title: Altered CD40 and E-cadherin expression--putative role in oral lichen planus.
abstract: BACKGROUND
  Oral lichen planus (OLP) is characterized among other features by apoptosis of basal keratinocytes. To identify potential regulatory mechanisms associated with basal cell apoptosis in OLP, we investigated the expression of CD40, CD40 ligand (CD40L), CD44 and epithelial (E)-cadherin.
  
  
  METHODS
  Biopsies from 22 patients with OLP were investigated by immunohistochemistry for detection of CD40, CD40L, E-cadherin, CD44, Laminin-5 and Collagen IV, double-labelling for CD40 and CD3, and in situ mRNA hybridization for CD40 and CD40L.
  
  
  RESULTS
  In actively diseased areas of OLP lesions, basal keratinocytes did not express CD40 and were focally E-cadherin-negative, in contrast to non-diseased areas and normal oral mucosa. Demonstration of intraepithelial T cells expressing CD40 and CD40L, indicates a potential role in inflammatory cell responses involved in the disease process of OLP.
  
  
  CONCLUSIONS
  T cells may orchestrate inflammatory cell responses in OLP via CD40-CD40L interactions. As basal keratinocytes downregulate CD40, they may escape CD40-CD40L-induced apoptosis in OLP. On the other hand, loss of E-cadherin expression may contribute to epithelial basal cell destruction and T-cell migration into the epithelial compartment in OLP.
authors.affiliation: Oral Pathology and Forensic Odontology, Institute of Oral Sciences, Faculty of Dentistry, University of Bergen, Bergen, Norway. evelyn.neppelberg@odont.uib.no
authors.forename: E
authors.initials: E
authors.lastname: Neppelberg
authors.forename: L L
authors.initials: LL
authors.lastname: Loro
authors.forename: G
authors.initials: G
authors.lastname: Oijordsbakken
authors.forename: A C
authors.initials: AC
authors.lastname: Johannessen
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis; D001485:Basement Membrane / Q000378:metabolism; D019013:CD40 Antigens / Q000096:biosynthesis*; D023201:CD40 Ligand / Q000096:biosynthesis*; D015820:Cadherins / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis*; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D015603:Keratinocytes / Q000378:metabolism; D017676:Lichen Planus, Oral / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D019013:CD40 Antigens; D015820:Cadherins; D018960:Hyaluronan Receptors; D023201:CD40 Ligand