Diagnostic value of serum high-mobility group box-1 in pediatric systemic lupus erythematosus.

BACKGROUND: High-mobility group box-1 (HMGB1) acts as a damage-associated molecular pattern or as an alarmin and it stimulates inflammatory and immunological activities. AIM: We sought to investigate serum HMGB1 protein expression in patients with pediatric systemic lupus erythematosus (pSLE) in relation to the disease characteristics and activity. PATIENTS AND METHODS: This is a controlled cross-sectional study which comprised 50 children and adolescents with Systemic lupus erythematosus (SLE) and 50 age- and sex-matched healthy subjects who served as a control group. Study measurements included clinical assessment, laboratory workup for SLE (complete blood count, erythrocyte sedimentation rate, serum creatinine, creatinine clearance and 24-hour urinary protein, C3 and anti-double-stranded DNA, lupus anticoagulant and anticardiolipin antibodies) and measurement of serum HMGB1 by enzyme-linked immunosorbent assay in patients and controls. RESULTS: Serum HMGB1 expression was significantly higher in the pSLE patients than the control group (P < 0.001). Patients with lupus nephritis (LN) had significantly higher serum HMGB1 as compared to those with normal kidneys (P < 0.04). Serum HMGB1 in LN patients correlated positively to the SLE Disease Activity Index (P < 0.0001), and 24 hours urinary proteins and negatively to creatinine clearance (P < 0.001). At a cut-off point of ≥40 µg/L, serum HMGB1 showed good diagnostic value for pSLE with sensitivity and specificity of 98% and 95%, respectively. CONCLUSION: Serum HMGB1 seems to be a reliable biomarker for diagnosis of pSLE and monitoring disease status, especially in LN. HMBG1 might prove to be a potential therapeutic target in LN.