Angiogenic microRNAs Linked to Incidence and Progression of Diabetic Retinopathy in Type 1 Diabetes

Circulating microRNAs (miRNAs) have emerged as novel biomarkers of diabetes. The current study focuses on the role of circulating miRNAs in patients with type 1 diabetes and their association with diabetic retinopathy. A total of 29 miRNAs were quantified in serum samples (n = 300) using a nested case-control study design in two prospective cohorts of the DIabetic REtinopathy Candesartan Trial (DIRECT): PROTECT-1 and PREVENT-1. The PREVENT-1 trial included patients without retinopathy at baseline; the PROTECT-1 trial included patients with nonproliferative retinopathy at baseline. Two miRNAs previously implicated in angiogenesis, miR-27b and miR-320a, were associated with incidence and with progression of retinopathy: the odds ratio per SD higher miR-27b was 0.57 (95% CI 0.40, 0.82; P = 0.002) in PREVENT-1, 0.78 (0.57, 1.07; P = 0.124) in PROTECT-1, and 0.67 (0.50, 0.92; P = 0.012) combined. The respective odds ratios for higher miR-320a were 1.57 (1.07, 2.31; P = 0.020), 1.43 (1.05, 1.94; P = 0.021), and 1.48 (1.17, 1.88; P = 0.001). Proteomics analyses in endothelial cells returned the antiangiogenic protein thrombospondin-1 as a common target of both miRNAs. Our study identifies two angiogenic miRNAs, miR-320a and miR-27b, as potential biomarkers for diabetic retinopathy.