Vanilloid Receptor Expression on Human Corneal Epithelial Cells

Abstract

Abstract: : Purpose: Vanilloid receptor 1 (VR1) is a member of the transient receptor potential (TRP) family of ion channels that has been identified on sensory neurons. VR1 is known to be activated by the plant vanilloid compound capsaicin, the main ingredient of hot chili peppers as well as by heat, protons, and extracellular acidification. We have recently demonstrated the presence of functional VR1 on human keratinocytes. In this study we determine if VR1 is present on human corneal epithelial cells. Methods: RT-PCR was used to investigate the in vitro expression of VR1 mRNA using a human corneal epithelial cell line. Immunofluoresence of cultured monolayers of these cells was performed to determine in vitro expression of the receptor using a specific anti-VR1 antibody. Similarly, the in vivo expression of VR1 was evaluated by immunohistochemistry of whole human cornea. Results: Constitutive expression of VR1 mRNA was observed in the human corneal epithelial cell line. Immunofluorescence of these cells demonstrated the presence of VR1. Immunohistochemistry of whole human cornea showed specific staining for VR1 in basal epithelial cells. Conclusions: We report for the first time that human corneal epithelial cells and human corneal epithelium constitutively express the capsaicin-sensitive vanilloid receptor VR1. The expression of VR1 on this non-neuronal epithelial tissue has important implications for both normal corneal homeostasis as well as for the corneal response to noxious agents such as pepper spray which activate this receptor.

Keywords: cornea: epithelium • cornea: basic science • inflammation