Abstract
Purpose :
Aldose reductase transgenic (AR-Tg) mice created to model diabetic eye disease showed an unexpected diabetes-independent phenotype involving cell swelling at the retinal nerve fiber layer and decreases in pattern ERG compared to controls. The purpose of our study was to identify the cell types and potential role of AR as a driver of this phenotype.
Methods :
PCR genotyping ruled out the Rd8 mutation of the Crb1 gene in this model. Retinal morphology was routinely assessed by H&E staining. Immunofluorescence was used for detection and quantitation of Brn3a as a marker for RGCs, GFAP and CRALBP for Müller glia, and Iba-1 for microglia, and a species-specific antibody to human AR (AKR1B1) to map transgene expression. GraphPad Prism was used to measure differences in comparison groups according to either t-test or 1 way ANOVA followed by Tukey's Multiple Comparison Test.
Results :
The human AR (hAR) transgene was designed using a hybrid lens crystallin gene promoter. As expected, strong immunostaining was observed in lens. Unexpectedly, we observed a significant (p<0.01) increase in the number of hAR-immunopositive cells in the RGC and inner nuclear layers compared to nontransgenic controls. By 18 weeks of age, and in the absence of experimentally-induced diabetes, AR-Tg mice developed a layer of swollen and vacuole-rich cells adjacent to the RGC layer (p=0.003). Treatment from birth with Sorbinil (0.25mg/ml in drinking water), a well characterized AR inhibitor, prevented these changes (p=0.003), suggesting that the change in cell morphology was associated with AR activity. Patterns of immunostaining with GFAP, CRALBP, and hAR species-specific antiserum suggest that the swollen cells are likely endfeet of Müller glia containing transgene-derived hAR. In addition, a proinflammatory phenotype characterized by increased numbers of activated retinal microglia was observed in AR-Tg retina compared to nontransgenic control (p<0.001) or after treatment with Sorbinil (p<0.01).
Conclusions :
Elevated levels of AR gene expression typical of the diabetic retina induce a proinflammatory phenotype in mouse Müller glia and retinal microglia. Sorbinil substantially prevented these structural and functional changes, suggesting that suppression of retinal inflammation by AR inhibitors may represent a novel approach to prevention of diabetic retinopathy.
This is a 2021 ARVO Annual Meeting abstract.