Expression and activity of matrix metalloproteinase-2 (MMP-2) in the development of rat first molar tooth germ

Immunohistochemical expression of matrix metalloproteinase-1, matrix metalloproteinase-2 and matrix metalloproteinase-9, myofibroblasts and Ki-67 in actinic cheilitis and lip squamous cell carcinoma

Matrix metalloproteinases (MMPs), myofibroblasts (MFs) and epithelial proliferation have key roles in neoplastic progression. In this study immunoexpression of MMP-1, MMP-2 and MMP-9, presence of MFs and the epithelial proliferation index were investigated in actinic cheilitis (AC), lip squamous cell carcinoma (LSCC) and mucocele (MUC). Thirty cases of AC, thirty cases of LSCC and twenty cases of MUC were selected for immunohistochemical investigation of the proteins MMP-1, MMP-2, MMP-9, α-smooth muscle actin (α-SMA) and Ki-67. The MMP-1 expression in the epithelial component was higher in the AC than the MUC and LSCC. In the connective tissue, the expression was higher in the LSCC. MMP-2 showed lower epithelial and stromal immunostaining in the LSCC when compared to the AC and MUC. The epithelial staining for MMP-9 was higher in the AC when compared to the LSCC. However, in the connective tissue, the expression was lower in the AC compared to other lesions. The cell proliferation rate was increased in proportion to the severity of dysplasia in the AC, while in the LSCC it was higher in well-differentiated lesions compared to moderately differentiated. There were no statistically significant differences in number of MFs present in the lesions studied. The results suggest that MMPs could affect the biological behaviour of ACs and LSCCs inasmuch as they could participate in the development and progression from premalignant lesions to malignant lesions.

TGF-β1 Suppresses Plasmin and MMP Activity in Flexor Tendon Cells via PAI-1: Implications for Scarless Flexor Tendon Repair

Flexor tendon injuries caused by deep lacerations to the hands are a challenging problem as they often result in debilitating adhesions that prevent the movement of the afflicted fingers. Evidence exists that tendon adhesions as well as scarring throughout the body are largely precipitated by the pleiotropic growth factor, Transforming Growth Factor Beta 1(TGF-β1), but the effects of TGF-β1 are poorly understood in tendon healing. Using an in vitro model of tendon healing, we previously found that TGF-β1 causes gene expression changes in tenocytes that are consistent with scar tissue and adhesion formation, including upregulation of the anti-fibrinolytic protein, PAI-1. Therefore, we hypothesized that TGF-β1 contributes to scarring and adhesions by reducing the activity of proteases responsible for ECM degradation and remodeling, such as plasmin and MMPs, via upregulation of PAI-1. To test our hypothesis, we examined the effects of TGF-β1 on the protease activity of tendon cells. We found that flexor tendon tenocytes treated with TGF-β1 had significantly reduced levels of active MMP-2 and plasmin. Interestingly, the effects of TGF-β1 on protease activity were completely abolished in tendon cells from homozygous plasminogen activator inhibitor 1 (PAI-1) knockout (KO) mice, which are unable to express PAI-1. Our findings support the hypothesis that TGF-β1 induces PAI-1, which suppresses plasmin and plasmin-mediated MMP activity, and provide evidence that PAI-1 may be a novel therapeutic target for preventing adhesions and promoting a scarless, regenerative repair of flexor tendon injuries.

Immunolocalization and activity of the MMP-9 and MMP-2 in odontogenic region of the rat incisor tooth after post shortening procedure

MMP-9 and MMP-2 are metalloproteinases which degrade the denatured collagen fibers. However, there is no report about roles of these MMPs in the odontogenic region of the adult rat incisor tooth under different eruption conditions. Male Wistar rats were divided in a normofunctional group (NF) in which their lower teeth remained in a normal eruption. In a hypofunctional group (HP) rats underwent shortening of their lower left incisor tooth every 2 days during 12 days. The eruption rate as well as the expression and activities of MMP-9 and MMP-2 were evaluated using imunohistochemistry and zymography. Although the shortening increased the eruption rate, no changes in the MMP-9 and MMP-2 were observed. We conclude that in adult rats, in opposite to development of tooth, the MMP-9 and MMP-2 present in the odontogenic region does not seem to play a direct role in the remodeling matrix, even after post-shortening procedures which to lead an acceleration of the eruption process in the incisor.

Immunohistochemical expression of matrix metalloproteinases 1, 2, and 9 in odontogenic myxoma and dental germ papilla

The aim of this study was to compare the immunohistochemical expression of matrix metalloproteinases (MMPs) 1, 2, and 9 in odontogenic myxomas and dental germ papillae. Twelve cases of odontogenic myxoma and eight tooth germ specimens were selected for analysis of the immunohistochemical expression and the pattern of distribution of MMPs 1, 2, and 9 in extracellular matrix (ECM), as well as of the number of MMP-positive cells. MMP-2 was expressed only in the ECM of myxomas (p<0.05). No significant difference was observed between ECM immunoreactivity for MMP-9 in myxomas and dental papillae (p>0.05). MMP-1 immunoreactivity was detected in most myxoma cases at a proportion similar to that observed in dental papillae (p>0.05). A significant difference was observed in the number of immunoreactive cells in myxomas (p<0.05), MMP-1 being present at higher proportions than MMPs 2 and 9. There was a gradient in the expression of MMPs in the ECM and in neoplastic cells of odontogenic myxomas, with higher immunoreactivity to MMP-1 and lower immunoreactivity to MMP-9. Taken together, our results suggest the existence of a coordinated mechanism between MMPs 1, 2, and 9 that aimed at the efficient degradation of extracellular matrix in odontogenic myxomas.