Toll-like receptor 4 and CD14 expression in human ciliary body and TLR-4 in human iris endothelial cells

Beatriz E. Brito, David O. Zamora, Robert A. Bonnah, Yuzhen Pan, Stephen R. Planck, James T. Rosenbaum

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

We investigated the expression of the functional endotoxin receptor proteins Toll-like receptor-4 and CD14 in human eyes. Toll-like receptor-4 and CD14 proteins were detected by immunohistochemical analysis of sections of whole human eyes embedded in paraffin with monoclonal antibodies against human toll-like receptor-4 (HTA-125), human CD14 (RPA-M1), or as a control, an irrelevant mouse IgG1k (MOPC-21). Incubation of explants with a neutralizing anti-toll-like receptor-4 monoclonal antibody was used to determine if lipopolysaccharide stimulation of tumor necrosis factor or interleukin-6 secretion was dependent on Toll-like receptor-4 activity. Reverse transcription-polymerase chain reaction was used to detect mRNAs for toll-like receptor-4, tumor necrosis factor-α, interleukin-1β, interleukin-6 and interleukin-8, 3hr after stimulation of cultured iris microvascular endothelial cells. By immunohistochemistry, human ciliary body non-pigmented epithelial cells showed strong expression of the endotoxin receptor proteins, toll-like receptor-4 and CD14. Toll-like receptor-4 antibodies significantly inhibited lipopolysaccharide-stimulated tumor necrosis factor secretion by the ciliary body. Toll-like receptor-4 mRNA was constitutively expressed in iris endothelial cells and slightly down-regulated by endotoxin. mRNA levels for tumor necrosis factor-α, interleukin-1β, interleukin-6 and interleukin-8 were all increased by endotoxin treatment. This is the first report that shows intraocular (ciliary body and iris) expression of toll-like receptor-4, other than in cornea. Our results show that the ciliary body also expresses CD14, which is anatomically colocalized with toll-like receptor-4. This suggests a potential interaction between both molecules during endotoxin activation of ciliary body cells. The juxtaposition of toll-like receptor-4 and CD14 in the anterior uveal tract helps to explain the sensitivity of the iris/ciliary body to bacterial endotoxin as seen in the standard animal model of endotoxin-induced uveitis.

Original languageEnglish (US)
Pages (from-to)203-208
Number of pages6
JournalExperimental Eye Research
Volume79
Issue number2
DOIs
StatePublished - Aug 1 2004

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Keywords

  • CD14
  • ciliary body
  • endothelial cells
  • human
  • iris
  • toll-like receptor-4

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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