title: Short-term heat pre-treatment modulates the release of HMGB1 and pro-inflammatory cytokines in hPDL cells following mechanical loading and affects monocyte behavior.
abstract: OBJECTIVE
  Heat shock proteins (HSP) act as cell-protective molecules that are upregulated upon thermal insult, hypoxia, and ischemia. Such ischemic conditions can be found during tissue remodeling associated with orthodontic tooth movement or trauma when compression forces lead to cell necrosis and subsequent clearance of cellular debris by immune competent cells. Host immune overreaction can result in undesired side effects such as tooth root resorption. Here, we analyzed whether heat pre-treatment would affect the initially catabolic host immune response induced by mechanical loading of human periodontal ligament (hPDL) cells, which represent major constituents of the tooth supporting apparatus involved in the regulation of periodontal remodeling.
  
  
  METHODS
  Fifth passage hPDL cells were exposed to an elevated temperature of 43° for 1 h prior to mechanical loading. Cell morphology, high mobility group box protein 1 (HMGB1), interleukin (IL)-6, and IL-8 expression were analyzed microscopically and by ELISA. The physiological relevance for monocyte behavior was tested in monocyte adhesion and osteoclast differentiation assays.
  
  
  RESULTS
  Short-term heat pre-treatment did not show any visible effect on hPDL cell morphology, but resulted in a significant downregulation of pro-inflammatory cytokines when being additionally loaded mechanically. Supernatants of heat-exposed hPDL cell cultures demonstrated a reduced impact on monocyte adhesion and osteoclastic differentiation.
  
  
  CONCLUSIONS
  Heat pre-treatment of hPDL cells induces cell-protective mechanisms towards mechanical stress and favors the reduction of cell stress associated effects on monocyte/macrophage physiology.
  
  
  CONCLUSIONS
  These data present the induction of heat shock proteins as a promising treatment option to limit undesired side effects of periodontal remodeling.
authors.affiliation: Department of Orthodontics, University of Bonn, Bonn, Germany. michael.wolf@ukb.uni-bonn.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Wolf
authors.affiliation: Department of Orthodontics, University of Bonn, Bonn, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Lossdörfer
authors.affiliation: Department of Orthodontics, Dental Clinic, University of Regensburg, Regensburg, Germany.
authors.forename: Piero
authors.initials: P
authors.lastname: Römer
authors.affiliation: Department of Orthodontics, Dental Clinic, University of Regensburg, Regensburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kirschneck
authors.affiliation: Department of Orthodontics, University of Bonn, Bonn, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Küpper
authors.affiliation: Experimental Dento-Maxillo-Facial Medicine, University of Bonn, Bonn, Germany.
authors.forename: James
authors.initials: J
authors.lastname: Deschner
authors.affiliation: Department of Orthodontics, University of Bonn, Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Jäger
mesh_terms: D015153:Blotting, Western; D002448:Cell Adhesion; D002454:Cell Differentiation; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D024243:HMGB1 Protein / Q000276:immunology*; D006358:Hot Temperature; D006801:Humans; D009000:Monocytes / Q000276:immunology*; D010010:Osteoclasts / Q000276:immunology; D010513:Periodontal Ligament / Q000166:cytology*; D013314:Stress, Mechanical
chemical_list: D016207:Cytokines; D024243:HMGB1 Protein
keywords: Heat shock proteins; Human PDL cells; Mechanical loading