title: Immune-Inflammatory Cell Profile and Receptor Activator of Nuclear Factor Kappa B Ligand/Osteoprotegerin Expression in Persistent Apical Periodontitis after Root Canal Retreatment Failure.
abstract: BACKGROUND
  This study assessed the immune-inflammatory profile and the expression of bone resorption activators receptor activator of nuclear factor kappa B ligand (RANKL) and inhibitor osteoprotegerin (OPG) in apical periodontitis (n = 20) that persisted after root canal retreatment.
  
  
  METHODS
  Immunohistochemistry was used to characterize lymphocyte populations (CD3+, CD45RO+, CD8+, and FoxP3+ cells), macrophages (CD68+), RANKL+ and OPG+ cells in persistent apical periodontitis (PAP) and primary periapical lesions (PPLs). By using quantitative real-time polymerase chain reaction, the mRNA expression of RANKL and OPG in PAP and periodontal ligament from healthy teeth was comparatively analyzed. The data were analyzed by Mann-Whitney, Pearson χ2, and Wilcoxon tests (5% level).
  
  
  RESULTS
  PAP showed an elevated number of FoxP3+ cells compared with PPL (P < .001). The number of CD68+ cells was reduced in the PAP samples compared with the PPLs (P < .001). Similar number of other lymphocyte populations was observed in PAP and PPLs (P > .05 for all comparisons). No differences in the RANKL, OPG, and immune-inflammatory cells were demonstrated when comparing PAP microscopically classified as cyst with those classified as granulomas (P > .05 for all comparisons). The assessment of mRNA expression revealed higher levels of RANKL and OPG in PAP compared with the periodontal ligament from healthy teeth (control) samples (P < .001). Also, a greater expression of RANKL in comparison with OPG was observed in PAP (P < .001).
  
  
  CONCLUSIONS
  These findings indicate that PAP consists of biologically active lesions that demonstrate potential of bone resorption (higher expression of RANKL) and is characterized by an immune-inflammatory cell profile that suggests a suppressive and regulatory environment (higher number of FoxP3+ cells and lower number of macrophages) favorable to more chronic clinical behavior.
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil. Electronic address: estrela3@terra.com.br.
authors.forename: Carlos
authors.initials: C
authors.lastname: Estrela
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Daniel de Almeida
authors.initials: Dde A
authors.lastname: Decurcio
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Júlio Almeida
authors.initials: JA
authors.lastname: Silva
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Aline Carvalho
authors.initials: AC
authors.lastname: Batista
authors.affiliation: University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Nathália Caroline
authors.initials: NC
authors.lastname: de Souza Lima
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Brunno Santos
authors.initials: BS
authors.lastname: de Freitas Silva
authors.affiliation: Department of Physiology and Pathology, São Paulo State University, Araraquara School of Dentistry, Araraquara, São Paulo, Brazil.
authors.forename: João Antonio Chaves
authors.initials: JA
authors.lastname: de Souza
authors.affiliation: Department of Physiology and Pathology, São Paulo State University, Araraquara School of Dentistry, Araraquara, São Paulo, Brazil.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Souza Costa
mesh_terms: D000328:Adult; D003786:Dental Pulp Cavity / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000276:immunology / Q000473:pathology; D008264:Macrophages / Q000276:immunology / Q000473:pathology; D008297:Male; D053244:Osteoprotegerin / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism; D010485:Periapical Periodontitis / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D053245:RANK Ligand / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism; D019233:Retreatment; D012390:Root Canal Therapy; D017211:Treatment Failure
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human
keywords: Apical periodontitis; RANK ligand; bone resorption; immunological cells; osteoprotegerin