An Observational Study on Cystic Alterations in Normal Dental Follicles Associated with Impacted Lower Third Molar for Early Intervention.

AIM: To evaluate the cystic changes in the radiographically normal dental follicle associated with impacted mandibular third molar. MATERIALS AND METHODS: This study was conducted on 80 patients. Samples were selected using a convenient sampling technique from the patients who had impacted mandibular third molars in Pell and Gregory's positions B and C, with follicular space less than 2.5 mm in diameter. After surgical removal of an impacted tooth, the dental follicle was sent for histopathologic evaluation. RESULTS: Pathologic alterations were found in 19% of cases out of 80 samples. Odontogenic keratocystic and dentigerous cystic changes were found in 7% of cases. A statistically significant cystic alteration was found in female patients and distoangular impacted teeth. CONCLUSION: This study shows a significant cystic alteration in the radiologically normal dental follicles. Clinical and radiographic features alone may not be a reliable indicator of the absence of pathology. Early intervention of impacted teeth will help to reduce morbidity due to the development of pathology. CLINICAL SIGNIFICANCE: This study will help educate patients on the risks of retaining impacted teeth, based on scientific facts, in order to minimize the risks and to assess the correlation of pathologic alterations with the depth of impaction and angular position of the impacted tooth.

Dental follicle mesenchymal stem cells ameliorated glandular dysfunction in Sjögren's syndrome murine model.

OBJECTIVE: Dental mesenchymal stem cells (MSCs) are potential for use in tissue regeneration in inflammatory diseases due to their rapid proliferating, multilineage differentiation, and strong anti-inflammatory features. In the present study, immunoregulatory and glandular tissue regeneration effects of the dental follicle (DF)MSCs in Sjögren's Syndrome (SS) were investigated. METHODS: Dental follicle (DF) tissues were obtained from healthy individuals during tooth extraction, tissues were digested enzymatically and DFMSCs were cultured until the third passage. DFMSCs were labeled with Quantum dot 655 for cell tracking analysis. The induction of the SS mouse model was performed by the injection of Ro60-273-289 peptide intraperitoneally. DFMSCs were injected intraperitoneally, or into submandibular, or lacrimal glands. Splenocytes were analyzed for intracellular cytokine (IFN-γ, IL-17, IL-10) secretion in T helper cells, lymphocyte proliferation, and B lymphocyte subsets. Histologic analysis was done for submandibular and lacrimal glands with hematoxylin-eosin staining for morphologic examination. RESULTS: The systemic injection of DFMSCs significantly reduced intracellular IFN-γ and IL-17 secreting CD4+ T cells in splenocytes (p<0.05), and decreased inflammatory cell deposits and fibrosis in the glandular tissues. DFMSCs differentiated to glandular epithelial cells in submandibular and lacrimal injections with a significant reduction in lymphocytic foci. The results showed that few amounts of DFMSCs were deposited in glandular tissues when applied intraperitoneally, while high amounts of DFMSCs were located in glandular tissues and differentiated to glandular epithelial cells when applied locally in SS murine model. CONCLUSION: DFMSCs have the potential for the regulation of Th1, Th17, and Treg balance in SS, and ameliorate glandular dysfunction. DFMSCs can be a beneficial therapeutic application for SS.

Immunomodulatory and Tissue-preserving Effects of Human Dental Follicle Stem Cells in a Rat Cecal Ligation and Perforation Sepsis Model.

BACKGROUND: Mesenchymal stem cells may be used for the treatment of sepsis. Dental follicle stem cells (DFSCs) are easily accessible but have not been studied in vivo or in clinical trials in sepsis models. AIM OF THE STUDY: We aim to elucidate DFSC effects on host immunological functions in a rat cecal ligation and perforation (CLP) sepsis model. METHODS: Adult male rats were categorized into group 1 (sham procedure SP), group 2 (SP + 1 × 106 DFSCs administered 0 h after SP), group 3 (CLP + saline), group 4 (CLP + 1 × 106 DFSCs administered 0 h after CLP), and group 5 (CLP + 1 × 106 DFSCs administered 4 h after CLP). Green fluorescent protein-labeled cells were used for imaging. Histopathological examination of ileal tissues was performed. RESULTS: A significant increase in the percentage of CD4+/CD25+/Foxp3+ Treg cells in groups 4 and 5 occurred compared with that in group 3. No significant changes in CD3+/CD4+ helper T-cells and CD3+/CD8+ cytotoxic T-cells were observed. Treatment with DFSCs at 4 h significantly decreased the level of TNF-α compared with that in group 3. No significant changes in IL-10 levels and lymphocyte proliferation suppression were observed. During histopathological examination, no high scoring (Chiu scores: 3 or 4) rats were observed in the curative treatment group (group 5). CONCLUSIONS: Treatment with DFSC after 4 h of sepsis induction downregulates tissue inflammatory responses by decreasing TNF-α levels and increasing Treg cell ratio. This also has a protective effect on intestinal tissues during sepsis.

Assessing pathogenic mutations in dental follicles as an attempt to identify early events in odontogenic tumours tumourigenesis.

OBJECTIVE: Driver oncogenic mutations have been reported in several benign neoplasms. While ameloblastomas show BRAF p.V600E mutations, adenomatoid odontogenic tumours harbour either KRAS p.G12R or p.G12 V. The lack of understanding of the core molecular changes involved in tumour initiation and progression represents a critical barrier to developing new strategies for cancer detection and prevention. Considering the fact that ameloblastoma and adenomatoid odontogenic tumours can originate from dental follicles, we hypothesized that the BRAF and KRAS mutations might be early events in odontogenic tumours tumourigenesis. We aimed to assess BRAF and KRAS mutations in dental follicles associated with asymptomatic impacted teeth. DESIGN: Forty-eight dental follicles containing odontogenic epithelial remnants were included in the study. As ameloblastomas most often occur in the posterior mandible and adenomatoid odontogenic tumours have a predilection for the anterior jaws, we assessed by allele-specific qPCR the presence of BRAF p.V600E in 32 dental follicles associated with impacted 3rd mandibular molar teeth and KRAS p.G12 V and KRAS p.G12R mutations in 16 dental follicle specimens obtained from around impacted anterior teeth. Sanger sequencing was used as an additional method. RESULTS: None of the dental follicle cases tested positive for the mutations. CONCLUSION: In conclusion, we tried to detect the early genetic events associated with odontogenic tumours development in dental follicles, but we were unable to showcase that BRAF p.V600E and KRAS p.G12R or p.G12 V mutations are the early genetic events associated with odontogenic tumours development.

IFN-γ stimulation of dental follicle mesenchymal stem cells modulates immune response of CD4+ T lymphocytes in Der p1+ asthmatic patients in vitro

Background: House dust mite (Dermataphagoides pteronyssinus) is a widespread risk factor in the development of asthma. CD4+ T lymphocytes have an important role in the pathogenesis of allergic asthma by polarizing to Th2 cells. Objective: We aimed to evaluate the immunoregulatory effects of dental follicle mesenchymal stem cells with and without IFN-γ stimulation on peripheral blood mononuclear cells of house dust mite sensitive asthmatic patients, and compared those with Dexamethasone as a systemic steroid. Material and methods: PBMC of asthmatic patients and healthy individuals separately cultured with or without DF-MSCs in the presence and absence of IFN-γ or Der p1 or Dexamethasone for 72h. CD4+ T proliferation, cell viability, CD4+CD25+FoxP3+ Treg cell frequency and cytokine profiles of PBMC were evaluated via flow cytometry. Results: DF-MSCs suppressed proliferation of CD4+ T lymphocytes (pCDmix < 0.01, pDerp1 < 0.01, pIFN < 0.005) by increasing the number of FoxP3 expressing CD4 + CD25 + T regulatory cells (pCDmix < 0.005, pDerp1 < 0.01, pIFN < 0.001) and suppressed lymphocyte apoptosis (pCDmix < 0.05, pDerp1< 0.05, pIFN < 0.05), while Dexamethasone increased the apoptosis and decreased Treg cell frequency in asthmatic patients. IFN-γ stimulation increased the suppressive effect of DF-MSCs and also enhanced the frequency of FoxP3 expressing CD4+CD25 + T regulatory cells. The cytokine levels were regulated by DF-MSCs by reducing IL-4 cytokine levels (pCDmix < 0.01, pDerp1 < 0.05, pIFN < 0.05) and upregulating IFN-γ levels (pCDmix < 0.01, pDerp1< 0.05, pIFN < 0.005) in asthmatic patients. Conclusion: IFN-γ stimulated DF-MSCs were found to have a high modulatory effect on CD4 + T cell responses, while Dexamethasone had an apoptotic effect on CD4+ T cells in asthmatic patients. DF-MSCs may be a new cell-based therapy option for allergic diseases including asthma

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IFN-γ stimulation of dental follicle mesenchymal stem cells modulates immune response of CD4+ T lymphocytes in Der p1+ asthmatic patients in vitro.

BACKGROUND: House dust mite (Dermataphagoides pteronyssinus) is a widespread risk factor in the development of asthma. CD4+ T lymphocytes have an important role in the pathogenesis of allergic asthma by polarizing to Th2 cells. OBJECTIVE: We aimed to evaluate the immunoregulatory effects of dental follicle mesenchymal stem cells with and without IFN-γ stimulation on peripheral blood mononuclear cells of house dust mite sensitive asthmatic patients, and compared those with Dexamethasone as a systemic steroid. MATERIAL AND METHODS: PBMC of asthmatic patients and healthy individuals separately cultured with or without DF-MSCs in the presence and absence of IFN-γ or Der p1 or Dexamethasone for 72h. CD4+ T proliferation, cell viability, CD4+CD25+FoxP3+ Treg cell frequency and cytokine profiles of PBMC were evaluated via flow cytometry. RESULTS: DF-MSCs suppressed proliferation of CD4+ T lymphocytes (pCDmix<0.01, pDerp1<0.01, pIFN<0.005) by increasing the number of FoxP3 expressing CD4+CD25+ T regulatory cells (pCDmix<0.005, pDerp1<0.01, pIFN<0.001) and suppressed lymphocyte apoptosis (pCDmix<0.05, pDerp1<0.05, pIFN<0.05), while Dexamethasone increased the apoptosis and decreased Treg cell frequency in asthmatic patients. IFN-γ stimulation increased the suppressive effect of DF-MSCs and also enhanced the frequency of FoxP3 expressing CD4+CD25+ T regulatory cells. The cytokine levels were regulated by DF-MSCs by reducing IL-4 cytokine levels (pCDmix<0.01, pDerp1<0.05, pIFN<0.05) and upregulating IFN-γ levels (pCDmix<0.01, pDerp1<0.05, pIFN<0.005) in asthmatic patients. CONCLUSION: IFN-γ stimulated DF-MSCs were found to have a high modulatory effect on CD4+ T cell responses, while Dexamethasone had an apoptotic effect on CD4+ T cells in asthmatic patients. DF-MSCs may be a new cell-based therapy option for allergic diseases including asthma.

Multiple Calcifying Hyperplastic Dental Follicles: A Case Report.

Multiple calcifying hyperplastic dental follicles (MCHDFs) are a rare condition of calcification in the follicles of multiple impacted teeth. Radiologically, they appear as multiple pericoronal radiolucencies with radiopaque foci. This report presents a case of MCHDFs in a 22-year-old man.

Study on site-specific expression of bone formation and resorption factors in human dental follicles.

We sought to investigate site-specific expression of bone-regulatory factors expressed by human dental follicles and to compare the stimulated expression of tumour necrosis factor (ligand) superfamily, member 11/tumour necrosis factor receptor superfamily, member 11b (RANKL/OPG) in human dental follicle cells (HDFCs) from different patients. Analysis of bone-regulatory markers in follicles from 12 different study participants was performed using RT-qPCR and immunofluorescence; apical and coronal segments from each dental follicle were processed independently. Four additional dental follicles were used for cell cultures; HDFCs were precultured in osteogenic medium to initiate differentiation and thereafter cultured with 10-6 M forskolin (FSK) to activate the protein kinase cAMP (PKA/cAMP) signalling pathway and induce RANKL/OPG expression. We demonstrate that RANKL expression is significantly higher in the coronal part of follicles than in the apical part. High levels of collagen type 1 (COL1), alkaline phosphatase (ALP) and Gap-junction protein, alpha 1, 43 kDa (CX43) were expressed, whereas expression of Sp7 transcription factor (OSX), bone morphogenetic protein 2 (BMP2), colony-stimulating factor 1 (CSF-1), chemokine (C-C motif) ligand 2 (MCP1), and OPG was low in all samples. The immunofluorescence localization of CSF-1, MCP1, osteocalcin (OCN), RANKL, and BMP2 was not specific for either part of the follicles. In conclusion, a consistently high expression of CX43 suggests that gap-junction communication in HDFCs is essential for the eruption process. Furthermore, the induced expression of RANKL in HDFCs varies significantly between individuals and may relate to clinical variations in tooth eruption.

RUNX2 mutation reduces osteogenic differentiation of dental follicle cells in cleidocranial dysplasia.

Disturbed permanent tooth eruption is common in cleidocranial dysplasia (CCD), a skeletal disorder caused by heterozygous mutation of RUNX2, but the mechanism underlying is still unclear. As it is well known that dental follicle cells (DFCs) play a critical role in tooth eruption, the changed biological characteristics of DFCs might give rise to disturbance of permanent tooth eruption in CCD patients. Thus, primary DFCs from one CCD patient and normal controls were collected to investigate the effect of RUNX2 mutation on the bone remodeling activity of DFCs and explore the mechanism of impaired permanent tooth eruption in this disease. Conservation and secondary structure analysis revealed that the RUNX2 mutation (c.514delT, p.172fs) found in the present CCD patient was located in the highly conserved RUNT domain and converted the structure of RUNX2. After osteogenic induction, we found that the mineralised capacity of DFCs and the expression of osteoblast-related genes, including RUNX2, ALP, OSX, OCN and Col Iα1, in DFCs was severely interfered by the RUNX2 mutation found in CCD patients. To investigate whether the osteogenic deficiency of DFCs from the CCD patient can be rescued by RUNX2 restoration, we performed 'rescue' experiments. Surprisingly, the osteogenic deficiency and the abnormal expression of osteoblast-associated genes in DFCs from the CCD patient were almost rescued by overexpression of wild-type RUNX2 using lentivirus. All these findings indicate that RUNX2 mutation can reduce the osteogenic capacity of DFCs through inhibiting osteoblast-associated genes, thereby disturbing alveolar bone formation, which serves as a motive force for tooth eruption. This effect may provide valuable explanations and implications for the mechanism of delayed permanent tooth eruption in CCD patients.

Porphyromonas gingivalis Peptidyl Arginine Deiminase Can Modulate Neutrophil Activity via Infection of Human Dental Stem Cells.

Periodontitis (PD) is a widespread chronic inflammatory disease in the human population. Porphyromonas gingivalis is associated with PD and can citrullinate host proteins via P. gingivalis peptidyl arginine deiminase (PPAD). Here, we hypothesized that infection of human dental follicle stem cells (hDFSCs) with P. gingivalis and subsequent interaction with neutrophils will alter the neutrophil phenotype. To test this hypothesis, we established and analyzed a triple-culture system of neutrophils and hDFSCs primed with P. gingivalis. Mitogen-activated pathway blocking reagents were applied to gain insight into stem cell signaling after infection. Naïve hDFSCs do not influence the neutrophil phenotype. However, infection of hDFSCs with P. gingivalis prolongs the survival of neutrophils and increases their migration. These phenotypic changes depend on direct cellular contacts and PPAD expression by P. gingivalis. Active JNK and ERK pathways in primed hDFSCs are essential for the phenotypic changes in neutrophils. Collectively, our results confirm that P. gingivalis modifies hDFSCs, thereby causing an immune imbalance.

Abnormal bone remodelling activity of dental follicle cells from a cleidocranial dysplasia patient.

OBJECTIVES: To explore the role of dental follicle cells (DFCs) with a novel cleidocranial dysplasia (CCD) causative gene RUNX2 mutation (DFCsRUNX2+/m ) in delayed permanent tooth eruption. MATERIALS AND METHODS: A CCD patient with typical clinical features was involved in this study. DFCsRUNX2+/m were cultured and DNA was extracted for RUNX2 mutation screening. Measurements of cell proliferation, alkaline phosphatase (ALP) activity, alizarin red staining and osteoblast-specific genes expression were performed to assess osteogenesis of DFCsRUNX2+/m . Co-culture of DFCs and peripheral blood mononuclear cells (PBMCs), followed tartrate-resistant acid phosphatase (TRAP) staining, real-time PCR and western blot were performed to evaluate osteoclast-inductive capacity of DFCsRUNX2+/m . RESULTS: A missense RUNX2 mutation (c. 557G>C) was found in DFCsRUNX2+/m from the CCD patient. Compared with normal controls, this mutation did not affect the proliferation of DFCsRUNX2+/m , but down-regulated the expression of osteogenesis-related genes, leading to a decrease in ALP activity and mineralisation. Co-culture results showed that DFCsRUNX2+/m reduced the formation of TRAP+ multinucleated cells and the expression of osteoclastogenesis-associated genes. Furthermore, the mutation reduced the ratio of RANKL/OPG in DFCsRUNX2+/m . CONCLUSIONS: DFCsRUNX2+/m disturbs bone remodelling activity during tooth eruption through RANK/RANKL/OPG signalling pathway and may thus be responsible for impaired permanent tooth eruption in CCD patients.

Multiple Calcifying Hyperplastic Dental Follicles: A Case Report and Literature Review.

Enlarged follicles associated with multiple unerupted teeth always comprise an area of considerable interest for oral and maxillofacial surgeons. The condition of multiple calcifying hyperplastic dental follicles is extremely rare and is characterized by multiple unerupted teeth with abundant calcifications and odontogenic epithelial rests in the enlarged dental follicles. We report an interesting case of multiple calcifying hyperplastic dental follicles in a 16-year-old healthy male patient.

Immunoexpression of tumour necrosis factor-α, interleukin-1α and interleukin-10 on odontogenic cysts and tumours.

AIM: To analyse the immunoreactivity of IL-1α, TNF-α and IL-10 in odontogenic cysts and tumours and to investigate possible associations with established biological behaviours of these different lesions. METHODOLOGY: Immunohistochemical expression of anti-IL-1α, anti-TNF-α and anti-IL-10 antibodies was assessed on epithelium and mesenchyme of 20 radicular cysts (RCs), 20 residual cysts (RECs), 20 dentigerous cysts (DCs), 18 solid ameloblastomas (SAs), 20 keratocystic odontogenic tumours (KCOTs) and 15 dental follicles (DFs). Comparative analysis of data was performed using the nonparametric Wilcoxon signed-rank test and Kruskal-Wallis's test. RESULTS: Significantly greater expression of IL-1α in the epithelium was noted in RC, KCOT and SA (P = 0.01), whilst IL-10 and TNF-α was in the epithelium of RC, DC and KCOT (P < 0.01). In the mesenchyme, significantly greater immunopositivity was observed for IL-1α, IL-10 and TNF-α in KCOT, DC and RC (P < 0.01). In epithelial and mesenchymal tissues, there were a significant number of cases of RC and DC with IL-1α < IL-10 ratio (P < 0.01), whilst SA and KCOT showed IL-1α > IL-10 (P < 0.01). There was a significantly greater percentage of DF, DC and KCOT with TNF-α > IL10 ratio (P < 0.01). CONCLUSION: These results suggest involvement of the proteins in the pathogenesis of odontogenic cysts and tumours, with emphasis on the highest immunoreactivity of osteolysis stimulating factors in tumours with aggressive biological behaviour, such as SA and KCOT.

Drug-induced premature senescence model in human dental follicle stem cells.

Aging is identified by a progressive decline of physiological integrity leading to age-related degenerative diseases, but its causes is unclear. Human dental pulp stem cells (hDPSCs) has a remarkable rejuvenated capacity that relies on its resident stem cells. However, because of the lack of proper senescence models, exploration of the underlying molecular mechanisms has been hindered. Here, we established a cellular model utilizing a hydroxyurea (HU) treatment protocol and effectively induced Human dental pulp stem cells to undergo cellular senescence. Age-related phenotypic changes were identified by augmented senescence-associated-ß-galactosidase (SA-ß-gal) staining, declined proliferation and differentiation capacity, elevated G0/G1 cell cycle arrest, increased apoptosis and reactive oxygen species levels. Furthermore, we tested the expression of key genes in various DNA repair pathways including nonhomologous end-joining (NHEJ) and homologous recombination (HR) pathways. In addition, our results showed that Dental pulp stem cells from young donors are more resistant to apoptosis and exhibit increased non-homologous end joining activity compared to old donors. Further transcriptome analysis demonstrate that multiple pathways are involved in the HU-induced Dental pulp stem cells ageing, including genes associated with DNA damage and repair, mitochondrial dysfunction and increased reactive oxygen species levels. Taken together, the cellular model have important implications for understanding the molecular exploration of Dental pulp stem cells senescence and aging.

Histopathological evaluation of dental follicles of clinically symptomatic and asymptomatic impacted third molars.

BACKGROUND AND AIMS: Surgical removal of impacted teeth is a common operation in oral surgery. Thus, pathological potential of impacted third molars is extensively studied. However, many of those studies based on data collected from analysis of radiographs only. The purpose of this retrospective study was to compare the follicles of symptomatic and asymptomatic impacted third molars histopathologically for a number of characteristics. MATERIALS AND METHODS: Records of the patients who had been previously operated for impacted third molars were reviewed. Eighty-three patients were selected and divided into two groups, clinically symptomatic and clinically asymptomatic. None of the patients had a radiographic pericoronal radiolucency of wider than 2.5 mm. Histopathological samples of the patients were obtained and re-examined by two pathologists. Two groups were statistically compared for 12 histological parameters. RESULTS: Eleven of the 12 parameters had statistically significant differences (P < 0.05), whereas one parameter (odontogenic remnants) was found not to be significantly different between the groups. CONCLUSION: A delay in impacted third molar surgery can lead to further pathological changes in dental follicles and can increase severity of the inflammation. Moreover, dimensions of the pericoronal radiolucency may not provide a correct interpretation of the pathological changes in the region.

The evaluation of Ki67, p53, MCM3 and PCNA immunoexpressions at the level of the dental follicle of impacted teeth, dentigerous cysts and keratocystic odontogenic tumors.

UNLABELLED: The aim of this study is to analyze the immunoexpression of Ki67, p53, MCM3 and PCNA markers in epithelial remnants of dental follicles of impacted teeth and to identify a possible correlation between the immunoexpression of these markers in dentigerous cysts and keratocystic odontogenic tumors in order to evaluate their evolutionary behavior. MATERIALS AND METHODS: A total of 102 cases were included in the study and divided into three subgroups: the first subgroup consisted of 62 cases with dental follicles of impacted teeth, the second included 20 cases of dentigerous cysts and the third subgroup comprised a number of 20 cases with keratocystic odontogenic tumors. Immunomarking with the four antibodies was performed. RESULTS: A positive marking was obtained in over 60% of the dental follicles for all markers. Statistically significant differences were also obtained in dentigerous cysts and keratocystic odontogenic tumors for Ki67, p53 and MCM3. Assessment of the four antibodies in the two layers of keratocystic odontogenic tumors shows a positive correlation between Ki67 and MCM3 both for the basal and parabasal layer, with slightly increased values in the latter. CONCLUSIONS: In order to determine the proliferative capacity of epithelial remnants in the dental follicles, Ki67 and PCNA, Ki67 and MCM3 are the most useful markers in practice; they have similar behavior and are more likely to help in distinguishing between dentigerous cysts and keratocystic odontogenic tumors.

E-cadherin regulators are differentially expressed in the epithelium and stroma of keratocystic odontogenic tumors.

BACKGROUND: The epithelial-mesenchymal transition (EMT) is the process where cells lose their epithelial features and acquire properties of typical mesenchymal cells. The dissociation of tumor cells due to changes in cell-cell adhesion is one of the key principles of tumor invasion and EMT. Thus, the knowledge of the molecular features of EMT in keratocyst odontogenic tumor (KOT) can provide useful markers to aid in the diagnosis and prognosis and perhaps contribute to an alternative therapeutic approach as it shows an aggressive clinical behavior and high recurrence rates. This study aimed to evaluate the EMT in KOT by the immunoexpression of E-cadherin, N-cadherin, Snail, and Slug and comparing to radicular cysts and dental follicles. METHODS: Thirty-two KOTs, 15 radicular cysts, and 08 dental follicles were used for immunohistochemistry, evaluating the extent, intensity, labeling pattern, cellular compartment in the epithelium and stroma, and the presence of inflammation. RESULTS: E-cadherin was preserved in most cases of keratocystic odontogenic tumor. N-cadherin was increased in the tumor epithelium, a result that was positively correlated with the heterogeneous and nuclear immunoexpression of Slug in the epithelium; Slug also correlated with high Snail immunoexpression. N-cadherin was positively correlated with Slug in the stroma of keratocystic odontogenic tumors. CONCLUSIONS: The high immunoexpression of Snail and nuclear Slug in keratocystic odontogenic tumors suggests these proteins as transcription factors without necessarily participating in 'cadherin switching'. However, the knowledge of their induction of the epithelial-mesenchymal transition in odontogenic tumors is still limited.

Immunohistochemical expression of matrix metalloproteinases in ameloblastomas and pericoronal follicles.

BACKGROUND: Ameloblastoma (AM) is a benign odontogenic neoplasm characterized by local invasiveness and recurrence. We compared the immunohistochemical expression of matrix metalloproteinases in different clinical types of AM as well as in normal odontogenic tissue. METHODS: Thirteen cases of solid AMs, five cases of unicystic AM and eight pericoronal follicles (PF) were selected and subjected to immunohistochemical investigation for matrix metalloproteinase-1, matrix metalloproteinase-2 and matrix metalloproteinase-9 expressions. RESULTS: The expressions of MMP-1 and MMP-2 were very high in the cytoplasm of cells throughout the entire epithelium and in fibroblasts from the adjacent connective tissue. MMP-9 expression was observed in the same location although with weaker staining. The Kruskal-Wallis test showed statistically significant differences in the epithelial expressions of MMP-1 and MMP-2; there was lower expression among solid AMs when compared with unicystic AM and PF. Compared to both types of AM, higher stromal expression of MMP-9 was found in PF. CONCLUSION: MMP-1, MMP-2 and MMP-9 seem to be associated with AM tumour behaviour as well as physiological tissue remodelling within PF.

