The role of neutrophil apoptosis in juvenile-onset systemic lupus erythematosus.
OBJECTIVE
Accumulation of apoptotic cells may lead to the development of systemic lupus erythematosus (SLE) through a breakdown in immune tolerance. Altered neutrophil apoptosis may contribute to nuclear autoantigen exposure, ultimately leading to autoantibody generation. This study aimed to determine whether neutrophil apoptosis is altered in patients with juvenile-onset SLE as compared with controls.


METHODS
Apoptosis was measured in neutrophils from patients with juvenile-onset SLE (n=12), adult-onset SLE (n=6), and pediatric patients with inflammatory (n=12) and noninflammatory (n=12) conditions. Annexin V staining and flow cytometry were used to determine neutrophil apoptosis. Proapoptotic and antiapoptotic proteins were measured in sera and in neutrophil cell lysates.


RESULTS
Neutrophil apoptosis was significantly increased in patients with juvenile-onset SLE as compared with the noninflammatory controls at time 0. Incubation of neutrophils with sera from patients with juvenile-onset SLE further increased neutrophil apoptosis as compared with incubation with sera from pediatric controls. Concentrations of TRAIL and FasL were significantly increased in sera from patients with juvenile-onset SLE, whereas interleukin-6, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were significantly decreased. Addition of GM-CSF to sera from patients with juvenile-onset SLE significantly decreased neutrophil apoptosis as compared with juvenile-onset SLE sera alone. The expression of proapoptotic proteins (caspase 3, Fas, and FADD) was elevated in juvenile-onset SLE neutrophils, whereas the expression of antiapoptotic proteins (cellular inhibitor of apoptosis 1 and 2 and X-linked inhibitor of apoptosis) was decreased. Neutrophil apoptosis correlated with biomarkers of disease activity (erythrocyte sedimentation rate and double-stranded DNA concentration) and the British Isles Lupus Assessment Group disease activity score.


CONCLUSIONS
Our data demonstrate an imbalance in proapoptotic and antiapoptotic factors in both neutrophils and sera from patients with juvenile-onset SLE. This imbalance results in increased neutrophil apoptosis in these patients. Correlations with markers of disease activity indicate that altered neutrophil apoptosis in juvenile-onset SLE patients may play a pathogenic role in this condition.
Midgley
Angela
A
Alder Hey Children's National Health Service Foundation Trust, Institute of Child Health, Royal Liverpool Children's Hospital-Alder Hey, Liverpool University, Liverpool, UK. angela.fahey@liv.ac.uk
McLaren
Zoe
Z
Moots
Robert J
RJ
Edwards
Steven W
SW
Beresford
Michael W
MW
D000293:Adolescent; D017209:Apoptosis / Q000187:drug effects; D001799:Blood Sedimentation; D053148:Caspase 3 / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D053222:Fas Ligand Protein / Q000097:blood; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000473:pathology*; D012720:Severity of Illness Index; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
C505533:FADD protein, human; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; D051034:Inhibitor of Apoptosis Proteins; D015850:Interleukin-6; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D053148:Caspase 3