The effect of triamcinolone acetonide or bevacizumab on the levels of proinflammatory cytokines after retinal laser photocoagulation in pigmented rabbits

Abstract

Although laser photocoagulation is a gold standard for the treatment of retinal ischemic diseases, thermal burn induces the inflammation and the progression of macular edema. To prevent this complication, combination therapy using anti-vascular endothelial growth factor (VEGF) drugs or steroids is clinically utilized, however the mechanisms are still unclear. In this study, we aimed to evaluate the changes in inflammatory and angiogenic cytokine levels in aqueous humor and vitreous body after intravitreal injection of bevacizumab (IVB) or triamcinolone (IVTA), as well as sub-Tenon injection of triamcinolone (STTA) after retinal laser photocoagulation in rabbits. Pigmented rabbits were treated with retinal laser photocoagulation and divided into 4 groups, namely Control (no additional treatment), IVB, IVTA or STTA accordingly. Samples of vitreous and aqueous humor were collected on post-treatment days 0, 1, 7 and 14. The levels of intraocular VEGF, interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1) and monocyte chemotactic protein-1 (MCP-1) were measured using an immunoassay. The levels of VEGF, IL-6, ICAM-1 and MCP-1 were significantly elevated 1 day after laser treatment. IVTA and STTA significantly reduced the increase in the levels of VEGF, IL-6, ICAM-1 and MCP-1, while IVB reduced that of VEGF only in aqueous humor and vitreous body. The protein amount in the aqueous humor transiently increased 1 day after laser, and was significantly prevented by IVTA or STTA but not IVB. Data showed that bevacizumab only reduced intraocular VEGF after laser, while triamcinolone suppressed both the expression of VEGF and proinflammatory cytokines. We propose that these cytokine profiles may play an important role in the pathogenesis of inflammation after photocoagulation and the underlying mechanism of treatment with anti-VEGF drug and steroids.

Keywords: Bevacizumab; Proinflammatory cytokine; Retinal laser photocoagulation; Triamcinolone acetonide; VEGF.