Postprandial remnant-like lipoproteins in hypertriglyceridemia

It has been proposed that remnants of chylomicrons and very-low-density lip oproteins (VLDL) are atherogenic: We have used an immunochemical method to isolate remnant-like particles (RLP) and measured them in terms of their ch olesterol and triglycerides (TG). RLP consist of apoB-48-containing triglyc eride-rich lipoproteins and remnant-like VLDL containing apoB-100. The stud y aim was to look for information from postprandial RLP data that could not be known from other markers of triglyceride-rich lipoproteins and fasting TG and RLP data alone. A total of 41 subjects were studied. Eight subjects had hypertriglyceridemia (HTG) and low high-density lipoprotein (HDL), 14 h ad combined hyperlipidemia (CH), 5 had the apo E2/2 genotype receiving gemf ibrozil, 10 were normolipidemic (NL) controls, and 4 had hypercholesterolem ia. As a whole group, there was correlation among 1) fasting TG, RLP choles terol (RLP-C), and RLP-TG but not VLDL apo B100, VLDL apo B48 and their res pective postprandial responses measured as incremental area under the curve (IAUC), 2) fasting TG and postprandial IAUC of RLP-C and RLP-TG, 3) RLP-C IAUC, RLP-TG IAUC, and TG IAUC, retinyl palmitate (RP) IAUC, and VLDL apo B 48 IAUC but not VLDL apo B100 IAUC. The HTG/low HDL-C and GH groups had hig her IAUC for RLP-C, RLP-TG, TG, and RP than the NL group. Fasting and postp randial RLP were triglyceride enriched in the HTG/low HDL-C group and to a lesser extent in the CH group. The HTG/low HDL-C and CH groups had a delay in their RLP-C but not RLP-TG peaks suggesting a delay in hepatic clearance of RLP and/or a protracted period of lipolysis and/or processing of RLP. T he fasting and postprandial RLP-C/RLP-TG and RLP-C/TG ratios were elevated in the apo E2/2 group in spite of gemfibrozil therapy. The increment-in pos tprandial RLP was, however, not exaggerated. Our data indicate that 1) post prandial RLP lipemia is enhanced in HTG subjects when compared with NL subj ects, 2) postprandial RLP lipemia is proportional to fasting RLP and TG lev els and mirrors, to a large extent,; increases in postprandial TG, RP, and VLDL apo B48 but not VLDL apo B100, 3) there are compositional differences in fasting and postprandial RLP in the three forms of HTG studied, RLP bein g triglyceride enriched in the HTG/low HDL-C group and to a lesser extent i n the CH group, and cholesterol-enriched in the apo E2/2 group, and 4) apo E2/2 subjects had high fasting and postprandial RLP-C concentrations in spi te of being on treatment with gemfibrozil and having normal fasting and pos tprandial TG concentrations.