Role of hypoxia-related proteins in invasion of ameloblastoma cells: crosstalk between NOTCH1, hypoxia-inducible factor 1α, a disintegrin and metalloproteinase 12, and heparin-binding epidermal growth factor.

AIMS: Ameloblastoma AME is a benign tumour characterized by local invasiveness, high recurrence rates, and diverse histological patterns. The oxygen concentration is reduced in specific areas of the tumour microenvironment, which leads to intratumoral hypoxia. Crosstalk between NOTCH1, a disintegrin and metalloproteinase 12 (ADAM-12), hypoxia-inducible factor 1α (HIF-1α) and heparin-binding epidermal growth factor (HB-EGF) under hypoxic conditions has been implicated in invadopodia formation, tumour invasiveness, and metastasis development. The aim of this study was to analyse the expression of these proteins, in order to further elucidate the mechanisms underlying AME invasiveness. METHODS AND RESULTS: Twenty cases of AME, eight calcifying cystic odontogenic tumours CCOTs and 10 samples of dental follicle were used to investigate the expression of these proteins by immunohistochemistry with the primary antibodies anti-NOTCH1, anti-ADAM-12, anti-HIF-1α, and anti-HB-EGF. Immunostaining results were expressed as the percentage of stained area in images acquired in an AxioScope microscope equipped with an AxioCamHRc camera and a × 40 objective. The results showed that immunoexpression of all proteins was higher in the AME samples than in the CCOT and dental follicle samples (P < 0.05). CONCLUSIONS: AME showed an increased presence of proteins associated with tumour invasiveness, which indicates a possible role of these proteins in the biological behaviour of this tumour.

Dental Follicle Cells Participate in Tooth Eruption via the RUNX2-MiR-31-SATB2 Loop.

Cleidocranial dysplasia (CCD) is characterized by the runt-related transcription factor 2 (RUNX2) mutation, which results in delayed tooth eruption due to disturbed functions of dental follicle. Accumulating evidence has revealed a key regulatory circuit, including RUNX2, miR-31, and special AT-rich binding protein 2 (SATB2) acting in concert in mesenchymal stem cell homeostasis and functions. However, whether such a regulatory loop works in dental follicle cells (DFCs) remains unknown. Herein, we investigated the roles of RUNX2-miR-31-SATB2 in DFCs from patients with CCD (DFCs-CCD) to advance our understanding regarding physical tooth eruption. We identified a novel mutation on exon 5 (c.634T>G, p.T212P) in RUNX2 via exome sequencing in the CCD patient with typical clinical presentations. Compared with DFCs from healthy donors, DFCs-CCD displayed significantly lower osteogenic, osteoclast-inductive, and matrix-degrading capacities and had lower RUNX2 (a transcriptional inhibitor of miR-31), higher miR-31, and downregulated SATB2. Lower ratios of RANKL/OPG and RANKL/RANK, as well as decreased expression of matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 2 (MMP2), would lead to inactivation of osteoclasts and suppression of bone matrix remodeling in DFCs-CCD. Furthermore, the roles of the RUNX2-miR-31-SATB2 loop in DFCs-CCD were revealed by endogenous miR-31 knockdown, which resulted in increased SATB2 and RUNX2, as well as osteoclast-inductive and matrix degradation capacities. Conversely, SATB2, RUNX2, MMP9, MMP2, and osteoclast-inductive factors expression declined upon ectopic miR-31 overexpression in normal DFCs. Importantly, neonatal mice with in vivo siRUNX2 delivery exhibited less activated osteoclasts around dental follicles and delayed tooth eruption. Together, these results suggest that RUNX2 mutation/haploinsufficiency disturbs osteoclast-inductive signaling in DFCs, which may be responsible for delayed tooth eruption in CCD patients. Manipulation of the RUNX2-miR-31-SATB2 loop may be a potential way to facilitate tooth eruption in CCD patients.