Suppression of Alkali Burn-Induced Corneal Neovascularization by Dendritic Cell Vaccination Targeting VEGF Receptor 2

Abstract

Purpose: : To investigate whether the induction of cytotoxic T lymphocytes (CTLs) targeting VEGF receptor 2 (VEGFR2) inhibits corneal neovascularization due to alkali injury.

Methods: : H-2Db-restricted peptide corresponding to amino acids 400 to 408 of VEGFR2 (VEGFR2400-408) was used as an epitope peptide. Dendritic cells (DCs) were harvested from bone marrow of C57BL/6 mice. Six-week-old C57BL/6 mice received subcutaneous injections of VEGFR2400-408- or gp70-pulsed mature DCs three times at six-day intervals. After the third immunization, corneal neovascularization was induced by alkali injury. Two weeks after the injury, the vascularized area was evaluated by lectin angiography. To confirm the peptide-specific CTL activities, CD8+ T cells from immunized mice were subjected to ELISA for interferon (IFN)-γ and tumor necrosis factor (TNF)-α production and 51Cr-release cytotoxicity assay. To determine the in vivo effector T cells, the immunized mice were intraperitoneally injected with an anti-CD4 or -CD8 depletion antibody.

Results: : Corneal neovascularization was significantly attenuated in mice immunized with VEGFR2400-408 as compared to those not immunized or immunized with gp70. VEGFR2400-408 or gp70, but not β-gal96-103, application led to dose-dependent induction of IFN-γ and TNF-α in the CD8+ T cells cocultured with stimulator cells. Cytotoxicity assays showed the specific lysis of MHC-matched cells expressing VEGFR2, but not β-gal96-103. In vivo depletion of CD8 +, but not CD4+, T cells significantly reversed the suppressive effect of VEGFR2400-408 immuinization on corneal neovascularization to the level observed in nonimmunized or gp70-immunized animals.

Conclusions: : These results indicate the possibility of DC vaccination targeting VEGFR2 as a novel therapeutic strategy for corneal chemical injury.

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