Expression and significance of Jagged1 in fibrovascular membranes of proliferative diabetic retinopathy

Objective

To observe the expression and significance of Jagged1 in fibrovascular membranes of proliferative diabetic retinopathy (PDR).

Methods

Sixty preretinal fibrovascular membrane specimens collected from fifty-seven patients (60 eyes) with PDR during vitrectomy in The Affiliated Hospital of Qingdao University from July 2014 to July 2015 were set as the PDR group. The patients were divided into the injection group (30 cases, 32 eyes) and non-injection group (27 cases, 28 eyes) according to whether they received anti-vascular endothelial factor drug intravitreally before surgery.Ranibizumab injections were administered to the patients in the injection group intravitreally 2-7 days before surgery.Eighteen macular epiretinal membrane specimens obtained from 18 non-diabetic patients were served as the control group.Hematoxylin-eosin staining was applied to observe the structural festures of specimers. The immunohistochemical staining was used to detect the expression levels of Jagged1, Delta-like 4(Dll4) and Notch1 in the injection and non-injection groups, and the real-time fluorescent quantitative polymerase chain reaction was performed to detect the relative expression levels of Jagged1, Dll4 and Notch1 mRNA in the three groups.Pearson linear correlation analysis was used to evaluate the relationships between the expression of Jagged1 mRNA and both Dll4 mRNA or Notch1 mRNA in the PDR fibrovascular membranes.This study protocol adhered to the Declaration of Helsinki and was approved by an Ethics Committee of The Affiliated Hospital of Qingdao University (No.QYFYWZLL25645). Written informed consent was obtained from each patient.

Results

The neovascularization was found in fibrovascular membranes of PDR with a light microscope, and the lumen of the new blood vessels in the injection group was narrow, but relatively dilated in the non-injection group.There was no neovascularization found in the macular epiretinal membranes.The immunohistochemical staining revealed that there was the positive expression of Jagged1, Dll4 and Notch1 proteins in all PDR membranes, mainly located in the vascular endothelium during neovascularization.The absorbance values of Jagged1, Dll4 and Notch1 proteins were 6.25±1.82, 6.87±1.89 and 5.12±2.14 respectively in the non-injection group, which were all higher than 1.46±0.37, 1.55±0.24 and 1.32±0.53 respectively in the injection group, showing statistically significant differences (t=5.168, P=0.014; t=6.012, P=0.008; t=3.453, P=0.030). There were statistically significant differences in Jagged1, Dll4 and Notch1 mRNA relative expression levels among the three groups (F=77.337, 62.305, 51.869; all at P<0.01). The relative expression levels of Jagged1, Dll4 and Notch1 mRNA in the fibrovascular membranes with PDR were significantly higher than those of control macular epiretinal membranes, and the relative expression levels of Jagged1, Dll4 and Notch1 mRNA of the injection group were significantly lower than those of the non-injection group (all at P<0.05). The expression level of Jagged1 mRNA was positively correlated with expression levels of both Dll4 and Notch1 mRNA (r=0.925, 0.950; both at P<0.05).

Conclusions

There is a high expression of Jagged1 in the vascular endothelium of fibrovascular membranes with PDR and the Jagged1 expression is positively correlated with the expression of Dll4 and Notch1.The effect of Jagged1 on the neovascularization in PDR may be related to Dll4 and Notch1.

Retinal neovascularization; Diabetic retinopathy, proliferative; Jagged1 protein