Clearance of postprandial lipoproteins in normolipemics: role of the apolipoprotein E phenotype.

The hepatic clearance of triglyceride-rich lipoproteins is mediated via apolipoprotein (apo) E which occurs in three common isoforms, apoE2, apoE3 and apoE4. To study the importance of the apoE isoforms on the response curves of different triglyceride-rich lipoproteins and the effect of chylomicron remnants on the composition of HDL, 37 normolipemics were investigated after a standardized fatty meal (8 apoE2/E2, 8 apoE2/E3, 8 apoE3/E3, 7 apoE3/E4 and 6 apoE4/E4). These individuals were matched for age, body mass index, fasting triglycerides, HDL-cholesterol, and apoA-I. A delayed chylomicron remnant clearance was observed only in apoE2 homozygotes, and this delay was neither correlated with fasting lip ds nor with peak lipoprotein concentrations. In apoE2/E3 heterozygotes, in contrast, the defective isoform E2 appears to be compensated for by the normal apoE isoform E3. In non-apo-E2/E2 individuals, the chylomicron remnant response was highly correlated with the magnitude of chylomicron and VLDL responses, with fasting triglycerides, and with the triglycerides enrichment and cholesterol depletion of HDL. These correlations were not observed in apoE2/E2. From these results we conclude that the chylomicron remnant response curve is an indicator of the extent of postprandial lipemia in non-apoE2/E2 individuals only.