title: TLR4 activation by lipopolysaccharide and Streptococcus mutans induces differential regulation of proliferation and migration in human dental pulp stem cells.
abstract: BACKGROUND
  Dental pulp stem cells (DPSCs) are suspected to be an important part of the innate immune response of dental pulp, which is triggered by microorganisms that progressively invade the human tooth during the formation of caries. This study was performed to elucidate the expression of toll-like receptor 4 (TLR4) in dental pulp of deep caries and to determine whether TLR4 modulates the proliferation and migration of DPSCs.
  
  
  METHODS
  Pulp tissue samples were collected from freshly extracted human wisdom tooth. Immunohistochemistry and immunofluorescence were performed to determine the distribution of TLR4 in healthy dental pulp and dental pulp in deep caries. DPSCs were cultured and purified by collecting multiple colonies. The proliferation and migration of DPSCs were examined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, scratch test, and transwell migration assay after stimulation with lipopolysaccharide and extracts from Streptococcus mutans. TLR4 messenger RNA (mRNA) and cytokine mRNA were evaluated with real-time polymerase chain reaction; TLR4 protein was examined with Western blot and immunocytochemistry.
  
  
  RESULTS
  TLR4 is expressed in the odontoblast layer and areas that colocalize with blood vessels to different levels in healthy teeth and teeth affected by caries. TLR4 mRNA, TLR4 protein, and mRNA of cytokine levels can be elevated with stimulations of LPS and extracts from S. mutans. Lipopolysaccharide and extracts from S. mutans treatment inhibited the proliferation of DPSCs but promoted migration; however, these changes were abolished when TLR4 was blocked by anti-TLR4 antibody.
  
  
  CONCLUSIONS
  These results suggest that TLR4 will be activated and regulate the proliferation and migration of DPSCs in deep caries. TLR4 may play an important role in the immune response by DPSCs.
authors.affiliation: Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Center of Oral Implantology, Guangdong Provincial Stomatological Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, China.
authors.forename: Xueling
authors.initials: X
authors.lastname: Zhan
authors.affiliation: Department of Stomatology, Maoming People's Hospital, Maoming, China.
authors.forename: Li
authors.initials: L
authors.lastname: Cui
authors.affiliation: Department of endodontics, Guangdong Provincial Stomatological Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Shuaimei
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yue
authors.affiliation: Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, China. Electronic address: bulingwu0605@yahoo.com.
authors.forename: Buling
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, China. Electronic address: endogao@gmail.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
mesh_terms: D000293:Adolescent; D000328:Adult; D018929:Cell Culture Techniques; D002465:Cell Movement / Q000276:immunology; D049109:Cell Proliferation; D002478:Cells, Cultured; D060833:Cellular Microenvironment / Q000276:immunology; D003731:Dental Caries / Q000382:microbiology; D003782:Dental Pulp / Q000098:blood supply / Q000166:cytology*; D004926:Escherichia coli / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology* / Q000494:pharmacology; D055806:Microvessels / Q000276:immunology; D009804:Odontoblasts / Q000276:immunology; D013234:Stem Cells / Q000737:chemistry / Q000187:drug effects / Q000276:immunology*; D013295:Streptococcus mutans / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000032:analysis / Q000276:immunology*; D055815:Young Adult
chemical_list: D008070:Lipopolysaccharides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4
keywords: Caries, dental pulp stem cells, immune response, toll-like receptor 4