Expression of Toll-like receptors in healthy and allergic conjunctiva

Ophthalmology. 2005 Sep;112(9):1528; discussion 1548-9. doi: 10.1016/j.ophtha.2005.04.009.


Purpose: To investigate the expression of toll-like receptors (TLRs) in healthy and active vernal keratoconjunctivitis (VKC) conjunctiva.

Design: Comparative nonrandomized interventional study.

Participants: Nine patients with vernal keratoconjunctivitis and 10 healthy subjects.

Methods: Normal and VKC conjunctiva were evaluated for TLR-2, TLR-4, and TLR-9 mRNA and proteins by relative real-time polymerase chain reaction and immunohistochemistry. Colocalization of TLRs was further evaluated by confocal microscopy and double-labeled immunofluorescence in T cells (CD4), mast cells (AA1), and eosinophils (EG2).

Main outcome measures: Identification of TLRs at molecular and biochemical levels and identification of inflammatory cells that coexpress these receptors.

Results: Toll-like receptor 2, TLR-4, and TLR-9 were expressed in normal and VKC conjunctival epithelium and stroma, both with a more intense immunoreactivity in the stroma. In VKC tissues, TLR-4 was upregulated, TLR-9 was downregulated, and TLR-2 was slightly decreased relative to normal tissues. Toll-like receptor 4 was localized on CD4+ lymphocytes, eosinophils, and mast cells, whereas lymphocytes and eosinophils, but not mast cells, expressed TLR-9.

Conclusions: Toll-like receptors are expressed in healthy and allergic conjunctiva. The upregulation or downregulation of these receptors and their presence on inflammatory cells suggest a role of TLRs in VKC.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • CD4-Positive T-Lymphocytes / immunology
  • Child
  • Child, Preschool
  • Conjunctiva / metabolism*
  • Conjunctivitis, Allergic / metabolism*
  • Eosinophils / immunology
  • Epithelium / metabolism
  • Female
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Immunoenzyme Techniques
  • Male
  • Mast Cells / immunology
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Microscopy, Confocal
  • RNA, Messenger / metabolism
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptor 9
  • Toll-Like Receptors
  • Up-Regulation


  • Membrane Glycoproteins
  • RNA, Messenger
  • Receptors, Cell Surface
  • TLR2 protein, human
  • TLR4 protein, human
  • TLR9 protein, human
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptor 9
  • Toll-Like Receptors