Urokinase and Plaminogen Activation in Vernal Keratoconjunctivitis Patiens

Abstract

Abstract: : Purpose: The serine protease, urokinase (uPA) is a potent chemoattractant for leukocytes and may be involved in the pathogenesis of vernal keratoconjunctivitis (VKC). Levels of plasminogen (P), uPA, tissue plasminogen activator (tPA) and their inhibitor, plasminogen activator inhibitor (PAI) were measured in tears and plasma of VKC patients with and without severe corneal damage. Methods: Tear samples were obtained from 20 active VKC patients and 15 normal subjects as a control group after clinical evaluation and tear cytology. Tear levels of uPA, tPA and PAI were measured by enzyme-linked immunosorbent assays (ELISA). Tissue expression of tPA, uPA and urokinase receptor (uPAR) were evaluated by immunohistochemistry. Results: Four VKC patients presented corneal ulcers, and 6 a mild keratopathy. Tear levels of uPA (1.26±0.89 vs 0.25±0.2 p<0.002) and tPA (6.29±3.5 vs 2.89±1.35, p=0.0099) were significantly increased in VKC patients compared to controls. Tear PAI tear levels were not detectable. No correlations were found between tear levels and clinical score or corneal involvement. However, uPA levels were correlated with the number of inflammatory cells in tears. Increased expression of plasminogen activators was found in VCK tissues compared to normal conjunctiva. Conclusions: Increased levels and activity of uPA and imbalance between uPA and PAI may be involved in the pathogenesis of VKC and in the inflammatory cell recruitment.

Keywords: conjunctivitis • inflammation • cytokines/chemokines