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Amalia Enriquez-De-Salamanca, Maria-Jesus Benito, Carmen Garcia-Vazquez, Michael E. Stern, Margarita Calonge; TLR-4 Expression Under Inflammatory Conditions In Ocular Surface Epithelial Cultured Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1834.
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Toll-like receptors (TLRs) are involved in inflammatory processes through the recognition of both exogenous ligands of microorganisms and endogenous ligands derived from damaged or necrotic tissues. Numerous studies have shown changes in the expression of TLRs in different epithelia under the action of the different profiles of cytokines and chemokines. The involvement of TLRs in ocular surface inflammation in particular TLR-4, has also been reported. The aim of this study was to determine whether the expression of TLR-4 on the ocular surface in vitro was modified under the influence of different proinflammatory conditions.
Corneal (HCE) and conjunctival (IOBA-NHC) epithelial cells were stimulated with TNF-α (25 ng/ml), IFN-γ (500 U/ml), interleukin (IL)-4, IL-13, and IL-17A (20 ng/ml) for 48h and with TGF-β1 and TGF-β2 (10 ng/ml) for 30 min and 48h in serum-free culture medium. TLR-4 expression was determined in basal and stimulated cells by SDS-PAGE and Western blotting and by immunofluorescence assays.
Both cell lines expressed TLR-4 basally. A significant upregulation of TLR-4 expression was observed in corneal epithelial cells after 48h stimulation with TNF-α and IL-17A. IL-17A+TNF-α significantly downregulated TLR-4 expression in HCE cells compared to IL-17A stimulation alone. TGF-β2 isoform treatment produced a significant decrease in TLR-4 expression in HCE cells both at 30 min and 48h, and in IOBA-NHC cells (only at 48h). TGF-β1 significantly decreased TLR-4 expression in IOBA-NHC cells at 48h.
These data show that TLR-4 expression in corneal and conjunctival epithelial cells may vary under different physiological and pathological conditions of the ocular surface by the action of cytokines and chemokines present, suggesting an additional contribution of these molecules to the ocular surface inflammatory processes through the modification of, at least, TLR-4 expression.
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