Adeno‐associated virus (AAV) knock‐down of amyloid precursor protein attenuates retinal ganglion cell degeneration in experimental glaucoma

Abstract

AbstractPurpose: Retinal ganglion cell (RGC) degeneration and visual field loss are distinctive features of primary open angle glaucoma. Similar pathologies have been observed in Alzheimer's Disease patients, concomitant to amyloid‐β aggregation. Here, we investigated the effect of amyloid precursor protein (APP) modulation in the retina and examined the potential neuroprotective effects of APP knock‐down (APP‐KD) in experimental glaucoma.Methods: AAV‐PHP.eB constructs for APP‐KD (NM_000484) and positive scramble controls were transfected in SH‐SY5Y neuroblastoma cells to validate their expression. Wild‐type C57BL/6J mice (n = 30) were then transduced with APP‐KD (n = 10) or scramble (n = 10) vectors intravenously. Experimental chronic glaucoma was induced via weekly intraocular microbead injections for 8 weeks. Inner retinal function was assessed using positive scotopic threshold response (pSTR) amplitudes. Structural RGC changes were quantified using haematoxylin and eosin staining and manual cell count.Results: All microbead‐injected eyes showed significantly increased intraocular pressure (Mean ± SEM; Microbead vs. Control; 27.98 ± 0.78 mmHg vs. 10.01 ± 0.13 mmHg). In glaucomatous conditions, there was significant preservation of the RGC layer in APP‐KD treated eyes, compared to scramble and microbead‐only eyes (p < 0.002) (Mean ± SEM; Microbead/APP‐KD vs. Microbead/Scramble vs. Microbead‐only; 41.57 ± 1.61 vs. 37.73 ± 1.50 vs. 35.43 ± 0.95 cells/300 μm). However, there was no significant changes in pSTR amplitudes of glaucomatous APP‐KD eyes, compared to scramble and microbead‐only eyes (p = 0.653).Conclusions: AAV‐PHP.eB mediated APP‐KD confers significant protection of the RGC layer in glaucomatous eyes, however this protection was not sustained functionally. The molecular mechanisms by which APP‐KD may impart neuroprotection and ameliorate APP neurotoxicity are unclear. Further studies will include biochemical evaluation of synaptic and cellular stress markers.