In vivo adenovirus-mediated delivery of a uPA/uPAR antagonist reduces retinal neovascularization in a mouse model of retinopathy

Abstract

Diabetic retinopathy and retinopathy of prematurity are among the leading causes of vision impairment throughout the world. Both diseases are characterized by pathological angiogenesis, which severely impairs vision. Extracellular proteinases play important roles in endothelial cell migration during angiogenesis. Amino-terminal fragment (ATF) is an angiostatic molecule that targets the uPA/uPAR system and inhibits endothelial cell migration. The angiostatic effect of ATF has been demonstrated in models of cancer, but has never been assessed in pathological retinal neovascularization. Endostatin also has angiostatic effects on tumor growth and retinal neovascularization.We used an adenoviral vector carrying the murine ATF (AdATFHSA) or endostatin gene coupled to human serum albumin (HSA) (AdEndoHSA) to increase the half-life of the therapeutic protein in the circulation. We induced retinopathy by exposing 7-day-old mice to high levels of oxygen. They were intravitreally injected with the vectors. Local injection of AdATFHSA or AdEndoHSA reduced retinal neovascularization by 78.1 and 79.2%, respectively. Thus, the adenovirus-mediated delivery of ATFHSA or EndoHSA reduces retinal neovascularization in a mouse model of hypoxia-induced neovascularization.

Blockade of VEGF-induced GSK/β-catenin signaling, uPAR expression and increased permeability by dominant negative p38α

“…It has been shown that constitutive activation of p38alpha is required for uPA/uPAR expression and matrix invasion by breast cancer cells (Huang et al, 2000). Inhibition of the uPA/uPAR system by uPAR gene deletion, pharmacological inhibitors or adenoviral delivery of the noncatalytic amino-terminal fragment of uPA reduces neovacularization in a mouse model of retinopathy of prematurity (Le Gat et al, 2003; McGuire et al, 2003). A recent study also demonstrated the critical role of p38 in regulating chronic inflammation-mediated angiogenesis through MMPs, the downstream target of uPA/uPAR system (Rajashekhar et al, 2011).…”

The uPAR System as a Potential Therapeutic Target in the Diseased Eye

“…Earlier results about the possibility to reduce neovessel formation in the retina by pharmacological interaction with the uPA/uPAR system can be traced back to 2003 when Le Gat et al have demonstrated anti-angiogenic efficacy of intravitreal delivery of ATF in a mouse model of OIR. As ATF binds to uPAR on the cell surface, it blocks the interaction between uPA and uPAR thus inhibiting uPA/uPAR-dependent neovascular tuft formation [53]. This study was the proof of concept that molecules disrupting the interaction between uPA and uPAR might be effective in counteracting retinal neovascular pathologies.…”

“…After the two-chain uPA is cleaved by a second round of proteolysis, a single chain form of uPA, which is about 250 times more active than the two-chain form, is generated together with an inhibitory amino-terminal fragment (ATF) (for Ref., see [52]). ATF binding to uPAR affects the interaction between uPA and uPAR with a consequent inhibition of the functional effects of uPAR activation (for Ref., see [53]). uPA binding to uPAR increases the activation of plasminogen into plasmin that is involved in the dissolution of ECM and basement membrane during tissue degradation (for Ref., see [52]).…”

In vitro and in vivo inhibition of proangiogenic retinal phenotype by an antisense oligonucleotide downregulating uPAR expression

“…This may explain why proliferative retinopathies are associated to overexpression of uPA/uPAR, which appears to be essential for the development of new vessels in the retinas of diabetic mice and rats [10,15]. This role has been confirmed by findings indicating that uPA/uPAR system inhibition or uPAR gene deletion prevent the increase in retinal vessel permeability in rodent models of ROP, DR and AMD, and reduce pathologic angiogenesis in mouse models of ROP and AMD [11,[15][16][17][18][19].…”