Apolipoprotein A1 Is Overexpressed in the Retina of Diabetic Patients

Abstract

To compare apolipoprotein A1 (ApoA1) expression in the retina from diabetic and nondiabetic donors. Case-control study. Diabetic postmortem eyes (n = 8) were compared with eyes (n = 8) from nondiabetic donors matched by age. Messenger ribonucleic acid (mRNA) of ApoA1 (quantitative reverse-transcriptase polymerase chain reaction) was measured separately in the neuroretina and retinal pigment epithelium (RPE). ApoA1 was assessed by immunofluorescence (confocal laser microscopy) and Western blot analysis. The presence of early diabetic retinal damage was evaluated by measuring the rate of apoptosis and glial activation. ApoA1 mRNA levels and ApoA1 immunofluorescence obtained in RPEs and in neuroretinas from diabetic donors were significantly higher than those obtained from nondiabetic donors. ApoA1 was expressed in all retina layers and it was more abundant in RPE than in the neuroretina in both diabetic and nondiabetic donors. In addition, ApoA1 immunofluorescence was significantly higher in all the layers of the neuroretina from diabetic patients. Densitometric analysis of immunoblots showed higher ApoA1 in the retinas from diabetic donors in comparison with nondiabetic donors, but the differences were at significant levels only for the RPE. ApoA1 overexpression is an early event in the retina of diabetic patients and can be involved in the physiopathology of diabetic retinopathy. In addition, RPE is the main source of ApoA1 within the retina. These findings my be relevant to aiming new treatment strategies toward reducing the development of diabetic retinopathy.