title: Interleukin-33 could play an important role in the pathogenesis of periodontitis.
abstract: OBJECTIVE
  Interleukin-33 (IL-33) controls T-helper type 2 (Th2) cytokines and the development of mast cells. This study aimed to investigate the expression of IL-33 and its association with RANKL and osteoprotegerin (OPG) in periodontal health and experimental periodontitis.
  
  
  METHODS
  Eighteen Wistar rats were assigned to two study groups of nine animals each: ligature only (LO) and nonligated (NL). Silk sutures were placed subgingivally, surrounding the right lower first molars. The animals were killed on day 11 after ligature placement, and the alveolar bone loss at the first molars was determined histometrically. Periodontal tissues were examined histopathologically to evaluate the differences between the groups. The expression of IL-33, RANKL and OPG was detected immunohistochemically.
  
  
  RESULTS
  The LO group showed significantly greater alveolar bone loss compared with the NL group (p < 0.05). The numbers of osteoclasts, osteoblasts and inflammatory cells were significantly higher in the LO group compared with the NL group (p < 0.05). Osteoblastic activity was significantly lower in the LO group than in the NL group (p < 0.05). There was significantly higher expression of IL-33 and RANKL and a greater number of OPG-positive cells in the LO group (p < 0.05). IL-33 expression showed a positive correlation with RANKL expression and with the number of mast cells (p < 0.05).
  
  
  CONCLUSIONS
  The experimental periodontitis group exhibited increased expression of IL-33 and RANKL compared with the healthy group. Additionally, there was a positive correlation between these expressions. According to these results, IL-33 could be associated with the pathogenesis of periodontal disease.
authors.affiliation: Department of Periodontology, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey.
authors.forename: S
authors.initials: S
authors.lastname: Köseoğlu
authors.affiliation: Department of Periodontology, Faculty of Dentistry, Akdeniz University, Antalya, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Hatipoğlu
authors.affiliation: Department of Periodontology, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Sağlam
authors.affiliation: Department of Periodontology, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey.
authors.forename: Ş
authors.initials: Ş
authors.lastname: Enhoş
authors.affiliation: Department of Pathology, School of Medicine, Necmettin Erbakan University, Konya, Turkey.
authors.forename: H H
authors.initials: HH
authors.lastname: Esen
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology / Q000473:pathology; D000818:Animals; D002452:Cell Count; D007249:Inflammation / Q000473:pathology; D000067596:Interleukin-33 / Q000502:physiology*; D008407:Mast Cells / Q000473:pathology; D010006:Osteoblasts / Q000473:pathology; D010010:Osteoclasts / Q000473:pathology; D010012:Osteogenesis / Q000502:physiology; D053244:Osteoprotegerin / Q000502:physiology; D010518:Periodontitis / Q000209:etiology* / Q000473:pathology; D053245:RANK Ligand / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013537:Sutures / Q000009:adverse effects
chemical_list: C553108:Il33 protein, rat; D000067596:Interleukin-33; D053244:Osteoprotegerin; D053245:RANK Ligand; C506032:Tnfrsf11b protein, rat
keywords: RANKL protein; alveolar bone loss; interleukin-33; osteoprotegerin; periodontal disease; rat