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Stromal expression of matrix metalloprotease-9 in middle ear cholesteatomas
E Shibosawa1, K Tsutsumi, T Takakuwa
1Department of Otolaryngology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
Background:
Matrix metalloprotease-9 (MMP-9) plays an important role in the degradation of extracellular matrix (ECM). In cholesteatoma there are significant changes in the composition of the ECM, supporting the view of a disturbed cell-ECM interaction. It has been reported that in cholesteatoma tissues, MMP-9 is expressed in epithelial cells but not in stromal cells. In this study, we report conflicting results regarding the identity of the cholesteatoma cells that express MMP-9.
Methods:
An immunohistochemical assay was performed to examine the expression of MMP-9 in 25 cases (formalin-fixed paraffin-embedded sections) of cholesteatoma, using an MMP-9-specific monoclonal antibody.
Results:
In all cholesteatomas examined, MMP-9 was expressed in the stromal cells but not in the epithelial cells. MMP-9 immunostaining was undetectable in external auditory meatal skin (n = 5) and tympanic membrane (n = 3).
Conclusions:
These results suggest that the MMP-9 expressed in stromal cells may be involved in the disturbed cell-ECM interaction associated with the process of cholesteatoma formation.
Insights
Matrix metalloprotease-9 (MMP-9) is found in cholesteatoma stromal cells, not epithelial cells, contrary to previous reports. This finding suggests MMP-9
Area of Science:
- Otorhinolaryngology
- Cell Biology
- Biochemistry
Background:
- Matrix metalloprotease-9 (MMP-9) is crucial for extracellular matrix (ECM) degradation.
- Cholesteatoma exhibits altered ECM composition, indicating disturbed cell-ECM interactions.
- Previous studies suggested MMP-9 expression in cholesteatoma epithelial cells, but not stromal cells.
Purpose of the Study:
- To investigate the cellular localization of MMP-9 expression in cholesteatoma.
- To clarify conflicting reports on MMP-9 expression in cholesteatoma tissues.
Main Methods:
- Immunohistochemical assay performed on 25 cholesteatoma tissue samples.
- Utilized an MMP-9-specific monoclonal antibody for detection.
- Compared expression in cholesteatoma with external auditory meatal skin and tympanic membrane samples.
Main Results:
- MMP-9 was consistently expressed in stromal cells of all examined cholesteatomas.
- MMP-9 expression was notably absent in the epithelial cells of cholesteatomas.
- No MMP-9 immunostaining was detected in normal external auditory meatal skin or tympanic membrane tissues.
Conclusions:
- Stromal cell expression of MMP-9 in cholesteatoma contradicts previous findings.
- MMP-9 in stromal cells may contribute to the aberrant cell-ECM interactions in cholesteatoma pathogenesis.
- Further research is warranted to elucidate the precise role of stromal MMP-9 in cholesteatoma development.