Cathepsin activity in cholesteatoma

Collagenolytic cathepsin, presumed to play an important role in bone destruction of cholesteatoma, was investigated in cholesteatoma epithelium, subepithelial granulation tissue, skin from the bony external auditory meatus and, temporal bone. The enzyme extracted from tissues was proven to be lysosomal cathepsin B by SDS gel electrophoresis in the use of human type I and type III collagen. α-N-benzoyl-DL-arginine-2-naphthylamide HCl (BANA) was supposed to be specific for cathepsin B, and so BANA-hydrolase activity was measured as collagen-degrading cathepsin. The results showed that tissues had cathepsin B with its optimal pH 6.0, and that cathepsin B activity revealed a significant increase in the subepithelial granulation tissue. A strong activity of acid phosphatase found in the subepithelial granulation tissue seems to reflect the existence of an active metabolism of substances in the granulation tissue. These findings suggest that collagen is resorbed in the subepithelial granulation tissue in the presence of cholesteatoma.