Expression of proline hydroxylase 2 in the membrane of proliferative diabetic retinopathy

Objective

To investigate the expression of proline hydroxylase 2 (PHD2) in the proliferatine membrane of proliferative diabetic retinopathy (PDR) and its relationship with PDR.

Methods

A prospective controlled clinical study was designed.The study included 8 PDR patients undergoing vitrectomy, 8 PDR patients receiving intravitreal injection of lucentis before vitrectomy, and 8 idiopathic macular epiretinal membrane (IMEM) patients without diabetes undergoing vitrectomy for in Inner Mongolia Autonomous Region People’s Hospital which served as PDR group, lucentis group and control group, respectively proliferative membrane was obtained during the vitrectomy surgery.Hematoxylin-eosin staining was used for histologic observation, immunofluorescence was used to examine the expression of PHD2, vascular endothelial growth factors (VEGF), glial fibrillary acidic protein (GFAP) and platelet endothelial cell adhesion molecule-1 (PECAM 1/CD31). The fluorescence intensities of PHD2, VEGF and GFAP in proliferative membrane were compared among different groups.This study followed the Helsinki declaration and was approved by Medical Ethics Committee of Inner Mongolia Autonomous Region People’s Hospital (No.20160603). Written informed consent was obtained from all subjects before entering the study.

Results

The morphology of PDR proliferative membrane was diversity, which consist of neovascularization, fibroblast-like cells, macrophages, neutrophils and lymphocytes, etc.The IMEM morphology proliferative membrane was mainly comsist of glial cells, with a small amount of fiber cells and macrophages.The membrane of lucentis group was observed with vascular atrophy and few fibroblast-like cells, vascular endothelial cells.PHD2, VEGF, GFAP and CD31 were all strongly positive expressed and co-expressed in the proliferative membrane of PDR.Besides, the glial cells aggregated in the film of non-perfused region, and the expression of GFAP in this area was obviously stronger than that in the well-perfused region; PHD2, VEGF, GFAP and CD31 were all weakly expressed in the proliferative membrane of lucentis group.Only in cell area, the expression of PHD2, VEGF and GFAP were weak in proliferative membrane.The fluorescence intensity of PHD2, VEGF and GFAP in proliferative membrane of control group were significantly different among the groups (all at P<0.001), and the fluorescence intensities of PHD2, VEGF and GFAP were significantly increased in the hyperplasia membrane of PDR group compared with those in lucentis group and control group (all at P<0.001).

Conclusions

PHD2, VEGF, GFAP and CD31 are all strongly expressed in the proliferative membrane of PDR.Lucentis can obviously decrease PHD2 expression.There may be pathways between VEGF and PHD2.Weak expression of PHD2 in IMEM membrane indicates that PHD2 is involved in the formation of IMEM.