamide Gel; Endothelium, Vascular; Female; Glycosaminoglycans; Hypercholesterolemia; Lipoproteins; Lipoproteins, LDL; Lipoproteins, VLDL; Male; Proteoglycans; Rabbits

We compared the effects of mild hypercholesterolemia and repeated endotoxin infusions on the biochemical composition of aortic intima and inner media of 24 piglets divided into 4 groups 5 days after weaning: controls on normal diet (group I); normal diet and endotoxin (group II); fat-supplemented diet (group III); and fat-supplemented diet and endotoxin (group IV). It was found that mild hypercholesterolemia increased the concentration of arterial esterified cholesterol and the relative amount of the fraction containing chondroitin sulphates A and C in total glycosaminoglycans. Endotoxin infusions partly prevented the increase of serum cholesterol caused by the fat-supplemented diet but had no independent effect on the arterial biochemical composition; nor did they affect the biochemical changes caused by hypercholesterolemia. When the results of all groups were combined, chondroitin sulphates A and C showed a significant positive correlation with the concentration of arterial esterified cholesterol and the percentage of linoleic acid in arterial cholesteryl esters. Serum total cholesterol did not correlate with arterial cholesterol fractions, but the ratio of high density lipoprotein-cholesterol to total serum cholesterol showed a negative association with arterial esterified cholesterol. The present findings indicate that (1) mild hypercholesterolemia is atherogenic in young piglets, and (2) changes in arterial glycosaminoglycan composition might be one of the earliest biochemical alterations in atherogenesis.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Cholesterol; Chondroitin Sulfates; Dermatan Sulfate; Diet, Atherogenic; Endotoxins; Glycosaminoglycans; Heparitin Sulfate; Hyaluronic Acid; Hypercholesterolemia; Lipids; Muscle, Smooth, Vascular; Phospholipids; Reference Values; Swine

The effect of chondroitin-6-sulfate, obtained from shark cartilage, on atherogenesis in rabbits fed a high-cholesterol diet was studied. Male Japanese white rabbits were housed for 10 weeks in three groups, one group was fed ordinary pellets and was injected intraperitoneally with saline (standard-diet group), one was fed pellets containing 1% cholesterol and was injected intraperitoneally with saline (cholesterol-diet group), and the third group was fed pellets containing 1% cholesterol, and was injected intraperitoneally with 10 mg of chondroitin-6-sulfate (C-6-S group). Injections were done daily. The plasma total cholesterol, and cholesterol from very low-density lipoprotein in the C-6-S group after 5 weeks in the test period, and low-density lipoprotein cholesterol in the C-6-S group at the end of the test period were lower than those of the cholesterol-diet group. Significantly fewer atherosclerotic lesions of the aortic surface were found macroscopically in the C-6-S group than in the cholesterol-diet group. The cholesterol, esterified cholesterol and calcium concentrations of the aortic intima-media in the C-6-S group were significantly lower than in the cholesterol-diet group. Hydroxyproline levels in these three groups were not different. The uronic acid concentration of the intima-media in the cholesterol-diet group was significantly higher than in the C-6-S group (P less than 0.02). Though the percentage of heparan sulfate on total glycosaminoglycans (GAGs) of the C-6-S group was lower than in the cholesterol-diet group, there were no significant differences in the percentages of dermatan sulfate and chondroitin-4/6-sulfate in total GAGs between the cholesterol-diet and C-6-S groups. These results suggest that chondroitin-6-sulfate suppresses cholesterol deposition in the aorta of rabbits fed a 1% cholesterol diet, probably partly due to a decrease in the plasma low-density lipoprotein cholesterol, and partly due to a change in arterial metabolism.

