Small, dense HDL 3 particles attenuate apoptosis in endothelial cells: pivotal role of apolipoprotein A-I.
Plasma high-density lipoproteins (HDLs) protect endothelial cells against apoptosis induced by oxidized low-density lipoprotein (oxLDL). The specific component(s) of HDLs implicated in such cytoprotection remain(s) to be identified. Human microvascular endothelial cells (HMEC-1) were incubated with mildly oxLDL in the presence or absence of each of five physicochemically distinct HDL subpopulations fractionated from normolipidemic human plasma (n= 7) by isopycnic density gradient ultracentrifugation. All HDL subfractions protected HMEC-1 against oxLDL-induced primary apoptosis as revealed by nucleic acid staining, annexin V binding, quantitative DNA fragmentation, inhibition of caspase-3 activity and reduction of cytoplasmic release of cytochrome c and apoptosis-inducing factor. Small, dense HDL 3c displayed twofold superior intrinsic cytoprotective activity (as determined by mitochondrial dehydrogenase activity) relative to large, light HDL 2b on a per particle basis (P < 0.05). Equally, all HDL subfractions attenuated intracellular generation of reactive oxygen species (ROS); such anti-oxidative activity diminished from HDL 3c to HDL 2b. The HDL protein moiety, in which apolipoprotein A-I (apoA-I) predominated, accounted for approximately 70% of HDL anti-apoptotic activity. Furthermore, HDL reconstituted with apoA-I, cholesterol and phospholipid potently protected HMEC-1 from apoptosis. By contrast, modification of the content of sphingosine-1-phosphate in HDL did not significantly alter cytoprotection. We conclude that small, dense, lipid-poor HDL 3 potently protects endothelial cells from primary apoptosis and intracellular ROS generation induced by mildly oxLDL, and that apoA-I is pivotal to such protection.
de Souza
Juliana A
JA
Dyslipoproteinemia and Atherosclerosis Research Unit (UMR939), National Institute for Health and Medical Research (INSERM), Hôpital de la Pitié, Paris, France.
Vindis
Cecile
C
Nègre-Salvayre
Anne
A
Rye
Kerry-Anne
KA
Couturier
Martine
M
Therond
Patrice
P
Chantepie
Sandrine
S
Salvayre
Robert
R
Chapman
M John
MJ
Kontush
Anatol
A
D016632:Apolipoprotein A-I / Q000097:blood / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D006801:Humans; D015151:Immunoblotting; D053440:Lipoproteins, HDL3 / Q000097:blood / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008246:Lysophospholipids / Q000097:blood / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology
D016632:Apolipoprotein A-I; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D053440:Lipoproteins, HDL3; D008077:Lipoproteins, LDL; D008246:Lysophospholipids; D017382:Reactive Oxygen Species; C099252:oxidized low density lipoprotein; C060506:sphingosine 1-phosphate; D045304:Cytochromes c; D053148:Caspase 3; D013110:Sphingosine