Purchase this article with an account.
L.-A. Tu, S. Guha, J. C. Lim, T. Eysteinsson, A. M. Laties, C. H. Mitchell; Stimulation of the P2X7 Receptor on RPE Cells Triggers a Rapid Release of IL-6. Invest. Ophthalmol. Vis. Sci. 2010;51(13):462.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The cytokine IL-6 may stimulate choroidal neovascularization (CNV), and inhibition of IL-6 reduces the vessel growth and inflammation in CNV models. While expression of the IL-6 gene is increased in RPE cells from diseased eyes, it is not currently known how IL-6 release is triggered. In other tissues, stimulation of the P2X7 receptor for ATP activates a pannexin hemichannel, which in turn activates the inflammasome and triggers cytokine release. In this study we asked whether a similar pathway could trigger IL-6 release from RPE cells.
Calcium levels were measured in ARPE-19 cells grown on 96 well plates loaded with fura-2 and excited at 340 and 380 nm. IL-6 release was determined with a chemiluminescent Elisa assay.
Stimulation of RPE cells with the P2X7 receptor agonist BzATP led to a large, sustained rise in calcium. This elevation was dependent upon the presence of extracellular calcium, was increased by removal of magnesium, and was inhibited by antagonists Brilliant Blue G, A438079 and KN-62. Together this strongly implicates the P2X7 receptor. The level of IL-6 in the bath was increased several fold after exposure of RPE cells to BzATP. Release was rapid, with levels raised 1, 15 and 60 min after exposure to BzATP began. The release of IL-6 was inhibited by pannexin channel blocker carbenoxolone (10 µM), suggesting pannexins may be involved in the release.
RPE cells possess functional P2X7 receptors. Their stimulation triggers a release of IL-6 that requires pannexin channels. It remains to be determined whether IL-6 release following stimulation of the P2X7 receptor enhances CNV.
This PDF is available to Subscribers Only