title: Immunohistochemical localization of oncostatin M in epithelialized apical periodontitis lesions.
abstract: OBJECTIVE
  To investigate the in situ location of oncostatin M (OSM) in epithelialized apical periodontitis lesions.
  
  
  METHODS
  Thirty periapical lesions of pulpal origin were collected with informed consent from patients at the time of apical surgery. Tissue specimens were fixed with 10% buffered formalin overnight, dehydrated in an ascending series of graded alcohol, and embedded in paraffin. Five micron sections from formalin-fixed, paraffin-embedded specimens were examined by immunohistochemistry. In addition, another section from each specimen was stained with haematoxylin and eosin to assess the presence of inflammatory infiltrates. Differences in OSM expression between tissue with low and high levels of inflammation were subsequently analyzed by Fisher's exact test.
  
  
  RESULTS
  Based on histological examination of haematoxylin and eosin stained sections, all specimens revealed the morphology of epithelialized apical periodontitis lesions. The results from immunohistochemistry demonstrated that OSM stain was detected in the inflammatory infiltrates, epithelium, connective tissue, and endothelium. The OSM signal was mainly expressed in endothelial cells (100%) followed by inflammatory cells (93.33%), epithelial cells (53.33%), and fibroblasts (16.67%). In addition, OSM expression was significantly higher in epithelialized apical periodontitis with higher levels of inflammatory infiltrates (P < 0.001).
  
  
  CONCLUSIONS
  Oncostatin M was found to be expressed in epithelialized apical periodontitis lesions and would form part of the cytokine network involved in the disease process of apical periodontitis.
authors.affiliation: Department of Pathology, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: C-H
authors.initials: CH
authors.lastname: Tsai
authors.forename: F-M
authors.initials: FM
authors.lastname: Huang
authors.forename: Y-C
authors.initials: YC
authors.lastname: Chang
mesh_terms: D016301:Alveolar Bone Loss / Q000378:metabolism; D016009:Chi-Square Distribution; D042783:Endothelial Cells / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D053683:Oncostatin M / Q000032:analysis / Q000096:biosynthesis*; D010485:Periapical Periodontitis / Q000378:metabolism* / Q000473:pathology; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D053683:Oncostatin M