Apolipoprotein B-48 and retinyl palmitate are not equivalent markers of postprandial intestinal lipoproteins

Abstract

This study compared retinyl palmitate and apolipoprotein (apo) B-48 as markers of postprandial triglyceride-rich lipoproteins. Nine non-diabetic men received an oral vitamin A-containing fat load. We measured retinyl palmitate, apoB-48, apoB-100, and triglyceride levels in S f Ͼ 400, S f 60-400 and S f 20-60 lipoproteins. The peak retinyl palmitate concentration was delayed compared to the peak apoB-48 concentration in each fraction. The discrepancy between retinyl palmitate and apoB-48 was further investigated in another study of 12 men. In that study, a fat load was given and 5 h later, lipolysis was stimulated in vivo with heparin (60 U/kg, i.v.) and the same parameters were followed. Thirty minutes after heparin, triglyceride levels decreased significantly in the three triglyceride-rich lipoprotein fractions (S f Ͼ 400, S f 60-400 and S f 20-60). ApoB-48 levels also fell significantly in the three triglyceride-rich lipoprotein fractions. In contrast, retinyl palmitate concentrations did not change significantly in S f Ͼ 400 and S f 60-400 fractions and increased significantly in the S f 20-60 fraction. Our results indicate that retinyl palmitate and apolipoprotein B-48 do not mark the same properties of postprandial intestinal lipoproteins. The metabolic pattern of apolipoprotein B-48 parallels that of triglyceride. One possible explanation for these obser vations is that the apoB-48-containing triglyceride-rich lipoproteins are metabolically heterogeneous and that older particles, those in circulation for a longer period of time, may be clear ed more rapidly than newer ones.-

Apolipoprotein B48 metabolism in chylomicrons and very low‐density lipoproteins and its role in triglyceride transport in normo‐ and hypertriglyceridemic human subjects

“…Of particular significance also was the observation that apoB48‐containing VLDL had prolonged residence times (unlike chylomicrons that were rapidly cleared from the bloodstream) and on this basis apoB48 carrying ‘remnants’ persisted in the circulation even in fasted individuals. Additionally, we observed that the metabolism of triglyceride and apoB100 in VLDL was affected by the appearance of chylomicrons, with inhibition of VLDL 1 lipolysis rates and an increment in the plasma concentration of VLDL 1 apoB100 in line with previously published observations .…”

“…With the emergence of new findings from genomics , epidemiology and clinical trials , regarding the relationship between triglyceride‐rich lipoproteins and CHD risk, and the identification of associated potential novel targets for intervention , there is a pressing need to understand in greater detail the integrated metabolism of chylomicrons and VLDL. The present study addresses this topic and, in particular, provides a metabolic explanation for the fact (as observed by us here and others before ) that apoB48‐containing triglyceride‐rich lipoproteins appear in both the VLDL and chylomicron density range during fat ingestion and, in our investigation, across the day accounted for around 25% of ‘VLDL’ particles. Further key findings were not only that there was continual low‐level basal secretion of apoB48‐containing particles by the intestine (i.e.…”

“…Investigating this pathway, however, has proved problematic due to its dynamic nature -chylomicrons appear as a wave following fat meals-and the need to distinguish it from very low-density lipoprotein (VLDL) mediated triglyceride transport that originates in the liver. Retinyl palmitate and apoB48 (a protein found solely in particles of intestinal origin: apoB100 in VLDL is exclusively liver-derived) have been used as tools to follow chylomicron metabolism [5][6][7]. However, the low abundance of apoB48 and its transient behaviour have presented challenges in the conduct and interpretation of kinetic studies.…”

Effects of lecithin in salad dressing on the plasma appearance of fat‐soluble micronutrients consumed in salads: contributions of chylomicrons and large VLDL (645.16)

“…Significant decreases in the apoB-100 content from baseline were observed at 7 h in the chylomicron fraction (P < 0.01) and at 5 h, 7 h, and 9.5 h in the VLDLA fraction (P < 0.01), and significant increases in the apoB-48 content from baseline were observed at 2 h and 3.5 h in the chylomicron fraction (P < 0.01) whereas no significant changes apoB-48 content were found in the VLDLA fraction (Figure 5). One lipoprotein particle only contains one type of apoB, and apoB-48 and apoB-100 are reliable biomarkers for intestine-and liver-derived lipoproteins, respectly (18)(19)(20). Thus, the changes in the apoB-48 and apoB-100 contents reflect the particle number changes in intestine-and liverderived lipoproteins, which means, in the postprandial state, the particle number of chylomicronsized enterogenous lipoproteins increased, and the particle number of chylomicron-and VLDLA-sized hepatogenous lipoproteins decreased.…”

“…(apoB-48) and apolipoprotein B-100 (apoB-100) are reliable biomarkers of lipoprotein particles of intestinal and hepatic origin, respectively (18)(19)(20). Therefore, an investigation of apoB-48 and apoB-100 in the plasma VLDLA fraction after a single meal could provide new insight regarding the origin of VLDLA.…”