ABSTRACT
PURPOSE: Examine the effect of (pigment epithelium-derived growth factor; PEDF) on laser-induced choroidal neovascularization (CNV). METHODS: Adult C57Bl/6 mice were anesthetized and four laser spots were placed in each quadrant of the fundus with a krypton red laser (614 nm, 50 microm, 0.05 second, 200 mW). Animals were treated with various doses of PEDF administered with miniosmotic pumps implanted subcutaneously. Seven days after laser treatment, mice were perfused with 3% FITC high-molecular-weight dextran, the eyes enucleated, and neovascularization analyzed by confocal microscopy. Data were recorded as the volume of the neovascular complex. The effect of PEDF on endothelial cell migration, vascular tube formation in synthetic basement membrane, and VEGF production was also determined. RESULTS: Mice receiving a lower dose of PEDF (90 microg/mL) had significantly decreased areas of CNV. A high dose of PEDF (360 microg/mL) significantly increased CNV, whereas an intermediate dose (180 microg/mL) of PEDF had no effect. PEDF inhibited endothelial cell migration and vascular tube formation at lower doses (0.5-5 microg/mL). High doses of PEDF (25-50 microg/mL) stimulated endothelial cell migration, enhanced vascular tube formation in vitro, and stimulated VEGF production from endothelial cells. Neutralizing anti-VEGF antibody completely reversed the stimulatory effects of high doses of PEDF on CNV in vivo. CONCLUSIONS: PEDF demonstrates opposing effects on CNV and endothelial cell function. Whereas low doses are inhibitory, high doses can augment the development of the neovasculature. These results suggest that the effects of PEDF on neovascularization are more complex than originally believed and that caution should be exercised when PEDF therapies are considered.
Subject(s)
Choroidal Neovascularization/chemically induced , Eye Proteins , Nerve Growth Factors , Serpins , Animals , Antibodies/pharmacology , Cell Movement/drug effects , Cells, Cultured , Choroidal Neovascularization/etiology , Dose-Response Relationship, Drug , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Eye Proteins/administration & dosage , Eye Proteins/pharmacology , Humans , Lasers , Mice , Mice, Inbred C57BL , Nerve Growth Factors/administration & dosage , Nerve Growth Factors/pharmacology , Serpins/administration & dosage , Serpins/pharmacology , Vascular Endothelial Growth Factor A/biosynthesis , Vascular Endothelial Growth Factor A/immunologyABSTRACT
Following elimination of a foreign invader, the immune system must return to its normal quiescent levels. This process requires removal of reactive immune cells when they are no longer needed. We have explored the role of Fas/Fas ligand (FasL) in terminating immunity and demonstrate that mice defective in these proteins have prolonged immune responses. Studies demonstrate that termination of immunity occurs via the interaction of Fas(+) lymphoid cells with FasL(+) nonlymphoid cells at the site of Ag challenge. Our results also show that FasL is absent in quiescent tissue but is rapidly up-regulated during the local immune reaction. This occurs through the production of IL-10. Thus, FasL and IL-10 work in concert to eliminate inflammatory cells and control the duration of an immune response.
Subject(s)
Apoptosis/immunology , Interleukin-10/physiology , Membrane Glycoproteins/physiology , Adoptive Transfer , Animals , Antigens/immunology , Fas Ligand Protein , Immunity, Cellular , Interleukin-10/biosynthesis , Interleukin-10/deficiency , Lymphoid Tissue/immunology , Lymphoid Tissue/metabolism , Membrane Glycoproteins/deficiency , Mice , Mice, Inbred BALB C , Mice, Mutant Strains , Models, Immunological , Picryl Chloride/immunology , T-Lymphocytes/immunology , T-Lymphocytes/transplantation , fas Receptor/genetics , fas Receptor/physiologyABSTRACT
PURPOSE: Define a role for Fas-FasL in oxygen-induced retinopathy and explore the mechanism of pigment-epithelium-derived growth factor (PEDF) inhibition in this model. METHODS: Seven-day-old mice C57BL/6J (B6), FasL-defective (B6-gld), or Fas-defective (B6-lpr) mice were exposed to 75% oxygen for 5 days (postnatal day [P]7-P12) and returned to room air. On day P17, vascular architecture was assessed microscopically after perfusion with FITC-dextran, and preretinal nuclei were quantified by PAS and hematoxylin staining. In some experiments, mice were treated intraperitoneally with PEDF. Vascular architecture and preretinal nuclei counts were compared with those in PBS-treated control animals. RESULTS: Oxygen-induced retinopathy was significantly increased in FasL-defective gld mice compared with wild-type B6 animals. This was manifested by an increase in the number of microaneurysms, neovascular tufts, and preretinal nuclei. PEDF treatment prevented retinopathy in B6, B6-gld, and B6-lpr mice. CONCLUSIONS: Fas-FasL interactions regulate the extent of oxygen-induced retinal neovascularization. The inhibition of neovascularization in B6 gld, and B6-lpr mice by PEDF suggests that Fas-FasL interactions are probably not the mechanism for inhibition in this model.
Subject(s)
Eye Proteins , Ischemia/metabolism , Membrane Glycoproteins/physiology , Nerve Growth Factors , Retinal Neovascularization/drug therapy , Retinal Neovascularization/metabolism , Retinal Vessels/metabolism , fas Receptor/physiology , Animals , Disease Models, Animal , Fas Ligand Protein , Fluorescein Angiography , Genotype , Hyperoxia/complications , Ischemia/drug therapy , Ischemia/pathology , Ligands , Mice , Mice, Inbred C57BL , Mice, Inbred MRL lpr , Proteins/therapeutic use , Retinal Neovascularization/pathology , Retinal Vessels/drug effects , Retinal Vessels/pathology , Serpins/therapeutic useABSTRACT
TRAIL is a recently described member of the TNF superfamily. The ability of TRAIL to induce apoptosis in a large number of tumors has stimulated interest in TRAIL as a tumor therapeutic agent. Although TRAIL mRNA is expressed in a number of tissues, its functional significance to various organs is unknown. Because tumors rarely develop in the eye, we have examined this organ for functional TRAIL expression. Our analysis revealed that TRAIL mRNA and protein are constitutively expressed on numerous ocular structures, including the cornea and retina. More importantly, ocular tissue displays functional TRAIL as determined by in vitro killing of TRAIL-sensitive tumor cell lines. Previous studies have shown that ocular tissue also expresses functional Fas ligand (FasL). To assess the contribution of TRAIL and FasL for tumor cell killing in the eye, cell lines susceptible to both TRAIL and FasL were examined. The results show that ocular tissue kills via either ligand, suggesting a compensatory mechanism between TRAIL and FasL. Collectively, these results provide physiological evidence for ocular TRAIL expression, and suggest a role for this molecule in tumor surveillance in an immune privileged site.
