Abstract
Purpose: :
Ocular exposure to Staphylococcal enterotoxin B (SEB) can result in systemic effects yet it is not known whether exposure of conjunctival epithelium to SEB results in changes in barrier function which promote access of SEB to underlying tissues. The purpose of this study was to examine regulation of human conjunctival epithelial cell monolayer (HCE) permeability in response to IL-8 and SEB as well as transcytosis of SEB across HCE.
Methods: :
HCE (IOBA-NHC cell line, University of Valladolid, Spain) were cultured on cell culture inserts and stimulated with various concentrations of SEB and/or IL-8 for 30 min then horseradish peroxidase (HRP) was added to the upper compartment. 60 min later, aliquots were collected from the lower compartment and HCE were lysed and collected. Concentration of HRP was measured fluorometrically using a commercially available kit (Molecular Probes) and SEB was measured using a commercially available ELISA (Toxin Technology).
Results: :
Lower concentrations of IL-8 enhanced HRP permeability through HCE (i.e., more HRP was measured in lower compartment), but higher concentrations of IL-8 inhibited HRP permeability. SEB enhanced HRP permeability through HCE in a dose dependent manner. No HRP was measured in the lysed cells regardless of stimuli, indicating paracellular diffusion rather than transcytosis. SEB was measured in both lysed cells and lower compartment indicating SEB transcytosis. Co-stimulation with SEB and IL-8 increased cell associated SEB.
Conclusions: :
IL-8, constitutively produced by HCE, may play a role in maintenance of conjunctival epithelial cell monolayer integrity through regulation of permeability. SEB transcytosis across HCE monolayers likely occurs via a specific receptor that may be upregulated by IL-8.
Keywords: conjunctiva • cell adhesions/cell junctions • Staphylococcus