Significance of Increased Accumulation of Type VI Collagen and Transforming Growth Factor βi in Tubulointerstitial Damage in Hypertensive Nephrosclerosis: An Immunohistochemical Study

Abstract

The distribution of type VI collagen and transforming growth factor β1 (TGF β1) was studied by immunohistochemistry in 12 renal biopsy specimens of hypertensive nephrosclerosis and five control cases. In control kidneys, the immunostaining of type VI collagen was found in the mesangium, glomerular basement membrane and tubular basement membrane. For TGF β, mesangium, glomerular basement membrane, tubular basement membrane and tubular epithelial cells stained positively in the control kidneys. In contrast to the control cases, markedly increased immunostaining for both type VI collagen and TGF β1 was consistently observed in tubulointerstitial damage in hypertensive nephrosclerosis. These immunohistochemical findings provide the evidence for a parallel increase of both type VI collagen and TGF β1 during the process of tubulointerstitial injury in hypertensive nephrosclerosis. From the results of the present study, it is speculated that TGF β1 may contribute to the tubulointerstitial injury by stimulating increased synthesis of various extracellular matrix including type VI collagen.