MMP-1 and MMP-8 expression in giant-cell fibroma and inflammatory fibrous hyperplasia.

The aim of this study is to compare the immunoexpression of metalloproteinases 1 and 8 in giant-cell fibroma, inflammatory fibrous hyperplasia and normal mucosa. Twenty-two cases of giant-cell fibroma, inflammatory fibrous hyperplasia and oral mucosa (control) each were subjected to immunohistochemistry using anti-metalloproteinase-1 and anti-metalloproteinase-8 antibodies. Eight images of each case were captured and analysed through the a) application of a count grid to count the number of positive neutrophils, macrophages, lymphocytes, plasma cells, fibroblasts and blood vessels to obtain the percentage of staining and b) semi-automated segmentation quantifying the stained area in square micrometres. Statistical tests included ANOVA Two-way, Kruskal Wallis and Games-Howell, with a significance level of 5%. An increased percentage of metalloproteinase-1-immunopositive blood vessels were observed in giant-cell fibroma (26.6±22.4; p=0.02) and inflammatory fibrous hyperplasia (34.3±31.5; p=0.01) compared with the control group (19.6±9.2). No significant differences in inflammatory cells, fibroblasts and total area of metalloproteinase-1 and -8 were noted among the three groups. Metalloproteinase-1 apparently acts within the pathogenesis of giant-cell fibroma and inflammatory fibrous hyperplasia.