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Maria B Grant, Yvonne Adu-Agyeiwaah, Cristiano P. Vieira, Bright Asare-Bediako, Sandra S Hammer, Sergio Li Calzi, Julia V Busik; Intravitreal administration of AAV2-SIRT1 reverses diabetic retinopathy (DR) in a murine model of type 2 diabetes (T2D). Invest. Ophthalmol. Vis. Sci. 2022;63(7):2310.
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© ARVO (1962-2015); The Authors (2016-present)
SIRT1, a nutrient-sensing deacetylase, regulates various cellular stress responses. Loss of SIRT1 in the diabetic retina causes inflammation, neurovascular degeneration and visual impairment. Here, we investigated the effect of intravitreal administration of AAV2-SIRT1 on DR in a model of T2D, the db/db mouse.
After 6-months of diabetes, db/db mice were injected intravitreally with either AAV2-SIRT1 (AAV2-SIRT1-db/db) or control virus (AAV2-GFP-db/db) and euthanized three months later. SIRT1 upregulation was confirmed by RT-PCR and IHC. Caspase-3, Iba1, and GFAP expression were examined using IHC. Hypoxia Green reagent, a membrane-permeant, fluorogenic probe that can detect cells that are adapting to a hypoxic environment, and specific retinal cell surface markers were used for flow cytometry. ERG and OKN response measurements were undertaken to determine changes in retinal neural function and visual response, respectively.
Retina of AAV2-SIRT1-db/db mice showed increased SIRT1 expression at mRNA (3.0±0.9 vs. 0.5±0.1, p<0.05) and protein (28.4±6.0 vs. 13.9±2.0, p<0.05) level compared to AAV2 GFP-db/db mice. Iba1+ microglia were reduced in AAV2-SIRT1-db/db mice (4.0±1.0 vs. 9.0±2.0; p<0.05 ) compared to AAV2-GFP-db/db. GFAP reactivity in retinal macroglia of AAV2-SIRT1-db/db (869.9±30.0) was reduced compared to AAV2 GFP-db/db mice (1258±30.0; p<0.01). Caspase-3 positive cells were reduced in AAV2-SIRT1-db/db mice (15.0±5) compared to AAV2 GFP-db/db mice (8.0±3.0; p<0.05). Simultaneous detection of hypoxia and cell surface markers demonstrated that AAV2-SIRT1 administration reduced the number of hypoxic endothelial cells, bipolar cells, and photoreceptors compared to AAV2-GFP as assessed by flow cytometery. The scotopic b-wave (326.0±43.0) was significantly improved in AAV-SIRT1-db/db compared to AAV2 GFP-db/db mice (188.0±39; p<0.05). OKN responses were also enhanced in AAV2-SIRT1-db/db mice (0.39±0.01 vs. 0.28±0.02; p<0.05).
Intravitreal administration AAV2-SIRT1 reversed DR through inhibiting retinal inflammation and apoptosis, reducing the number of hypoxic retinal cells, and improving the function of retinal neural cells and visual responses.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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