S208 – Catabolism of Gycoconjugates in Cholesteatoma Tissue

Abstract

Objectives 1) To determine the activity of N-acetylo-beta-D-hexosaminidase (HEX), alpha-mannosidase (alpha-MAN) and beta-galactosidase (beta-GAL)in acquired cholesteatoma and normal retroauricular skin specimens. 2) To assess the level of catabolism of glycoconjugates in assays of cholesteatoma extracts, quantifying HEX, alpha-MAN and beta-GAL. Methods Cholesteatomas (n=21) and normal adult post-auricular skin, served as controls(n=21), were collected during surgery in 2006–2007. Exoglycosidases activity was evaluated by determination, the amount of released p-nitrophenol from p-nitrophenol derivatives of appropriate sugars (beta-N-acetylglucosamine, alpha-mannose, and beta-galactose). Statistical analysis was conducted using the Student's t-test; p<0.05 was regarded as significant. Results In 19 of 21 specimens we observed significantly higher activity of investigated enzymes in cholesteatoma tissue compared with control tissue (p<0.05). Mean activity of HEX, alpha-MAN and beta-GAL from the cholesteatoma cells was adequate: 68.55 ±30.77 nkat/g, 1.85 ±1.14 nkat/g and 1.92 ±1.11 nkat/g wet tissue. In the control probes, adequate: HEX: 31.79 ±10.02 nkat/g, alpha-MAN: 0.69 ±0.24 nkat/g and beta-GAL: 0.86±0.22 nkat/g wet tissue. The correlation of two variables: enzyme activity in cholesteatoma and enzyme activity in skin specimens was positive. Pearson's coefficient was equal r= 0.3815 (HEX), r= 0.527 (alpha-MAN) and r= 0.489 (beta-GAL). Conclusions Catabolic reactions involving glycoproteins, glycolipids, and proteoglycans may play a role in the pathogenesis of acquired cholesteatoma. The present data indicating that lysosomal exoglycosidases HEX, alpha-MAN and beta-GAL are significantly and consistently elevated suggest the need to further assess correlations between levels of HEX, alpha-MAN and beta-GAL and cholesteatoma behavior. Further research should also evaluate the relative importance of these particular exoglycosidases in considering the spectrum of identified inflammatory mediators.