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Antonia M Joussen

Publications and source records attributed to Antonia M Joussen.

At least 19 recordsLinked to original sources
PubMed2007

Geldanamycin treatment reduces neovascularization in a mouse model of retinopathy of prematurity.

BACKGROUND: The benzoquinoid antibiotic 17-allylaminogeldanamycin (17-AAG) inhibits the Ras/Raf/MEK and PI3-Kinase signaling pathways and down-regulates vascular endothelial factor expression. Here we use a mouse model of oxygen-induced retinopathy to investigate the effect of 17-AAG on retinal neovascularization and vascular recovery. MATERIAL AND METHODS: C57BL/6 mice were exposed to 75% oxygen from postnatal day 7 (P7) to P12 and recovered in room air thereafter. Beginning with P12 mice were treated for 5 days by daily IP injection of 17-AAG (12.5 mg/kg body weight) micro dispersed in an emulsion of 4% Lipoid EPC, 5% sucrose, and 0.9% NaCl or Wortmannin (100 microg/kg body weight). On P17, the retinal vascular and avascular area, neovascular blood vessel tufts, and main vessel tortuosity were quantified after perfusion of the mice with FITC-Concanavalin A. The mRNA levels of VEGF, angiopoietin 1 and 2 were quantified by real-time RT-PCR. RESULTS: After 17-AAG treatment, a reduction of the vascular area was measured from 37.8 +/- 5.2% to 30.8 +/- 5.7% (P = 0.005), and an increase of the avascular area from 10.8 +/- 5.6% to 20.3 +/- 6.6% (P = 0.001). No alteration of the vascular pattern, the number of blood vessel tufts and the main vessel tortuosity was achieved by treatment with the PI-3 kinase inhibitor Wortmannin. After treatment with 17-AAG, the numbers of tufts (127.9 33.2) were different from the controls (173.7 +/- 55.2, P = 0.035), but not the main vessel tortuosity. No significant change in VEGF and angiopoietin 1 mRNA expression could be achieved with either of the treatments. Wortmannin treatment also did not change the angiopoietin 2 mRNA level, whereas the level was reduced in 17-AAG treated mice retina from 436-fold (+/- 64) to 200-fold (+/-55) (P = 0.035). CONCLUSION: An IP injection of 17-AAG is able to reduce angioproliferative retinopathy in a mouse model for oxygen-induced retinopathy. Our data indicate that the mechanism does not involve a direct or indirect reduction of the VEGF mRNA level, but acts downstream of the VEGF pathway. Thus, 17-AAG probably does not work by PI-3 kinase inhibition but via the Ras/Raf/MEK pathway. These data underline the potential utility of tyrosine kinase inhibitors in hypoxia induced neovascularization.

Angiopoietin-1↗
PubMed2006

Effect of gravity in long-term vitreous tamponade: in vivo investigation using perfluorocarbon liquids and semi-fluorinated alkanes.

PURPOSE: In order to investigate whether gravity is the reason for retinal degeneration in long-term vitreous tamponade, perfluorohexyloctane (F6H8), perfluorodecalin (PFD), and a mixture of F6H8/PFD were compared. MATERIALS AND METHODS: Each group of 5 rabbits received a 3-month tamponade with either PFD (pure) (1.93 g/cm(3)), F6H8 (pure) (1.33 g/cm(3)), or a 1:1 mixture of F6H8/PFD (1.62 g/cm(3)). Electroretinograms (ERG) were performed pre- and postoperatively. Lower and upper retinal areas were compared using immunohistochemical methods. Transmission electron microscopy was performed to investigate alterations in the photoreceptors. RESULTS: All three substances were tolerated well in rabbit eyes for up to 3 months. Dispersion was seen earliest with PFD and latest with pure F6H8. None of the substances demonstrated inflammatory reactions or vascular alterations. ERGs were not considerably altered with any of the substances. Histology of the retina showed alterations in the cell counts within the inner and outer nuclear layer that were not attributable to the gravity of the tamponading agent. CONCLUSION: In contrast to previously published work, this study did not detect any tamponade-related structural damage of the retina after a 3-months tamponade in the rabbit model. Based upon this study, we conclude that gravity might not be causally linked to retinal damage.

Animals↗
PubMed2006

Histological evidence for revascularisation of an autologous retinal pigment epithelium--choroid graft in the pig.

