High-sugar high-fat treatment induces autophagy of retinal microvascular endothelial cells.

Objective: To investigate the role of high-sugar high-fat treatment in inducing autophagy of rat retinal microvascular endothelial cells.

Methods: The optimal concentrations and time points of glucose and oxidized low-density lipoprotein (ox-LDL) in inducing rat retinal microvascular endothelial cells were determined by examining the proliferate rate by CCK-8 assay. They were divided into control group (blank control), model group (treatment of 50 mM glucose and 10 μg/ml ox-LDL for 24 h), chloroquine group (treatment of 20 μM chloroquine, 50 mM glucose and 10 μg/ml ox-LDL for 24 h), resveratrol group (treatment of 50 μM resveratrol, 50 mM glucose and 10 μg/ml ox-LDL for 24 h) and MITO-Tempol group (treatment of 20 μM MITO-Tempol, 50 mM glucose and 10 μg/ml ox-LDL for 24 h). Reactive oxygen species (ROS) level in rat retinal microvascular endothelial cells induced with high sugar high-fat treatment was measured by flow cytometry. In addition, protein levels of cathepsin B and cathepsin D in rat retinal microvascular endothelial cells induced with high sugar high-fat treatment were examined by immunofluorescence, and protein levels of LC3 A/B and the autophagy substrate P62 were detected by Western blot.

Results: Primary retinal microvascular endothelial cells were isolated from neonatal Sprague-Dawley (SD) rats. ROS level was significantly higher in model group than that of control group (P < 0.05). Compared with that of model group, ROS level was significantly reduced in chloroquine group and MITO-Tempol group, which was significantly elevated in resveratrol group (P < 0.05). Positive expressions of cathepsin B and cathepsin D were significantly reduced in model group than those of control group (P < 0.05). They were significantly elevated in chloroquine group and MITO-Tempol group, and reduced in resveratrol group than those of model group (P < 0.05). LC3 A/B and P62 were significantly upregulated in model group than those of control group (P < 0.05). Compared with those of model group, LC3 A/B and P62 were significantly downregulated in chloroquine group and MITO-Tempol group, and upregulated in resveratrol group (P < 0.05).

Conclusion: High-sugar high-fat treatment induces autophagy of rat retinal microvascular endothelial cells, which can be intervened to a certain extent by chloroquine and MITO-Tempol.