Expression of Podocyte Related Proteins and TGF-β1, WT-1 in Minimal Change Disease and Focal Segmental Glomerulosclerosis

OBJECTIVE: Focal segmental glomerulosclerosis and minimal change disease are primary renal diseases representing with proteinuria. Following the identification of the role of podocyte-related molecules in the glomerular filtration barrier and the detection of the pivotal role of nephrin in the development of congenital nephrotic syndrome, the assessment and expression profiles of these proteins in acquired nephrotic syndrome have also come into question.

MATERIAL and METHODS: Renal biopsies from 74 patients with diagnoses of MCD, FSGS and nonspecific mesangial proliferation were included in this study. The light microscopic sections were re-examined and the definitive diagnoses were recorded. Nephrin, podocin, synaptopodin, WT-1 and TGF-β1 distribution were examined by immunohistochemistry. The histopathological parameters examined were correlated with clinical parameters.

RESULTS: The predominant staining pattern for all three podocyte-related proteins in FSGS was coarse granular and it was statistically significant between groups. FSGS cases showed a statistically significant loss in the glomerular expression of WT-1 compared to the other two groups. TGF-β1 expression was considerably higher in FSGS and it was correlated to the degree of interstitial fibrosis, inflammation and tubular atrophy.

CONCLUSION: The staining patterns of podocyte-related proteins, WT-1 and TGF-β1 expressions are definitely different in FSGS. This may reflect just a distributional change but a possible renal pathogenetic role has to be elucidated.