Guanghua School of Stomatology & Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, 510055, Guangdong, People's Republic of China.
Mol Immunol. 2019 Jul;111:11-18. doi: 10.1016/j.molimm.2019.03.012. Epub 2019 Apr 3.
Endodontic infection is a widespread oral problem. DNA methylation is a key epigenetic modification that plays important roles in various inflammatory responses, but its role in dental pulp inflammation is poorly understood. In this study, we assessed the expression of DNA methyltransferases (DNMTs) in human dental pulp cells (hDPCs) during lipopolysaccharide (LPS)-induced inflammation and found that DNMT3B mRNA expression was reduced and DNMT1 mRNA and protein levels decreased significantly. Pretreatment with the DNMT inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR) significantly enhanced the expression of the inflammatory cytokines IL-6 and IL-8 in LPS-stimulated hDPCs, indicating that DNA methylation may play a role in hDPC inflammation. Studies have reported that some microRNAs (miRNAs) are involved in dental pulp infection. DNA methylation can modulate the inflammatory response by regulating miRNA expression, but this phenomenon has not yet been reported in pulp inflammation. The present study used next-generation sequencing to examine the effect of 5-Aza-CdR on the miRNA expression profile of LPS-treated hDPCs, and the results showed that 5-Aza-CdR pretreatment changed the miRNA expression pattern in hDPCs during inflammation. Among the changed miRNAs, miR-146a-5p, which is a pulp inflammation-related miRNA, demonstrated the most noticeably altered expression. miR-146a-5p could be induced by LPS in hDPCs, and 5-Aza-CdR preincubation or DNMT1 knockdown markedly increased its expression level. However, no significant difference was found in the methylation pattern of the MIR146A promoter with 5-Aza-CdR pretreatment or DNMT1 knockdown in LPS-stimulated hDPCs. These results indicate that DNA methylation may regulate the LPS-induced inflammatory response by changing the miRNA expression in hDPCs.
牙髓感染是一种广泛存在的口腔问题。DNA 甲基化是一种关键的表观遗传修饰，在各种炎症反应中发挥着重要作用，但它在牙髓炎症中的作用还知之甚少。在本研究中，我们评估了 DNA 甲基转移酶 (DNMTs) 在脂多糖 (LPS) 诱导的人牙髓细胞 (hDPCs) 炎症中的表达，发现 DNMT3BmRNA 表达减少，DNMT1mRNA 和蛋白水平显著降低。DNMT 抑制剂 5-氮杂-2′-脱氧胞苷 (5-Aza-CdR) 预处理显著增强了 LPS 刺激的 hDPCs 中炎症细胞因子 IL-6 和 IL-8 的表达，表明 DNA 甲基化可能在 hDPC 炎症中发挥作用。已有研究报道，一些 microRNAs (miRNAs) 参与了牙髓感染。DNA 甲基化可以通过调节 miRNA 的表达来调节炎症反应，但这种现象在牙髓炎症中尚未报道。本研究使用下一代测序技术研究了 5-Aza-CdR 对 LPS 处理的 hDPCs 中 miRNA 表达谱的影响，结果表明 5-Aza-CdR 预处理改变了 hDPCs 在炎症过程中的 miRNA 表达模式。在改变的 miRNA 中，与牙髓炎症相关的 miR-146a-5p 表达变化最明显。miR-146a-5p 可被 LPS 诱导表达，5-Aza-CdR 预孵育或 DNMT1 敲低可显著增加其表达水平。然而，在 LPS 刺激的 hDPCs 中，用 5-Aza-CdR 预处理或 DNMT1 敲低后，MIR146A 启动子的甲基化模式没有明显差异。这些结果表明，DNA 甲基化可能通过改变 hDPCs 中的 miRNA 表达来调节 LPS 诱导的炎症反应。
