Platelet-activating factor acetylhydrolase is mainly associated with electronegative low-density lipoprotein subfraction.
BACKGROUND
Electronegative LDL [LDL(-)], a modified subfraction of LDL present in plasma, induces the release of interleukin-8 and monocyte chemotactic protein-1 from cultured endothelial cells.


RESULTS
We demonstrate that platelet-activating factor acetylhydrolase (PAF-AH) is mainly associated with LDL(-). LDL(-) had 5-fold higher PAF-AH activity than the nonelectronegative LDL subfraction [LDL(+)] in both normolipemic and familial hypercholesterolemic subjects. Western blot analysis after SDS-PAGE confirmed these results, because a single band of 44 kDa corresponding to PAF-AH appeared in LDL(-) but not in LDL(+). Nondenaturing polyacrylamide gradient gel electrophoresis demonstrated that PAF-AH was bound to LDL(-) regardless of LDL size. In accordance with the above findings, nonesterified fatty acids, a cleavage product of PAF-AH, were increased in LDL(-) compared with LDL(+).


CONCLUSIONS
The high PAF-AH activity observed in LDL(-) could be related to the proinflammatory activity of these lipoproteins toward cultured endothelial cells.
Benítez
Sonia
S
Servei de Bioquímica and Institut de Recerca, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Sánchez-Quesada
José Luis
JL
Ribas
Vicent
V
Jorba
Oscar
O
Blanco-Vaca
Francisco
F
González-Sastre
Francesc
F
Ordóñez-Llanos
Jordi
J
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000201:enzymology*; D007249:Inflammation / Q000201:enzymology; D008077:Lipoproteins, LDL / Q000097:blood / Q000737:chemistry*; D010741:Phospholipases A / Q000737:chemistry*; D012016:Reference Values
D005230:Fatty Acids, Nonesterified; D008077:Lipoproteins, LDL; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase