title: Cytokeratin 15 can be used to identify the limbal phenotype in normal and diseased ocular surfaces.
abstract: OBJECTIVE
  To elucidate the expression pattern of K15, K19, K14, and K12 in human and mouse ocular surface epithelium as putative markers of epithelial phenotype.
  
  
  METHODS
  Immunohistochemical staining with specific antibodies for K15, K19, K14, and K12 was performed in human donor cornea tissue and normal ICR mouse corneas, with emphasis on localization of immunopositive cells. Immunohistochemistry was performed in a limbus-deficient mouse model as well as in clinical samples of pannus surgically removed from a thermal burn and a patient with Saltzmann's dystrophy. Staining patterns were classified as limited to the most basal layer (K(bas)), basal and suprabasal layers (K(bas-sup)), predominantly in suprabasal layers (K(sup)) and negative staining (K(-)).
  
  
  RESULTS
  In human conjunctival epithelium, strong expression of K15 was observed in basal cells, whereas K19 was expressed in both basal and suprabasal layers (K15(bas)/K19(bas-sup)/K12(-)). Limbal epithelial cells were K15(bas-sup)/K19(bas-sup)/K12(sup), whereas epithelial cells in the central cornea were K15(-)/K19(bas-sup)/K12(bas-sup). In contrast, the mouse ocular surface demonstrated a different expression pattern of K15 and K19 than did the human tissue in the conjunctiva (K15(bas-sup)/K19(bas)/K12(-)) and the limbus (K15(bas-sup)/K19(bas)/K12(sup)). Neither K15 nor K19 was expressed in the central mouse cornea (K15(-)/K19(-)/K12(bas-sup)). Similar cytokeratin expression was observed in conjunctivalized corneas in mice and in surgically removed pannus tissue.
  
  
  CONCLUSIONS
  Although the expression of K15 and K19 differ in humans and mice, specific staining patterns can be used to characterize the epithelial phenotype in normal and diseased ocular surface.
authors.affiliation: Cornea Center and Department of Ophthalmology, Tokyo Dental College, Chiba, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Yoshida
authors.forename: Shigeto
authors.initials: S
authors.lastname: Shimmura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kawakita
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Miyashita
authors.forename: Seika
authors.initials: S
authors.lastname: Den
authors.forename: Jun
authors.initials: J
authors.lastname: Shimazaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tsubota
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D003228:Conjunctiva / Q000166:cytology*; D003316:Corneal Diseases / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D053551:Keratin-12 / Q000378:metabolism; D053547:Keratin-14 / Q000378:metabolism; D053569:Keratin-15 / Q000378:metabolism*; D053539:Keratin-19 / Q000378:metabolism; D016850:Limbus Corneae / Q000166:cytology*; D051379:Mice; D008813:Mice, Inbred ICR; D010641:Phenotype
chemical_list: D015415:Biomarkers; D053551:Keratin-12; D053547:Keratin-14; D053569:Keratin-15; D053539:Keratin-19