Urinary MMP-9/NGAL ratio as a potential marker of FSGS in nephrotic children

Abstract

Background: The study was undertaken to develop a potential new markers for distinguishing minimal change nephrotic syndrome (MCNS) and focal segmental glomerulosclerosis (FSGS) in children. We hypothesized that matrix metalloproteinase-9/neutrophil gelatinase-associated lipocalin (MMP-9/NGAL) is a better marker of focal sclerosis in the glomerulus then matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 (MMP-9/TIMP-1) and matrix metalloproteinase-2/tissue inhibitor of metalloproteinase-2 MMP2/TIMP-2.

Methods: The present study used a sample of 36 children and adolescents subdivided into two groups: I - 20 children with MCNS, subjected to examination twice: A - in relapse of nephrotic syndrome, before treatment and B - after regression of proteinuria; II - 16 children with FSGS. MMPs and TIMPs and NGAL levels were measured in the urine using ELISA kit. MMP-9/TIMP-1, MMP-2/TIMP-2 and MMP-9/NGAL ratios were calculated.

Results: Median NGAL/cr. was significantly higher in MCNS and FSGS patients when compared to healthy controls. Both, NGAL and MMP-9 urinary levels were significantly elevated in FSGS subjects, as compared with control subjects. Contrary to FSGS children, in MCNS group, before treatment only NGAL/cr., but not MMP-9/cr. was increased. Urinary concentrations of NGAL and MMP-9 were highly associated with each other (NGAL/cr. vs. MMP-9/cr., r=0.485, p<0.01). Median urine MMP-9/NGAL ratio in FSGS patients was significantly higher than in patients with MCNS. We also found that significant increase in MMP-9/NGAL was associated with FSGS [odds ratio (OR) - 9.0; confidence interval (CI) 1.97-41.07].

Conclusion: MMP-9/NGAL ratio may serve as differentiation marker between MCNS and FSGS in nephrotic children.