Periodontitis lesions at teeth with advanced attachment and bone loss exhibit quantitative and qualitative differences in relation to gingivitis lesions at teeth with no attachment and bone loss. It is suggested that the large number and high density of plasma cells are the hallmarks of advanced periodontitis lesions and the most conspicuous difference in relation to long-standing gingivitis lesions.
Epigenetic modifications of DNA and its associated proteins influence gene expression. The -1087 interleukin-10 (IL10) gene polymorphism is associated with differences in IL10 expression. The objectives of this study were to analyze the effect of DNA methylation and histone modifications on IL10 gene expression, the differences in epigenetic modifications between GG and AA genotypes of the -1087 IL10 gene polymorphism, and the methylation pattern in the region close to the -1087 position. Using B cells obtained from subjects with GG and AA genotypes we demonstrated that treatment with histone deacetylase inhibitors and 5-aza-2-deoxycytidine resulted in an increase in the production of IL10 mRNA. The chromatin immunoprecipitation assay revealed that stimulation with lipopolysaccharide resulted in a higher fold increase in the acetylation of histone H4 and in the methylation of histone H3 for GG genotype cells than for AA genotype cells. The increase in acetylation of histone H3 was larger for AA genotype cells than for GG genotype cells. For unstimulated cells the acetylation and methylation of histone H3 were higher for GG genotype cells than for AA genotype cells, while AA genotype cells had a higher increase in acetylation of histone H4. DNA methylation assays revealed that the three CpG sites distal to the -1087 site were methylated in blood cells and gingival tissues.
DNA methylation is an important epigenetic mechanism involved in the regulation of gene expression, and a reduction in DNA methylation influences cell-cycle progression and cell differentiation in inflammatory cells. The aim of the present study was to analyze the DNA-methylation pattern at local and global/systemic levels in patients with periodontitis and gingivitis. Twenty-one subjects with generalized, severe periodontitis and 17 subjects with gingival inflammation but no attachment loss were recruited. Gingival biopsies and peripheral blood samples were collected and prepared for immunohistochemical analysis of 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), ten-eleven translocation 2 (TET2), and DNA methyltransferase 1 (DNMT1). Whilst a similar pattern for 5mC and 5hmC DNA methylation was found in both types of lesions, a significantly larger proportion of TET2-positive cells was found in periodontitis lesions than in gingivitis lesions. Quantitative real-time PCR analysis showed no differences between gingivitis and periodontitis lesions regarding expression of TET2 and isocitrate dehydrogenase (IDH) genes, while the global level of 5hmC was significantly higher in blood than in tissue in patients with periodontitis. It is suggested that epigenetic changes are more common in periodontitis lesions than in gingivitis lesions and that such changes are tissue specific.
Background
T helper17 cells (Th17) are key targets in the evaluation of differences between “destructive” and “non‐destructive” periodontal lesions. The aim of the present study was to analyze the density of interleukin‐17 (IL‐17) producing T cells and IL‐17 mRNA expression in lesions representing severe periodontitis and longstanding gingivitis.
Methods
Two groups of patients were recruited. The gingivitis group consisted of 28 patients, 41–70 years old, with evident signs of gingival inflammation but no attachment loss. The periodontitis group consisted of 36 patients, 33–67 years of age. A gingival biopsy was obtained from one selected diseased site from each patient and prepared for immunohistochemical and reverse transcription, quantitative polymerase chain reaction (RT‐qPCR) analysis.
Results
Although the density of CD3 positive cells (T cells) did not differ between the two types of lesions, the total number and density of cells positive for CD3+CD161 (IL‐17‐producing T‐cells) were larger in periodontitis than in long‐standing gingivitis lesions. About 30% of CD3‐cells in periodontitis lesions were also positive for CD161. The corresponding figure for gingivitis samples was 15%. Analysis of covariance (ANCOVA) analysis revealed that differences between periodontitis and gingivitis samples remained after adjusting for smoking, age, and gender. In addition, males had larger proportions of IL‐17 producing T cells than females in both groups. The IL‐17 mRNA expression was higher in periodontitis than in gingivitis samples.
Conclusion
It is suggested that IL‐17 producing T cells represent a significant feature in the detection of differences between destructive and non‐destructive lesions.
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