Abstract
Purpose: :
It is known that epithelial permeability is increased after allergen challenge, and that epithelial barrier functions are altered in inflammatory bowel disease and asthma. However, little is known about the barrier function of the conjunctival epithelium during allergic inflammation. The aims of this study were to investigate localization and expression levels of the tight junction protein ZO-1 and the adhesion molecule E-cadherin, and to assess integrity of the epithelial barrier in a murine model of allergic conjunctivitis.
Methods: :
Female BALB/c mice were sensitized by footpad injection and topical treatment (eye drops) of short ragweed pollen (SRW) with aluminum hydroxide. Allergen challenge involved topical administration of SRW in phosphate buffered saline (PBS), with PBS alone administered as a control. Immunofluorescence was used to analyze the distribution and intensity of ZO-1 and E-cadherin in the conjunctival tissues in this allergic model.
Results: :
In the naïve conjunctiva, ZO-1 was consistently detected in the apical layer of the epithelium, and E-cadherin was found in the basal layer. Following allergen challenge, expression levels of both ZO-1 and E-cadherin decreased markedly in the conjunctival epithelium. In contrast, when a histamine blocker was administered prior to allergen challenge, ZO-1 and E-cadherin expression and localization were similar to those of control mice.
Conclusions: :
Altered expression of ZO-1 and E-cadherin correlates with destabilization of the conjunctival epithelium and loss of ocular surface integrity in murine allergic conjunctivitis. This decrease in conjunctival surface integrity could lead to increased penetration of allergen, which may in turn trigger epithelial destruction and exacerbate ocular allergic responses.
Keywords: conjunctivitis • cell adhesions/cell junctions • immunohistochemistry