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Q. Cui, Y. Huang, N. van Rooijen, C. P. Pang; Association of PI3K and JAK Pathways and Macrophages in Retinal Ganglion Cell Survival After Acute Elevation of Intraocular Pressure in Rats With Different Autoimmune Backgrounds. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4366.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the roles of PI3K/akt and JAK/STAT pathways and macrophages in retinal ganglion cell (RGC) survival following acute intraocular pressure (IOP) elevation in experimental autoimmune encephalomyelitis (EAE)-resistant Sprague Dawley (SD) and Fischer 344 (F344) and EAE-susceptible Lewis rats.
All experiments were conformed to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. IOP elevation was performed at 110mmHg for 2 hrs. Two inhibitors for each pathway were used. Intravitreal injections of each inhibitor were performed 3, 9, and 15 days after IOP elevation. FluoroGold was applied to retrogradely label surviving RGCs. Macrophages in the retina was identified by ED1 immunostaining. Phagocytic cells were removed by application of clodronate liposomes when necessary. Western blot and immunohistochemistry were used to examine the pathway activities and their locations in the retina, respectively. Retinal explants were used to examine the effect of the inhibitors on RGC viability in vitro.
Acute IOP elevation activated both pathways in the retina, and pathway activities were located in ganglion cell layer (GCL) and outer segments of photoreceptors. Macrophages of Lewis rats reacted dramatically and invaded in large number into the eye soon after IOP elevation whereas recruitment of macrophages was minor in SD and F344 rats. Concomitant with the dramatic increase in macrophage invasion was the great loss of RGCs (over 90%) in Lewis rats compared with 27% in SD and 25% in F344 rats 2-week after IOP elevation. Inhibition of these pathways resulted in further macrophage invasion into the eye and decreased RGC viability in all strains. Removal of macrophages reduced the inhibitors-induced RGC death. In SD rats, similar observations were also obtained in retinal explants.
Our data demonstrate that though PI3K/akt and JAK/STAT pathways mediate RGC survival after IOP elevation in all strains, macrophages react differently to IOP elevation and contribute to different extent of RGC loss in rats with different autoimmune backgrounds.
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