Comparison of cytokine levels from undiluted vitreous of untreated patients with retinal vein occlusion

Abstract

To compare cytokines in undiluted vitreous of treatment-naïve patients with macular oedema without vitreomacular traction secondary to branch (BRVO), central (CRVO) and hemi-central (H-CRVO) retinal vein occlusion. Ninety-four patients (median age 72 years, 42 men) underwent an intravitreal combination therapy, including a single-site 23-gauge core vitrectomy and the application of bevacizumab and dexamethasone due to vision-decreasing macular oedema. Among these were 43 patients with BRVO, 35 with CRVO and 16 patients with hemi-CRVO, which were distributed in a fresh or old retinal vein occlusion type (seven or more months after onset). Undiluted vitreous samples were analysed for interleukin 6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and vascular endothelial growth factor (VEGF-A) with cytometric BEAD assay. Vitreous samples from patients with idiopathic epiretinal membrane served as controls (n = 14). The mean cytokine values were highest in the CRVO group with IL-6 = 64.7 pg/ml (SD ± 115.8), MCP-1 = 1015.8 pg/ml (±970.1) and VEGF-A = 278.4 pg/ml (±512.8), followed by the H-CRVO group with IL-6 = 59.9 pg/ml (SD ± 97.5), MCP-1 = 938.8 pg/ml (±561.1) and VEGF-A = 211.5 pg/ml (±232.4). The BRVO group had IL-6 = 23.2 pg/ml (SD ± 48.8), MCP-1 = 602.6 g/ml (±490.3) and VEGF-A = 161.8 pg/ml (±314.4). The values of MCP-1 and VEGF-A were significantly different for CRVO or H-CRVO versus BRVO. All values were significantly higher than in the control samples, which had 6.2 ± 3.4 pg/ml (IL-6), 253 ± 74 pg/ml (MCP-1) and 7 ± 4.9 pg/ml (VEGF-A). Within the old RVO type, only MCP-1 was significantly different for CRVO or H-CRVO versus BRVO. Both inflammatory markers and VEGF-A were higher in CRVO and H-CRVO than in BRVO undiluted vitreous samples. It seems that monocyte recruitment to the vessel wall, which might underlie the importance of eosinophils in tissue remodelling after RVO, is of special interest owing to the significant difference in MCP-1 in the older RVO types.