gms | German Medical Science

Neovascular diseases as a consequence of ischemia as seen secondary to vein occlusion, in retinopathy of prematurity, and in proliferative diabetic retinopathy, belong to the leading causes of vision impairment in developed nations. A mouse model of oxygen induced retinopathy allows investigating the role of growth factors and signaling pathways in genetically altered mice. Furthermore, topical or systemic application of inhibitory substances can be analyzed with respect to neovascular growth, retinal development and neuronal-vascular interaction.

We examined the influence of the inflammation modulator TNFα, of kinase signaling pathways, and the involvement of integrin on retinal neovascularization. Knock out mice or wild type controls were exposed to 75% oxygen from postnatal day 7 to day 12 and recovered at room air thereafter. Retinal vascularization was investigated in flat mount preparations after Concanavalin A labeling of endothelial cells from day 6 to 20. Density slicing was used to quantify vascular, avascular area and neovascular blood vessel tufts. Pre-retinal neovascularization was determined as the number of retinal neovascular cell nuclei anterior to the internal limiting membrane. Retinal mRNA expression of VEGF and Angiopoietin 1 and 2 as well as PDGF were quantified by real-time RT-PCR.

TNF-Rp55 and TNF-Rp75 deficient mice demonstrated similar retinal development and vascularization under normoxic conditions, although the gene expression of VEGF, Angiopoietin 1 and 2 and PDGFb changed. Treatment with oxygen resulted in a significantly reduced vascularization in Rp55^-/- but not Rp75^-/- on P20.

After treatment with a benzoquinoid antibiotic (17-AAG) the number of neovascular tufts was different from the controls, but not the main vessel tortuosity. No significant change in VEGF and angiopoietin 1 mRNA expression could be achieved with either of the treatments. A single intravitreal injection of an α5β1 integrin inhibiting molecule resulted in a significant reduction of the vascularized area and the number of retinal neovascular cell nuclei per section was significantly reduced.

Our work demonstrates, first, that inhibition of TNFα via TNF-Rp55 can alter retinal development and angiogenesis, second, that an i.p. injection of 17-AAG is able to reduce angioproliferative retinopathy, and third, that a single intravitreal injection of an integrin inhibitor reduces angiogenesis in a mouse model of oxygen induced retinopathy. These data underscore the potential effectiveness of inhibitory treatments as modulators in oxygen-induced retinopathy.