MyD88 hypermethylation mediated by DNMT1 is associated with LTA-induced inflammatory response in human odontoblast-like cells

  • Runsha Meng
  • Di Li
  • Zhihui Feng
  • Qiong XuEmail author
Regular Article


Dental caries is a chronic, infectious, and destructive disease that allows bacteria to break into the dental pulp tissue. As caries-related bacteria invade the human dentinal tubules, odontoblasts are the first line of dental pulp that trigger the initial inflammatory and immune responses. DNA methylation is a key epigenetic modification that plays a fundamental role in gene transcription, and its role in inflammation-related diseases has recently attracted attention. However, whether DNA methylation regulates the inflammatory response of human odontoblasts is still unknown. In the present study, we investigated the expression of DNA methyltransferase (DNMT)-1 in lipoteichoic acid (LTA)-stimulated human odontoblast-like cells (hOBs) and found that DNMT1 expression showed a decline that is contrary to the transcription of inflammatory cytokines. Knockdown of the DNMT1 gene increased the expression of several cytokines, including IL-6 and IL-8, in the LTA-induced inflammatory response. DNMT1 knockdown increased the phosphorylation of IKKα/β, IκBα, and p65 in the NF-κB pathway and the phosphorylation of p38 and ERK in the MAPK pathway; however, only the NF-κB pathway inhibitor PDTC suppressed both IL-6 and IL-8 expression, whereas inhibitors of the MAPK pathway (U0126, SB2035580, and SP600125) did not. Furthermore, DNMT1 knockdown upregulated the expression of MyD88 and TRAF6 but only attenuated the MyD88 gene promoter methylation in LTA-treated hOBs. Taken together, these results demonstrated that DNMT1 depletion caused hypomethylation and upregulation of MyD88, which resulted in activation of the NF-κB pathway and the subsequent release of LTA-induced inflammatory cytokines in hOBs. This study emphasizes the critical role of DNA methylation in the immune defense of odontoblasts when dental pulp reacted to caries.


DNA methylation DNMT1 Human odontoblast-like cells Inflammation Lipoteichoic acid Myeloid differentiation primary response gene 88 



This work was financially supported by the National Natural Science Foundation of China (81771058).

Compliance with ethical standards

Conflict of interest

The authors confirm that there are no conflicts of interest.


