Expressions and clinical significances of miR-15 and miR-29a in serum of patients with diabetic retinopathy

Objective To analyze the expression levels of miR-15 and miR-29a in serum of patients with diabetic retinopathy (DR) and their diagnostic values for DR. Methods 155 patients (155 eyes) with type 2 diabetes mellitus (DM) were treated in our hospital from June 2016 to August 2018, according to the occurrence of retinopathy and the degree of retinopathy, the patients were divided into five groups: 50 cases of non-retinopathy group (NDR group), 56 cases of simple retinopathy group (SDR group), 49 cases of proliferative retinopathy group (PDR group) and another 50 healthy persons in the same period were selected as the control group. Triglyceride (TG), total cholesterol (TC), and fasting blood glucose (FPG) were measured. Levels of serum miR-15 and miR-29a were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Pearson correlation method was used to analyze the relationships between levels of serum miR-15 and miR-29a with clinical indicators in DR patients. Receiver operating characteristic curve (ROC) was used to evaluate the diagnostic values of miR-15 and miR-29a in DR. Results The relative expression of miR-15 in serum of NDR group, SDR group, and PDR group were lower than that of control group (P<0.05), and the relative expression of miR-15 in NDR group, SDR group, and PDR group decreased gradually (P<0.05); the relative expression of miR-29a in serum of NDR group, SDR group, and PDR group were higher than that of control group (P<0.05), and the mRNA relative expression of miR-29a in NDR group, SDR group, and PDR group increased gradually (P<0.05); the expression of serum miR-15 in DR patients was negatively correlated with urinary albumin/creatinine (UACR), glycosylated hemoglobin (HbA1c) and the course of DM (r=-0.732, -0.492, -0.589, P<0.05); the expression level of miR-29a was positively correlated with UACR, HbA1c and the course of DM (r=0.744, 0.508, 0.556, P<0.05); the areas under the ROC curve (AUC) of miR-15 and miR-29a for DR diagnosis were 0.796 (95% CI: 0.724-0.857) and 0.677 (95% CI: 0.597-0.749), with diagnostic thresholds 0.63 and 1.11, sensitivities 84.9% and 53.8%, specificities 65.3% and 79.6%, repectively; miR-29a was a risk factor for DR, while miR-15 was a protective factor for DR. Conclusions The expression of mir-15 and miR-29a in the serum of DR patients is decreased, which is related to the degree of retinopathy and can be used as biomarkers for early diagnosis of DR. Key words: Diabetic retinopathy; miR-15; miR-29a; Early diagnosis