Serum microRNA-221 as a biomarker for diabetic retinopathy in patients associated with type 2 diabetes

AIM: To investigate the candidate microRNA(miRNA), miR-221 as a novel biomarker for diabetic retinopathy(DR) in patients associated with type 2 diabetes(T2D).METHODS: The subjects involved were divided into four groups: healthy control(HC), no diabetic retinopathy(NDR), non-proliferative diabetic retinopathy(NPDR) and proliferative diabetic retinopathy(PDR) group. Serum miR-221 was validated by real-time quantitative reversetranscription polymerase chain reaction(qRT-PCR). Also, serum angiotensin II(Ang II) and vascular endothelial growth factor(VEGF) were examined by enzyme-linked immunosorbent assay. In addition, receiver operating characteristic(ROC) curve was performed to explore the diagnostic accuracy of miR-221, Ang Ⅱ and VEGF for DR in patients with T2D. Spearman’s rank correlation coefficient was executed to estimate the correlations of serum miR-221 with metabolic parameters and serum markers in patients with T2D.RESULTS: Primarily, serum miR-221, Ang Ⅱ and VEGF were increased significantly in T2D patients compared to HC participant respectively, and progressive up-regulated in NDR, NPDR and PDR groups(P<0.001). Additionally, miR-221 in serum was remarkably positively correlatedwith metabolic parameters such as glycated hemoglobin(r=0.310, P=0.002) and homeostasis model assessment for insulin resistance(r=0.413, P<0.001), as well as serum markers for instance Ang Ⅱ(r=0.667, P<0.001) and VEGF(r=0.499, P<0.001). Furthermore, serum miR-221(AUC, 0.894; 95%CI, 0.833-0.955; P<0.001), Ang Ⅱ(AUC, 0.888; 95%CI, 0.828-0.949; P<0.001) and VEGF(AUC, 0.785; 95%CI, 0.695-0.875; P<0.001) had evidently diagnostic efficiency in DR, and miR-221 is the most effective among them.CONCLUSION: Serum miR-221 as a potential biomarker could be related to not only occurrence but also progression for DR in patients with T2D. However, a prospective clinical trial is warranted.