title: Antigen-presenting cell marker expression and phagocytotic activity in periodontal ligament cells.
abstract: BACKGROUND
  Periodontal ligament (PDL) cells are the main cellular constituents of the periodontium, maintain the integrity of the connective tissue, and impact pathology in periodontitis. The aim of this study was to analyze whether PDL cells recognize foreign particles and participate in the immune response to periodontal pathogens.
  
  
  METHODS
  Expression of surface proteins characteristic of antigen-presenting cells (APCs) (major histocompatibility complex [MHC] class II, CD40, CD80, CD86) was analyzed in PDL cells after challenge with the cytokines interleukin (IL)-1β, IL-17A, and interferon-gamma (IFN-γ) or with heat-killed Aggregatibacter actinomycetemcomitans using real-time PCR and flow cytometry. Confocal laser scanning microscopy, transmitted light microscopy, flow cytometry, and time-lapse microscopy were applied to analyze their phagocytotic capacity of collagen (carboxylate-modified microspheres), non-periodontal (Escherichia coli) and periodontal (Aggregatibacter actinomycetemcomitans) pathogens. Furthermore, it was examined whether cytokine activation of PDL cells affects the phagocytosis of collagen or bacteria.
  
  
  RESULTS
  PDL cells upregulated MHC class II after cytokine stimulation on transcriptional level, whereas co-stimulatory molecules characteristic of professional APCs were not induced. Analyses on protein level revealed that MHC class II was not constitutively expressed in all PDL cell lines used. PDL cells phagocytosed both collagen and bacteria via acidic vesicles, suggesting the formation of phagosomes. Phagocytosis could be partially inhibited by inhibitors of phagocytosis, i.e., dynasore and wortmannin. Pre-incubation with cytokines did not further enhance the phagocytosis rate of collagen or bacteria.
  
  
  CONCLUSIONS
  These results suggest that PDL cells do not only represent bystanders in periodontal infections, but display non-professional APC characteristics, suggesting possible participation in immune reactions of the oral cavity.
authors.affiliation: Department of Orthodontics, Medical Faculty, University of Bonn, Bonn, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Konermann
authors.forename: J
authors.initials: J
authors.lastname: Deschner
authors.forename: J P
authors.initials: JP
authors.lastname: Allam
authors.forename: N
authors.initials: N
authors.lastname: Novak
authors.forename: J
authors.initials: J
authors.lastname: Winter
authors.forename: S L
authors.initials: SL
authors.lastname: Baader
authors.forename: S
authors.initials: S
authors.lastname: Jepsen
authors.forename: A
authors.initials: A
authors.lastname: Jäger
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology; D000730:Androstadienes / Q000494:pharmacology; D017951:Antigen Presentation / Q000276:immunology*; D000938:Antigen-Presenting Cells / Q000145:classification* / Q000276:immunology; D018122:B7-1 Antigen / Q000032:analysis; D051940:B7-2 Antigen / Q000032:analysis; D019013:CD40 Antigens / Q000032:analysis; D018929:Cell Culture Techniques; D003094:Collagen / Q000276:immunology; D034281:Dynamins / Q000037:antagonists & inhibitors; D004926:Escherichia coli / Q000276:immunology; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007371:Interferon-gamma / Q000276:immunology; D020381:Interleukin-17 / Q000276:immunology; D053583:Interleukin-1beta / Q000276:immunology; D010513:Periodontal Ligament / Q000166:cytology* / Q000276:immunology; D010586:Phagocytes / Q000145:classification* / Q000502:physiology; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*; D010588:Phagosomes / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D019013:CD40 Antigens; C497964:CD86 protein, human; D000949:Histocompatibility Antigens Class II; D006835:Hydrazones; C508717:IL17A protein, human; D007166:Immunosuppressive Agents; D020381:Interleukin-17; D053583:Interleukin-1beta; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D000081082:Phosphoinositide-3 Kinase Inhibitors; D007371:Interferon-gamma; D003094:Collagen; D034281:Dynamins; D000077191:Wortmannin