Intravitreal injection of bortezomib attenuates choroidal neovascularization by antagonizing VEGF and PDGF-mediated signaling

Abstract

Purpose : Exudative age-related macular degeneration (exAMD) is characterized with choroidal neovascularization (CNV). The formation of CNV involves the roles of retinal pigment epithelial cells (RPE), choroidal endothelial cell (CE), interstitial mural cell and smooth muscle cell as well as pro-angiogenic factors and inflammatory cytokines. The mainstay treatment for exAMD is anti-VEGF therapy but only the minority of patients respond to the treatment，and the majority relapse upon administration withdrawal or develop resistance over the course of the anti-VEGF treatment. This study is to investigate the efficacy and mechanism of bortezomib against CNV.

Methods : Laser photocoagulation was used to create CNV in mice. The volume of angiogenesis was assessed with isolectin GS-IB4 labeling in choroidal flat-mount. The content of pro-angiogenic factor, vascular endothelial growth factor (VEGF) or inflammatory cytokine, interleukin-1β (IL-1β) in the supernatants of ARPE-19 cell cultures and the amout of PDGF produced by retinal/choroidal endothelial cells were examined with the enzyme-linked immunosorbent assay (ELISA). Electroretinography was used to examine the impact of retinal physiology under administration of bortezomib.

Results : we demonstrated that invtravitreal injection of sub-toxic doses of bortezomib (Bor_sub) dose-dependently inhibited angiogenesis in a CNC murine model, and we further characterized the underpinning. In vivo, Bor_sub injection attenuated the protein levels of phospho-VEGF receptor 2 (p-VEGFR-2) and phospho-PDGF receptor β (p-PDGFRβ) in choroid/RPE tissue; Bor_sub inhibited the recruitment of mural cells to neovessels. In vitro, pre-treatment with Bor_sub (i) attenuated production of VEGF and interleukin-1 β induced by tumor necrosis factor alpha primed RPE; (ii) reduced PDGF production in retinal/choroidal endothelial cells. Similar scotopic and photopic responses were detected between Bor_sub and vehicle-injected eyes by recording electroretinography.

Conclusions : Altogether, intravitreal injection of Bor_sub significantly reduced angiogenesis in a CNV murine model without compromising retinal function; the efficacy is ascribed to its effects of antagonizing VEGF/Flk-1 pathway and PDGFβ signaling.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Fig 1. Intravitreal injection of Bor_sub reduced CNV volume in laser-induced choroidal neovascularization.