Abstract
Abstract: :
Purpose: Toll–like receptors (TLR) are a family of pattern–recognition receptors that detect the conserved molecular products of microorganisms. They play an important role in innate immune response against microbial infection. This study has investigated the expression of TLRs on human ocular surface epithelial cells. Methods: RNA from human conjunctival (Cj) impression cytology specimens was extracted from normal individuals and pterygium patients. Corneal mRNA was extracted from cells collected by laser aided micro–cell dissection (PALM) from normal human donor cornea tissue. Human Cj and limbal epithelial cells were harvested by dispase digestion from donor tissue and cultured. The expression of TLRs was analyzed by Taqman gene expression probe and real time PCR. Results: Of the 10 members of TLRs, TLR1,2,3 and 5 were consistently found expressed in cornea, limbal and Cj epithelial cells. Message of TLR4, 6 and 9 were detected in cultured limbal and Cj epithelial cells at low levels as assessed by ΔCt values (compared to ß–actin). In pterygium patient samples, TLR4 and TLR7 expression was also detected. Additionally, the expression of TLR1, 3 and 5 were lower in pterygium samples than normals, while the expression of TLR2 was not changed. The same patterns of regulation were also found in cultured Cj cells after UVB (20mJ/cm2) exposure. The expression of TLR1–4 was also up–regulated upon lipopolysaccharide stimulation in cultured Cj epithelial cells. Conclusions: The regulated expression of multiple TLRs indicated the existence of a complicated defense system against microbial infections on human ocular surface epithelial cells.
Keywords: inflammation • cornea: epithelium • immunomodulation/immunoregulation