Intraocular expression of endostatin reduces VEGF‐induced retinal vascular permeability, neovascularization, and retinal detachment

Abstract

Endostatin, a proteolytic fragment of collagen XVIII, is an endogenous inhibitor of tumor angiogenesis that also inhibits choroidal neovascularization. In this study, we assessed the effects of increased intraocular expression of endostatin on vascular endothelial growth factor (VEGF)-induced changes in the retina. After subretinal injection of a pair of gutless adenoviral vectors (AGV) designed to provide tamoxifen-inducible expression of endostatin, diffuse endostatin immunoreactivity was induced thoroughout the retina by administration of tamoxifen. Induction of endostatin in double transgenic mice with doxycycline-induced expression of VEGF in the retina resulted in significant suppression of leakage of intravascular [3H]mannitol into the retina. The ability of endostatin to reduce VEGF-induced retinal vascular permeability was confirmed by using [3H]mannitol leakage and two other parameters, fluorescein leakage and retinal thickness, after subretinal injection of a bovine immunodeficiency lentiviral vector coding for endostatin (BIV-vectored endostatin, or BIVendostatin). Subretinal injection of BIVendostatin resulted in more discrete, less intense staining for endostatin in the retina than that seen with the inducible AGV system, which suggested lower levels and allowed visualization of sites where endostatin was concentrated. Endostatin staining outlined retinal blood vessels, which suggested endostatin binding to a component of vessel walls. More prolonged or higher level expression of VEGF in the retina resulted in neovascularization and retinal detachment, both of which were also significantly reduced by BIVendostatin. These data suggest that endostatin may be an endogenous inhibitor of vasopermeability as well as neovascularization. In patients with diabetic retinopathy, endostatin gene transfer may provide a way to decrease the risk of three causes of visual loss: macular edema, neovascularization, and retinal detachment.

Endostatin modulates VEGF-mediated barrier dysfunction in the retinal microvascular endothelium

“…Indeed, an in vivo study by Takahashi et al (2003) showed intraocular expression of endostatin suppressed leakage of intravascular [ 3 H] mannitol into the retina. However, it was not possible to determine concentrations of endostatin that have an effect using this experimental approach.…”

“…This peptide can prevent tumour angiogenesis (O'Reilly et al, 1997) and has also been shown to be efficacious in the eye by preventing retinal and choroidal neovascularisation (Mori et al, 2001, Auricchio et al, 2002and Le Gat et al, 2003. Endostatin may also prevent vasopermeability responses by growth factors and recent studies have suggested that endostatin can reduce VEGF-induced retinal vascular permeability in double transgenic mice with inducible expression of VEGF 165 in the retina (Takahashi et al, 2003). VEGF-induced permeability was assessed via [ 3 H] mannitol permeation, fluorescein angiography and assessment of edema was conducted by measurement of retinal thickness.…”

“…VEGF-induced permeability was assessed via [ 3 H] mannitol permeation, fluorescein angiography and assessment of edema was conducted by measurement of retinal thickness. These recent studies reported mice, when given sub-retinal injections of a bovine immunodeficiency viral vector expressing endostatin, showed a marked decrease in retinal vascular permeability, neovascularisation and retinal detachment (Takahashi et al, 2003). However, exact concentrations of endostatin required to decrease the VEGF induced permeability and effects on tight junction expression were not elucidated.…”

Angiopoietin 1 inhibits ocular neovascularization and breakdown of the blood–retinal barrier

“…The doxycycline inducible promoter system in transgenic mice is a very useful tool, which in past studies has allowed detailed exploration of the effects of VEGF 19,20 and brain-derived neurotrophic factor in the retina. 21 It requires generation of two transgenic mice, one in which reverse tetracycline transactivator is coupled to a promoter that drives its expression ubiquitously or in a certain tissue.…”

Seeing the light: New insights into the molecular pathogenesis of retinal diseases

“…Expression of pigment epithelium-derived factor (PEDF) has been shown to suppress ocular neovascularization in several models (Mori et al, 2001a(Mori et al, ,b, 2002Auricchio et al, 2002;Raisler et al, 2002;Gehlbach et al, 2003a) and a phase I trial in patients with neovascular AMD showed promise . Other promising transgenes for treatment of ocular neovascularization include endostatin, which reduces excessive vascular permeability in addition to suppressing neovascularization (Auricchio et al, 2002;Takahashi et al, 2003), angiostatin (Lai et al, 2001a;Raisler et al, 2002;Igarashi et al, 2003), and soluble VEGF receptor 1 (Honda et al, 2000;Lai et al, 2001bLai et al, , 2005Bainbridge et al, 2002;Gehlbach et al, 2003b;Rota et al, 2004).…”