Serum neutrophil gelatinase-associated lipocalin as a biomarker of disease activity in pediatric lupus nephritis

Abstract

Background: Neutrophil gelatinase-associated lipocalin (NGAL) is expressed in immature neutrophil precursors and in epithelial cells during both inflammation and neoplastic transformation. A recent prospective pediatric study demonstrated that concentrations of NGAL in urine and plasma represent novel, sensitive, and specific biomarkers for early identification of acute kidney injury following cardiac surgery. Objective: To assess the relationship of serum NGAL levels with disease activity in pediatric systemic lupus erythematosus (SLE) with special emphasis on lupus nephritis. Methods: The study included 30 children and adolescents with pediatric SLE with a mean age of 16.48±3.524 years. Patients were clinically and laboratory evaluated and categorized into those with nephritis and those without nephritis. Activity was assessed using SLEDAI score, NGAL levels were measured in the sera of included patients and were compared to those of 20 matched controls using ELISA. Results: Serum NGAL was significantly higher in SLE patients in comparison to the controls (z=-5.962, p < 0.001). Furthermore serum NGAL was significantly higher in SLE patients with nephritis and in those without nephritis in comparison to the controls (p < 0.001 in both). Serum NGAL was higher in SLE patients with nephritis in comparison to those without nephritis, yet the results are borderline regarding statistical significance (p=0.05). Levels of serum NGAL correlated significantly with disease activity as assessed by SLE disease activity index (SLEDAI) (r=0.485, p < 0.01). There was a significant correlation between serum NGAL and urinary protein to creatinine ratio, 24hr urinary protein and BUN of SLE patients. Conclusion: Our results suggest that serum NGAL represents a novel biomarker for disease activity in pediatric SLE patients, and a marker of severity of renal involvement.

Keywords: SLE, NGAL, SLEDAI, lupus nephritis

Egypt J Pediatr Allergy Immunol 2011;9(1):15-20