title: Immunohistochemical detection of Mycoplasma salivarium in oral lichen planus tissue.
abstract: BACKGROUND
  Oral lichen planus (OLP) is a T-cell-mediated inflammatory disease; however, its exact etiology is unknown. Hyperkeratosis is often observed in OLP lesions. Previous studies have revealed the localization of Mycoplasma salivarium in the epithelial cells of oral leukoplakia with hyperkeratosis. Herein, we investigated the presence of M. salivarium in OLP tissue by immunohistochemistry to determine the causative factor of OLP.
  
  
  METHODS
  Forty-one formalin-fixed, paraffin-embedded samples obtained from 31 patients with OLP were examined. Ten samples of normal-appearing oral mucosa were used as controls. Immunohistochemistry (IHC) was performed using anti-M. salivarium monoclonal antibodies.
  
  
  CONCLUSIONS
  Mycoplasma salivarium was detected in the epithelium and lymphocyte infiltrate area in 24 of 41 OLP samples (58.5%). The bacteria were intracellularly localized in epithelial cells, while it was unclear whether they were also localized in lymphocyte cells or in the extracellular spaces among the lymphocytes in the subepithelial lymphocyte infiltrate area. Little or no staining was observed in the epithelium in the normal-appearing mucosa samples. Sawtooth rete ridge formation was observed in 21 OLP samples (51.2%), and a significant positive correlation between sawtooth rete ridge formation and IHC positivity was demonstrated. However, the role of M. salivarium in the epithelium and lamina propria of OLP tissue remains unknown.
authors.affiliation: Division of Oral and Maxillofacial Surgery, Department of Oral and Maxillofacial Reconstructive Surgery, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Harumi
authors.identifier: http://orcid.org/0000-0003-2704-0857
authors.initials: H
authors.lastname: Mizuki
authors.affiliation: Division of Oral and Maxillofacial Surgery, Department of Oral and Maxillofacial Reconstructive Surgery, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Abe
authors.affiliation: Division of Oral and Maxillofacial Surgery, Department of Oral and Maxillofacial Reconstructive Surgery, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Kogi
authors.affiliation: Division of Anatomical and Cellular Pathology, Department of Pathology, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Toshinari
authors.initials: T
authors.lastname: Mikami
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D017676:Lichen Planus, Oral / Q000382:microbiology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000382:microbiology / Q000473:pathology; D009175:Mycoplasma Infections / Q000382:microbiology / Q000473:pathology*; D045804:Mycoplasma salivarium
keywords: Mycoplasma salivarium; etiology; immunohistochemistry; oral lichen planus; sawtooth rete ridge