  1. Adcock IM, Tsaprouni L, Bhavsar P, Ito K (2007) Epigenetic regulation of airway inflammation. Curr Opin Immunol 19:694–700CrossRefGoogle Scholar
  2. Afgar A, Fard-Esfahani P, Mehrtash A, Azadmanesh K, Khodarahmi F, Ghadir M, Teimoori-Toolabi L (2016) MiR-339 and especially miR-766 reactivate the expression of tumor suppressor genes in colorectal cancer cell lines through DNA methyltransferase 3B gene inhibition. Cancer Biol Ther 17:1126–1138CrossRefGoogle Scholar
  3. Backdahl L, Bushell A, Beck S (2009) Inflammatory signalling as mediator of epigenetic modulation in tissue-specific chronic inflammation. Int J Biochem Cell Biol 41:176–184CrossRefGoogle Scholar
  4. Bardag-Gorce F, Li J, Oliva J, Lu SC, French BA, French SW (2010) The cyclic pattern of blood alcohol levels during continuous ethanol feeding in rats: the effect of feeding S-adenosylmethionine. Exp Mol Pathol 88:380–387CrossRefGoogle Scholar
  5. Benakanakere M, Abdolhosseini M, Hosur K, Finoti LS, Kinane DF (2015) TLR2 promoter hypermethylation creates innate immune dysbiosis. J Dent Res 94:183–191CrossRefGoogle Scholar
  6. de Camargo Pereira G, Guimaraes GN, Planello AC, Santamaria MP, de Souza AP, Line SR, Marques MR (2013) Porphyromonas gingivalis LPS stimulation downregulates DNMT1, DNMT3a, and JMJD3 gene expression levels in human HaCaT keratinocytes. Clin Oral Investig 17:1279–1285CrossRefGoogle Scholar
  7. Carrouel F, Staquet MJ, Keller JF, Baudouin C, Msika P, Bleicher F, Alliot-Licht B, Farges JC (2013) Lipopolysaccharide-binding protein inhibits toll-like receptor 2 activation by lipoteichoic acid in human odontoblast-like cells. J Endod 39:1008–1014CrossRefGoogle Scholar
  8. Cheng C, Huang C, Ma TT, Bian EB, He Y, Zhang L, Li J (2014) SOCS1 hypermethylation mediated by DNMT1 is associated with lipopolysaccharide-induced inflammatory cytokines in macrophages. Toxicol Lett 225:488–497CrossRefGoogle Scholar
  9. Couble ML, Farges JC, Bleicher F, Perrat-Mabillon B, Boudeulle M, Magloire H (2000) Odontoblast differentiation of human dental pulp cells in explant cultures. Calcif Tissue Int 66:129–138CrossRefGoogle Scholar
  10. De Oliveira NF, Andia DC, Planello AC, Pasetto S, Marques MR, Nociti FH Jr, Line SR, De Souza AP (2011) TLR2 and TLR4 gene promoter methylation status during chronic periodontitis. J Clin Periodontol 38:975–983CrossRefGoogle Scholar
  11. Durand SH, VFAR (2006) Lipoteichoic acid increases TLR and functional chemokine expression while reducing dentin formation in in vitro differentiated human odontoblasts. J Immunol 176:2880–2887CrossRefGoogle Scholar
  12. Farges JC, Carrouel F, Keller JF, Baudouin C, Msika P, Bleicher F, Staquet MJ (2011) Cytokine production by human odontoblast-like cells upon Toll-like receptor-2 engagement. Immunobiology 216:513–517CrossRefGoogle Scholar
  13. Farges JC, Alliot-Licht B, Baudouin C, Msika P, Bleicher F, Carrouel F (2013) Odontoblast control of dental pulp inflammation triggered by cariogenic bacteria. Front Physiol 4:326CrossRefGoogle Scholar
  14. Foulks JM, Parnell KM, Nix RN, Chau S, Swierczek K, Saunders M, Wright K, Hendrickson TF, Ho KK, McCullar MV, Kanner SB (2012) Epigenetic drug discovery: targeting DNA methyltransferases. J Biomol Screen 17:2–17CrossRefGoogle Scholar
  15. Hahn CL, Liewehr FR (2007) Innate immune responses of the dental pulp to caries. J Endod 33:643–651CrossRefGoogle Scholar
  16. Han SH, Kim JH, Martin M, Michalek SM, Nahm MH (2003) Pneumococcal lipoteichoic acid (LTA) is not as potent as staphylococcal LTA in stimulating Toll-like receptor 2. Infect Immun 71:5541–5548CrossRefGoogle Scholar
  17. Horst OV, Tompkins KA, Coats SR, Braham PH, Darveau RP, Dale BA (2009) TGF-beta1 inhibits TLR-mediated odontoblast responses to oral bacteria. J Dent Res 88:333–338CrossRefGoogle Scholar
  18. Hosokawa Y, Hirao K, Yumoto H, Washio A, Nakanishi T, Takegawa D, Kitamura C, Matsuo T (2016) Functional roles of NOD1 in odontoblasts on dental pulp innate immunity. Biomed Res Int 2016:9325436CrossRefGoogle Scholar
  19. Huang X, Kong G, Li Y, Zhu W, Xu H, Zhang X, Li J, Wang L, Zhang Z, Wu Y, Liu X, Wang X (2016) Decitabine and 5-azacitidine both alleviate LPS induced ARDS through anti-inflammatory/antioxidant activity and protection of glycocalyx and inhibition of MAPK pathways in mice. Biomed Pharmacother 84:447–453CrossRefGoogle Scholar
  20. Jiang M, Xiang Y, Wang D, Gao J, Liu D, Liu Y, Liu S, Zheng D (2012) Dysregulated expression of miR-146a contributes to age-related dysfunction of macrophages. Aging Cell 11:29–40CrossRefGoogle Scholar
  21. Jones PA (2012) Functions of DNA methylation: islands, start sites, gene bodies and beyond. Nat Rev Genet 13:484–492CrossRefGoogle Scholar
