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BE Brito, RA Bonnah, DO Zamora, SR Planck, JT Rosenbaum; Expression of Toll-like Receptor-4 (TLR-4) and CD14 in Human Ciliary Body Epithelium and TLR-4 in Iris Endothelial Cells . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1562.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine if there is intraocular expression in human eye of the functional endotoxin receptor proteins Toll-like receptor-4 (TLR-4) and CD14. Methods: TLR-4 and CD14 expression were determined by immunohistochemical analysis of sections of whole human eyes embedded in paraffin using monoclonal antibodies against human TLR-4 (HTA-125, 10 µg/ml donated by Dr. K. Miyake, (Saga Medical School,Japan), human CD14 (RPA-M1, 10 µg/ml) or as a control, an irrelevant mouse IgG1k (MOPC-21, 10 µg/ml). Reverse transcription-polymerase chain reaction was used to detect mRNAs for TLR-4, TNFα, IL-1, IL-6 and IL-8, 3 hours after stimulation of cultured iris microvascular endothelial cells. Results: By immunohistochemistry, human ciliary body non-pigmented epithelial cells showed strong expression of the endotoxin receptor proteins, TLR-4 and CD14. Epithelial corneal cells showed a weak expression of TLR-4 and CD14. TLR-4 mRNA expression in iris endothelial cells was constitutively expressed and slightly down regulated by endotoxin. mRNA levels for TNFα, IL-1, IL-6 and IL-8 were all increased by endotoxin treatment. Conclusion: This is the first report that shows intraocular expression of TLR-4, other than cornea. The ciliary body also expresses CD14, which is anatomically colocalized with TLR-4. This suggests a potential interaction between both molecules during endotoxin activation of ciliary body cells. Endotoxin-induced uveitis is a stadard animal model. The juxtaposition of TLR-4 and CD14 in the anterior uveal tract helps to explain the sensitivity of the iris to bacterial endotoxin.
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