Delineation of the role of pre-beta 1-HDL in cholesterol efflux using isolated pre-beta 1-HDL.
OBJECTIVE
The role of pre-beta1-high density lipoprotein (pre-beta1-HDL) in cholesterol efflux was investigated by separating human plasma into purified pre-beta1-HDL and pre-beta1-HDL-deficient plasma by using a monoclonal antibody specifically reacting with pre-beta1-HDL.


RESULTS
When compared with whole plasma, pre-beta1-HDL-deficient plasma was equally efficient in promoting cholesterol efflux from human skin fibroblasts and THP-1 human macrophage cells. When added at the same apolipoprotein A-I concentration, pre-beta1-HDL was less effective than whole plasma in promoting cholesterol efflux from fibroblasts but equally effective in promoting cholesterol efflux from THP-1 cells. However, pre-beta1-HDL-deficient plasma reconstituted with 16% pre-beta1-HDL was more active than whole plasma, demonstrating that pre-beta1-HDL does promote cholesterol efflux actively. The amount of cellular cholesterol present in reisolated pre-beta1-HDL was 1.5- to 2-fold greater after incubation of the cells with whole plasma than after incubation of the cells with pre-beta1-HDL-deficient plasma or plasma treated with the anti-pre-beta1-HDL antibody. However, the anti-pre-beta1-HDL antibody did not inhibit cholesterol efflux.


CONCLUSIONS
We conclude that whereas pre-beta1-HDL is capable of taking up cellular cholesterol, its presence in plasma is not essential for cholesterol efflux, at least in vitro. Instead, pre-beta1-HDL may be the first product of apolipoprotein A-I lipidation during the formation of HDL but may not play a major role in transferring cellular cholesterol to HDL.
Sviridov
Dmitri
D
Baker Medical Research Institute, Melbourne, Victoria, Australia. Dmitri.Sviridov@Baker.edu.au
Miyazaki
Osamu
O
Theodore
Kally
K
Hoang
Anh
A
Fukamachi
Isamu
I
Nestel
Paul
P
D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D002847:Chromatography, Agarose; D005347:Fibroblasts / Q000378:metabolism; D053442:High-Density Lipoproteins, Pre-beta; D006801:Humans; D008075:Lipoproteins, HDL / Q000172:deficiency / Q000302:isolation & purification* / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism; D010949:Plasma / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D012685:Sepharose / Q000031:analogs & derivatives* / Q000378:metabolism; D012867:Skin / Q000166:cytology; D013997:Time Factors
D000911:Antibodies, Monoclonal; D053442:High-Density Lipoproteins, Pre-beta; D008075:Lipoproteins, HDL; C036210:immunoglobulin G-sepharose; D012685:Sepharose; D002784:Cholesterol