Significance of Osteopontin Expression in the Progression of Human Focal Segmental Glomerulosclerosis

ABSTRACT

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.