title: A molecular signature of epithelial host defense: comparative gene expression analysis of cultured bronchial epithelial cells and keratinocytes.
abstract: BACKGROUND
  Epithelia are barrier-forming tissues that protect the organism against external noxious stimuli. Despite the similarity in function of epithelia, only few common protective mechanisms that are employed by these tissues have been systematically studied. Comparative analysis of genome-wide expression profiles generated by means of Serial Analysis of Gene Expression (SAGE) is a powerful approach to yield further insight into epithelial host defense mechanisms. We performed an extensive comparative analysis of previously published SAGE data sets of two types of epithelial cells, namely bronchial epithelial cells and keratinocytes, in which the response to pro-inflammatory cytokines was assessed. These data sets were used to elucidate a common denominator in epithelial host defense.
  
  
  RESULTS
  Bronchial epithelial cells and keratinocytes were found to have a high degree of overlap in gene expression. Using an in silico approach, an epithelial-specific molecular signature of gene expression was identified in bronchial epithelial cells and keratinocytes comprising of family members of keratins, small proline-rich proteins and proteinase inhibitors. Whereas some of the identified genes were known to be involved in inflammation, the majority of the signature represented genes that were previously not associated with host defense. Using polymerase chain reaction, presence of expression of selected tissue-specific genes was validated.
  
  
  CONCLUSIONS
  Our comparative analysis of gene transcription reveals that bronchial epithelial cells and keratinocytes both express a subset of genes that is likely to be essential in epithelial barrier formation in these cell types. The expression of these genes is specific for bronchial epithelial cells and keratinocytes and is not seen in non-epithelial cells. We show that bronchial epithelial cells, similar to keratinocytes, express components that are able to form a cross-linked protein envelope that may contribute to an effective barrier against noxious stimuli and pathogens.
authors.affiliation: Dept of Pulmonology, Leiden University Medical Center, Leiden, Albinusdreef 2, 2333 ZA Leiden, The Netherlands. j.b.vos@lumc.nl
authors.forename: Joost B
authors.initials: JB
authors.lastname: Vos
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Datson
authors.forename: Antoine H
authors.initials: AH
authors.lastname: van Kampen
authors.forename: Angela C
authors.initials: AC
authors.lastname: Luyf
authors.forename: Renate M
authors.initials: RM
authors.lastname: Verhoosel
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Zeeuwen
authors.forename: Diana
authors.initials: D
authors.lastname: Olthuis
authors.forename: Klaus F
authors.initials: KF
authors.lastname: Rabe
authors.forename: Joost
authors.initials: J
authors.lastname: Schalkwijk
authors.forename: Pieter S
authors.initials: PS
authors.lastname: Hiemstra
mesh_terms: D000465:Algorithms; D001483:Base Sequence; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D020224:Expressed Sequence Tags; D015870:Gene Expression / Q000187:drug effects; D023281:Genomics; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D008957:Models, Genetic; D005810:Multigene Family; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D017931:DNA Primers; D053583:Interleukin-1beta; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha