Increase of MT1-MMP, TIMP-2 and Ki-67 proteins in the odontogenic region of the rat incisor post-shortening procedure

Effects of a Single Dose of X-Ray Irradiation on MMP-9 Expression and Morphology of the Cerebellum Cortex of Adult Rats

Although radiation is a strategy widely used to inhibit cancer progression, which includes those of the neck and head, there are still few experimental reports on radiation effects in the cerebellum, particularly on the morphology of its cortex layers and on the Matrix metalloproteinases' (MMPs') expression, which, recently, seems to be involved in the progression of some mental disorders. Therefore, in the present study, we evaluated the morphology of the cerebellum close to the expression of MMP-9 from 4 up to 60 days after a 15-Gy X-ray single dose of X-ray irradiation had been applied to the heads of healthy adult male rats. The cerebellum of the control and irradiated groups was submitted for an analysis of cell Purkinje count, nuclear perimeter, and chromatin density using morphometric estimatives obtained from the Feulgen histochemistry reaction. In addition, immunolocalization and estimative for MMP-9 expression were determined in the cerebellar cortex on days 4, 9, 14, 25, and 60 after the irradiation procedure. Results demonstrated that irradiation produced a significant reduction in the total number of Purkinje cells and a reduction in their nuclear perimeter, along with an increase in chromatin condensation and visible nuclear fragmentation, which was also detected in the granular layer. MMP-9 expression was significantly increased on 4, 9, and 14 days, being detected around the Purkinje cells and in parallel fibres at the molecular layer. We conclude that the effects of a single dose of 15-Gy X-ray irradiation in the cerebellum were an increase in MMP-9 expression in the first 2 weeks after irradiation, especially surrounding the Purkinje cells and in the molecular layers, with morphological changes in the Purkinje cell and granular cell layers, suggesting a continuous cell loss throughout the days evaluated after irradiation.

Matrix Metalloproteinases in Dental and Periodontal Tissues and Their Current Inhibitors: Developmental, Degradational and Pathological Aspects

Objectives: This review article aims to describe some of the roles of Matrix metalloproteinases (MMPs) in enamel, dentine, dental caries, hybrid layer degradation, pulp and periodontal tissues, throwing light on their current inhibitors. The article addresses the potential of MMPs to serve as biomarkers with diagnostic and therapeutic value. Design: The sections of this review discuss MMPs’ involvement in developmental, remodeling, degradational and turnover aspects of dental and periodontal tissues as well as their signals in the pathogenesis, progress of different lesions and wound healing of these tissues. The literature was searched for original research articles, review articles and theses. The literature search was conducted in PubMed and MEDLINE for articles published in the last 20 years. Results: 119 published papers, two textbooks and two doctoral theses were selected for preparing the current review. Conclusions: MMPs are significant proteases, of evident contribution in dental and periapical tissue development, health and disease processes, with promising potential for use as diagnostic and prognostic disease biomarkers. Continuing understanding of their role in pathogenesis and progress of different dental, periapical and periodontal lesions, as well as in dentine-pulp wound healing could be a keystone to future diagnostic and therapeutic regimens.

Antibiotics Disturb Dentin Formation and Differentiation of Dental Pulp Stem Cells: The Role of Microbiota in Cellular Turnover of Mouse Incisor

Dentin formation was dependent on osteo-/odontogenic differentiation of dental pulp stem cells (DPSCs). It was observed in previous studies that antibiotic treatment in a clinical and animal model resulted in impaired mineralization of dental tissues. We previously reported that microbiota maintained the function of bone marrow mesenchymal stem cells, while whether microbiota dysbiosis caused by antibiotic treatment contributed to DPSCs dysfunction and impaired dentin formation is still not known. In this study, we aimed to clarify the role of microbiota or its metabolic products on dental mineralization and the function of DPSCs. Mice were treated with antibiotics to disrupt microbiota; then, the growth rate and histological characteristics of incisors as well as the biological characteristics of DPSCs in vitro were compared with specific pathogen-free (SPF) mice. In antibiotic-treated mice (AbT), we found a diminished quantity of microbiota and reduced growth rate of mechanical injured incisor, as well as decreased colony-forming rate and impaired ability of osteo-/odontogenic differentiation of DPSCs, in comparison to SPF mice. Colonization of AbT mice with SPF mice replanted the microbiota by cohousing (conventionalized (ConvD)) and normalized the growth rate of injured incisors and colony-forming and osteo-/odontogenic differentiation ability of DPSCs. Giving short-chain fatty acids (SCFAs) by oral gavage after antibiotic treatment also rescued the growth rate of incisors and the differentiation ability of DPSCs and enhanced proliferation ability of DPSCs. Collectively, gut microbiota could make contribution to maintain continuous growth of injured rodent incisor and differentiation capacity of DPSCs; SCFAs might play a crucial role in this process.

Expression of the matrix metalloproteinases 2 and 9 in the rat small intestine during intrauterine and postnatal life

The expressions of matrix metalloproteinases 2 and 9 have been described during the development, as an example in heart and tooth but not in the small intestine yet. In this context, this study aimed to evaluate the expressions of MMP-2 and MMP-9 in the small intestine of Wistar rats during intrauterine (IU) and postnatal (PN) life. Expressions were determined on the 15th and 18th days of IU life and the 3rd, 10th, 17th, 25th, and 32nd days of PN life. Intestinal samples obtained from six animals were submitted to zymography, immunohistochemistry, and staining with Masson's trichrome. The results showed that MMP-2 and MMP-9 were not expressed during IU life; however, after birth, MMP-9 was immunolocalized in the goblet and mast cells. In conclusion, our results showed that MMP-2 and MMP-9 were not expressed in absorptive epithelial cells during the IU period of the small intestine but after birth, MMP-9 was expressed in the goblet cells, and mast cells present in the lamina propria.

MT1-MMP and its potential role in the vertebrate intestinal morphogenesis

Membrane type 1-matrix metalloproteinase (MT1-MMP) is involved in numerous biological processes, including morphogenesis. However, the role of MT1-MMP in the development of the vertebrate intestine is poorly understood. This study aimed to evaluate the expression of MT1-MMP in the intestine of rats and chickens along the embryonic and postnatal periods using immunohistochemistry. Results revealed a remarkable spatiotemporal correlation between MT1-MMP expression and intestinal villi morphogenesis in both vertebrates. However, the villi morphogenesis process was found to be different in chickens to that of rats. Moreover, extensive MT1-MMP labeling was observed in the entire villus epithelium from birth until the complete maturation of the small intestinal mucosa in both vertebrates. From these results, we suggest that MT1-MMP contributes to intestinal development, particularly to villi morphogenesis, in both vertebrates. However, further studies are necessary to confirm the role of MT1-MMP in this cellular process. In addition, we performed validation of the primary antibody against human MT1-MMP for adult chickens.

Effect of radiotherapy on the eruption rate and morphology of the odontogenic region of rat incisors

OBJECTIVE

The goal in this study was to evaluate the results of doses of 5 and 15 Gy of radiation in odontogenic region of the rats inferior mandibular-incisors by a histological analysis and the rate of eruptions.

DESIGN

Animals were divided into three groups: control, radiotherapy 5 Gy and radiotherapy 15 Gy. In which tooth-eruption-rate was measured every two days.

RESULTS

Animals in Group 5 Gy presented values similar to those of the control group. Animals in Group 15 Gy presented reduction in tooth-eruption-rate as of the sixth day of the experiment, vast disorganization of odontoblasts and ameloblasts, apparent reduction in cell population in the follicle region and alterations in cervical loop formation of the dental organ.

CONCLUSIONS

It was concluded that there was a difference between the researched doses, and histological alteration at 15 Gy lead to statistical reduction in tooth-eruption-rate.

Effect of interrupted eruption on the enamel organ of the rat incisor

The aim of this study was to investigate the behavior of rat incisor tissues during the inhibition of tooth eruption. Twenty Sprague-Dawley rats were used in this study, and incisor eruption was inhibited by a screw pin. Animals were sacrificed 1, 3, 7 and 14 days after the start of the experiment. Cross-sections at the mesial point of the mandibular first molar and sagittal sections of the mandibular tooth germ area were examined using immunohistochemical and immunofluorescence methods. For morphometric analysis, numbers of TRAP-positive cells were calculated against the total number of cells. In cross-sections from the experimental group, dentin was thickened and pulp tissue was constricted day by day. On days 1, 3 and 7, nestin-positive cells were observed in all odontoblast cell bodies and processes, while on day 14 fewer nestin-positive cells were seen than in the control group. On day 14, the mesial area of the periodontal ligament was constricted and the number of TRAP-positive cells in the mesial area was significantly higher than in the control group. In sagittal sections, enamel formation was found to be increased on days 7 and 14. Furthermore, in the enamel matrix amelogenin was expressed more strongly than in the control group. PCNA-positive cells were significantly increased in cells of the tooth germ compared with the control group. These results suggest that inhibition of tooth eruption accelerates the apical elongation with resorption of the mesial area of the alveolar bone and stimulates cell proliferation with thickened enamel towards the apical end.

MT1-MMP expression in the odontogenic region of rat incisors undergoing interrupted eruption

MT1-MMP (membrane type matrix metalloproteinase-1) has been considered an important membrane-type matrix metalloproteinase involved in the remodeling process in tissue and organ development, including the processes of the tooth and root growth and dental eruption. Therefore, the aims of this study were to evaluate MT1-MMP expression in the odontogenic region, as well as the eruption rate and morphology of the lower-left rat incisor, where the eruption process was interrupted for 14 days by a steel wire attached from the center of the incisor labial face and braced to the first molar. In the interrupted eruption group, the eruption rate was significantly reduced, producing drastic morphological alterations in the tooth germ and socket area. The MT1-MMP expression was widespread in the dental follicle, in both groups studied (normal and interrupted eruption groups); however a significant decrease in immunostaining was observed in the interrupted eruption group. Results indicate that MT1-MMP may have an important role in the process of dental eruption.

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.