Distribution of human plasma PLTP mass and activity in hypo- and hyperalphalipoproteinemia.
Plasma phospholipid transfer protein (PLTP) plays an important role in lipoprotein metabolism and reverse cholesterol transport. We have recently reported that plasma PLTP concentration correlates positively with plasma HDL cholesterol (HDL-C) but not with PLTP activity in healthy subjects. We have also shown that PLTP exists as active and inactive forms in healthy human plasma. In the present study, we measured plasma PLTP concentration and PLTP activity, and analyzed the distribution of PLTP in normolipidemic subjects (controls), cholesteryl ester transfer protein (CETP) deficiency, and hypo-alphalipoproteinemia (hypo-ALP). Plasma PLTP concentration was significantly lower (0.7 +/- 0.4 mg/l, mean +/- SD, n = 9, P < 0.001) in the hypo-ALP subjects, and significantly higher (19.5 +/- 4.3 mg/l, n = 17, P < 0.001) in CETP deficiency than in the controls (12.4 +/- 2.3 mg/l, n = 63). In contrast, we observed no significant differences in plasma PLTP activity between controls, hypo-ALP subjects, and CETP deficiency (6.2 +/- 1.3, 6.1 +/- 1.8, and 6.8 +/- 1.2 micro mol/ml/h, respectively). There was a positive correlation between PLTP concentration and plasma HDL-C (r = 0.81, n = 89, P < 0.001). By size exclusion chromatography analysis, we found that the larger PLTP containing particles without PLTP activity (inactive form of PLTP) were almost absent in the plasma of hypo-ALP subjects, and accumulated in the plasma of CETP deficiency compared with those of controls. These results indicate that the differences in plasma PLTP concentrations between hypo-ALP subjects, CETP deficiency, and controls are mainly due to the differences in the amount of the inactive form of PLTP.
Oka
Tomoichiro
T
Research Division, R & D Center, BioMedical Laboratory, Inc., 1361-1 Matoba, Kawagoe, Saitama, Japan.
Yamashita
Shizuya
S
Kujiraoka
Takeshi
T
Ito
Mayumi
M
Nagano
Makoto
M
Sagehashi
Yukiko
Y
Egashira
Tohru
T
Nanjee
M Nazeem
MN
Hirano
Ken-ichi
K
Miller
Norman E
NE
Matsuzawa
Yuji
Y
Hattori
Hiroaki
H
D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002352:Carrier Proteins / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood*; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D006951:Hyperlipoproteinemias / Q000097:blood*; D008297:Male; D008565:Membrane Proteins / Q000097:blood*; D008875:Middle Aged; D049294:Phospholipid Transfer Proteins
D002352:Carrier Proteins; D008076:Cholesterol, HDL; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins