Hui Tianqian, A Peng, Zhao Yuan, Wang Chenglin, Gao Bo, Zhang Ping, Wang Jun, Zhou Xuedong, Ye Ling
State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
J Endod. 2014 Aug;40(8):1132-8. doi: 10.1016/j.joen.2014.01.031. Epub 2014 Apr 16.
Dental pulp has limited capability to regenerate, which happens in the early stage of pulpitis. An ambiguous relationship exists; inflammation may impair or support pulp regeneration. Epigenetics, which is involved in cell proliferation and inflammation, could regulate human dental pulp cell (HDPCs) regeneration. The aim of this study was to determine the role of the epigenetic mark, enhancer of zeste homolog 2 (EZH2), in the inflammation, proliferation, and regeneration of dental pulp. We used trimethylated histone H3 lysine 27(H3K27me3) and its lysine demethylase 6B (KDM6B) to monitor functional effects of altered EZH2 levels.
We detected epigenetic marks (EZH2, H3K27me3, and KDM6B) in pulp tissue by immunohistochemistry and immunofluorescence. EZH2 levels in HDPCs in inflammatory responses or differentiation were analyzed by quantitative polymerase chain reaction and Western blot. Quantitative polymerase chain reaction was used to assess the effects of EZH2 inhibition on interleukins in HDPCs upon tumor necrosis factor alpha stimulation. Cell proliferation was tested by cell counting kit-8, cell cycle, and apoptosis analysis. HDPC differentiation was investigated by quantitative polymerase chain reaction, alkaline phosphatase activity, and oil red O staining.
EZH2 and H3K27me3 were decreased, whereas KDM6B was increased in infected pulp tissue and cells, which were similar to HDPC differentiation. EZH2 inhibition suppressed IL-1b, IL-6, and IL-8 messenger RNA (mRNA) in HDPCs upon inflammatory stimuli and impeded HDPC proliferation by decreasing cell number, arresting cell cycle, and increasing apoptosis. Suppressed EZH2 impaired adipogenesis, peroxisome proliferator-activated receptor r (PPAR-r), and CCAAT-enhancer binding protein a (CEBP/a) mRNA in adipogenic induction while enhancing alkaline phosphatase activity, Osx, and bone sialoprotein (BSP) mRNA in mineralization induction of HDPCs.
EZH2 inhibited HDPC osteogenic differentiation while enhancing inflammatory response and proliferation, suggesting its role in pulp inflammation, proliferation, and regeneration.
牙髓的再生能力有限，这种情况发生在牙髓炎的早期。存在一种不明确的关系；炎症可能损害或促进牙髓再生。涉及细胞增殖和炎症的表观遗传学可以调节人牙髓细胞（HDPCs）的再生。本研究的目的是确定表观遗传标记物——zeste同源物2增强子（EZH2）在牙髓炎症、增殖和再生中的作用。我们使用三甲基化组蛋白H3赖氨酸27（H3K27me3）及其赖氨酸去甲基化酶6B（KDM6B）来监测EZH2水平改变的功能影响。
我们通过免疫组织化学和免疫荧光检测牙髓组织中的表观遗传标记物（EZH2、H3K27me3和KDM6B）。通过定量聚合酶链反应和蛋白质免疫印迹分析炎症反应或分化过程中HDPCs中的EZH2水平。定量聚合酶链反应用于评估EZH2抑制对肿瘤坏死因子α刺激后HDPCs中白细胞介素的影响。通过细胞计数试剂盒-8、细胞周期和凋亡分析来检测细胞增殖。通过定量聚合酶链反应、碱性磷酸酶活性和油红O染色来研究HDPCs的分化。
在感染的牙髓组织和细胞中，EZH2和H3K27me3水平降低，而KDM6B水平升高，这与HDPCs的分化情况相似。EZH2抑制在炎症刺激后抑制了HDPCs中IL-1β、IL-6和IL-8信使核糖核酸（mRNA）的表达，并通过减少细胞数量、阻滞细胞周期和增加凋亡来阻碍HDPCs的增殖。EZH2抑制在脂肪生成诱导中损害脂肪生成、过氧化物酶体增殖物激活受体γ（PPAR-γ）和CCAAT增强子结合蛋白α（CEBP/α）mRNA的表达，而在HDPCs的矿化诱导中增强碱性磷酸酶活性、Osx和骨唾液蛋白（BSP）mRNA的表达。
EZH2抑制HDPCs的成骨分化，同时增强炎症反应和增殖，表明其在牙髓炎症、增殖和再生中的作用。
