Mitochondrial hyperpolarization and ATP depletion in patients with systemic lupus erythematosus.
OBJECTIVE
Peripheral blood lymphocytes (PBLs) from systemic lupus erythematosus (SLE) patients exhibit increased spontaneous and diminished activation-induced apoptosis. We tested the hypothesis that key biochemical checkpoints, the mitochondrial transmembrane potential (deltapsim) and production of reactive oxygen intermediates (ROIs), mediate the imbalance of apoptosis in SLE.


METHODS
We assessed the deltapsim with potentiometric dyes, measured ROI production with oxidation-sensitive fluorochromes, and monitored cell death by annexin V and propidium iodide staining of lymphocytes, using flow cytometry. Intracellular glutathione levels were measured by high-performance liquid chromatography, while ATP and ADP levels were assessed by the luciferin-luciferase assay.


RESULTS
Both deltapsim and ROI production were elevated in the 25 SLE patients compared with the 25 healthy subjects and the 10 rheumatoid arthritis patients. Intracellular glutathione contents were diminished, suggesting increased utilization of reducing equivalents in SLE. H2O2, a precursor of ROIs, increased deltapsim and caused apoptosis in normal PBLs. In contrast, H2O2-induced apoptosis and deltapsim elevation were diminished, particularly in T cells, and the rate of necrotic cell death was increased in patients with SLE. The intracellular ATP content and the ATP:ADP ratio were reduced and correlated with the deltapsim elevation in lupus. CD3:CD28 costimulation led to transient elevation of the deltapsim, followed by ATP depletion, and sensitization of normal PBLs to H2O2-induced necrosis. Depletion of ATP by oligomycin, an inhibitor of F0F1-ATPase, had similar effects.


CONCLUSIONS
T cell activation and apoptosis are mediated by deltapsim elevation and increased ROI production. Mitochondrial hyperpolarization and the resultant ATP depletion sensitize T cells for necrosis, which may significantly contribute to inflammation in patients with SLE.
Gergely
Peter
P
State University of New York, College of Medicine, Syracuse 13210, USA.
Grossman
Craig
C
Niland
Brian
B
Puskas
Ferenc
F
Neupane
Hom
H
Allam
Fatme
F
Banki
Katalin
K
Phillips
Paul E
PE
Perl
Andras
A
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D017209:Apoptosis / Q000276:immunology; D018106:CD28 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008213:Lymphocyte Activation / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000276:immunology; D008875:Middle Aged; D008928:Mitochondria / Q000502:physiology*; D009336:Necrosis; D016877:Oxidants / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
D018106:CD28 Antigens; D017252:CD3 Complex; D016877:Oxidants; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D005978:Glutathione; D019803:Glutathione Disulfide