Elevated vascular endothelial growth factor levels in the urine of patients with minimal-change nephrotic syndrome

BACKGROUND: Vascular endothelial growth factor (VEGF) is a selective endothelial mitogen and vascular permeability factor (VPF), that is mainly produced by activated monocytes/macrophages and T cells. To our knowledge, very little is known about the involvement of VEGF in minimal-change nephrotic syndrome (MCNS). The aim here was to define further the involvement of VEGF in MCNS. PATIENTS AND METHODS: Urine samples were obtained from 20 MCNS patients. The disease controls included 20 patients with IgA nephropathy (IgAN). The samples were assayed for VEGF protein by a sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared with normal controls, markedly increased urinary levels of VEGF were detected in both MCNS and IgAN patients with the nephrotic syndrome (NS). The urinary VEGF (uVEGF) levels correlated with the degree ofproteinuria in MCNS and IgAN patients. Moreover, when individual MCNS patients were followed through their clinical illness, uVEGF levels were increased during the active phase and decreased as the patients went into remission. Our main concern is to distinguish between two possibilities: Increases in uVEGF excretion might indeed relate to specific glomerular pathology and thus have a pathophysiological role. Alternatively, uVEGF may be derived from the circulation and as such may be nothing more than an assay for proteinuria. In fact, given the strict correlation between uVEGF excretion and the amount of proteinuria, the second possibility appears quite conceivable. CONCLUSION: Therefore, this may be a coincidental finding which has no bearing on the pathophysiology of MCNS.