title: Gene expression profile of compressed primary human cementoblasts before and after IL-1β stimulation.
abstract: OBJECTIVE
  Root resorptions due to a reduced repair function of cementoblasts are common side effects during orthodontic tooth movement (OTM). The mechanisms, which lead to an impaired cementoblast function, are not fully understood. Therefore, we aimed to investigate changes in the gene expression of cementoblasts during mechanical stimulus under inflammatory conditions.
  
  
  METHODS
  Human primary cementoblasts (HPCB) were exposed to compression for 6 h or stimulation with IL-1β for 96 h and subsequent 6 h compression. Genome-wide expression analysis was performed using microarray analysis. Prominent gene expression alterations (COX2, AXUD1, FOSB, CCL2, IFI6, and PTGES) were verified by quantitative RT-PCR (qRT-PCR) in two HPCB populations. A caspase 3/7 activity assay was used to determine caspase-3 and caspase-7 activity in stressed cells.
  
  
  RESULTS
  Gene expression cluster analysis revealed apoptosis as an important process induced under both conditions. Apoptosis (pro- and anti-apoptotic) related gene expression was most relevant after pro-inflammatory stimulation and compression. qRT-PCR analysis confirmed significant up-regulation of COX2, AXUD1, and FOSB in both HPCB populations after compression, while selected genes significantly increased after pro-inflammatory stimulation and compression. Compression of cementoblasts increased caspase. The combination of pro-inflammatory stimulation and compression led to a slightly smaller increase of caspase activity.
  
  
  CONCLUSIONS
  Gene ontology analysis showed that compressed HPCB up-regulate genes that are associated with apoptosis. Combining compression with a pro-inflammatory stimulus (IL-1β) augmented the positive regulation of apoptosis-related pathways. The induction of apoptosis related gene expression (pro- and anti-apoptotic genes) in cementoblasts suggests an involvement of apoptosis in cementoblast regulation during OTM.
  
  
  CONCLUSIONS
  As apoptosis is induced in HPCB after compression and inflammation, it is conceivable that HPCB cell death might contribute to root resorptions due to a loss of repair activity of cementoblasts. Further studies should be conducted to clarify the implication of the identified genes on root resorptions in order to develop therapeutic strategies to prevent a shortening of roots.
authors.affiliation: , Heidelberg, Germany, katja.diercke@med.uni-heidelberg.de.
authors.forename: Katja
authors.initials: K
authors.lastname: Diercke
authors.forename: Sebastian
authors.initials: S
authors.lastname: Zingler
authors.forename: Annette
authors.initials: A
authors.lastname: Kohl
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lux
authors.forename: Ralf
authors.initials: R
authors.lastname: Erber
mesh_terms: D003739:Dental Cementum / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D053583:Interleukin-1beta / Q000008:administration & dosage*
chemical_list: D053583:Interleukin-1beta