title: Immunohistochemical localization of NALP3 inflammasome in experimental periapical lesions.
abstract: OBJECTIVE
  To explore the role of NALP3 inflammasome [NALP3, its effector molecule apoptosis associated speck-like protein (ASC), caspase-1, interleukin (IL)-1β and IL-18] in the development of periapical lesions in rats.
  
  
  METHODS
  Periapical lesions were developed within 21 days after mandibular first molar pulp exposure in Sprague-Dawley rats. The animals were randomly sacrificed at 0, 1, 3, 7, 10, 14 and 21 days after pulpal exposure. The bilateral mandibles were extracted for histological processing, then they were haematoxylin-eosin (HE) stained to examine inflammation infiltration in the apical region and immunohistochemically examined for the NALP3 inflammasome signalling pathway. Data were analysed by one-way analysis of variance and the Pearson(') s correlation and linear tendency test.
  
  
  RESULTS
  NALP3 was detected in the cytoplasm of fibroblasts, monocytes, neutrophils, macrophages and vascular endothelial cells in the periapical region. From day 1 to day 21, the number of NALP3-positive cells ascended and was significantly correlated with the intensity of inflammatory infiltration (r = 0.776, P < 0.01). ASC, caspase-1, IL-1β and IL-18 were all expressed in the inflammatory periapical tissues. The positive cell counts of IL-1β and IL-18 were significantly correlated with that of NALP3, and r = 0.718, P < 0.01; r = 0.688, P < 0.01, respectively.
  
  
  CONCLUSIONS
  NALP3 inflammasome is expressed in the inflammatory periapical tissues. This cytokine-signalling pathway may therefore be crucial in the regulatory control of inflammatory responses in periapical tissues and the development of periapical lesions.
authors.affiliation: Department of Conservative Dentistry and Endodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei, China.
authors.forename: S
authors.initials: S
authors.lastname: Liu
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D058847:Inflammasomes / Q000378:metabolism*; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D051381:Rats; D017207:Rats, Sprague-Dawley; D019227:Tooth Apex / Q000378:metabolism* / Q000473:pathology
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C573346:Nlrp3 protein, rat
keywords: IL-18; IL-1β; NALP3 inflammasome; inflammation; periapical lesions