Evaluation of gelatinases, tissue inhibitor of matrix metalloproteinase-2, and myeloperoxidase protein in healthy and inflamed human dental pulp tissue.

INTRODUCTION: The aim of this study was to compare the gelatinolytic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and the expression of tissue inhibitor of matrix metalloproteinase (TIMP)-2 and myeloperoxidase protein (MPO) in clinically healthy human pulp and inflamed pulp tissue specimens. METHODS: Twenty dental pulps clinically diagnosed as inflammatory tissues and 20 healthy pulp tissues from enclosed third molars were harvested and evaluated. The gelatinolytic activity for MMP-2 and MMP-9 was assessed by using the zymography technique, TIMP-2 gene expression was evaluated using the enzyme-linked immunosorbent assay, and MPO was determined using the MPO assay. RESULTS: Data showed increased levels of MMP-9, active MMP-2, TIMP-2, and MPO in inflammatory pulp tissues compared with healthy tissues (P < .05). No statistical difference could be observed for pro-MMP-2 (P > .05). CONCLUSIONS: Although all samples were associated with MMP-2 expression, the active form of this MMP was observed only in inflamed pulps. Inflamed pulps showed an up-regulation of MMP-9, TIMP-2, and MPO.

Up-regulation of p38 mitogen-activated protein kinase during pulp injury-induced glial cell/neuronal interaction in the rat thalamus.

INTRODUCTION: We have recently reported that the signal of pulp injury induces both neuronal and glial cell activation in the contralateral thalamus in rats, although the mechanisms of the glial cell/neuronal interaction remain unclear. This study was undertaken to test our hypothesis that p38 mitogen-activated protein kinase (MAPK) signaling pathways are involved in the pulp injury-induced glial cell/neuronal interaction in the thalamus. METHODS: A local anesthetic (lidocaine with epinephrine) or saline (control) was injected into the tissue surrounding the left mandibular first molar of Wistar rats. The tooth was then pulp-exposed, and the cavity was sealed with flowable composite. After 0 (normal pulp with local anesthetic or saline pretreatment), 24, and 72 hours, the contralateral side of thalamus was retrieved and subjected to immunohistochemistry for phospho-p38 MAPK and glial fibrillary acidic protein and real-time polymerase chain reaction analysis of p38-MAPK family (MAPK 13 and MAPK 14) mRNAs. RESULTS: The area immunopositive to phospho-p38 MAPK increased until 72 hours after pulp exposure in both local anesthetic-pretreated and saline-pretreated animals, but the rate of increase was lower in the local anesthetic-pretreated animals. The density of glial fibrillary acidic protein-expressing astrocytes showed a significant increase only in the saline-pretreated animals. Expression levels of MAPK 13 and MAPK 14 mRNAs increased at 24 hours and still higher at 72 hours in the saline-pretreated animals. Notably, MAPK 13 and MAPK 14 mRNA levels at 24 and 72 hours in the local anesthetic-pretreated animals showed significantly lower levels than those in the saline-pretreated animals. CONCLUSIONS: It was concluded that pulp injury-induced up-regulation of MAPK 13, MAPK 14, and phospho-p38 MAPK in the thalamus was suppressed by the local anesthetic pretreatment, suggesting the involvement of p38 MAPK signaling pathways in the glial cell-neuronal interaction induced by pulpal nociception.

Cysteine cathepsins in human carious dentin.

Matrix metalloproteinases (MMPs) are important in dentinal caries, and analysis of recent data demonstrates the presence of other collagen-degrading enzymes, cysteine cathepsins, in human dentin. This study aimed to examine the presence, source, and activity of cysteine cathepsins in human caries. Cathepsin B was detected with immunostaining. Saliva and dentin cysteine cathepsin and MMP activities on caries lesions were analyzed spectrofluorometrically. Immunostaining demonstrated stronger cathepsins B in carious than in healthy dentin. In carious dentin, cysteine cathepsin activity increased with increasing depth and age in chronic lesions, but decreased with age in active lesions. MMP activity decreased with age in both active and chronic lesions. Salivary MMP activities were higher in patients with active than chronic lesions and with increasing lesion depth, while cysteine cathepsin activities showed no differences. The results indicate that, along with MMPs, cysteine cathepsins are important, especially in active and deep caries.

Activation of p38 mitogen-activated protein kinase in rat periapical lesions.

The purpose of this study was to investigate the activation of p38 mitogen-activated protein kinase (MAPK) during the development of periapical lesions in rats. Periapical lesions developed within 28 days after pulp exposure of mandibular first molars in Wistar rats. The animals were sacrificed randomly at 0, 7, 14, 21, and 28 days after pulpal exposure. The jaws that contained the first molar were obtained and routinely prepared for immunohistochemistry and enzyme histochemistry. A few phosphorylated p38 MAPK (P-p38)-positive cells and osteoclasts could be observed on day 7; both peaked in number on day 14. In the 21- and 28-day samples, the P-p38 MAPK expression decreased and fewer osteoclasts were observed. From day 7 to day 28, a significant positive correlation was found between P-p38 MAPK expression and osteoclasts. These findings showed that the activation of p38 MAPK might be associated with bone resorption in periapical lesions.

A real time quantitative PCR analysis and correlation of COX-1 and COX-2 enzymes in inflamed dental pulps following administration of three different NSAIDs.

Dental pain is encountered daily by clinicians. Nonsteroidal anti-inflammatory drugs (NSAIDs) commonly used for pain management are traditionally cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibitors, and more recently selective COX-2 inhibitors. This study was designed to identify and quantify COX-1 and COX-2 gene expression level in inflamed rat molar pulps after administration of three NSAIDs: Celebrex, Vioxx, and Advil. Fifty male Wistar rats had their first and second molar pulps exposed and sealed with Cavit for 4 days. Rats were randomly divided into the three drug groups and two control groups. RNA was isolated from the rat pulps. Real Time Quantitative Reverse Transcriptase-Polymerase Chain Reaction assay, a relatively new PCR technique, was used to quantify COX-1 and COX-2 mRNA. Statistical analysis demonstrated no significant differences in COX-1 and COX-2 levels among the drug groups. However, Vioxx and Advil significantly reduced COX-2 expression levels compared to inflamed (positive control) pulps (p < 0.05).