Serum exosomal miR-377-3p inhibits retinal pigment epithelium proliferation and offers a biomarker for diabetic macular edema

OBJECTIVES: Diabetic macular edema (DME) is a complication of diabetes mellitus that leads to diabetic retinopathy. Thus far, the role of serum exosomal microRNAs (miRNAs) in DME progression remains elusive. This study investigated serum exosomal miRNAs from patients with type 2 diabetes (T2D) and DME to identify miRNAs associated with expression of vascular endothelial growth factor (VEGF), a pivotal component in DME progression; it also evaluated the diagnostic values of these miRNAs for DME. METHODS: Serum was collected from patients with T2D who did (n = 20) and did not have DME (n = 24). Exosomes were isolated from serum and subjected to real-time polymerase chain reaction, western blotting, luciferase reporter, and miRNA profiling analyses. RESULTS: VEGF was significantly upregulated in ARPE-19 cells treated with exosomes from patients with T2D and DME, compared with exosomes from patients with T2D alone. Among the top 10 downregulated miRNAs identified during exosomal miRNA profiling, miR-377-3p inhibited the expression of VEGF. Luciferase reporter assays confirmed that miR-377-3p could directly regulate VEGF expression. Receiver operating characteristic analysis identified serum exosomal miR-377-3p as a potential biomarker for DME. CONCLUSION: Serum exosomal miR-377-3p inhibits VEGF expression to suppress retinal pigment epithelium proliferation and offers a diagnostic biomarker for DME.