Soluble Urokinase Receptor Levels in Secondary Focal Segmental Glomerulosclerosis

Soluble urokinase receptor (suPAR) has been reported to be a possible permeability factor causing primary focal segmental glomerulosclerosis (FSGS) in recent years. We investigated the plasma and urinary suPAR levels in patients with 3 common types of secondary FSGS: Alport's syndrome (Alport-FSGS), obesity-related FSGS, and diabetic nephropathy.

Fifty-two secondary FSGS patients diagnosed by kidney biopsy, including 8 with Alport-FSGS, 20 with obesity-related FSGS, and 24 with diabetic nephropathy, were enrolled in the study in the period from January 2008 to June 2014 at the Renal Division, Peking University First Hospital. Fifty-six healthy donors and 74 patients with primary FSGS, 14 with minimal-change disease, and 29 with membranous nephropathy were used as healthy controls and disease controls, respectively. Plasma and urinary suPAR concentrations were measured with commercial ELISA kits, and their correlations with clinical and pathological data were analyzed.

Both plasma and urinary suPAR levels in the total secondary FSGS group were significantly higher than in healthy controls (p < 0.0001 and p< 0.001, respectively). There was no significant difference in levels of plasma and urinary suPAR in the Alport-FSGS, obesity-related FSGS, and diabetic nephropathy groups (p = 0.64 and p = 0.72, respectively). The plasma suPAR level was not correlated with estimated glomerular filtration rate and urine protein.

The levels of plasma and urinary suPAR in patients with Alport-FSGS, obesity-related FSGS, and diabetic nephropathy were increased. Plasma suPAR might be a pathogenetic participation factor or a useful marker of glomerular diseases with FSGS-associated podocytopathy but is not necessarily a circulating permeability factor.