MMP-7 and TIMP-1, new targets in predicting poor wound healing in apical periodontitis.

INTRODUCTION: Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) are strongly associated with tissue destruction because of inflammation. In this study, we investigated the expression of MMPs and TIMPs messenger RNA and protein levels in apical periodontitis lesions. METHODS: Tissue samples from patients presenting clinical signs of chronic apical abscess (CAA) or asymptomatic apical periodontitis (AAP) were collected postoperatively and used for gene expression analysis of MMP-2, -3, -7, -9, -14, -16, and -25; TIMP-1; and TIMP-2 in real-time polymerase chain reaction. Immunohistochemistry was also performed to detect the expression of MMP-7 and TIMP-1 proteins. Lastly, U-937 cells were induced to terminal differentiation into macrophages, infected with purified Escherichia coli lipopolysaccharide, and assessed for the expression of MMP-7 and TIMP-1 using immunocytochemistry and confocal microscopy. RESULTS: Significantly higher messenger RNA levels were found for all genes in AAP and CAA samples when compared with healthy control samples (P < .001). AAP cases exhibited significantly higher TIMP-1 when compared with CAA cases, whereas CAA cases showed higher MMP-2, MMP-7, and MMP-9 messenger RNA levels (P < .05). We also detected positive the expression of MMP-7 and TIMP-1 proteins in the tissue samples. The expression of both MMP-7 and TIMP-1 were increased in lipopolysaccharide-stimulated cells compared with nonstimulated cells and appear to colocalize in the Golgi apparatus. CONCLUSIONS: MMPs appear to have an influential role in CAA cases in which ongoing tissue destruction is observed. TIMPs are preferentially associated with AAP, perhaps as a subsequent defense mechanism against excessive destruction. Taken together, our findings implicate MMP and TIMP molecules in the dynamics of inflammatory periapical lesion development.

Histochemical localization of neutral proteases released during development of rat periradicular lesion.

OBJECTIVE: The purpose of the present study was to examine the role of various neutral proteases released during the development of periradicular lesion. DESIGN: This lesion produced by pulpal exposure of mandibular first molar in rat. The histological and histometrical changes in periapical tissue examined. The presence of neutrophil elastase, cathepsin G, collagenase 2, gelatinase B, and secretory leukocyte protease inhibitor (SLPI) was immunohistochemically evaluated in the periapical tissue. RESULTS: After pulpal exposure, some inflammatory cells were present in the periapical tissue at 7 days, and periapical inflammation gradually increased. Alveolar bone resorption observed after 14 days and apical abscess found after 21 days. After 14 days, the area of periradicular lesion significantly increased compared from normal one (p<0.05). Neutrophil elastase, cathepsin G, collagenase 2, and gelatinase B were detected around the root apex at 14 days, then these proteases increased gradually and demonstrated in and around the abscess at 21 and 28 days. Morphologically, these protease-expressing cells are almost polymorphic and polynuclear shaped after 14 days. These cells significantly increased after 14 days compared from normal one (p<0.05). However, SLPI detected after 21 days around apical root. It significantly increased after 21 days (p<0.05). CONCLUSIONS: These results suggested that neutrophil elastase, cathepsin G, collagenase 2, and gelatinase B induce the destruction of periapical tissue. We demonstrated that these neutral proteases released play an important role in development of periradicular lesion.

The zymographic evaluation of gelatinase (MMP-2 and -9) levels in acute and chronic periapical abscesses.

OBJECTIVE: This study investigated the presence and levels of matrix metalloproteinases (MMP)-2 and -9 in periapical abscesses. STUDY DESIGN: Eighteen samples of intracanal exudates containing pus were collected from teeth with clinically and radiographically verified primary or secondary acute and chronic apical abscesses. Pro- and active forms of MMP-2 and MMP-9 levels were analyzed by using substrate gel zymography followed by an image analysis system. Statistical analysis was performed using the Kruskall-Wallis and Mann-Whitney U tests with Bonferroni adjustment. RESULTS: Both forms of MMP-9 were detected in all pus samples and demonstrated marked differences among the experimental groups (P < .05). Primary or secondary acute apical abscess samples demonstrated significantly higher MMP-9 levels compared with MMP-2 levels (P < .01). However, MMP-2 could not be detected in chronic apical abscesses. CONCLUSION: According to the results of this study, gelatinases might affect the pathogenesis of acute and chronic periapical abscesses.