[The expression of matrix metalloproteinase-1 and interleukin-1-alpha messenger ribonucleic acid in human middle ear cholesteatoma].

OBJECTIVE

To explore the expression of matrix metalloproteinase-1 (MMP1), tissue inhibitor of metalloproteinase-1(TIMP1) and interleukin-1-alpha messenger ribonucleic acid(IL-1 alpha mRNA) in acquired middle ear cholesteatoma, and to evaluate their roles in the molecular mechanisms of bone resorption.

METHODS

Tissue specimens from 32 cases of acquired middle ear cholesteatoma and 14 cases of external ear skin were examined by immunohistochemical S-P method for MMP1 and TIMP1, and by in situ hybridization for IL-1 alpha mRNA.

RESULTS

All 32 samples of cholesteatoma showed a stronger expression of MMP1 than the external ear skin. The integral absorbency of MMP1 in the two types of tissues were 2,018.26 +/- 174.89 and 1,428.35 +/- 123.39, respectively, with statistically significant difference between them. Neither of the two types of epithelial cells showed a remarkable expression of TIMP1. The cells hybridized for the antisence probes IL-1 alpha mRNA were only confined to the basal layer; in cholesteatoma, besides the basal cell layers, keratinocytes of the suprabasal cell layers were also found to contain specific hybridizations. The level of IL-1 alpha mRNA measured in cholesteatoma was significantly higher than that in the external ear skin.

CONCLUSION

The overexpression of MMP1 and a derailment of the normally controlled MMPs-TIMPs system could play an active role in the molecular mechanisms of cholesteatoma invasion into the bone. The upregulation of IL-1 alpha might contribute to the increasing secretions of MMP1 in cholesteatoma.