Extracellular DNA (ecDNA) is a potential marker and predictor in several inflammatory diseases. Periodontitis, a chronic inflammatory disease, is associated with epithelial cell death and could lead to release of DNA. Our aim was to analyze salivary DNA concentration and deoxyribonuclease (DNase) activity in periodontitis patients. We hypothesized that salivary ecDNA will be higher than in controls and could serve as a marker of periodontitis severity. Samples of saliva were collected from 25 patients with chronic periodontitis and 29 age-matched controls. DNA was quantified fluorometrically in whole saliva, as well as in supernatants after centrifugation (depletion of cells at 1600× g) and in double-centrifuged supernatants (depletion of cell debris at 1600× g and 16,000× g). The subcellular origin of ecDNA was assessed using real-time PCR. In comparison to controls, patients with periodontitis had twofold higher salivary DNA (p < 0.01), higher mitochondrial DNA in centrifuged supernatants (p < 0.05) and lower nuclear ecDNA in double-centrifuged samples (p < 0.05). No correlations were found between salivary DNA and oral health status, but mitochondrial DNA positively correlated with papillary bleeding index in centrifuged samples. Salivary DNase activity was comparable between the groups. In conclusion, we proved that salivary DNA is higher in periodontitis. The source of the higher mitochondrial DNA in cell-free saliva and the causes of lower nuclear ecDNA remain to be elucidated. Further studies should focus on the role of mitochondrial DNA as a potential driver of inflammation in periodontitis.

中文翻译：

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牙周炎患者唾液细胞外DNA和DNA酶活性

细胞外DNA（ecDNA）是几种炎症性疾病的潜在标志物和预测因子。牙周炎是一种慢性炎性疾病，与上皮细胞死亡有关，并可能导致DNA释放。我们的目的是分析牙周炎患者唾液中的DNA浓度和脱氧核糖核酸酶（DNase）活性。我们假设唾液ecDNA的含量将高于对照组，并且可以作为牙周炎严重程度的标志。从25位慢性牙周炎患者和29位年龄匹配的对照组中收集唾液样本。对整个唾液，离心后的上清液（1600× g的细胞耗竭）和双倍离心的上清液（1600× g和16,000×的细胞碎片耗竭）中的DNA进行荧光定量分析。g）。ecDNA的亚细胞起源使用实时PCR进行评估。与对照组相比，牙周炎患者的唾液DNA高两倍（p <0.01），离心上清液的线粒体DNA高（p <0.05），而双重离心样品的核ecDNA较低（p<0.05）。唾液DNA与口腔健康状况之间未发现相关性，但在离心样品中线粒体DNA与乳头出血指数呈正相关。两组之间的唾液DNase活性相当。总之，我们证明了牙周炎中唾液DNA较高。无细胞唾液中较高线粒体DNA的来源以及较低核ecDNA的原因尚待阐明。进一步的研究应集中于线粒体DNA作为牙周炎炎症潜在驱动因素的作用。