RESUMO
Endostatin is a cleavage product of collagen XVIII that inhibits tumor angiogenesis and growth. Interferon alpha2a blocks tumor angiogenesis and causes regression of hemangiomas, but has no effect on choroidal neovascularization (CNV). Therefore, inhibitors of tumor angiogenesis do not necessarily inhibit ocular neovascularization. In this study, we used an intravenous injection of adenoviral vectors containing a sig-mEndo transgene consisting of murine immunoglobulin kappa-chain leader sequence coupled to sequence coding for murine endostatin to investigate the effect of high serum levels of endostatin on CNV in mice. Mice injected with a construct in which sig-mEndo expression was driven by the Rous sarcoma virus promoter had moderately high serum levels of endostatin and significantly smaller CNV lesions at sites of laser-induced rupture of Bruch's membrane than mice injected with null vector. Mice injected with a construct in which sig-mEndo was driven by the simian cytomegalovirus promoter had approximately 10-fold higher endostatin serum levels and had nearly complete prevention of CNV. There was a strong inverse correlation between endostatin serum level and area of CNV. This study provides proof of principle that gene therapy to increase levels of endostatin can prevent the development of CNV and may provide a new treatment for the leading cause of severe loss of vision in patients with age-related macular degeneration.
Assuntos
Inibidores da Angiogênese/genética , Corioide/irrigação sanguínea , Colágeno/genética , Terapia Genética/métodos , Neovascularização Patológica/prevenção & controle , Fragmentos de Peptídeos/genética , Adenoviridae/genética , Inibidores da Angiogênese/sangue , Animais , Colágeno/sangue , Colágeno Tipo XVIII , Endostatinas , Expressão Gênica , Genes Reporter/genética , Vetores Genéticos , Injeções Intravenosas , Fígado/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Neovascularização Patológica/patologia , Fenômenos Fisiológicos Oculares , Fragmentos de Peptídeos/sangue , Recombinação GenéticaRESUMO
1. Six potent aldose reductase inhibitors (ARI), three spirohydantoin (I to III) and three spirosuccinimide (IV to VI) compounds, showed similar IC50 activities in vitro for the inhibition of rat lens aldose reductase, but their ED50 values in diabetic rats varied as much as 20-fold in the lens and 50-fold in the sciatic nerve tissue. Pharmacokinetic studies were undertaken to investigate these findings. Structure-pharmacokinetic relationships were studied following i.v. administration to cynomolgus monkeys. 2. The clearance (CL) of each spirosuccinimide ARI was faster (greater than 5 times) than that of the corresponding spirohydantoin compound. In both series the CL values of the C(4) methyl and methoxy analogues were 4-fold greater than those for the unsubstituted compounds, although the CL values of the methoxy and methyl derivatives in the same series were not significantly different. 3. The volumes of distribution (Vss) of the spirohydantoins were about one-half those of the corresponding spirosuccinimides, and the Vss values of the parent compounds of both ARI series did not differ dramatically from those of their methyl and methoxy analogues. 4. All six compounds were eliminated from plasma in a biexponential fashion. The half-lives (lambda 1 and lambda 2) of the spirohydantoin compounds were much longer than those of the corresponding spirosuccinimide compounds, and the unsubstituted compounds had longer half-lives than their methyl and methoxy derivatives. The longest lambda 1 and lambda 2 half-lives were observed for imirestat, while two of the spirosuccinimides had the shortest half-lives. 5. These results indicate that the relationships observed between the in vitro and in vivo activities of the six ARI can be attributed to structurally dependent differences in metabolic clearance.