  22. Keller JF, Carrouel F, Staquet MJ, Kufer TA, Baudouin C, Msika P, Bleicher F, Farges JC (2011) Expression of NOD2 is increased in inflamed human dental pulps and lipoteichoic acid-stimulated odontoblast-like cells. Innate Immun 17:29–34CrossRefGoogle Scholar
  23. Khachatoorian R, Dawson D, Maloney EM, Wang J, French BA, French SW, French SW (2013) SAMe treatment prevents the ethanol-induced epigenetic alterations of genes in the Toll-like receptor pathway. Exp Mol Pathol 94:243–246CrossRefGoogle Scholar
  24. Kim TW, Lee SJ, Oh BM, Lee H, Uhm TG, Min JK, Park YJ, Yoon SR, Kim BY, Kim JW, Choe YK, Lee HG (2016) Epigenetic modification of TLR4 promotes activation of NF-kappaB by regulating methyl-CpG-binding domain protein 2 and Sp1 in gastric cancer. Oncotarget 7:4195–4209Google Scholar
  25. Love RM, Jenkinson HF (2002) Invasion of dentinal tubules by oral bacteria. Crit Rev Oral Biol Med 13:171–183CrossRefGoogle Scholar
  26. McDermott E, Ryan EJ, Tosetto M, Gibson D, Burrage J, Keegan D, Byrne K, Crowe E, Sexton G, Malone K, Harris RA, Kellermayer R, Mill J, Cullen G, Doherty GA, Mulcahy H, Murphy TM (2016) DNA methylation profiling in inflammatory bowel disease provides new insights into disease pathogenesis. J Crohns Colitis 10:77–86CrossRefGoogle Scholar
  27. Meng R, Mo Z, Xu Q (2017) The mechanism of LTA-induced inflammatory microenvironment in human odontoblast-like cells. Clin J Stomatol Res (Electronic Edition) 11:257–265Google Scholar
  28. Morath S, Stadelmaier A, Geyer A, Schmidt RR, Hartung T (2002) Synthetic lipoteichoic acid from Staphylococcus aureus is a potent stimulus of cytokine release. J Exp Med 195:1635–1640CrossRefGoogle Scholar
  29. Paakkonen V, Bleicher F, Carrouel F, Vuoristo JT, Salo T, Wappler I, Couble ML, Magloire H, Peters H, Tjaderhane L (2009) General expression profiles of human native odontoblasts and pulp-derived cultured odontoblast-like cells are similar but reveal differential neuropeptide expression levels. Arch Oral Biol 54:55–62CrossRefGoogle Scholar
  30. Ryu YH, Baik JE, Yang JS, Kang SS, Im J, Yun CH, Kim DW, Lee K, Chung DK, Ju HR, Han SH (2009) Differential immunostimulatory effects of Gram-positive bacteria due to their lipoteichoic acids. Int Immunopharmacol 9:127–133CrossRefGoogle Scholar
  31. Shaddox LM, Mullersman AF, Huang H, Wallet SM, Langaee T, Aukhil I (2017) Epigenetic regulation of inflammation in localized aggressive periodontitis. Clin Epigenetics 9:94CrossRefGoogle Scholar
  32. Shanmugam MK, Sethi G (2013) Role of epigenetics in inflammation-associated diseases. Subcell Biochem 61:627–657CrossRefGoogle Scholar
  33. Shen J, Liu Y, Ren X, Gao K, Li Y, Li S, Yao J, Yang X (2016) Changes in DNA methylation and chromatin structure of pro-inflammatory cytokines stimulated by LPS in broiler peripheral blood mononuclear cells. Poult Sci 95:1636–1645CrossRefGoogle Scholar
  34. Shen J, Wu S, Guo W, Liang S, Li X, Yang X (2017) Epigenetic regulation of pro-inflammatory cytokine genes in lipopolysaccharide-stimulated peripheral blood mononuclear cells from broilers. Immunobiology 222:308–315CrossRefGoogle Scholar
  35. Staquet MJ, Carrouel F, Keller JF, Baudouin C, Msika P, Bleicher F, Kufer TA, Farges JC (2011) Pattern-recognition receptors in pulp defense. Adv Dent Res 23:296–301CrossRefGoogle Scholar
  36. Takeuchi O, Akira S (2001) Toll-like receptors; their physiological role and signal transduction system. Int Immunopharmacol 1:625–635CrossRefGoogle Scholar
  37. Venza I, Visalli M, Fortunato C, Ruggeri M, Ratone S, Caffo M, Caruso G, Alafaci C, Tomasello F, Teti D, Venza M (2012) PGE2 induces interleukin-8 depression in human astrocytoma through coordinated DNA demethylation and histone hyperacetylation. Epigenetics 7:1315–1330CrossRefGoogle Scholar
  38. Wang HC, Chen CW, Yang CL, Tsai IM, Hou YC, Chen CJ, Shan YS (2017a) Tumor-associated macrophages promote epigenetic silencing of gelsolin through DNA methyltransferase 1 in gastric cancer cells. Cancer Immunol Res 5:885–897CrossRefGoogle Scholar
  39. Wang L, Yao J, Sun H, He K, Tong D, Song T, Huang C (2017b) MicroRNA-101 suppresses progression of lung cancer through the PTEN/AKT signaling pathway by targeting DNA methyltransferase 3A. Oncol Lett 13:329–338CrossRefGoogle Scholar
  40. Zhang S, Barros SP, Moretti AJ, Yu N, Zhou J, Preisser JS, Niculescu MD, Offenbacher S (2013) Epigenetic regulation of TNFA expression in periodontal disease. J Periodontol 84:1606–1616Google Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Guanghua School of Stomatology & Guangdong Provincial Key Laboratory of StomatologySun Yat-sen UniversityGuangzhouChina

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