Immunohistochemical analysis of extracellular components in the glomerular sclerosis of patients with glomerulonephritis.

Immunofluorescence and immunoperoxidase staining was carried out to determine correlations between the progression of glomerular sclerosis and changes in the amount or distribution of glomerular extracellular components, including type I, III, IV, and VI collagens, laminin and fibronectin, in patients with IgA nephropathy, membranoproliferative glomerulonephritis and rapidly progressive glomerulonephritis. Staining of type I and III collagens was not observed in glomeruli from normal individuals or patients with mild glomerulonephritis. In the advanced stages of glomerulonephritis, the staining of type IV and VI collagens, laminin and fibronectin was marked in the glomerular mesangium, and the distribution of fibronectin extended to the glomerular capillary walls in the sclerotic lesions of glomeruli. However, the staining intensity of type IV collagen, laminin and fibronectin was gradually decreased during the progression of glomerular sclerosis. On the other hand, the staining of type I and III collagens was observed focally in sclerotic or hyalinotic glomeruli and around such glomeruli in those patients. Light microscopic examination revealed that patients who showed marked staining of type I and III collagens by immunofluorescence had severe damage of Bowman's capsules. These results suggest that the hyperproduction and/or invasion of interstitial collagens, i.e., types I and III, are closely linked to the progression of glomerular sclerosis and hyalinosis in patients with various types of glomerulonephritis.