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Increased conjunctival expression of protease activated receptor 2 (PAR-2) in seasonal allergic conjunctivitis: a role for abnormal conjunctival epithelial permeability in disease pathogenesis?
  1. S Yeoh,
  2. M Church,
  3. P Lackie,
  4. J McGill,
  5. M Mota,
  6. P Hossain
  1. Division of Infection, Inflammation & Immunity, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK
  1. Correspondence to Parwez Hossain, Division of Infection, Inflammation & Immunity, MP104, Southampton Eye Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK; parwez{at}


Aims 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.

  • Conjunctival epithelium
  • seasonal allergic conjunctivitis
  • HSP-70
  • PAR-2, conjunctiva
  • immunology

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  • Funding Funded by University of Southampton.

  • Competing interests None.

  • Patient consent Obtained

  • Ethics approval This study was conducted with the approval of the Southampton and South West Joint Research Ethics Committee (REC 036/02) and was conducted in accordance with the tenets of the Declaration of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.