Vitreous levels of interleukin-6 and vascular endothelial growth factor are related to diabetic macular edema

Abstract

Purpose: To investigate whether interleukin-6 (IL-6) or vascular endothelial growth factor (VEGF) is related to diabetic macular edema (DME) in subjects without posterior vitreous detachment (PVD).

Design: Retrospective case-control study.

Participants: Twenty-six subjects who had DME without PVD and 12 subjects who had nondiabetic ocular disease (the control group).

Methods: Vitreous fluid samples were obtained at vitreoretinal surgery, and the IL-6 and VEGF levels in vitreous fluid and plasma were measured by enzyme-linked immunosorbent assay.

Main outcome measures: Vitreous levels of IL-6 and VEGF in DME subjects without PVD.

Results: The vitreous levels of both IL-6 and VEGF were significantly higher in the subjects with DME than in control subjects (P<0.0001 and P<0.0001, respectively). The vitreous level of IL-6 was significantly correlated with that of VEGF (P<0.0001). Vitreous levels of both IL-6 and VEGF were significantly higher in subjects with hyperfluorescent DME than in those with minimally fluorescent DME (P = 0.0008 and P = 0.0038, respectively).

Conclusions: We found that the levels of both IL-6 and VEGF were elevated in the vitreous fluid of subjects with hyperfluorescent DME. Our results suggest that IL-6 and VEGF may promote an increase of vascular permeability in DME subjects without PVD. Interleukin-6 may possibly induce an increase of vascular permeability through a paracrine effect on VEGF in these subjects.