Aliskiren reduces vascular pathology in diabetic retinopathy and oxygen-induced retinopathy in the transgenic (mRen-2)27 rat

Aim/hypothesis We examined whether the renin inhibitor, aliskiren, provides similar or greater protection than ACE inhibition from non-proliferative diabetic retinopathy and from the proliferative neoangiogenesis of oxygen-induced retinopathy. Methods Transgenic (m Ren-2 )27 rats, which overexpress mouse renin and angiotensin in extra-renal tissues, were studied. For diabetic studies, non-diabetic, diabetic (streptozotocin, 55 mg/kg), diabetic + aliskiren (10 mg kg −1 day −1 , pump), or diabetic + lisinopril (10 mg kg −1 day −1 , drinking water) rats were evaluated over 16 weeks. For oxygen-induced retinopathy studies, rats were exposed to 80% oxygen (22 h/day) from postnatal days 0 to 11, and then room air from postnatal days 12 to 18. Aliskiren (10 or 30 mg kg −1 day −1 , pump) or lisinopril (10 mg kg −1 day −1 , drinking water) was administered during retinopathy development between postnatal days 12 and 18. Results Systolic BP in diabetic (m Ren-2 )27 rats was reduced with 10 mg kg −1 day −1 aliskiren, but only lisinopril normalised systolic blood pressure. In diabetic (m Ren-2 )27 rats, 10 mg kg −1 day −1 aliskiren and lisinopril reduced retinal acellular capillaries and leucostasis to non-diabetic levels. In oxygen-induced retinopathy, neoangiogenesis and retinal inflammation (leucostasis, ED-1 immunolabelling) were partially reduced by 10 mg kg −1 day −1 aliskiren and normalised by 30 mg kg −1 day −1 aliskiren, whereas lisinopril normalised neoangiogenesis and reduced leucostasis and ED-1 immunolabelling. Aliskiren and lisinopril normalised retinal vascular endothelial growth factor expression; however, only aliskiren reduced intercellular adhesion molecule-1 to control levels. Conclusions/interpretation Aliskiren provided similar or greater retinal protection than ACE inhibition and may be a potential treatment for diabetic retinopathy.