Abstract
Purpose :
Previous work highlights the detrimental effect elevated retinal cholesterol levels have on diabetic retinopathy (DR) progression. We have shown that downregulation of LXRα/SIRT1 results in dysregulated cholesterol metabolism and increased retinal cholesterol levels. In turn, elevated cholesterol levels lead to the formation of retinal cholesterol crystals (CC), exacerbating the pro-inflammatory and apoptotic milieu present in the diabetic retina. The focus of this study was to investigate the therapeutic potential of cholesterol lowering drugs in preventing CC-induced retinal damage in endothelial cells and in a type 2 diabetic mouse model.
Methods :
Human retinal endothelial cells (HREC) were treated with CC (2mg/ml) and/or CC pretreated with Atorvastatin (10mM), Rosuvastatin (10mM), or α cyclodextrin (10mM) for 24hrs. Inflammation was measured via IL6 and IL8 levels by qRTPCR. Cell survival was determined via trypan blue exclusion assay. Type 2 diabetes was modeled in vivo via the db/db mouse model. Alpha cyclodextrin was administered three times a week for 2 weeks via subcutaneous injections (4g/kg). Cholesterol crystals were visualized using SEM and quantified using ImageJ software analysis.
Results :
Pretreatment of CC with Atorvastatin, Rosuvastatin, or α cyclodextrin reduced the amount of crystals when compared to non-treated controls ex vivo. In culture, administration of CC significantly upregulated IL6 and IL8 expression (p<0.0001; n=3) in retinal endothelial cells. Treatment with Atorvastatin (p<0.05), Rosuvastatin (p<0.001), or α cyclodextrin (p<0.0001) significantly prevented CC-induced IL6 and IL8 upregulation (n=3). CC significantly increased cell death (p<0.01) after 24hrs while pretreatment with Atorvastatin, Rosuvastatin, or α cyclodextrin prevented CC-induced cell death (n=3). Lastly, long term type 2 diabetes (6 months) significantly increased the amount of retinal CC (p<0.05; n=5) while treatment with α cyclodextrin significantly reduced crystal formation in diabetic mice (p<0.01; n=3).
Conclusions :
Increased retinal cholesterol levels, resulting from long term diabetes, leads to the formation of pro-inflammatory CC formation. Treatment with cholesterol lowering and/or dissolving therapeutics is an effective strategy to reduce retinal inflammation and cell death by preventing CC induced retinal damage.
This is a 2021 ARVO Annual Meeting abstract.