Evaluation of vitreous levels of advanced glycation end products and angiogenic factors as biomarkers for severity of diabetic retinopathy.

BACKGROUND/AIMS: Glyceraldehyde-derived advanced glycation end products (glycer-AGE; also called Toxic-AGE [TAGE]) play a crucial role in the pathogenesis of diabetic angiopathy. However, the relationships between vitreous glycer-AGE levels and diabetic retinopathy (DR) severity, and between glycer-AGE levels and the levels of other angiogenic factors remain unknown. We investigated the correlation between levels of vitreous biomarkers, including glycer-AGE and angiogenic factors (vascular endothelial growth factor [VEGF], interleukin [IL]-8, leptin, placental growth factor [PlGF], endoglin, and fibroblast growth factor [FGF]-2) in patients with DR, using three DR staging groups.

METHODS

In this cross-sectional study, we examined 33 eyes from 33 patients with diabetes mellitus who underwent a vitrectomy (non-proliferative DR [NPDR, n = 8]; PDR with simple vitreous haemorrhage [VH, n = 17]; or PDR with a fibrovascular proliferative membrane [FVM, n = 8]). Vitreous levels of glycer-AGE and VEGF were evaluated using enzyme-linked immunosorbent assays. Vitreous levels of IL-8, leptin, PlGF, endoglin, and FGF-2 were evaluated using beaded assay methods.

RESULTS

Vitreous levels of glycer-AGE in the FVM group were significantly higher than those in the NPDR and VH groups (all p < 0.05). Vitreous levels of VEGF (r = 0.85, p = 1.7 × 10-6) and leptin (r = 0.60, p = 5.0 × 10-3) were significantly correlated with levels of PlGF.

CONCLUSION

The two systems (VEGF-PlGF-leptin and glycer-AGE) were represented in these measured biomarkers. High vitreous levels of both VEGF and glycer-AGE may be linked to more severe DR, suggesting that anti-VEGF and anti-TAGE therapy may be an important part of the therapeutic strategy for DR.