BACKGROUND: Translocation of a free autologous graft consisting of retinal pigment epithelium (RPE), Bruch's membrane, choriocapillaris and choroid in patients with exudative age-related macular degeneration is currently being evaluated in clinical practice. Angiographic studies in these patients suggest that their grafts become revascularised. AIM: To investigate the histological evidence of revascularisation of the graft in a porcine model. METHODS: In 11 pigs (11 eyes), an RPE-choroid graft was translocated from the mid-periphery to an intact or an intentionally damaged RPE and Bruch's membrane at the recipient site. The eyes were enucleated 1 week or 3 months after surgery. Tissue sections were evaluated using immunohistochemistry. RESULTS: Bridging vessels between recipient layer and graft were identified from 1 week to 3 months after surgery. This reconnection occurred regardless of whether the Bruch's membrane of the recipient site was left intact or intentionally damaged at the time of transplantation. The vasculature of the graft appeared open and perfused. Vessels with transcapillary pillars and conglomerates of small new vessels were present in the graft. CONCLUSIONS: This study showed histological evidence for revascularisation by angiogenesis of a free autologous RPE-choroid graft.

Animals↗
PubMed2006

Inhibition of TNF-alpha reduces laser-induced choroidal neovascularization.

To investigate the role of the TNF-alpha in the development of laser-induced choroidal neovascularization (CNV) in a mouse model. Four separate laser burns were applied to induce ruptures of Bruch's membrane and subsequent choroidal neovascularization in C57BL/6J mice. TNF-alpha protein expression was semiquantitatively assessed by Western blot analysis of the choroidal and RPE layer from mice with or without laser treatment. To investigate the effect of TNF-alpha inhibition on CNV formation, animals were treated for 7 days via intraperitonealy implanted osmotic pumps either 3 days before or after laser injury with recombinant TNF receptor P75 (etanercept), a chimeric monoclonal antibody (infliximab), or a purified rat anti-mouse/rat TNF monoclonal antibody (TNF-mAb), respectively. Fluorescein angiography, flat-mount preparations, and histopathology were performed at day 7, 10, or 14 after laser treatment. Western blotting demonstrated that TNF-alpha expression was 4.57-fold higher in the choroid and RPE one week after laser injury compared to control mice without laser. When evaluated one and two weeks after laser injury, etanercept and infliximab given from the 3rd day before laser-damage significantly reduced CNV size and pathological fluorescein leakage compared to the control group after laser treatment only. The inhibitory effect of the monoclonal TNF-alpha antibody on CNV formation was evident two weeks after photocoagulation but not after one week. Only etanercept administered 3 days after laser injury still reduced significantly the development of CNV lesions. Histopathology confirmed that CNV lesions in treated mice were smaller in size compared to the control animals without TNF inhibitor treatment. In conclusion, anti-TNF-alpha treatment with different inhibitors reduces both the size and the leakage of laser-induced CNV. These results suggest the involvement of TNF-alpha in the development of laser-induced CNV and its potential use as a therapeutic agent in the age-related macular degeneration.

Animals↗
PubMed2006

Overexpression of FasL in retinal pigment epithelial cells reduces choroidal neovascularization.

Choroidal neovascularization (CNV) is responsible for the severe visual loss in age-related macular degeneration. CNV formation is considered to be due to an imbalance between pro- and antiangiogenic factors that lead to neovascular growth from the choriocapillaris into the subretinal space. To define whether FasL overexpression in retinal pigment epithelial cells (RPE) can inhibit choroidal neovascularization through Fas-FasL-mediated apoptosis, we examined the role of this pathway in a mouse model of laser-induced choroidal neovascularization. FasL was expressed in the retinal pigment epithelium of transgenic mice. Polymerase chain reaction (PCR), immunoblot, and immunohistochemistry confirmed that the transgene FasL was specifically expressed in RPE. The established laser model was used to induce choroidal neovascularization (CNV) in wild-type (WT) and transgenic mice. CNV formation was compared with respect to fluorescein angiographic leakage (at days 0 and 14 after laser injury) and histological appearance. The lesions were assessed on RPE-choroidal flatmounts after CD31-labeling and with confocal microscopy after perfusion with rhodamine-labeled concanavalin A (Con A). Apoptosis was quantified by TUNEL positivity and caspase activation. FasL mRNA and protein were highly expressed in the RPE of the transgenic mice before and after laser photocoagulation. In contrast, FasL was only weakly expressed in the RPE layer of WT C57BL/6J mice. While ruptures of Bruch's membrane and CNV formation were observed histologically two weeks after laser photocoagulation in transgenic as well as control eyes, the shape and size of CNV lesions were reduced in the transgenic mice. The area of leakage was decreased by 70% in FasL transgenic mice compared with WT mice (P<0.005). The number of TUNEL-positive cells was greater in FasL-overexpressing mice and correlated with the expression of activated caspases. Th expression of other antiangiogenic factors such as PEDF remained unchanged. The specific overexpression of FasL in RPE layer reduced CNV formation in our laser model. Our results strongly point to the FasL-Fas pathway as a potential therapeutic target in controlling pathological choroidal neovascularization.

Animals↗
PubMed2006

Comparison of intact and denuded amniotic membrane as a substrate for cell-suspension culture of human limbal epithelial cells.

BACKGROUND: We have previously developed a limbal epithelial culture system using a cell-suspension method on denuded amniotic membrane (AM). However, other workers reported that intact AM is advantageous for limbal epithelial culture in that it preserves stem cell characteristics. In this study, we cultivated human limbal epithelial cell-suspensions on both intact and denuded AM and compared the morphology and adhesion of the limbal epithelial cells on these two substrates. METHODS: Human limbal epithelial cells were dissociated from donor eyes using dispase and gentle pipetting and then seeded onto intact and denuded AM as cell suspension. Limbal epithelial cells on AM were co-cultured with a MMC-treated 3T3 fibroblast feeder layer and epithelial differentiation was promoted by air lifting. Cultures were examined by light, scanning and transmission electron microscopy and differences in cellular attachments and intercellular spacing were quantified. Basement membrane complexes were examined by indirect immunofluorescence. RESULTS: Limbal cells grown on denuded AM were well stratified and differentiated. Cells were well attached to each other and to the basement membrane. In contrast, limbal cells cultured on intact AM failed to stratify and in places formed a monolayer. The culture on denuded AM had significantly (P<0.001) more desmosomal junctions as well as significantly (P<0.001) more junctional attachments to the carrier than the intact culture. In addition, the intercellular spaces between cells cultivated on denuded AM were significantly (P<0.001) smaller than those between cells grown on the intact substrate. In cultures on both denuded and intact AM, the basement membrane zone displayed a positive staining for collagen VII, integrins alpha-6 and beta-4 and laminin 5. CONCLUSIONS: We successfully cultivated well-stratified and -differentiated limbal cells on denuded AM, while on the intact AM limbal cells failed to stratify and in places formed only a monolayer of cells. The limbal cells cultivated on denuded AM were well attached to the AM stroma and were morphologically superior to the limbal epithelium cultivated on intact AM. We conclude that for purposes of transplantation of differentiated epithelial sheets, denuded AM is probably the more practical carrier for human limbal epithelial cell cultures when using our cell-suspension culture system.

3T3 Cells↗
PubMed2006

Varied expression of functionally important genes of RPE and choroid in the macula and in the periphery of normal human eyes.

BACKGROUND: Topographic differences in RPE and choroid between macular and peripheral areas of the eye may predispose to morphologic and cell survival changes with aging. An understanding of the molecular events that distinguish RPE and choroid by their spatial location could give hints for the identification of survival factors and the development of new therapeutic approaches. To determine the mRNA expression of functionally important genes in RPE and choroid of morphologically normal human eyes, tissue patches were dissected from the macula and peripheral locations. METHODS: The mRNA levels of 29 genes with known functions or expression in the RPE/choroid were quantified in these sections by real time RT-PCR. Variations in the mRNA expression were determined due to differences in the mean normalized expression (MNE) between different peripheral locations, left and right eye of the same donor, and eyes of different donors. RESULTS: In the macula, the lysosomal enzyme cathepsin D (1.27E+00+/-1.54E-01) and the MERTK ligand Gas6 (1.08E+00+/-1.60E-01) had the highest MNE, whereas the apoptosis inducer Fas-Ligand (1.41E-04+/-6.46E-05) and the ROS internalization receptor CD36 (2.15E-04+/-1.11E-05) demonstrated the lowest expression. Interestingly, the PEDF expression (1.80E-01+/-4.56E-02) was 10 times higher than the VEGF expression (1.84E-02+/-2.46E-03) in the macular area. For most of the analyzed genes (52%, e.g. MERTK, integrin alphaV and beta5, RPE65, tyrosinase, VEGF) there was equal gene expression in the macula and in the periphery. For 31% of the genes (e.g. CD36, MAP1B) there was higher expression in the macula and for 17% of the genes (e.g. 11-cis RDH, VEGF-R2, PEDF) there was higher expression in the periphery. CONCLUSIONS: Whereas most of the analyzed genes expressed in RPE and choroid had equal mRNA expression levels in the macula and the periphery with donor dependent variations, there are important exceptions in genes that are involved in the maintenance of a specific vascular status in the macula (PEDF, VEGF and VEGR-R2) and in the recycling of rod outer segments (11-cis RDH). Applying this technique to the gene expression analysis of patients with AMD could identify those genes that are involved in molding of the disease.

