title: Interferon-gamma down-regulates claudin-1 and impairs the epithelial barrier function in primary cultured human thyrocytes.
abstract: OBJECTIVE
  Proinflammatory cytokines are known to affect the follicular epithelium in autoimmune thyroid disease. Here we investigated the effect of interferon-gamma (IFN-gamma) on the barrier function of primary cultured human thyrocytes.
  
  
  METHODS
  Graves' thyroid follicle segments were cultured as a tight and polarised monolayer on the filter of a bicameral chamber, thereby allowing the in vivo epithelial characteristics to be maintained.
  
  
  METHODS
  Transepithelial electrical resistance was measured with a Millicell ERS ohmmeter. The tight junction proteins claudin-1 and occludin were analysed by immunofluorescence and Western blotting. Cell morphology was studied by transmission electron microscopy.
  
  
  RESULTS
  Thyrotrophin (TSH; 1 mU/ml) promoted the development of a tight epithelium monitored as a persistent increase in the transepithelial resistance to about 800 omega x cm2. IFN-gamma (100 U/ml), on the other hand, decreased the resistance to 60-150 omega x cm2 after 48 h. In IFN-gamma-treated cells the expression of claudin-1, but not that of occludin, was decreased along with a diminished intracellular and cell surface immunostaining. In addition, claudin-1 was disrupted at cell-cell contacts. IFN-gamma also caused profound cell shape changes and a multilayered cellular organisation, without ultrastructural or biochemical (caspase-3 activity) signs of cytotoxicity. TSH was unable to counteract the effects of IFN-gamma.
  
  
  CONCLUSIONS
  IFN-gamma destroys the barrier function of filter-cultured human thyroid epithelial cells. The loss of barrier involves down-regulation and an altered distribution of claudin-1. This novel effect of IFN-gamma on target cells in thyroid autoimmunity might be of pathophysiological relevance to the exposure of hidden autoantigens.
authors.affiliation: Institute of Anatomy and Cell Biology, Sahlgrenska Academy at Göteborg University, Box 420, 40530 Göteborg, Sweden. sofia.tedelind@anatcell.gu.se
authors.forename: S
authors.initials: S
authors.lastname: Tedelind
authors.forename: L E
authors.initials: LE
authors.lastname: Ericson
authors.forename: J O
authors.initials: JO
authors.lastname: Karlsson
authors.forename: M
authors.initials: M
authors.lastname: Nilsson
mesh_terms: D016764:Cell Polarity / Q000187:drug effects; D062445:Claudin-1; D015536:Down-Regulation / Q000187:drug effects; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D006111:Graves Disease / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000494:pharmacology*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000276:immunology; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D062793:Occludin; D011994:Recombinant Proteins; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D013972:Thyrotropin / Q000276:immunology; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology
chemical_list: C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D011994:Recombinant Proteins; D007371:Interferon-gamma; D013972:Thyrotropin