Analysis of tryptase-positive mast cells and immunoexpression of MMP-9 and MMP-13 in periapical lesions

To evaluate the immunoexpression of tryptase, MMP-9 and MMP-13 in periapical lesions, correlating them with the type of lesion, intensity of the inflammatory infiltrate and thickness of the epithelial lining.

Twenty periapical granulomas (PGs), twenty radicular cysts (RCs) and twenty residual radicular cysts (RRCs) were submitted to immunohistochemical analysis using antitryptase, anti-MMP-9 and anti-MMP-13 antibodies. Immunoexpression of MMP-9 and MMP-13 was quantitatively evaluated both in the connective tissue of all lesions and in the epithelial lining of RCs and RRCs. Tryptase-positive mast cells were counted only in the connective tissue. The data were analysed using Kruskal-Wallis and Fisher's exact tests, as well as Spearman's correlation test (P < 0.05).

In comparison with RCs and RRCs, PGs exhibited higher immunoexpression of tryptase, MMP-9 and MMP-13 (P = 0.002, P = < 0.001 and P < 0.001, respectively). In comparison with lesions with inflammatory infiltrates grades I and II, lesions with inflammatory infiltrate grade III had higher median percentages of MMP-13-positive cells (P = 0.003) and a tendency for higher expression of MMP-9 (P = 0.059). No significant difference was observed between the expression of the studied markers and epithelial thickness (P > 0.05). There were positive correlations between the number of tryptase-positive mast cells and the immunoexpression of MMP-9, as well as between the immunoexpression of MMP-9 and MMP-13.

A larger number of tryptase-positive mast cells and greater enzymatic activity of MMP-9 and MMP-13 were found in PGs compared to RCs and RRCs. These findings are a characteristic of the dynamics of periapical diseases.