Age-related macular degeneration: etiology, pathogenesis, and therapeutic strategies.

Objective To investigate the role of macrophages in the development of laser-induced choroidal neovascularization (CNV) by selective depletion with liposomal clodronate (Cl(2)MDP-LIP). Methods Laser photocoagulation was used to induce CNV in wild-type C57BL/6J mice. Animals were treated with intravenous (IV) and/or subconjunctival (SC) Cl(2)MDP-LIP or PBS-LIP at the following time points: 2 days before, immediately after, 2 days before and immediately after, or 2 days after laser injury. CNV responses were compared on the basis of en masse volumetric measurements and fluorescein angiography after laser photocoagulation. Macrophages were identified by immunostaining for F4/80, and vascular endothelial growth factor (VEGF) expression was quantified by ELISA. Results Macrophages invaded the site of laser injury within 1 day of photocoagulation and peaked at 3 days. IV Cl(2)MDP-LIP significantly decreased the volume of CNV and angiographic leakage when administered 2 days before and/or immediately after laser injury, but not when administered 2 days after injury. SC Cl(2)MDP-LIP significantly decreased lesion volume when coadministered with IV PBS-LIP but not IV Cl(2)MDP-LIP. IV Cl(2)MDP-LIP was significantly more beneficial when administered 2 days before laser injury than immediately after, but combining SC Cl(2)MDP-LIP with IV treatment eliminated this difference. Reduction in CNV volume correlated with VEGF protein levels and number of infiltrating macrophages. Conclusions Generalized macrophage depletion reduced the size and leakage of laser-induced CNV and was associated with decreased macrophage infiltration and VEGF protein. These findings define the role of the macrophage as a critical component in initiating the laser-induced CNV response.

Macrophage Depletion Inhibits Experimental Choroidal Neovascularization

Purpose Vascular endothelial growth factor (VEGF) is upregulated by hypoxia and is a major stimulatory factor for retinal neovascularization in ischemic retinopathies such as diabetic retinopathy. This study sought to determine if VEGF is a stimulatory factor in a murine model of choroidal neovascularization (CNV). Methods Mice with laser-induced ruptures in Bruch's membrane were treated with vehicle alone; a drug that inhibits both VEGF and platelet-derived growth factor (PDGF) receptor kinases; a drug that inhibits PDGF, but not VEGF receptor kinase; or genistein, a nonspecific kinase inhibitor. After two weeks, CNV was quantified and compared. Results Blockade of phosphorylation by VEGF and PDGF receptors caused dramatic, almost complete inhibition of CNV. Genistein also had an inhibitory effect, but less so than the VEGF/PDGF receptor blocker. Blockade of phosphorylation by PDGF receptors, but not VEGF receptors, had no significant effect on CNV. Conclusions These data and our previous study, which demonstrated that a kinase inhibitor that blocks VEGF and PDGF receptors and several isoforms of protein kinase C causing dramatic inhibition of CNV, suggest that VEGF signaling plays a critical role in the development of CNV in this model. If safety is established, the effect of inhibiting VEGF receptor kinase activity should be investigated in patients with CNV.

VEGF is major stimulator in model of choroidal neovascularization.

Laser eye injuries.

A reproducible model of subretinal neovascularization has been developed, an important first step in the study of disciform macular degeneration. The methodology and clinical description of subretinal neovascularization in the primate have been provided and histopathologic and electron microscopic correlations included. This model provides a most promising and useful mechanism for the evaluation of the many different factors and hypotheses that have been proposed for the genesis of the disciform response. In humans, it probably has more relevance to the traumatically induced disciform process, particularly that after laser therapy, than to the senile degenerative process. The purpose of this investigation is to develop the animal model by which many different theories regarding the pathogenesis of the disciform response can be tested. These initial studies relate to ischemia, hemorrhage, the inflammatory response, and position in relation to the center of the vascular-free zone as factors important in the development and evolution of subretinal neovascularization.

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V. Victoria-Troncoso

Papers

Neovascularization after Argon Laser Photocoagulation of Macular Lesions

Treatment of ligneous conjunctivitis.

Scléromalacie perforante et collagénose

Etude pathologique, histochimique, pathogénique et thérapeutique de la conjonctivite ligneuse

The Histiochemical Structure of the Vitreous Fibers Studied by Phase Contrast Microscopy