Upregulation of VEGF in murine retina via monocyte recruitment after retinal scatter laser photocoagulation

Abstract

Purpose: This study was conducted to determine changes in the expression of vascular endothelial growth factor (VEGF) in murine retina after retinal scatter laser photocoagulation.

Methods: Photocoagulation (PHC) was performed on wild-type C57BL/6J mice using a diode laser, and the eyes were enucleated 1, 2, 3, 4, 7, and 14 days after laser treatment. VEGF and monocyte chemoattractant protein (MCP)-1 levels in the sensory retina and retinal pigmented epithelial (RPE) cells in both tissues were measured by ELISA. The VEGF mRNA was measured by real-time RT-PCR. Leukocyte infiltration into the RPE-choroid was determined by flow cytometry. VEGF comparisons between mice subjected to PHC and those treated with monocyte recruitment inhibitor (anti-MCP-1) were performed and statistically analyzed. The expression of VEGF and MCP-1 in the retina was determined by immunohistochemistry.

Results: VEGF protein levels significantly increased 1 day after PHC in both the RPE-choroid and the sensory retina. VEGF concentrations were maximum at day 3 after photocoagulation and stayed elevated until day 7. The number of choroid-infiltrating macrophages was markedly increased in mice with laser treatment compared with those without laser treatment. VEGF expression decreased after treatment with neutralized antibody to monocyte recruitment. We demonstrate that MCP-1 expression in the retina increased markedly after scatter laser photocoagulation by immunohistochemistry and ELISA.

Conclusions: Retinal scatter laser photocoagulation induced upregulation of VEGF in the sensory retina and RPE-choroid at an early period. The authors speculate that the major source of VEGF in the retina after retinal scatter laser photocoagulation is the recruited monocytes.