Immunohistochemical Analysis of Type III and IV Collagens in Tubulointerstitial Damage in Human Benign Nephrosclerosis

Prolonged hypertension causes structural changes including glomerulosclerosis and tubulointerstitial damage of the kidney, termed benign nephrosclerosis. It is generally accepted that, in benign nephrosclerosis, increased accumulation of extracellular matrix in the glomeruli results in glomerulosclerosis. Little is known, however, about the possible role of the extracellular matrix in the tubulointerstitial damage in benign nephrosclerosis. In this study, the possible roles of type IV basement-membrane collagen and type III interstitial collagen in tubulointerstitial damage caused by hypertension were explored. Immunohistochemical techniques were used to investigate the distribution of type III and type IV collagens in the kidney sections of 15 patients with benign nephrosclerosis with tubulointerstitial damage and in 10 controls. In the control renal sections strong immunostaining for type III collagen was found in the interstitium and immunostaining for type IV collagen was present in the tubular basement membrane and weakly in the interstitium. In the patients with tubulointerstitial damage there was increased immunostaining for both type III and type IV collagens in the expanded interstitium and damaged tubules than was found in the control kidney sections. These findings indicate that increased accumulation of both type III and type IV collagens might play a significant role in the tubulointerstitial damage in benign nephrosclerosis.