title: Adenovirus-mediated gene transfer of Lp-PLA2 reduces LDL degradation and foam cell formation in vitro.
abstract: Oxidation of LDL generates biologically active platelet-activating factor (PAF)-like phospholipid derivatives, which have potent proinflammatory activity. These products are inactivated by lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme capable of hydrolyzing PAF-like phospholipids. In this study, we generated an adenovirus (Ad) encoding human Lp-PLA2 and injected 10(8), 10(9), and 10(10) plaque-forming unit doses of Adlp-PLA2 and control AdlacZ intra-arterially into rabbits to achieve overexpression of Lp-PLA2 in liver and in vivo production of Lp-PLA2-enriched LDL. As a result, LDL particles with 3-fold increased Lp-PLA2 activity were produced with the highest virus dose. Increased Lp-PLA2 activity in LDL particles decreased the degradation rate in RAW 264 macrophages after standard in vitro oxidation to 60-80% compared with LDL isolated from LacZ-transduced control rabbits. The decrease was proportional to the virus dose and Lp-PLA2 activity. Lipid accumulation and foam cell formation in RAW 264 macrophages were also decreased when incubated with oxidized LDL containing the highest Lp-PLA2 activity. Inhibition of the Lp-PLA2 activity in the LDL particles led to an increase in lipid accumulation and foam cell formation. It is concluded that increased Lp-PLA2 activity in LDL attenuates foam cell formation and decreases LDL oxidation and subsequent degradation in macrophages.
authors.affiliation: A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, FIN-70211 Kuopio, Finland.
authors.forename: Päivi
authors.initials: P
authors.lastname: Turunen
authors.forename: Johanna
authors.initials: J
authors.lastname: Jalkanen
authors.forename: Tommi
authors.initials: T
authors.lastname: Heikura
authors.forename: Hanna
authors.initials: H
authors.lastname: Puhakka
authors.forename: Jouni
authors.initials: J
authors.lastname: Karppi
authors.forename: Kristiina
authors.initials: K
authors.lastname: Nyyssönen
authors.forename: Seppo
authors.initials: S
authors.lastname: Ylä-Herttuala
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D005487:Foam Cells / Q000378:metabolism / Q000473:pathology*; D018014:Gene Transfer Techniques; D006801:Humans; D050356:Lipid Metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism / Q000473:pathology*; D010741:Phospholipases A / Q000235:genetics* / Q000378:metabolism; D054467:Phospholipases A2; D011817:Rabbits; D051381:Rats
chemical_list: D008077:Lipoproteins, LDL; D010741:Phospholipases A; D054467:Phospholipases A2; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase