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.
BACKGROUND Osteopontin (OPN) is a cytokine related to cell-matrix adhesion and cell survival and is expressed in the distal convoluted tubules in normal adult kidneys. Only one in vitro study has investigated the role of OPN in mechanically stretched podocytes and their actin cytoskeleton rearrangement. METHODS Glomerular OPN expression was investigated in biopsies from patients with human idiopathic focal segmental glomerulosclerosis (FSGS) (n = 25) and in normal renal biopsies (n = 16) by immunohistochemistry. RESULTS OPN was expressed in the podocytes from patients with FSGS. OPN expression increased in podocytes from both non-sclerotic hypertrophic and sclerotic glomerular tufts in patients with FSGS compared to the podocytes in normal controls. CONCLUSIONS The results suggest that OPN plays a role in the early adaptive response of podocytes to the increased mechanical load caused by glomerular hypertrophy preceding FSGS. OPN was involved in cell-matrix adhesion and influenced the detachment delay of podocytes from the glomerular basement membrane and apoptosis.
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Podocyte Expression of Osteopontin and FSP-1/S100A4 in Human Crescentic Glomerulonephritis Ghil Suk Yoon, Tae Sook Kim The Korean Journal of Pathology.2011; 45(3): 237. CrossRef