title: Regulation of p53 under hypoxic and inflammatory conditions in periodontium.
abstract: OBJECTIVE
  Different studies suggest that inflammation as well as hypoxia leads to an increase of p53 protein levels. However, the implication of p53 during oral inflammatory processes is still unknown. The aim of this study was therefore to investigate the effect of hypoxia and inflammation on p53 regulation in human periodontium in vitro and in vivo.
  
  
  METHODS
  Under hypoxic and normoxic conditions, human primary periodontal ligament (PDL) fibroblasts (n = 9) were stimulated with lipopolysaccharides (LPS) from Porphyromonas gingivalis (P.g.), a periodontal pathogenic bacterium. After different time points, cell viability was tested; p53 gene expression, protein synthesis, and activation were measured using quantitative RT-PCR, immunoblotting, and immunofluorescence. Moreover, healthy and inflamed periodontal tissues were obtained from 12 donors to analyze p53 protein in oral inflammatory diseases by immunohistochemistry.
  
  
  RESULTS
  LPS-P.g. and hypoxia initially induced a significant upregulation of p53 mRNA expression and p53 protein levels. Nuclear translocation of p53 after inflammatory stimulation supported these findings. Hypoxia first enhanced p53 levels, but after 24 h of incubation, protein levels decreased, which was accompanied by an improvement of PDL cell viability. Immunohistochemistry revealed an elevation of p53 immunoreactivity in accordance to the progression of periodontal inflammation.
  
  
  CONCLUSIONS
  Our data indicate that p53 plays a pivotal role in PDL cell homeostasis and seems to be upregulated in oral inflammatory diseases.
  
  
  CONCLUSIONS
  Upregulation of p53 may promote the destruction of periodontal integrity. A possible relationship with carcinogenesis may be discussed.
authors.affiliation: Department of Orthodontics, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany. svenja.memmert@ukb.uni-bonn.de.|Section of Experimental Dento-Maxillo-Facial Medicine, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Bonn, Germany. svenja.memmert@ukb.uni-bonn.de.
authors.forename: S
authors.initials: S
authors.lastname: Memmert
authors.affiliation: Department of Orthodontics, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Gölz
authors.affiliation: Department of Orthodontics, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Pütz
authors.affiliation: Department of Orthodontics, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Jäger
authors.affiliation: Section of Experimental Dento-Maxillo-Facial Medicine, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Bonn, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Deschner
authors.affiliation: Clinic of Oral and Maxillofacial Surgery, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Bonn, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Appel
authors.affiliation: Clinic and Polyclinic of Anesthesiology and Intensive Care Medicine, Faculty of Medicine, University of Bonn, Bonn, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Baumgarten
authors.affiliation: Department of Orthodontics, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Rath-Deschner
authors.affiliation: Clinic and Polyclinic of Anesthesiology and Intensive Care Medicine, Faculty of Medicine, University of Bonn, Bonn, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Frede
authors.affiliation: Department of Orthodontics, Center of Dento-Maxillo-Facial Medicine, Faculty of Medicine, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Götz
mesh_terms: D002470:Cell Survival; D005347:Fibroblasts / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D000860:Hypoxia; D015151:Immunoblotting; D007150:Immunohistochemistry; D007249:Inflammation; D008070:Lipopolysaccharides; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D016966:Porphyromonas gingivalis; D060888:Real-Time Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D016159:Tumor Suppressor Protein p53
keywords: Hypoxia; Inflammation; PDL; Periodontal ligament cells; Periodontium; p53