title: Increased conjunctival expression of protease activated receptor 2 (PAR-2) in seasonal allergic conjunctivitis: a role for abnormal conjunctival epithelial permeability in disease pathogenesis?
abstract: OBJECTIVE
  Aeroallergen exposure to the conjunctival epithelium in seasonal allergic conjunctivitis (SAC) may induce a cellular stress response that disrupts the barrier properties of the conjunctival epithelium, resulting in allergic disease. Whether such changes occur in SAC is unknown. Epithelial permeability is known to be increased when protease activated receptor 2 (PAR-2) is activated. We evaluated the expression of PAR-2 in patients with SAC-in-season (SACS) and compared it with control non-atopic subjects or those with out-of-season allergic conjunctivitis (OSAC).
  
  
  METHODS
  Six SACS, eight normal and four OSAC specimens were examined immunohistochemically for PAR-2 and quantified in a masked fashion for the percentage of epithelia stained for each marker using Image-J software. Conjunctival epithelial heights were measured in all groups to confirm the presence of allergic eye disease.
  
  
  RESULTS
  Mean percentage staining of PAR-2 was significantly greater in SACS that in normal specimens (73.4 ± 15.4% vs 32.8 ± 30.0%, p=0.038) or in OSAC (73.4 ± 15.4% vs 1.4 ± 2.2%, p=0.01). Mean conjunctival epithelial height was significantly raised in SACS (63.8 ± 9.0 μm) versus controls (44.7 ± 11.2 μm) (p=0.003, unpaired t test).
  
  
  CONCLUSIONS
  Conjunctival epithelial PAR-2 is significantly upregulated in SAC. This supports the view that disruption of the barrier properties of the conjunctival epithelium is an important event in SAC pathogenesis.
authors.affiliation: Division of Infection, Inflammation & Immunity, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK.
authors.forename: S
authors.initials: S
authors.lastname: Yeoh
authors.forename: M
authors.initials: M
authors.lastname: Church
authors.forename: P
authors.initials: P
authors.lastname: Lackie
authors.forename: J
authors.initials: J
authors.lastname: McGill
authors.forename: M
authors.initials: M
authors.lastname: Mota
authors.forename: P
authors.initials: P
authors.lastname: Hossain
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D002463:Cell Membrane Permeability; D003228:Conjunctiva / Q000201:enzymology* / Q000473:pathology; D003233:Conjunctivitis, Allergic / Q000201:enzymology* / Q000473:pathology; D018450:Disease Progression; D004848:Epithelium / Q000201:enzymology* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D044464:Receptor, PAR-2 / Q000096:biosynthesis*; D013194:Staining and Labeling
chemical_list: D015415:Biomarkers; D044464:Receptor, PAR-2