Podocyte Expression of Osteopontin and FSP-1/S100A4 in Human Crescentic Glomerulonephritis

ABSTRACT

BACKGROUND: Osteopontin (OPN) is a cytokine associated with a cell-matrix via integrins. Fibroblast specific protein-1 (FSP-1), known as S100A4, has been implicated in cell migration by non-muscle myosin. We investigated whether the role of OPN and FSP-1/S100A4 expression in their contribution to the podocyte phenotype change to form podocyte bridge and cellular crescent. METHODS: Glomerular expression of OPN and FSP-1/S100A4 in renal biopsies of 16 patients with crescentic glomerulonephritis (CrGN) and 13 normal renal biopsies were studied by immunohistochemistry. RESULTS: The expression of OPN and FSP-1/S100A4 was increased in the podocytes of glomeruli, with and without crescents, in patients with CrGN. Neither OPN nor FSP-1/S100A4 was expressed in glomeruli from the normal controls (p<0.01). A significant positive correlation was found between the expression of OPN in glomerular tufts and cellular crescents, and the expression of OPN and FSP-1/S100A4 in glomerular tufts (p<0.05). CONCLUSIONS: The results suggest that OPN plays a role in early podocyte attachment to Bowman's capsule, and FSP-1/S100A4 potentiate podocyte contribution to cellular crescent formation by inducing cellular migration and growth.