Changes in aqueous concentrations of various cytokines after intravitreal bevacizumab and subtenon triamcinolone injection for diabetic macular edema

Abstract

Purpose: The purpose of this study was to compare the changes in the aqueous cytokine levels after intravitreal bevacizumab with those after combined intravitreal bevacizumab and subtenon triamcinolone injection in diabetic macular edema (DME).

Methods: This study examined 24 eyes of 23 patients with DME. Each patient with DME received randomly either an intravitreal injection of bevacizumab (IVBe) or IVBe with a subtenon triamcinolone injection (IVBe + STTA). Best corrected visual acuity and foveal thickness were evaluated and aqueous samples were obtained before and 4 weeks after the injection. The aqueous concentrations of interleukin (IL)-6, IL-8, interferon-induced protein (IP)-10, monocyte chemotactic protein (MCP)-1, platelet-derived growth factor (PDGF)-AA, and vascular endothelial growth factor (VEGF) were measured using a multiplex bead assay.

Results: After the injection, the foveal thickness decreased more in the IVBe + STTA group than in the IVBe group (P = 0.042). The MCP-1, PDGF-AA, and VEGF levels decreased significantly in the IVBe + STTA group (p = 0.013, p = 0.004 and p = 0.018 respectively), but only the VEGF level decreased in the IVBe group (p = 0.001). IL-8 was significantly increased in the IVBe + STTA group (p = 0.003) but the changes in the VEGF levels were smaller than in the IVBe group (p = 0.025).

Conclusion: Intravitreal bevacizumab and subtenon triamcinolone injection reduces the VEGF, MCP-1 and PDGF-AA levels and increases the IL-8 level in the plural cytokine profiles of patients with DME, which might explain the limited therapeutic effect of combination therapy.

Keywords: Aqueous cytokines; Bevacizumab; Combination therapy; Diabetic macular edema; Interleukin(IL)-8; Subtenon triamcinolone injection.