Tryptase increases proliferative activity of human conjunctival fibroblasts through protease-activated receptor-2

Naoko Asano-Kato, Kazumi Fukagawa, Naoko Okada, Murat Dogru, Kazuo Tsubota, Hiroshi Fujishima

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


PURPOSE. Tryptase that is released by mast cell degranulation has recently been thought to play a key role in wound healing in allergic bronchitis. Conjunctival fibroblasts secrete mediators and extracellular matrices that could exacerbate inflammation and papillary formation in allergic conjunctivitis. This study was conducted to investigate the effect of tryptase on the proliferation of conjunctival fibroblasts and studied whether this effect was mediated by protease-activated receptor (PAR)-2. METHODS. Conjunctival fibroblasts were cultured with or without tryptase (0.1 ng/mL to 1.0 μg/mL), and the proliferation rate was assessed after 48 hours. The effects of tryptase inhibitors (leupeptin, benzamidine) and a PAR-2 agonist (SLIGKV) were examined. The existence of PAR-2 mRNA and protein in conjunctival fibroblasts was examined by RT-PCR and Western blot analysis, respectively. The existence of PAR-2 in cultured conjunctival fibroblasts and conjunctival papillae from patients with vernal keratoconjunctivitis, as well as conjunctival tissue from normal subjects was examined by immunohistochemistry. RESULTS. Conjunctival fibroblast proliferation was upregulated by tryptase in a dose-dependent manner (P < 0.001). Leupeptin and benzamidine inhibited tryptase-induced fibroblast proliferation (P < 0.05), and SLIGKV mimicked tryptase's effect. PAR-2 mRNA and protein were detected in cultured conjunctival fibroblasts using RT-PCR and Western blot analysis. PAR-2 immunoreactivity in both the cultured conjunctival fibroblasts and in stromal cells in excised conjunctival tissues was observed. CONCLUSIONS. Tryptase increased conjunctival fibroblast proliferation and this response appeared to be mediated by PAR-2. Mast cells are the most likely source of tryptase in the conjunctiva and may play an important role in chronic exacerbations with conjunctival papillary formation in allergic conjunctivitis.

Original languageEnglish
Pages (from-to)4622-4626
Number of pages5
JournalInvestigative Ophthalmology and Visual Science
Issue number12
Publication statusPublished - 2005 Dec
Externally publishedYes

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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