Abstract
Purpose: :
To assess an association between intraocular inflammatory mediators in vitreous or aqueous humor and diabetic retinopathy.
Methods: :
Vitreous levels of the cytokines IL-1beta, IL-6, and TNF-alpha were analyzed by an ELISA-mimicking technique in diabetic patients with active, proliferative diabetic retinopathy and in non-diabetic patients with other vitreoretinal disease. Intraocular production was estimated by adjustment of vitreous for serum protein levels. Aqueous levels of the cytokines IL-6, IL-8 and TNF-alpha, the leukocyte chemokines GM-CSF, MCP-1 and RANTES, as well as the neovascular growth factors VEGF and FGF-2 were analyzed by multiplex bead assay in diabetic patients with no, mild or moderate diabetic retinopathy and in non-diabetic patients undergoing cataract surgery.
Results: :
Vitreous and aqueous levels of IL-6 were higher in diabetic patients [157.5 (25.0-1401.0) pg/ml; median, range, vs 44.0 (5.0-4425.0) pg/ml, p=0.021, and 12.5 (4.4-79.5) pg/ml and 4.9 (3.3-66.5) pg/ml, p=0.008, respectively]. The ratio between vitreous and serum levels of IL-6 was high in both diabetic and non-diabetic patients [55.5:1 and 16:1] suggesting intraocular production. Vitreous levels of TNF-alpha were lower in diabetic patients [18.0 (8.0-46.0) pg/ml and 22.0 (13.0-47.0) pg/ml, respectively; p=0.034] but the ratio between vitreous and serum TNF-alpha levels was high in both groups (2:1 and 3.4:1, respectively), despite higher serum TNF-alpha levels in diabetic patients [9.0 (5.0-53.0) pg/ml vs 6.7 (3.0-11.0) pg/ml, respectively, p<0.001]. The other vitreous and aqueous inflammatory mediator levels were similar in diabetic and non-diabetic subjects.
Conclusions: :
Increased intraocular levels of IL-6 and TNF-alpha suggests that inflammation is active in early and late stages of diabetic retinopathy.
Keywords: cytokines/chemokines • diabetic retinopathy • pathobiology