Cathepsin activity in cholesteatoma.

Area of Science:

• Biochemistry
• Pathology
• Otolaryngology

Background:

• Cholesteatoma involves bone destruction, with collagenolytic cathepsins suspected as key players.
• Lysosomal cathepsin B is implicated in extracellular matrix degradation.
• Understanding the role of cathepsin B in cholesteatoma is crucial for therapeutic strategies.

Purpose of the Study:

• To investigate the presence and activity of collagenolytic cathepsin B in cholesteatoma tissues.
• To determine the specific location and level of cathepsin B activity within cholesteatoma and surrounding tissues.
• To correlate cathepsin B activity with bone resorption processes in cholesteatoma.

Main Methods:

• Enzyme extraction from cholesteatoma epithelium, subepithelial granulation tissue, external auditory meatus skin, and temporal bone.
• Identification of the enzyme as lysosomal cathepsin B using SDS gel electrophoresis with human type I and type III collagen.
• Measurement of BANA-hydrolase activity as a specific assay for collagen-degrading cathepsin B.

Main Results:

• Cathepsin B was detected in all investigated tissues, with an optimal pH of 6.0.
• A significant increase in cathepsin B activity was observed in the subepithelial granulation tissue.
• High acid phosphatase activity was also found in the subepithelial granulation tissue, indicating active metabolism.

Conclusions:

• Collagenolytic cathepsin B is present in cholesteatoma tissues.
• Subepithelial granulation tissue exhibits elevated cathepsin B activity, suggesting its role in collagen resorption.
• These findings support the hypothesis that collagen degradation in the subepithelial granulation tissue contributes to cholesteatoma progression.