Characterization and quantification of serum lipoprotein subfractions by capillary isotachophoresis: relationships with lipid, apolipoprotein, and lipoprotein levels

Abstract

Human serum lipoproteins are currently defined according to their density as well as according to their electrophoretic mobility. They can be fractionated into discrete subspecies which exhibit variations in their structure and function. Capillary electrophoresis has been suggested to be a potential analytical strategy in understanding metabolic lipoprotein heterogeneity. In a sample of 35 normolipidemic subjects, we analyzed ceramide-labeled serum lipoproteins by capillary isotachophoresis linked to laser-induced fluorescent detection. Capillary isotachophoresis showed advantage to be an automated, rapid (6 min) and reproducible (CV < 7%) separation mode, on-line monitoring lipoprotein subfractions according to net charge. HDL were separated into three subfractions: i) the fast migrating HDL correlated positively with serum apoA-I (P < 0.05) and negatively with triglyceride (P < 0.01) concentrations, ii) the intermediate migrating HDL involved in HDL-cholesterol delivery and inversely related to LDL particles concentration (P < 0.001), and iii) the slow migrating preβ1HDL. Triglyceride level was significantly associated with two fractions: i) the VLDL fraction correlated positively with apoE serum concentration (P < 0.01), and ii) the IDL fraction closely and positively associated with apoC-III-containing lipoprotein level (P < 0.001). Two LDL subfractions were positively related to LDL-cholesterol (0.05 ⩽ P < 0.01) and might characterize, respectively, small dense and large buoyant LDL subfractions: i) the fast migrating LDL, positively linked to apoB concentration and to LpCIII:B (P < 0.01) reflecting altered IDL metabolism, and ii) the slow migrating LDL. Analytical capillary isotachophoresis of fluorescent-stained lipoprotein subfractions might represent an efficient qualitative and quantitative tool which would afford complementary information on lipoprotein metabolism to current clinical lipoprotein analysis.—Schlenck, A., B. Herbeth, G. Siest, and S. Visvikis. Characterization and quantification of serum lipoprotein subfractions by capillary isotachophoresis: relationships with lipid, apolipoprotein, and lipoprotein levels. J. Lipid Res. 1999. 40: 2125–2133.

Keywords

• lipoprotein subfractions
• capillary isotachophoresis
• HDL-cholesterol
• LDL-cholesterol
• apolipoproteins
• lipoprotein particles