title: EZH2, a potential regulator of dental pulp inflammation and regeneration.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  EZH2 inhibited HDPC osteogenic differentiation while enhancing inflammatory response and proliferation, suggesting its role in pulp inflammation, proliferation, and regeneration.
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Tianqian
authors: T
authors: Hui
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Peng
authors: P
authors: A
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Yuan
authors: Y
authors: Zhao
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Chenglin
authors: C
authors: Wang
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Bo
authors: B
authors: Gao
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Ping
authors: P
authors: Zhang
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Jun
authors: J
authors: Wang
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
authors: Xuedong
authors: X
authors: Zhou
authors: State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China. Electronic address: yeling@scu.edu.cn.
authors: Ling
authors: L
authors: Ye
mesh_terms: D050156:Adipogenesis / Q000502:physiology; D000469:Alkaline Phosphatase / Q000032:analysis; D017209:Apoptosis / Q000502:physiology; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000032:analysis; D002113:Calcification, Physiologic / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic / Q000502:physiology; D006657:Histones / Q000032:analysis; D006801:Humans; D058574:Integrin-Binding Sialoprotein / Q000032:analysis; D053583:Interleukin-1beta / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D016209:Interleukin-8 / Q000032:analysis; D056484:Jumonji Domain-Containing Histone Demethylases / Q000032:analysis; D010012:Osteogenesis / Q000502:physiology; D047492:Peroxisome Proliferator-Activated Receptors / Q000032:analysis; D063151:Polycomb Repressive Complex 2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D011671:Pulpitis / Q000503:physiopathology*; D012038:Regeneration / Q000502:physiology*; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; C508606:CXCL8 protein, human; D006657:Histones; C508600:IL6 protein, human; D058574:Integrin-Binding Sialoprotein; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D047492:Peroxisome Proliferator-Activated Receptors; D000076182:Sp7 Transcription Factor; C478163:SP7 protein, human; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D056484:Jumonji Domain-Containing Histone Demethylases; C524220:KDM6B protein, human; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D000469:Alkaline Phosphatase
keywords: Cell proliferation; EZH2; human dental pulp cells; inflammation; regeneration