Department of Periodontology, University of North Carolina, Chapel Hill, NC, USA.
J Clin Periodontol. 2010 Nov;37(11):953-61. doi: 10.1111/j.1600-051X.2010.01616.x.
The goal of this investigation was to determine whether epigenetic modifications in the IFNG promoter are associated with an increase of IFNG transcription in different stages of periodontal diseases.
DNA was extracted from gingival biopsy samples collected from 47 total sites from 47 different subjects: 23 periodontally healthy sites, 12 experimentally induced gingivitis sites and 12 chronic periodontitis sites. Levels of DNA methylation within the IFNG promoter containing six CpG dinucleotides were determined using pyrosequencing technology. Interferon gamma mRNA expression was analysed by quantitative polymerase chain reactions using isolated RNA from part of the biological samples mentioned above.
The methylation level of all six analysed CpG sites within the IFNG promoter region in the periodontitis biopsies {52% [interquartile range, IQR (43.8%, 63%)]} was significantly lower than periodontally healthy samples {62% [IQR (51.3%, 74%)], p=0.007} and gingivitis biopsies {63% [IQR (55%, 74%)], p=0.02}. The transcriptional level of IFNG in periodontitis biopsies was 1.96-fold and significantly higher than tissues with periodontal health (p=0.04). Although the mRNA level from experimental gingivitis samples exhibited an 8.5-fold increase as compared with periodontally healthy samples, no significant methylation difference was observed in experimental gingivitis sample.
A hypomethylation profile within IFNG promoter region is related to an increase of IFNG transcription present in the chronic periodontitis biopsies, while such an increase of IFNG in experimentally induced gingivitis seems independent of promoter methylation alteration.
本研究旨在探讨干扰素γ（IFNG）启动子的表观遗传修饰是否与牙周病不同阶段 IFNG 转录的增加有关。
从 47 名受试者的 47 个不同部位的牙龈活检样本中提取 DNA：23 个牙周健康部位、12 个实验性龈炎部位和 12 个慢性牙周炎部位。采用焦磷酸测序技术测定 IFNG 启动子内包含六个 CpG 二核苷酸的 DNA 甲基化水平。采用定量聚合酶链反应（PCR）分析上述部分生物样本中分离的 RNA 中干扰素γ mRNA 的表达。
在牙周炎活检样本中，IFNG 启动子区域内六个分析 CpG 位点的甲基化水平{52% [四分位距（IQR）（43.8%，63%）]}明显低于牙周健康样本{62% [IQR（51.3%，74%）]，p=0.007}和龈炎活检样本{63% [IQR（55%，74%）]，p=0.02}。牙周炎活检样本中 IFNG 的转录水平是牙周健康组织的 1.96 倍，且明显升高（p=0.04）。尽管实验性龈炎样本的 IFNG mRNA 水平与牙周健康样本相比表现出 8.5 倍的增加，但在实验性龈炎样本中未观察到启动子甲基化的显著差异。
IFNG 启动子区域内的低甲基化谱与慢性牙周炎活检样本中 IFNG 转录的增加有关，而实验性龈炎中 IFNG 的增加似乎与启动子甲基化改变无关。
