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.

Methylation pattern of IFN-γ and IL-10 genes in periodontal tissues.

UNLABELLED: DNA methylation is characterized by the addition of methyl groups in cytosines within CpG islands. Unmethylated CpGs are related to transcriptionally active structure, whereas methylated CpG recruits methyl-binding proteins that promote chromatin compaction. DNA methylation can influence the expression of cytokines and affect the development of periodontal disease. OBJECTIVES: The purpose of the present study was to evaluate the methylation status of the interferon gamma (IFN-γ) and interleukin-10 (IL-10) genes in periodontal tissues. DESIGN: Methylation-specific polymerase chain reaction (MSP) and DNA sequencing analysis were used to verify the DNA methylation status of the IFN-γ and IL-10 genes, respectively, in samples from subjects without periodontitis and individuals with chronic periodontitis. Histological sections stained by hematoxylin-eosin were used for histopathological evaluation of samples. RESULTS: The methylation status of the IFN-γ and IL-10 genes was similar among the groups. Most of the samples were positive for IFN-γ methylation. Only 11% of the periodontitis group showed unmethylated DNA. Considering the IL-10 gene, no unmethylated sample was observed. The profile of total or partial methylation was detected in CpGs evaluated. CONCLUSIONS: The results showed evidence that methylation of IFN-γ and IL-10 genes is a usual feature on periodontal tissues. Further studies are needed to determine the functional relevance of these alterations.

Gingival overgrowth in cyclosporine, tacrolimus, or sirolimus-based immunosuppressive regimens and the single nucleotide IL-6 (-174 G/C) gene polymorphism.

OBJECTIVE: Interleukin-6 (IL-6) may be involved in drug-induced gingival overgrowth (GO). The present study was conducted to assess the association between IL-6 (-174 G/C) gene polymorphism and GO in renal transplant recipients under cyclosporine (CsA), tacrolimus (Tcr), or sirolimus (Sir)-based regimens. METHODS: Within an eligible population, 45 unrelated subjects were selected for each CsA, Tcr, and Sir group, totaling a sample of 135 subjects. GO was visually assessed and subjects were assigned as controls (non-responders) or cases (responders) in a post hoc definition. IL-6 gene polymorphism was assessed using the polymerase chain reaction amplification and digestion. The distribution of genotypes and allele frequencies in responders and non-responders were compared using the Chi-squared test. RESULTS: The number of responders was 27 (60.0%), 13 (28.9%), and 7 (15.6%) in the CsA, Tcr, and Sir groups, respectively. No differences could be observed at frequencies of -174GG, -174CG, and -174CC genotypes when comparing responders to non-responders in the CsA, Tcr, and Sir groups. Similar to genotypes, allele frequencies showed no differences between responders and non-responders in all groups. CONCLUSIONS: No association between IL-6 (-174 G/C) gene polymorphism and gingival overgrowth was observed in renal transplant recipients under CsA, Tcr, or Sir-based immunosuppressive maintenance regimens.

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.

Molecular alterations in the tumor suppressor gene WWOX in oral leukoplakias.

Oral leukoplakia is the most prevalent and potentially malignant disorder of the oral mucosa. Previous studies have demonstrated that molecular changes of the WWOX gene (WW-domain containing oxidoreductase), a candidate tumor suppressor gene located at 16q23.3-24.1 that spans FRA16D, the second most common fragile site, are present in several malignant neoplasias, including oral squamous cell carcinoma. In this report, the role of the WWOX gene was investigated in 23 cases of oral leukoplakias. Using nested RT-PCR and immunohistochemistry, altered mRNA transcription and/or reduced Wwox protein expression was observed in 35% of the lesions when compared with normal mucosa. The majority of lesions (4/6) with altered transcripts had a reduction in the expression of Wwox protein. Although normal WWOX expression was found in some lesions with dysplasia, all lesions with WWOX mRNA and/or protein expression showed histological evidence of dysplasia and none of the cases without dysplasia presented this alteration. These results show that the WWOX gene alteration is an early genetic alteration and may contribute to oral carcinogenesis.