Expression of serum factors in patients with diabetic retinopathy and its relationship with disease stages

  Objective  To investigate the expressions of extracellular superoxide dismutase (ecSOD), brain-derived neurotrophic factor(BDNF) and angiopoietin-2(Ang-2) in patients with diabetic retinopathy(DR) and their relationships with the stages of the disease.

  Methods  A total of 126 diabetic patients were divided into non-diabetic retinopathy group (NDR, 40 cases), background diabetic retinopathy group (BDR, 44 cases), and proliferative diabetic retinopathy group (PDR, 42 cases) according to diabetic retinopathy stages. At the same time, 40 healthy people in the same period were selected as control group. The general data, fasting blood glucose (FBG), glycosylated hemoglobin(HbA1c), serum ecSOD, BDNF and Ang-2 levels were compared among the four groups. The correlations between DR stages and serum ecSOD, BDNF as well as Ang-2 were analyzed. The clinical values of serum ecSOD, BDNF, Ang-2 alone and their combination in the diagnosis of DR were evaluated.

  Results  The levels of FBG and HbA1c in the NDR group, BDR group and PDR group were significantly higher than those in the control group (P < 0.05), but there were no significant between-group differences in NDR group, BDR group and PDR group (P>0.05). The levels of serum ecSOD, BDNF and Ang-2 in DR patients increased with the increase of pathological grading (P < 0.05). Spearman correlation analysis showed that there was a positive correlation between the stages of DR and the levels of serum ecSOD, BDNF as well as Ang-2 (P < 0.05). The area under the curve (AUC) of ecSOD in diagnosis of DR was 0.836, the cut-off value was 113.43 ng/mL, the sensitivity and specificity were 73.02% and 95.00%, respectively. The AUC of BDNF in the diagnosis of DR was 0.774, the cut-off value was 1.66 ng/mL, the sensitivity and specificity were 71.25% and 94.55%, respectively. The AUC of Ang-2 in the diagnosis of DR was 0.862, the cutoff value was 1.69 μg/L, the sensitivity and specificity were 80.16% and 90.00%, respectively. The AUC of combined detection was 0.904, sensitivity and specificity were 91.27% and 98.03%, respectively.

  Conclusion  The levels of serum ecSOD, BDNF and Ang-2 in DR patients are significantly increased, and they are closely related to the stages of retinopathy, which are expected to be important indexes for DR diagnosis, treatment and prognosis evaluation.