Topics: Animals; Aorta; Arteriosclerosis; Calcium; Chondroitin; Chondroitin Sulfates; Glycosaminoglycans; Heparin; Hydroxyproline; Hypercholesterolemia; Lipid Metabolism; Lipolysis; Lipoproteins; Male; Platelet Aggregation; Rabbits

Arterial wall sulfated glycosaminoglycans (GAG) of matrix proteoglycans have been implicated in the retention of plasma low density lipoproteins in the early stages of atherosclerosis. We have studied modifications in porcine aortic GAG composition after 4 and 11 weeks of diet-induced hypercholesterolemia. After these time intervals no grossly visible atherosclerotic lesions were discerned. GAG changes were correlated with tissue LDL accumulation estimated by quantification of immunochemically-identifiable apolipoprotein B (apoB). Values of apoB ranged from less than 10 to 250 ng/mg wet weight of aorta, and correlated significantly with tissue total cholesterol contents. Although total GAG concentrations did not differ between a normolipemic control and the two diet groups, apoB showed a significantly positive correlation with the percent of total GAG that was chondroitin sulfate and a significantly negative correlation with the percent of total GAG that was dermatan sulfate. Total tissue cholesterol likewise demonstrated similar correlations with GAG. Since areas of the aorta were chosen that were devoid of intimal thickening, these metabolic changes may occur in the inner part of the arterial tunica media. The results suggest that the accumulation of plasma LDL in the arterial wall following hypercholesterolemia may induce alterations in arterial GAG composition, presumably by affecting GAG synthesis by medial smooth muscle cells.

Topics: Animals; Aorta; Apolipoproteins B; Cholesterol; Cholesterol, Dietary; Chondroitin Sulfates; Dermatan Sulfate; Glycosaminoglycans; Hypercholesterolemia; Immunoassay; Lipoproteins, LDL; Male; Swine

Male Dutch-belted rabbits were fed a pelleted 0.5% cholesterol diet for 8 weeks. A control group was maintained on basal pelleted diet for the same period of time. Prior to sacrifice both groups received i.v. 3H-inulin. Plasma and aortic sections were assayed for 3H-inulin activity. Aortic sections were also analyzed for glycosaminoglycan concentrations. A ratio of the aortic 3H-inulin activity to the plasma 3H-inulin activity was calculated and expressed as a permeability index. Mean plasma activity of 3H-inulin was significantly lower in the control group, suggesting increased aortic permeability in the cholesterol-fed animals. Glycosaminoglycan concentrations were significantly higher in the control group, and significant negative correlations were detected between glycosaminoglycan concentrations and permeability index in all animals. These findings are consistent with the hypothesis that sufficient glycosaminoglycan levels are important to maintaining the permeability characteristics of the endothelial layer.

Topics: Animals; Aorta, Thoracic; Arteries; Arteriosclerosis; Cholesterol, Dietary; Chondroitin Sulfates; Diet, Atherogenic; Endothelium; Glycosaminoglycans; Hypercholesterolemia; Inulin; Male; Permeability; Rabbits

The sulfated glycosaminoglycan, heparin, was found to release 125I-labeled low density lipoprotein (125I-LDL) from its receptor site on the surface of normal human fibroblasts. Measurement of the amount of 125I-LDL released by heparin permitted the resolution of the total cellular uptake of 125I-LDL at 37 degrees C into two components: first, an initial rapid, high affinity binding of the lipoprotein to the surface receptor, from which the 125I-LDL could be released by heparin, and second, a slower process attributable to an endocytosis of the receptor-bound lipoprotein, which rendered it resistant to heparin release. At 4 degrees C the amount of heparin-releasable 125I-LDL was similar to that at 37 degrees C, but interiorization of the lipoprotein did not occur at the lower temperature. The physiologic importance of the cell surface LDL receptor was emphasized by the finding that mutant fibroblasts from a subject with homozygous Familial Hypercholesterolemia, which lack the ability to take up 125I-LDL at 37 degrees C, did not show cell surface binding of 125I-LDL, as measured by heparin release, at either 4 degrees C or 37 degrees C. Although heparin released 125I-LDL from its binding site, it did not release 3H-concanavalin A from its surface receptor, and conversely, alpha-methyl-D-mannopyranoside, which released 3H-concanavalin A, did not release surface-bound 125I-LDL. When added to the culture medium simultaneously with LDL, heparin prevented the binding of LDL to its receptor and hence prevented the LDL-mediated suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. The uptake of LDL by fibroblasts is proposed as a model of receptor-mediated adsorptive endocytosis of macromolecules in human cells.

Topics: Cell Membrane; Cells, Cultured; Chondroitin Sulfates; Concanavalin A; Dermatan Sulfate; Endocytosis; Heparin; Hypercholesterolemia; Lipoproteins, LDL; Methylmannosides; Receptors, Drug; Temperature