Abstract
Purpose :
Photoreceptors are both the most abundant and the most metabolically active cells in the retina, and they are susceptible to undergoing metabolic alterations in response to hyperglycemia. We hypothesized that high glucose induces changes in gene expression in rod photoreceptors that in turn may affect the progression of diabetic retinopathy.
Methods :
The streptozocin (STZ) and the Akita mouse models of diabetic retinopathy and their appropriate littermate controls were used. In the STZ model, diabetes was induced in 4 week-old C57BL/6j mice. Diabetes was confirmed when fasting plasma glucose became persistently elevated (>300 mg/dL) and experiments were performed at 10 weeks of diabetes. Rod photoreceptors were isolated from the retinas of diabetic mice and littermate controls, and their gene expression profiles were analyzed by RNA sequencing. For in vitro experiments, rod photoreceptors were isolated from the retinas of C57BL/6j wild-type mice, and treated with high D-glucose (25mM D-glucose) or control (low glucose (5mM D-glucose), or high L-glucose (25 mM L-glucose) as osmotic control) for 24–48 hours in primary dissociated rod photoreceptor cultures. The rod photoreceptor-conditioned media were tested and their effects on the induction of inflammatory cytokines in mouse Müller cells and retinal microvascular endothelial cells were quantified by RT-PCR. The effect of rod photoreceptor-conditioned media on transendothelial electrical resistance (TEER) was measured with the electrical cell-substrate impedance sensing method.
Results :
Diabetes induced upregulation of transcripts for tnf (3-fold, P=0.006) and il1a (2.2-fold, P=0.001) in rod photoreceptors from diabetic mouse models. Rod photoreceptors treated with high D-glucose in vitro significantly induced Tnf (15.5-fold, P<0.001), Il1b (10.8-fold, P=0.04), and Il6 (5.4-fold, P=0.007) expression by Müller cells compared to rod photoreceptors treated with control media. Rod photoreceptors treated with high D-glucose induced Tnf (3.6-fold, P=0.005) expression by retinal microvascular endothelial cells. Conditioned media from rod photoreceptors treated with high D-glucose significantly decreased TEER compared to control media.
Conclusions :
Diabetes induces expression of inflammatory cytokines by rod photoreceptors, which may play a direct role in activating processes involved in the progression of diabetic retinopathy.
This is a 2020 ARVO Annual Meeting abstract.