Abstract
Purpose: :
To investigate the response to Poly(I:C) challenge in the barrier function of hTERT immortalized conjunctival and corneal epithelium.
Methods: :
Conjunctival and corneal epithelial cells immortalized by preventing telomere shortening by transduction with hTERT were cultured on 12-mm Transwell filters at a density of 4 x 105 cells/cm2. The cultured epithelia were stimulated with 25µg/ml Poly(I:C), an analog of viral double-stranded RNA produced during viral replication. The transepithelial electrical resistance (TER) was measured using endohm electrodes and an EVOM voltohmmeter (World Precision Instruments, LTD., Hertfordshire, UK). Tight junction (TJ)-related protein ZO-1, occludin, and claudin-1,-4, and -7 mRNA expressions after 1 to 36 hours of exposure to Poly(I:C) were analyzed using quantitative reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemistry was used to clarify the change of the tissue distribution of those proteins.
Results: :
Poly(I:C) challenge increased the TER of the corneal and conjunctival epithelia in a time- and dose-dependent manner. Production of TJ-related protein mRNA was elevated after stimulation with Poly(I:C). The localization of those proteins was unchanged, but the intensity of the immunostaining showed a tendency to increase.
Conclusions: :
Corneal and conjunctival epithelium forms a barrier that isolates the eye from the outside environment, and this barrier is created by TJs. Poly(I:C) is a toll-like receptor 3 ligand. Poly(I:C) challenge, which mimics a viral infection, increased the barrier function of ocular surface epithelia. Thus, we theorize that the increased barrier function must be a kind of defense reaction to viral infection, as this increase occurs through the TJ.
Keywords: cornea: epithelium • conjunctiva • cell adhesions/cell junctions