Human corneal epithelial cells express functional PAR-1 and PAR-2.
PURPOSE: The objective of this study was to examine whether HCECs express functional proteinase-activated receptor (PAR)-1 and -2 and evaluate the effects of receptor activation on corneal epithelial cell proinflammatory cytokine production. METHODS: Expression of PAR-1 and -2 mRNAs was determined by RT-PCR in cultured primary human corneal epithelial cells (HCECs) and the human corneal epithelial cell line HCE-T. Localization of PAR-1 and -2 in whole normal human corneas was determined by immunofluorescence with PAR-1 and -2 antibodies. The functional competence of PAR-1 and -2 in corneal epithelial cells was assessed by measuring the rapid induction of intracellular [Ca(2+)] in response to thrombin, trypsin, and specific receptor-activating peptides derived from the tethered ligands of the PAR receptors. HCE-T expression of cytokines (IL-6, IL-8, and TNFalpha) in response to activation of PAR-1 and -2 was measured by quantitative RT-PCR and ELISA. RESULTS: Functional PAR-1 and -2 were expressed in both HCECs and HCE-T cells. Immunoreactivity for PAR-1 and -2 was detected in the outer epithelial layer of the cornea in whole human corneal sections. Activation of PAR-1 and -2 led to upregulation in HCE-T cells of both expression of mRNA and secretion of the proinflammatory cytokines IL-6, IL-8, and TNFalpha. CONCLUSIONS: The results show for the first time that functional PAR-1 and -2 are present in human cornea. Activation of these receptors results in the production of various corneal epithelial cell proinflammatory cytokines. These observations indicate that PAR-1 and -2 may play an important role in modulating corneal inflammatory and wound-healing responses. These receptors may be useful therapeutic targets in several corneal disease processes.[1]References
- Human corneal epithelial cells express functional PAR-1 and PAR-2. Lang, R., Song, P.I., Legat, F.J., Lavker, R.M., Harten, B., Kalden, H., Grady, E.F., Bunnett, N.W., Armstrong, C.A., Ansel, J.C. Invest. Ophthalmol. Vis. Sci. (2003) [Pubmed]
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