Fig. 3.

Cholesterol metabolism in control and diabetic retina. The input is controlled by the local production by most retinal cells, and uptake from circulation by RPE cells through CD36, SR-B, and LDLR. The output is through oxidation to oxysterols, LXR activation, and production of ABCA1, ABCG1, and ApoE that control cholesterol efflux through RPE and endothelial cells (left). In diabetes, owing to the blood-retinal barrier breakdown there is an increase in nonspecific cholesterol entry, and reduction of LXR activity and cholesterol efflux, leading to an increased cholesterol accumulation in the retina (right). GLC, ganglion cell layer; INL, inner nuclear layer; IPL, inner plexiform layer; IS, photoreceptor inner segment; ONL, outer nuclear layer; OPL, outer plexiform layer; OS, photoreceptor outer segment; RPE, retinal pigment epithelium.