Differential expression of toll-like receptor mRNA in corneal epithelium of ruminants

Purpose The present study was carried out to identify and assess the expression levels of toll-like receptors (TLRs) 1-10 mRNA in corneal epithelial cells of buffalo, goat, sheep and bull. Materials and methods The globes from the respective species were collected and the corneal epithelium was denuded. The expression levels of the different TLR mRNAs were assessed by densitometry of the band intensities following reverse transcriptase polymerase chain reaction (RT-PCR). Results In all species TLR5 and TLR7 were highly expressed with lower levels of TLR10. The TLR6 mRNA levels were the lowest in the cornea of bull. The TLR2 expression was high in sheep and bulls, while TLR4 mRNA was higher in sheep alone. The level of the other TLRs varied across other species. Conclusion Based on these observations it may be inferred that these animals would be resistant to flagellin (TLR5) and single-stranded RNA viruses (TLR7), while sheep alone may show more resistance to lipo-polysaccharide (TLR4) and peptidoglycan (TLR2)-mediated injury of the cornea. This work reports for the first time the expression of TLR mRNAs in the corneal epithelial cells of farm animals. The relationship of the TLR mRNA levels to corneal disease susceptibilities and pathogenicity remains to be explored further.