Beta-VLDL accumulation in familial dysbetalipoproteinemia is associated with increased exchange or diffusion of chylomicron lipids to apo B-100 containing triglyceride-rich lipoproteins.
To gain more insight into the accumulation of beta-very low density lipoprotein (beta-VLDL) in familial dysbetalipoproteinemia (FD), we followed the courses of the levels of retinyl palmitate (rp), alpha-tocopherol (alpha-T) and apolipoprotein (apo) B-48 in various lipoprotein fractions for up to 48 h in eight patients with FD and six normolipidemic control subjects after an oral fat load (50 g fat/m2 containing 150000 IU of rp and 5000 IU of alpha-T). Alpha-T was added because of its rapid transfer to other lipoproteins. Fasting apo B-48 concentration in FD was normal to strongly elevated, dependent on the fasting lipid concentrations. 3 h after fat loading, total apo B-48 content did not abnormally increase; while the apo B-100 content in the triglyceride-rich lipoprotein fraction remained stable. The levels of both vitamins increased considerably, especially in the remnant fraction (Sf 15-100), which in due course exclusively contained apo B-100 in most hyperlipidemic patients. This, together with the observation that peaks for rp and alpha-T were observed 3-6 h later than for apo B-48 strongly suggests that both vitamins transfer or diffuse rapidly towards the apo B-100 containing VLDL. RP is thus more a marker for this process, which also comprises chylomicron lipids, than a specific marker for chylomicrons. This process, first described here, appears decisive in the pathogenesis of FD.
Demacker
P N
PN
Department of Medicine, University Hospital Nijmegen, Netherlands. p.demacker@aig.azn.nl
Bredie
S J
SJ
Vogelaar
J M
JM
Hectors
M P
MP
van Heijst
P
P
Stuyt
P M
PM
Stalenhoef
A F
AF
D000328:Adult; D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000097:blood* / Q000737:chemistry; D002914:Chylomicrons / Q000097:blood* / Q000737:chemistry; D006801:Humans; D006952:Hyperlipoproteinemia Type III / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood* / Q000737:chemistry; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood / Q000737:chemistry
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D002914:Chylomicrons; D008079:Lipoproteins, VLDL; D014280:Triglycerides