The Urinary Podocyte as a Marker for the Differential Diagnosis of Idiopathic Focal Glomerulosclerosis and Minimal-Change Nephrotic Syndrome

Abstract

Background/Aims: Detection of podocytes in the urine sediment of children indicates that severe podocyte injury occurred in the glomerulus. Focal glomerulosclerosis (FGS) and minimal-change nephrotic syndrome (MCNS) are kidney diseases characterized by massive proteinuria. The aim of the present study was to determine whether urinary podocytes can be detected in patients with idiopathic FGS or MCNS and whether immunosuppression therapy alters these cells. Methods: Twenty patients with MCNS (nephrotic stage, n = 12; remission stage, n = 8), 15 patients with FGS and 20 healthy controls were included in the present study. Urinary podocytes were stained by immunofluorescence. All patients with MCNS at the nephrotic stage received prednisolone for 6 months, and all patients with FGS received some form of immunosuppression therapy including prednisolone, cyclophosphamide or mizoribine for 12 months. Results: The 12 nephrotic-stage MCNS patients achieved remission after treatment. Seven of the 15 FGS patients also achieved remission, but the other 8 remained in the nephrotic stage. Urinary podocytes were not detected in any patient with MCNS nor were they detected in healthy controls. Urinary podocytes were detected in all FGS patients (mean, 4.2 cells/ml) before treatment and the number of cells decreased in the 7 patients who achieved remission. The number of podocytes was unchanged in the other 8 patients even after treatment. Conclusion: Urinary podocytes may be a useful diagnostic indicator for differentiation between FGS and MCNS. These cells may also mark disease progression in cases of FGS.

Ultrastructural Features and Expression of Cytoskeleton Proteins of Podocyte from Patients with Minimal Change Disease and Focal Segmental Glomerulosclerosis

“…A significantly higher frequency of mat-like condensation of microfilaments and detachment of podocyte foot process from GBM was identified in FSGS than in MCD. Several studies had demonstrated that urinary podocytes were significantly higher in patients with FSGS as compared with those of MCD, [21,22] which might be consistent with the results of our study. The current study suggested that mat-like condensation of microfilaments of podocyte and the detachment of foot process from GBM might be used as a diagnostic indicator for FSGS at the ultrastructural level.…”

Relationship between Urinary Podocytes and Kidney Diseases

“…Several studies have also indicated that the number of PDX-positive cells in the urine falls after various therapeutic interventions in patients with FSGS, LN, HSP, IgAN, PSGN, and DN. [20][21][22][23][24][25][26] Compared with other markers, PDX proved to be the most reproducible marker for podocyte assessment in the urine of these patients. According to Vogelmann et al, 27 the cells that stained positive for PDX also stained positive for 30-40% of the other podocyte-specific markers.…”

Cell Biology of the Glomerular Podocyte

“…VIII and IX). Hara and coworkers (156,157,305) have indeed detected cells positive for podocyte marker in the urine of a variety of renal diseases. Interestingly, a reduction in urinary podocyte excretion was found with improved glycemic control in early diabetic nephropathy (304).…”