Expression levels of purinergic receptors in the endothelium of human and murine cornea

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Abstract

Purpose

Since loss of corneal endothelial cells (EC) due to cell death is the major problem in numerous corneal conditions as well as in tissue storage for corneal transplantation, finding ways to improve cell survival is of great importance. Purinergic receptors P2RY [G protein-coupled receptors] and P2RX [ligand-gated ion channels] are both known to be implicated in inflammation and apoptosis pathways, therefore modulation of these receptors may provide an efficient way to increase EC survival. The aim of this study was to study expression levels of P2RY2 and P2RX7 receptors (P2R) in murine and human corneal endothelium, as well as the association to the purinergic receptor ligand ATP.

Methods

Expression levels of P2R were determined by qRealTime-PCR relying on untreated and Interleukin-1b-treated murine and human EC. EC apoptosis was also studied in response to ATP in a “cornea-in-a-cup” assay.

Results

In murine EC P2RX7 were significantly predominant compared to P2RY1 and P2RY2, while in human EC P2RY2 were significantly prevailing compared to P2RX7. Exposure to ATP in increasing concentrations resulted in a steady increase of apoptosis. As indicators of EC stress, changes in cell size (polymegathism) and cell shape (loss of EC hexagonality, polymorphism) could be demonstrated.

Conclusion

Our data describe distinct differences in P2R expression levels in murine versus human EC showing the limitations of using the mouse model in P2R EC research. As P2R seem to be evenly distributed over the entire concave surface of the EC monolayer, inhibiting P2R interaction with their ligands (e.g. extracellular ATP) may present an effective way to prevent EC apoptosis.

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