Immunohistochemical and transcriptional expression of the matrix metalloproteinases MMP-2 and MMP-9 in normal and pathological human oral mucosa.

The oral cavity is exposed to chronic or recurrent, physical and chemical trauma that could lead to mucosal reactions (e.g. hyperplasia, dysplasia and tumors). The objective of this study is to investigate the expression and the possible changes of the two matrix metalloproteinases MMP-2 and MMP-9 in normal and pathological human oral mucosa samples. Normal oral mucosa samples and three different types of pathological conditions (hyperplasia, dysplasia and carcinoma) were used for this study. Immunohistochemical analysis was used to evaluate protein expression for the two enzymes, while Reverse Transcription ? Polymerase Chain Reaction (RT-PCR) was used to investigate gene expression. Image analysis was used to give a quantitative evaluation of the immunohistochemical data. In control samples we identified a weak expression of both MMP-2 and MMP-9 in the epithelial layers. In hyperplasia samples MMPs expression is limited to epithelial layers but the immunoreactivity is more intense than in the control. In dysplasia and carcinoma samples the two matrix metalloproteases are expressed not only in epithelium but also in some cells of the connective tissue and in the vessel walls. Qualitative RT-PCR and image analysis confirmed the immunohistochemical data. The results obtained in this study suggest the existence of a possible relationship between the entity of morphological disorganization of the oral mucosa in different pathologies and the increase of MMP-2 and MMP-9 expression.