Abstract
Purpose :
We previously reported that polyriboinosinic-polyribocytidylic acid [poly(I:C)], a synthetic analog of viral double-strand RNA that is produced during viral replication, strengthens both the tight junction (TJ) barrier and the glycocalyx barrier of corneal epithelium. Poly(I:C) is a ligand of toll-like receptor 3 (TLR3), a member of innate immune receptors family. In this present study, we investigated whether or not the increase of the barrier function by Poly(I:C) in immortalized human corneal epithelial cells (HCLEs) is via TLR3.
Methods :
Immortalized HCLEs were cultured on 12-mm Transwell filters (n=12) at a density of 4x105 cells/cm2. The cultured cells were then stimulated with 25µg/ml of Poly(I:C). To block TLR-3, TLR3/dsRNA Complex Inhibitor (EMD Millipore) was added to the medium until the final concentration became 100μM. Since TLR3/dsRNA Complex Inhibitor contains cytotoxic dimethyl sulfoxide (DMSO), the same concentration of DMSO was added to the medium as a control. After 24-hours exposure to Poly(I:C), transepithelial electrical resistance (TER), which indicates the TJ function, was measured using EndOhm electrodes (World Precision Instruments). The mRNA expressions of mucin 1, mucin 16, and galectin-3, components of the glycocalyx barrier, were analyzed by real-time polymerase chain reaction.
Results :
Stimulation with Poly(I:C) increased the TER and mucin 1, mucin 16, and galectin-3 mRNA expression after 24-hours exposure to Poly(I:C) (p<0.01). TLR3 inhibitor blocked both increases by Poly(I:C) stimulation (p<0.01).
Conclusions :
The findings in this study show that Poly(I:C) increases the barrier function of HCLEs via TLR3, and that Poly(I:C) challenge, which mimics a viral infection, increases the barrier function of ocular-surface epithelia via a member of the innate immune receptors family, thus suggesting that the increased barrier function must be a kind of host defense reaction against viral infection.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.