Oxidized low density lipoproteins induce apoptosis in human lymphocytes: involvement of mitogen-activated protein kinases.
Oxidized low density lipoproteins (oxLDL), macrophages and T-lymphocytes are present in atherosclerotic lesions. We and others have shown that oxLDL is cytotoxic for macrophages, endothelial, smooth muscle and activated T-lymphocytes and induce apoptosis. Here we demonstrate that (i) oxidized LDL (oxLDL), oxidized VLDL (oxVLDL) and hydrogen peroxide (H2O2) induce apoptosis in human T-lymphocytes and (ii) mitogen-activated protein kinases are involved in this process. Apoptosis was monitored by immunofluorescence microscopy and flow cytometry for annexin V binding, Apo 2.7 expression, the TUNEL reaction and caspase 3 activity. In the presence of oxLDL (100 microg/ml), oxVLDL (50 microg/ml) and H2O2 (5 mM), the fraction of apoptotic cells increased within 6 hours to more than 70%. Preincubation of lymphocytes with the MAPKK inhibitor PD-98059 and the p38MAPK inhibitor SB-203580 almost completely abolished these effects. Furthermore, oxLDL and H2O2 but not native LDL strongly enhanced phosphorylation of JNK, p38MAPK and p42/44MAPK. The results suggest that in the resting lymphocyte apoptosis triggered by oxidized lipoproteins and oxidative stress depends on the activation of p44/42MAPK and p38MAPK cascades.
Bustamante
M
M
Laboratory of Molecular Biology, Faculty of Medicine, Catholic University of Concepción, 2850 Alonso de Ribera Street, Concepción, Chile. mbustamante@ucsc.cl
Díaz
F
F
Muñoz
M
M
Gross
H-J
HJ
Rivas
C I
CI
Llancaqueo
A
A
Núñez
L
L
Campos
L
L
Kirsten
L
L
Grandón
J
J
González
M
M
Barra
V
V
Vera
J C
JC
Bachem
M G
MG
D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000032:analysis / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011725:Pyridines / Q000494:pharmacology; D013601:T-Lymphocytes / Q000378:metabolism*; D013997:Time Factors
D017304:Annexin A5; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D008077:Lipoproteins, LDL; D011725:Pyridines; C099252:oxidized low density lipoprotein; D020928:Mitogen-Activated Protein Kinases; D053148:Caspase 3; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one