Pharmacological and fasting-induced activation of SIRT1/LXRα signaling alleviates diabetes-induced retinopathy

Abstract

In diabetes, the retina, a tissue with unique metabolic needs, demonstrates dysregulation of the intricate balance between nutrient availability and utilization. This results in cholesterol accumulation, pro-inflammatory and pro-apoptotic changes, and consequently neurovascular damage. Sirtuin 1 (SIRT1), a nutrient sensing deacetylase, is downregulated in the diabetic retina. In this study, the effect of SIRT1 stimulation by fasting or by pharmacological activation using SRT1720, was evaluated on retinal cholesterol metabolism, inflammation and neurovascular damage. SIRT1 activation, in retinal endothelial cells (REC) and neuronal retinal progenitor cells (R28), led to Liver X Receptor alpha (LXRα) deacetylation and subsequent increased activity, as measured by increased ATP-binding cassette transporter (ABC) A1 and G1 mRNA expression. In turn, increased cholesterol export resulted in decreased REC cholesterol levels. SIRT1 activation also led to decreased inflammation. SIRT1 activation, in vivo, prevented diabetes-induced inflammation and vascular and neural degeneration.Diabetes-induced visual function impairment, as measured by electroretinogram and optokinetic response, was significantly improved as a result of SIRT1 activation. Taken together, activation of SIRT1 signaling is an effective therapeutic strategy that provides a

Lipid metabolism dysregulation in diabetic retinopathy

“…Moreover, SIRT1 stimulation by fasting or by pharmacological activation using SRT1720 leads to LXR deacetylation and subsequent increased activity, as measured by increased ATP-binding cassette transporter (ABC) A1 and ABCG1 mRNA expression. Increased cholesterol export resulted in decreased retinal endothelial cell (REC) cholesterol levels ( 91 ). SIRT1 activation, in vivo, prevented diabetes-induced inflammation and vascular and neural degeneration ( 91 ).…”

“…Increased cholesterol export resulted in decreased retinal endothelial cell (REC) cholesterol levels ( 91 ). SIRT1 activation, in vivo, prevented diabetes-induced inflammation and vascular and neural degeneration ( 91 ). Of interest, Cyp46a1 −/− mice have normal fasting blood glucose levels but a 1.8-fold increase in retinal cholesterol.…”