Relationship between soluble urokinase-type plasminogen activator receptor and serum biomarkers of endothelial activation in patients with idiopathic nephrotic syndrome

Background Serum levels of soluble urokinase-type plasminogen activator receptor (suPAR) are high in some patients with idiopathic nephrotic syndrome (INS). Given that suPAR constitutes a predictor of vascular disease and has been associated with endothelial dysfunction, we hypothesized that suPAR levels are related to endothelial activation or dysfunction in INS patients. The aims of this study were to evaluate the relationship between serum concentrations of endothelial biomarkers and suPAR in patients with different histological patterns of INS and healthy controls, and to determine the demographic, clinical and biochemical characteristics of INS patients that influence suPAR serum levels. Methods This observational, cross-sectional study included patients with INS, diagnosed with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS) or membranous nephropathy (MN) by renal biopsy. Patient demographic, clinical and biochemical characteristics were recorded and blood samples were obtained at the time of diagnosis. Measurements of suPAR and endothelial molecules via serum levels were performed using Enzyme-Linked ImmunoSorbent Assay kits. Results Patients with nephrotic syndrome (n = 152) caused by FSGS, MCD or MN had increased circulating levels of endothelial markers. suPAR levels positively correlated with age and the serum levels of almost all endothelial markers. Generally, endothelial cell molecules positively correlated with each other. suPAR levels were not associated with the histopathological pattern of INS. Conclusions In patients with INS secondary to FSGS, MCD and NM, circulating levels of suPAR are independent of the primary renal disease, and significantly associated with age, glomerular filtration rate and the levels of various endothelial markers.