Comparison of miRNA expression profiles in individuals with chronic or aggressive periodontitis

OBJECTIVES

MicroRNAs (miRNAs) may play an important role in inflammatory response. However, the involvement of miRNAs in the pathogenesis of periodontitis is unclear. The present study aimed to compare the miRNA expression profiles in individuals with chronic (CP) or aggressive (AP) periodontitis.

MATERIALS AND METHODS

Eighteen non-smoker individuals (CP = 9 and AP = 9) without any history of systemic diseases or previous periodontal therapies were selected at the Clinics of Periodontology from the Federal University of Minas Gerais. Gingival tissue samples were collected during the initial periodontal therapy. miRNAs were isolated, and expression patterns of 754 miRNAs were assessed with a quantitative miRNA PCR array. miRNAs expression profiles were compared between CP and AP groups.

RESULTS

There were no differences observed in the miRNAs expression profiles between CP and AP (p > 0.05). According to the microarray analyses, the most expressed miRNAs in both groups were hsa-miR-1274b, hsa-let-7b-5p, hsa-miR-24-3p, hsa-miR-19b-3p, hsa-miR-720, hsa-miR-126-3p, hsa-miR-17-3p and hsa-miR-21-3p.

CONCLUSION

Findings suggested no differences in miRNAs expression profiles between chronic and aggressive forms of periodontitis. The overexpression of specific miRNAs could provide insights into the pathogenesis of both forms of the disease.

MicroRNA profiling reveals dysregulated microRNAs and their target gene regulatory networks in cemento-ossifying fibroma

BACKGROUND

Cemento-ossifying fibroma (COF) is a benign fibro-osseous neoplasm of uncertain pathogenesis, and its treatment results in morbidity. MicroRNAs (miRNA) are small non-coding RNAs that regulate gene expression and may represent therapeutic targets. The purpose of the study was to generate a comprehensive miRNA profile of COF compared to normal bone. Additionally, the most relevant pathways and target genes of differentially expressed miRNA were investigated by in silico analysis.

METHODS

Nine COF and ten normal bone samples were included in the study. miRNA profiling was carried out by using TaqMan® OpenArray® Human microRNA panel containing 754 validated human miRNAs. We identified the most relevant miRNAs target genes through the leader gene approach, using STRING and Cytoscape software. Pathways enrichment analysis was performed using DIANA-miRPath.

RESULTS

Eleven miRNAs were downregulated (hsa-miR-95-3p, hsa-miR-141-3p, hsa-miR-205-5p, hsa-miR-223-3p, hsa-miR-31-5p, hsa-miR-944, hsa-miR-200b-3p, hsa-miR-135b-5p, hsa-miR-31-3p, hsa-miR-223-5p and hsa-miR-200c-3p), and five were upregulated (hsa-miR-181a-5p, hsa-miR-181c-5p, hsa-miR-149-5p, hsa-miR-138-5p and hsa-miR-199a-3p) in COF compared to normal bone. Eighteen common target genes were predicted, and the leader genes approach identified the following genes involved in human COF: EZH2, XIAP, MET and TGFBR1. According to the biology of bone and COF, the most relevant KEGG pathways revealed by enrichment analysis were proteoglycans in cancer, miRNAs in cancer, pathways in cancer, p53-, PI3K-Akt-, FoxO- and TGF-beta signalling pathways, which were previously found to be differentially regulated in bone neoplasms, odontogenic tumours and osteogenesis.

CONCLUSION

miRNA dysregulation occurs in COF, and EZH2, XIAP, MET and TGFBR1 are potential targets for functional analysis validation.

Expression, polymorphism and methylation pattern of interleukin-6 in periodontal tissues

Periodontitis is considered an inflammatory disorder of bacterial etiology that results in periodontal tissue destruction, as a result of complex interactions between periodontal pathogens, host and immune response. Genetic and epigenetic mechanisms may modulate the individual response since it is able to influence the gene expression. The aim of this study was to evaluate the impact of -174 G/C polymorphism and the methylation status of the promoter region of IL-6 gene on the expression of IL-6 in gingival samples from individuals with chronic periodontitis. Gingival biopsies were collected from 21 patients with chronic periodontitis and 21 controls. Histologic sections stained by hematoxylin-eosin were used for histopathological evaluation. The IL-6 gene expression was assessed by quantitative real-time PCR. The polymorphism IL-6 -174 C/G was studied by polymerase chain reaction (PCR) amplification and restriction endonuclease digestion (HspII). Methylation-specific polymerase chain reaction was used to verify the DNA methylation pattern. The number of inflammatory cells in tissue fragments from individuals with chronic periodontitis was higher than in the control group and the inflammatory infiltrate was predominantly mononuclear. The expression of IL-6 was higher in the group with periodontitis. In polymorphism assay, no statistical difference in the distribution of genotypes and alleles in both groups were observed. The most of samples were partially methylated. No difference was observed in methylation pattern from two different regions of the IL-6 gene among groups. The high expression of IL-6 is an important factor related to chronic periodontitis, but was not associated with methylation status or the -174 (G/C) genetic polymorphism, suggesting that other mechanisms are involved in this gene transcription regulation.

Oral cGVHD screening tests in the diagnosis of systemic chronic graft-versus-host disease

To determine the diagnostic properties of oral manifestations and histological features of graft-versus-host disease (GVHD) screening tests in the diagnosis of systemic chronic graft-versus-host disease (cGVHD). Sixty patients having undergone allogeneic haematopoietic stem cell transplantation were selected. The patients were submitted to a clinical oral examination to assess symptoms and clinical changes in the oral mucosa. Histopathologic analysis of the lower lip oral mucosa (LLOM) and salivary glands (SG) was also performed. Systemic cGVHD was used for a comparison to oral cGVHD. The accuracy of oral cGVHD tests was low for all methods (58.4% and 52.6% for white lesions and white/red lesions, respectively, in the clinical analysis; 50.4% for the presence of oral pain; and 66.8% and 55.1% for LLOM and SG histopathologic tests, respectively). However, the presence of oral pain had good diagnostic properties [specificity: 100.0, 95% confidence interval (CI): 88.0-100.0; positive predictive value (PPV): 100.0, 95% CI: 94.4-100.0; and negative predictive value (NPV): 72.0, 95% CI: 57.3-83.3]. Moreover, SG alterations revealed by the histopathological analysis also exhibited good diagnostic properties (sensitivity: 98.6, 95% CI: 81.5-99.8; PPV: 71.1, 95% CI: 62.1-79.7; NPV: 85.9 95% CI: 32.9-99.4). The clinical severity of oral lesions and histophatological changes in the LLOM did not exhibit adequate diagnostic properties, whereas both oral pain and SG histopathological analysis exhibited adequate properties for the diagnosis of systemic cGVHD. Histological changes in lip oral mucosa and salivary glands together with a clinical manifestation of the disease in the oral mucosa can be useful to determining the systemic cGVHD.

Hypomethylation of tumor suppressor genes in odontogenic myxoma

Odontogenic myxoma (OM) is an ectomesenchymal benign odontogenic tumor characterized by spindle or stellate-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. DNA methylation is characterized by the addition of methyl groups in cytosines within CpG islands in the promoter gene. DNA methylation can decrease the expression of tumor suppressor genes and contribute to the development of neoplastic lesions. The aim of study was to evaluate the methylation pattern of the tumor suppressor genes P16 (CDKN2A), P21 (CDKN1A), P27 (CDKN1B), P53 (TP53) and RB1 in OM and dental pulp. Methylation was evaluated using methylation-specific polymerase chain reaction (PCR). The transcription was studied in some cases by using reverse transcription quantitative PCR. A higher frequency of unmethylated P27, P53, and RB1 samples was observed in the OM when compared with the dental pulp. OM expressed mRNA of all the genes evaluated. Considering all the samples together, the expression of Rb was higher in the unmethylated samples compared with the partially methylated samples. This investigation revealed hypomethylation of the genes P27, P53, and RB1 in OM. In addition, methylation of tumor suppressor genes was found to be an usual event in normal dental pulp.

Methylation pattern of the IFN-gamma gene in human dental pulp

INTRODUCTION

DNA methylation is characterized by the addition of methyl groups in cytosines within cytosine-phosphate-guanine (CpG) islands. Unmethylated islands are related with transcriptionally active structure, whereas methylated DNA recruits methyl-binding proteins that promotes chromatin compaction. Although epigenetic events can influence the expression of cytokines, such events have not been investigated in dental pulp yet. The purpose of the present study was to evaluate the methylation status of the interferon gamma (IFN-gamma) gene in human dental pulp affected by inflammation compared with pulp tissue of impacted molar teeth and to verify the impact of methylation status in the expression pattern of the gene.

METHODS

Methylation-specific polymerase chain reaction (MSP) was used to verify the DNA methylation status of the IFN-gamma gene in 16 human dental pulps affected by inflammation and in 16 pulp samples of impacted molar teeth. Histologic sections stained by hematoxylin-eosin were used for histopathological evaluation, and the expression of IFN-gamma was assessed by quantitative real-time PCR (qPCR).

RESULTS

Although total methylation was observed in 43.75% of the samples of normal dental pulp tissues, partial methylation or unmethylation was found in 93.75% of the samples of inflamed pulp tissues. All the samples with total methylation in MSP showed no transcription of IFN-gamma. The qPCR results showed expression of IFN-gamma in 5 of 10 samples with partial methylation.

CONCLUSION

The present study gives the first evidence of the possible participation of epigenetic events in the development of dental pulp inflammation.

Reduced expression of mir15a in the blood of patients with oral squamous cell carcinoma is associated with tumor staging

MicroRNAs (miRNAs) mir15a and let7a are important regulators of bcl-2, ras and c-myc proteins. Considering that these miRNAs are commonly altered in many human cancers and that these proteins are reported to be altered in oral squamous cell carcinoma (OSCC), we investigated them in a set of OSCC cases. The miRNAs as well as the proteins were evaluated in the tumor and blood of 20 patients by real-time quantitative PCR and immunohistochemistry, respectively. The expression of mir15a and bcl-2 proteins in the tumors was not associated with each other or with tumor staging. On the other hand, we found reduced expression of this miRNA in the blood of patients with an advanced stage of OSCC and with lymph node metastasis. The expression of let7a in the tumor and blood was not associated with tumor size, lymph node metastasis, tumor staging and immunoexpression of ras and c-myc proteins. In conclusion, the present study shows that reduced expression of mir15a is associated with OSCC staging.

DNA methyltransferase expression in odontogenic cysts and tumours

Epigenetic silencing of gene expression by promoter CpG island hypermethylation is promoted by the enzymes, DNA methyltransferases (DNMTs). DNMT3a is mainly involved in de novo methylation, whereas DNMT1 acts mainly as a maintenance methyltransferase. The purpose of this study was to investigate the immunoexpression of DNMT1 and DNMT3a in a set of odontogenic cysts and tumours. Formalin-fixed and paraffin-embedded tissue samples of eight radicular cysts, 10 odontogenic keratocysts (OKC), eight adenomatoid odontogenic tumours (AOT), 16 ameloblastomas and eight samples of normal mucosae were included in the study. The DNMT1 and DNMT3a proteins were identified by using a highly sensitive polymer-based system. We found that the normal oral mucosa, OKC, AOT, radicular cyst and ameloblastomas samples showed a widespread nuclear and cytoplasmic immunopositivity for DNMT1. Some radicular cysts, ameloblastomas, AOT and OKC samples presented a positive cytoplasmic reaction for DNMT3a, while negative staining was observed in the normal oral mucosa. Nuclear positivity was found only in the suprabasal cell layers of three OKC samples. Our study shows an increased expression of DNMT3a in odontogenic cysts and tumours, confirming that epigenetic mechanisms are involved in the development of these tumours.