title: Immunoexpression of interleukin 17 in apical periodontitis lesions.
abstract: BACKGROUND
  Interleukin (IL)-17 expression has been detected in apical periodontitis lesions, but its role in the disease process remains unclear. The present study compared the expression of IL-17 in periradicular cysts and granulomas and evaluated the association of this cytokine with clinical and radiographic findings.
  
  
  METHODS
  Apical periodontitis lesions (18 cysts and 20 granulomas) were obtained from 38 patients subjected to periradicular surgery. Some clinical, radiographic, and cone-beam computed tomographic features were recorded. Silanized slides containing paraffin sections were used for the immunohistochemical reactions using anti-IL-17 antibody. Image analysis was performed using an optical microscope, and each sample was divided into 5 high-power fields, which were evaluated for the expression of IL-17 in the epithelium and connective tissues. Results were evaluated for correlations with the lesion size and the occurrence of symptoms and sinus tract.
  
  
  RESULTS
  Expression of IL-17 was significantly higher in cysts than in granulomas (P = .02). Among the periradicular cysts, a thin epithelium showed significantly increased labeling for IL-17 when compared with a hyperplastic epithelium (P = .003). IL-17 expression was usually associated with focal accumulations of polymorphonuclear leukocytes. No association of IL-17 expression with symptoms, sinus tract, or lesion size was observed (P > .05).
  
  
  CONCLUSIONS
  The present study reinforces the notion that IL-17 may take part in the pathogenesis of apical periodontitis lesions. A role in the exacerbation of chronic inflammation and cyst formation is suspected. Further studies are required to shed light on the specific functions of IL-17 in periradicular inflammatory processes.
authors.affiliation: Department of Endodontics and Immunohistochemistry Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: Natasha C
authors.initials: NC
authors.lastname: Ajuz
authors.affiliation: Department of Endodontics and Immunohistochemistry Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil; Department of Endodontics, Faculty of Dentistry, Grande Rio University, Duque de, Caxias, RJ, Brazil.
authors.forename: Henrique
authors.initials: H
authors.lastname: Antunes
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Grande Rio University, Duque de, Caxias, RJ, Brazil.
authors.forename: Thais A
authors.initials: TA
authors.lastname: Mendonça
authors.affiliation: Department of Endodontics and Immunohistochemistry Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: Fábio R
authors.initials: FR
authors.lastname: Pires
authors.affiliation: Department of Endodontics and Immunohistochemistry Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
authors.affiliation: Department of Endodontics and Immunohistochemistry Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil. Electronic address: luadias@hotmail.com.
authors.forename: Luciana
authors.initials: L
authors.lastname: Armada
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography / Q000379:methods; D003238:Connective Tissue / Q000276:immunology / Q000473:pathology; D003751:Dental Fistula / Q000276:immunology / Q000473:pathology; D004848:Epithelium / Q000276:immunology / Q000473:pathology; D005260:Female; D006801:Humans; D006965:Hyperplasia; D007091:Image Processing, Computer-Assisted / Q000379:methods; D020381:Interleukin-17 / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000276:immunology / Q000473:pathology; D010484:Periapical Granuloma / Q000000981:diagnostic imaging / Q000276:immunology / Q000473:pathology; D010485:Periapical Periodontitis / Q000000981:diagnostic imaging / Q000276:immunology* / Q000473:pathology; D011842:Radicular Cyst / Q000000981:diagnostic imaging / Q000276:immunology / Q000473:pathology
chemical_list: D020381:Interleukin-17
keywords: Apical periodontitis; immunohistochemistry; interleukin 17; periradicular cyst; periradicular granuloma