Increased levels of vascular endothelial growth factor and interleukin-6 in the aqueous humor of diabetics with macular edema

Abstract

PURPOSE: To investigate the relationship between diabetic macular edema and the levels of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in aqueous humor and plasma. DESIGN: Comparative cross-sectional study. METHODS: Fifty-four eyes from 54 diabetic patients were used. The concentrations of VEGF and IL-6 in undiluted aqueous specimens (obtained from the eyes during cataract surgery) and in plasma were measured by an enzyme-linked immunosorbent assay. To assess blood-aqueous barrier function, the aqueous flare intensity was measured by a laser flare-cell meter as an estimate of the aqueous protein level. RESULTS: The aqueous levels of VEGF and IL-6 were significantly correlated with the severity of macular edema (ρ = 0.628, P < .001 and ρ = 0.517, P < .01, respectively), as well as with the aqueous protein concentration (ρ = 0.618, P < .001 and ρ = 0.588, P < .001, respectively). Aqueous levels of VEGF and IL-6 were significantly higher than their respective plasma levels (both P < .001). In addition, the aqueous level of VEGF was significantly correlated with that of IL-6 (ρ = 0.537, P < .01). Furthermore, the status of the posterior vitreous significantly correlated with the severity of macular edema (ρ = 0.618, P < .0001). CONCLUSIONS: These results suggest that both VEGF and IL-6 are produced together in the intraocular tissues, and are involved in the pathogenesis of macular edema.