Lipid profiling of lipoprotein X: Implications for dyslipidemia in cholestasis.
Lipoprotein X (Lp-X) is an abnormal lipoprotein that may typically be formed in intra- and extrahepatic cholestasis and potentially interfere with lipid analysis in the routine lab. To gain insight into lipid class and species composition, Lp-X, LDL and HDL from cholestatic and control serum samples were subjected to mass spectrometric analysis including phospholipids (PL), sphingolipids, free cholesterol (FC), cholesteryl esters (CE) and bile acids. Our analysis of Lp-X revealed a content of 46% FC, 49% PL with 34% phosphatidylcholine (PC) as main PL component. The lipid species pattern of Lp-X showed remarkable high fractions of mono-unsaturated species including PC 32:1 and PC 34:1 and phosphatidylethanolamine (PE) 32:1 and 34:1. LDL and HDL lipid composition in the same specimens strongly reflected the lipid composition of Lp-X with increased PC 32:1, PC 34:1, PE 32:1, PE 34:1 and FC accompanied by decreased CE compared to controls. Comparison of Lp-X and biliary lipid composition clearly indicates that Lp-X does not originate from a sole release of bile lipids. Moreover, these data present evidence for increased hepatic fatty acid and PL synthesis which may represent a reaction to high hepatic FC level observed during cholestasis.
Institute of Clinical Chemistry and Laboratory Medicine, University Medical Centre, 93042 Regensburg, Germany.
Susanne
S
Heimerl
Institute of Clinical Chemistry and Laboratory Medicine, University Medical Centre, 93042 Regensburg, Germany.
Alfred
A
Boettcher
Clinic for Internal Medicine, I, DONAUISAR Klinikum, 94469 Deggendorf, Germany.
Harald
H
Kaul
Institute of Clinical Chemistry and Laboratory Medicine, University Medical Centre, 93042 Regensburg, Germany. Electronic address: gerhard.liebisch@ukr.de.
Gerhard
G
Liebisch
D001646:Bile / Q000737:chemistry / Q000378:metabolism*; D002779:Cholestasis / Q000378:metabolism*; D050171:Dyslipidemias / Q000378:metabolism*; D006801:Humans; D008073:Lipoprotein-X / Q000737:chemistry / Q000378:metabolism*
D008073:Lipoprotein-X
Cholestasis; Lipidomics; Lipoproteins; Lp-X; Mass spectrometry