Expression of Remodelling Enzymes (MMP-2, MMP-9) in Normal and Pathological Oral Mucosa Samples

Abstract

Introduction. The oral cavity contains many structures compressed in a small area. It is exposed to chronic or recurrent, physical and chemical trauma leading to mucosal reactions (e.g. hyperplasia, dysplasia and tumors). For a long time, our group has been studying the expression of some metalloproteinases (MMP-2, MMP-9) in healthy and pathological human oral mucosa through immunohistochemistry and RT-PCR to investigate the entity of the remodelling process in the different cases. Matherials and Methods. In this paper we investigate a sample of normal oral mucosa and four pathological samples (mucocele, fibroma, dysplasia and carcinoma). We identified the localization of MMP-2 and MMP-9 through immunohistochemistry and gene expression through RT-PCR analysis. Results. In control sample we identified a weak expression of both metalloproteinases (MMP-2, MMP-9) in the upper epithelial layers. The reactivity of the two enzymes is emphasized with higher intensity in pathological samples where a strong inflammatory activity is present (e.g. hyperplasia, dysplasia) or where there is a distruption of the architecture (as in tumors) while in localized lesions a functional silence is detected (mucocele). Particularly, in lesions like hyperplasia and dysplasia where (though it is present a inflammatory condition) the bio-architecture is preserved, the immunoreactivity is expressed only in the upper epithelial cell layers; while in more serious lesions (like tumors), where the architecture is fully disorganizated, the immunoreactivity is expressed also in deeper epithelial layers, in few connnective cells and in vessels wall. Qualitative RT-PCR analysis confirmed the expression of MMP-2 and MMP-9 in both normal and pathological oral mucosa samples. Conclusions. Our data suggest that there is a relationship between the increase of MMP-2 and MMP-9 expression and the entity of morphological disorganization according with the well known role of these enzymes.