Urinary Neutrophil Gelatinase-Associated Lipocalin and Urinary Soluble CXCL16 as Biomarkers of Activity in Pediatric Lupus Nephritis

One of the challenges of treating patients with lupus nephritis (LN) is to assess disease activity. The aim of this study was to measure the urinary neutrophil gelatinase-associated lipocalin (uNGAL) and urinary soluble chemokine (C-X-C motif) ligand 16 (CXCL16) levels in children and adolescents with systemic lupus erythematosus (SLE) and investigate whether they are elevated in active LN. This study was conducted on 80 patients diagnosed as SLE by the Systemic Lupus International Collaborating Clinics criteria and 60 apparently healthy individuals as controls. Global and renal disease activities were evaluated by Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and renal SLEDAI, respectively. uNGAL and urinary CXCL16 were measured for all participants by ELISA. Renal biopsy was done for all cases at initial diagnosis and was graded using ISN/RPS classification. uNGAL and CXCL16 were higher in patients than in the controls (8.9 ± 3.56 ng/dl and 1067 ± 367 ug/L vs. 2.26 ± 1.95 ng/dl and 471 ± 106 ug/L, respectively). uNGAL had higher sensitivity and specificity than urinary CXCL16 as predictor of LN (95% and 90% vs. 85% and 80%, respectively). There was significant positive correlations between uNGAL levels, 24-h urinary proteins (r = 0.732, P = 0.001), and SLEDAI (r = 0.359, P = 0.001). There was also significant positive correlations between urinary CXCL16 levels, 24-h urinary proteins (r = 0.47, P = 0.001), and SLEDAI (r = 0.17, P = 0.001). uNGAL and CXCL16 were reliable indicators of the activity of LN.