Statin treatment increases the sialic acid content of LDL in hypercholesterolemic patients

Low density lipoprotein (LDL) with low sialic acid content has been reported to cause intracellular cholesterol accumulation, and therefore desialylation has been proposed to be an atherogenic modification of LDL. However, it is not known whether hypolipidemic treatment has any effect on LDL sialylation. Accordingly, we investigated the sialic acid/apolipoprotein (apo) B ratio of total LDL and its subfractions in 26 moderately hypercholesterolemic patients at baseline and after treatment with statins for 2-3 months. Cholesterol and triglyceride levels were reduced in all apo B-containing lipoproteins, including all LDL subfractions, while the sialic acid ratio was increased in total LDL and in all its subfractions. Cholesterol concentrations and sialic acid ratios were inversely correlated in light and dense LDL subfractions both before and during statin treatment, and the greater the decrease in cholesterol and apo B contents of dense LDL, the higher was the increase in its sialic acid ratio. Furthermore, the lower the baseline sialic acid ratio of dense LDL, the greater was the reduction in its lipid and apo B concentrations. In conclusion, inhibition of cholesterol synthesis by statin treatment increased sialic acid/apo B ratio in LDL proportionately to the decrease of LDL apo B and cholesterol.

Sialic acid content of low-density lipoprotein in women with coronary artery disease

A low sialic acid content in low-density lipoprotein (LDL) has been associated with coronary artery disease (CAD) in studies that have included mostly male subjects. We compared the sialic acid-to-apolipoprotein B ratios of total LDL and its subfractions in middle-aged women with CAD (CAD+, n = 22) with those ratios in healthy female control subjects (CAD-, n = 11). CAD+ subjects had a lower sialic acid ratio in total LDL and in its subfractions as compared with results in CAD- subjects. In total, light, and dense LDL, the sialic acid ratio was negatively correlated with the respective cholesterol and phospholipid concentrations, and in very dense LDL, it was negatively correlated with triglyceride concentration. In multivariate analysis, CAD and LDL cholesterol contributed to the explanation of the variability of LDL sialic acid ratios. In summary, a low sialic acid-to-apolipoprotein B ratio in LDL was associated with the presence of CAD in middle-aged women with mild to moderate hypercholesterolemia.

Sialic acid content of low density lipoprotein and its relation to lipid concentrations and metabolism of low density lipoprotein and cholesterol

A low sialic acid content in low density lipoprotein (LDL) has been associated with atherogenicity and coronary artery disease (CAD) in many but not all studies. We investigated associations of the sialic acid-to-apolipoprotein B (apoB) ratio of LDL with lipoprotein lipid concentrations, kinetics of LDL, metabolism of cholesterol, and the presence of CAD in 98 subjects (CAD(+), n = 56; CAD(-), n = 42). The sialic acid ratios of total, dense, and very dense LDL were lower in the CAD(+) than CAD(-) subjects, especially at high sialic acid ratios. The LDL sialic acid ratio was inversely associated with respective lipid and apoB concentrations and positively with lipid-to-apoB ratios of LDL. The transport rates (TRs) for total and dense LDL apoB were negatively associated with their sialic acid ratios. The sialic acid ratio of dense LDL, but not that of total LDL, was inversely correlated with serum levels of cholesterol precursor sterols, indicators of cholesterol synthesis, and positively with serum levels of plant sterols, indicators of cholesterol absorption. In addition, the TR for dense LDL was positively correlated with cholesterol synthesis. In conclusion, a low LDL sialic acid ratio was associated with CAD, high numbers of small LDL particles, and a high TR for LDL apoB, and in dense LDL also with high synthesis and low absorption of cholesterol.

Sialic acid content of LDL and lipoprotein metabolism in combined hyperlipidemia and primary moderate hypercholesterolemia

Low density lipoprotein (LDL) with low sialic acid content has been shown to cause intracellular lipid accumulation and therefore is suggested to be atherogenic. We investigated the sialic acid content of total LDL and its subfractions, and their relations to lipoprotein kinetics in 22 subjects with primary moderate hypercholesterolemia (IIa) and in 21 subjects with combined hyperlipidemia (IIb) matched for age, sex, BMI and the frequency of coronary artery disease. Sialic acid to protein ratio decreased gradually from VLDL and IDL to light and dense LDL and HDL, but was high in very dense LDL probably due to presence of Lp(a). Sialic acid to apo B ratio was significantly lower in dense and very dense subfractions of IIb than IIa. The sialic acid/apo B ratios of dense and very dense LDL subfractions were interrelated and were negatively associated with their cholesterol and triglyceride concentrations, and with the transport rate (TR) for dense LDL apo B. The only metabolic variable differing between the groups was the TR for dense LDL apo B, which was significantly higher in IIb vs. IIa. In addition, the TR for dense LDL apo B was positively associated with the esterification percentage of LDL cholesterol. In conclusion, low sialic acid content in dense and very dense LDL subfractions was associated with enhanced TR for LDL apo B and type IIb dyslipidemia.