Abstract

Glomerulosclerosis represents a pathological hallmark of progressive glomerular injury. Mesangial cell proliferation and accumulation of extracellular matrix (ECM) proteins in the mesangial area frequently precede the formation of glomerulosclerosis. To understand the role of platelet-derived growth factor (PDGF) and ECM in the development of glomerulosclerosis, we examined the expression of type IV collagen, laminin, fibronectin, and PDGF in 45 renal biopsies diagnosed with IgA nephropathy (IgAN) using a standard peroxidase antiperoxidase (PAP) technique. Normal control specimens were obtained from four nephrectomy specimens diagnosed with renal cell carcinoma. As compared with normal controls, type IV collagen increased in 68%, fibronectin in 73%, laminin in 51%, and PDGF in 36% of patients with IgA nephropathy. The staining intensity of PDGF, type IV collagen, and fibronectin increased significantly in cases with moderate to severe mesangial cell proliferation than cases without. In the areas of glomerulosclerosis, the staining intensity of type IV collagen, laminin, and PDGF decreased, whereas that of fibronectin increased. These results suggest that mesangial cell proliferation in relation to increased PDGF expression in IgAN could stimulate the expression of type IV collagen, laminin and fibronectin leading to mesangial expansion. They also suggest that ECM decreased in advanced glomerulosclerosis. Deposition of fibronectin, which originates mainly from the blood stream, increases during the course of progressive glomerulosclerosis, whereas other ECM components decrease in advanced glomeruloslresosis.

• Keywords: IgA nephropathy;Extracellular matrix;PDGF