Urinary exosomal WT1 in childhood nephrotic syndrome.

BACKGROUND: Recently, urinary exosomal WT1 has been proposed as a novel biomarker for simple podocyte injury. We investigated urinary exosomal WT1 to confirm its role as a non-invasive biomarker for predicting steroid responsiveness or renal pathological conditions in patients with idiopathic nephrotic syndrome (NS). CASE DIAGNOSIS: Forty children with active NS were recruited. Twenty-eight (70%) were steroid-sensitive, including 3 with minimal change NS (MCNS) and 1 with focal segmental glomerulosclerosis (FSGS). The remaining 12 (30%) were steroid-resistant, including 8 with FSGS and 4 with MCNS. Urinary exosomes were isolated by a differential centrifugation method, and WT1 was measured by Western blot analysis. RESULTS: WT1 was detected in 25 patients (62.5%). There was no significant difference in the proportion of the patients with a detectable amount of WT1 according to steroid responsiveness or renal pathological condition, the amount of WT1 showed no significant difference according to steroid responsiveness or renal pathological condition, and there was no significant difference in the amount of proteinuria between patients with or without detectable WT1. CONCLUSIONS: Urinary exosomal WT1 was detected in some patients with NS. However, its role as an appropriate biomarker in childhood NS was not verified in this study.