title: Immunocompetent cells and cytokine expression in the rat periodontal ligament at the initial stage of orthodontic tooth movement.
abstract: OBJECTIVE
  The aim of the present study is to investigate the involvement of immunocompetent cells, pro-inflammatory cytokines and HSP, to evaluate a change of periodontal ligament during the initial stage of orthodontic tooth movement.
  
  
  METHODS
  In the present study, we investigated the distributional density of immunocompetent cells, the localisation of cytokines, and the expression levels of their mRNA in the periodontal ligament during the initial stage of orthodontic tooth movement, using immunohistochemistry and real-time PCR.
  
  
  RESULTS
  Orthodontic tooth movement led to significant recruitment of OX6(+) cells and ED1(+) cells in the rat PDL. Double-immunofluorescence staining showed that some ED1(+) cells expressed pro-inflammatory factors of IL-1β and TNF-α in the PDL during orthodontic tooth movement. Real-time PCR analysis revealed that the expression levels of IL-1β (Il1b) and TNF-α (Tnf) mRNA gradually increased following its decrease after 1h of orthodontic tooth movement. These findings suggest that ED1(+) cells are involved in the expression of TNF-α and IL-1β and the subsequent regulation of bone resorption on pressure side. HSP27 (Hspb1) mRNA levels were significantly increased as compared with the control at 1h of the initial stage of treatment.
  
  
  CONCLUSIONS
  ED1(+) cells involved in the expression of TNF-α and IL-1β may play an important role in the initial reaction of the PDL and in the induction of the osteoclastic bone resorption during orthodontic tooth movement.
authors.affiliation: Department of Orthodontics, Tsurumi University School of Dental Medicine, Tsurumi, Tsurumi-ku, Yokohama, Japan. baba-shunsuke@tsurumi-u.ac.jp
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Baba
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kuroda
authors.forename: Chihiro
authors.initials: C
authors.lastname: Arai
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Sato
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000938:Antigen-Presenting Cells / Q000378:metabolism*; D001862:Bone Resorption; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D053583:Interleukin-1beta / Q000378:metabolism*; D008297:Male; D010513:Periodontal Ligament / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014087:Tooth Movement Techniques; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D055551:HSP27 Heat-Shock Proteins; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha