Circulating VEGF and TGF-beta1 in children with idiopathic nephrotic syndrome

The implications of vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-beta) on the development of proteinuria were studied by measuring the mRNA and protein levels of VEGF and TGF-beta1 in 43 children with primary nephrotic syndrome.

Twenty-seven patients were in the active nephrotic phase at the time of sampling (Group 1), and 16 were in remission (Group 2). In Group 1, 16 were steroid-responders (Group 1a) and 11 were nonresponders (Group 1b). Minimal change lesion (MCL) in 11 patients and focal segmental glomerulosclerosis (FSGS) in 8 were confirmed by renal biopsy. The mRNA expressions of peripheral blood lymphocytes and the plasma levels of proteins were measured by semi-quantitative RT-PCR and ELISA, respectively.

Plasma VEGF concentration was higher in Group 1 (204+/-137 pg/mL) than Group 2 (91+/-72 pg/mL) (P=0.002). However, there was no significant difference either between Group 1a (184+/-146 pg/mL) and Group 1b (258+/-134 pg/mL) or between patients with FSGS (330+/-122 pg/mL) and those with MCL (146+/-112 pg/mL). The VEGF mRNA expression showed changes similar to VEGF protein expression, and there was no statistical significance. Plasma levels and mRNA expressions of TGF-beta1 were similar in all groups.

These results suggest that circulating VEGF is associated with proteinuria both in steroid-responsive and steroid-resistant primary nephrotic syndrome in children.