Serum and urinary levels of IL-18 and its inhibitor IL-18BP in systemic lupus erythematosus.
Overproduction of inflammation-related cytokines plays an important role in systemic lupus erythematosus (SLE). A crucial cytokine is IL-18, a member of the IL-1 family involved in the regulation of both innate and acquired immune responses. The aim of this study was to evaluate free IL-18 levels in the serum and urine of SLE patients, in order to establish their relationship with other biomarkers of disease activity. Serum and urine levels of IL-18 and IL-18BP were measured by ELISA in 50 SLE patients and in 32 healthy subjects; free IL-18 was calculated using the law of mass action. Serum levels of total IL-18, IL-18BP and free IL-18 were higher in SLE patients than in healthy controls. Total and free serum IL-18 levels were higher in patients with active disease (with nephritis or active non-renal disease), and correlated with the ECLAM score. Urinary levels of total and free IL-18 were higher in patients than in controls, but did not correlate with disease activity. The data collected in this study show that increased levels of both IL-18 and its natural inhibitor IL-18BP, characterise SLE. Despite the overproduction of IL-18BP, free IL-18 is still significantly higher in SLE patients than in controls, and its serum levels are a marker of disease activity.
Clinical Immunology Unit, Department of Internal Medicine, University of Pisa, Via Roma 67, Pisa, Italy. p.migliorini@med.unipi.it
Paola
P
Migliorini
Consuelo
C
Anzilotti
Federico
F
Pratesi
Paola
P
Quattroni
Marco
M
Bargagna
Charles A
CA
Dinarello
Diana
D
Boraschi
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood* / Q000652:urine*; D020382:Interleukin-18 / Q000097:blood* / Q000652:urine*; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D055815:Young Adult
D015415:Biomarkers; D036341:Intercellular Signaling Peptides and Proteins; D020382:Interleukin-18; C118370:interleukin-18 binding protein