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Rafael Lani, Mariana Santana Dias, Tabata Granja Araujo, William W Hauswirth, Adalmir Morterá Dantas, Mario Fiorani Junior, Hilda Petrs Silva, Rafael Linden; Neuroprotection by overexpression of transcription factor Max in experimental glaucoma.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):6137.
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© ARVO (1962-2015); The Authors (2016-present)
To test for neuroprotection in two different models of glaucoma in vivo, following overexpression of the transcription factor Max using adeno-associate viral vectors (rAAV).
Lister Hooded rats (1 month-old) were intravitreally injected with either rAAV-Max or rAAV-GFP (3μL/injection; 1x108 viral particles). One month later, animals were subject either to optic nerve crush (ONC) during 30 seconds at 1 mm from the posterior pole of the eyeball, using a self-locking forceps, or to ocular hypertension (OHT) induced by cauterization of the limbal vasculature around the cornea. IOP of the latter animals was followed daily using a calibrated tonometer (TonoPen XL). At various time points after surgery, the rats were functionally evaluated through the optokinetic tracking (OptoMotry©) response, as well as with both flash- and pattern-elicited electroretinogram. The eyes were removed after euthanasia, then the retinas were flat-mounted and examined by histo- and immunofluorescence microscopy.
The rAAVs successfully transduced the RGC layer, and robust overexpression of the transgenes was clear at one month after treatment. In both non-injected as well as rAAV-GFP injected eyes, ONC produced diffuse RGC loss, while after OHT the RGC loss was most pronounced at the superior and temporal quadrants of the retina. In both glaucoma models, the retinae of rAAV-Max injected eyes contained a higher density of RGCs compared with both non-injected and rAAV-GFP injected eyes. In addition, evidence was found in the OHT group of functional neuroprotection already at 2 weeks after surgery, as indicated by the amplitude of the PERG at a range of spatial frequencies. Also, at 1 month after surgery, loss of optokinetic response was prevented in the rAAV-Max treated animals, as compared with control operated animals.
The results showed both morphological and functional neuroprotection provided by overexpression of the Max transcription factor in two in vivo models of glaucoma. The findings are consistent with our previous evidence that, following axon damage, nuclear exclusion of Max precedes the retrograde degeneration of RGCs. Moreover, the current results suggest that gene therapy based on the overexpression of Max may provide a novel therapeutic strategy for prevention of ongoing RGC degeneration in glaucoma.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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