Inhibition of sortilin reduces neuronal and vascular damage after ischemia/reperfusion through reduced inflammatory and autophagy actions in retinal Müller cells.

Purpose: Our goal was to explore whether inhibition of sortilin could protect the retina against ischemia/reperfusion (I/R) damage, as well as explore whether this inhibition could reduce inflammatory mediators in retinal Müller cells. Methods: We used both primary human Müller cells and a rat Müller cell line (rMC-1) grown in normal (5 mM) or high (25 mM) glucose. Some cells were treated with AF38469, a small-molecule inhibitor of sortilin. We performed western blotting for the inflammatory mediators, tumor necrosis factor α, and NOD-like receptor protein 3. We also measured protein levels of lysosome-associated membrane glycoprotein 2 (LAMP2), a marker of autophagy, and cleaved caspase 3, a marker of apoptosis, in the cells. We then tested the actions of eye drops containing AF38469 on mice exposed to I/R. We assessed neuronal damage at 2 days post-I/R and vascular damage at 10 days post-I/R. Results: High-glucose culturing conditions significantly increased inflammatory, autophagic, and apoptotic markers in both primary human Müller and rat Müller cells. All markers were reduced by treating the cells with AF38469. AF38469 eye drops also significantly reduced I/R-induced neuronal and vascular damage. Conclusion: These studies demonstrate that sortilin regulates the inflammatory, autophagic, and apoptotic pathways in Müller cells grown in high glucose. Inhibition of sortilin using AF38469 eye drops also reduced I/R-induced retinal damage.