Aged↗
PubMed2006

Autologous translocation of the choroid and retinal pigment epithelium in age-related macular degeneration.

PURPOSE: To evaluate the autologous translocation of peripheral choroid and retinal pigment epithelium (RPE) in 45 eyes of 43 patients with age-related macular degeneration (AMD). DESIGN: Prospective nonrandomized study. METHODS: All patients had visual loss due to AMD (n = 5 classic membranes, n = 14 occult, n = 2 mixed, n = 16 pigment epithelial detachment (PED), n = 5 subretinal hemorrhage, n = 3 geographic atrophy). After extraction of the neovascular complex, an autologous peripheral full-thickness explant of RPE, Bruch membrane, and choroid was translocated from the midperiphery to the macula. RESULTS: Preoperative distant visual acuity ranged from 20/800 to 20/40. Reading vision ranged from 1.4 logarithm of reading acuity determination (logRAD) to 0.5 logRAD (0.04 to 0.32 Snellen equivalent). Revision surgery was required in 22 eyes as a result of proliferative vitreoretinopathy (PVR), retinal detachment, macular pucker, or vitreous hemorrhage. In eight patients, the patch was renewed. At six months, distant visual acuity ranged from light perception to 20/50 (increase of 15 letters in four eyes). Reading vision ranged from 1.4 to 0.4 logRAD. Visual outcome was unrelated to the type of AMD. Vascularization of the transplant was visible on indocyanine green (ICG) angiography in 40 of 42 eyes. In most patients, autofluorescence of the pigment epithelium was coincident with revascularization of the graft. Fixation on the patch was positively related to visual acuity. CONCLUSIONS: Autologous translocation of a full-thickness transplant of choroid and RPE usually results in a vascularized and functioning graft. Vascularization was even achieved in patients with geographic atrophy. Fixation stability and microperimetry before the patch translocation may be helpful in selecting patients who will profit from surgery.

Aged↗
PubMed2006

The role of PDGF receptor inhibitors and PI3-kinase signaling in the pathogenesis of corneal neovascularization.

PURPOSE: Corneal neovascularization remains an unsolved therapeutic problem. Platelet-derived growth factor (PDGF) is directly linked to vessel formation and stabilization. This study was undertaken to elucidate the mechanisms by which PDGF exerts its effects on corneal angiogenesis. METHODS: Corneal neovascularization was induced in C57 mice by removal of the limbal epithelium. When mature vessels appeared after 7 days, mice were treated with the PDGF receptor-beta inhibitor AG 1296 or the phosphatidylinositol 3-kinase (PI3-K)-inhibitors wortmannin and LY294002, respectively, using an intraperitoneally implanted miniosmotic pump. At day 14 after scraping, corneas of treated and untreated (control) mice were dissected and immunostained with FITC-CD31 antibody for endothelial cells and with Cy3-SMA (smooth muscle actin) for pericytes. VEGF (vascular endothelial growth factor), ang1/2 (angiopoietin 1 and 2), and PDGF mRNA levels of treated and untreated corneas were determined by real-time RT-PCR. RESULTS: Mice treated with the PDGF inhibitor AG 1296 showed an inhibition of corneal neovascularization of 21.1% and a reduction of pericytes of 52% in the newly formed vessels compared with untreated animals. VEGF, ang1, ang2, and PDGF mRNA expression was reduced in the corneas of AG 1296-treated mice compared with the respective control. Treatment with the PI3-K inhibitors wortmannin and LY29002 had similar effects, inducing a decrease in corneal neovascularization and a reduction of VEGF, ang1, ang2, and PDGF mRNA levels. CONCLUSIONS: Inhibition of the PDGF signal pathway results in loss of pericytes and a reduction in vessel density in the neovascularized cornea that correlates with reduced expression of PDGF, ang1/2, and VEGF mRNA. Furthermore, PI3-K was shown to be involved in the regulation of VEGF, ang1, and PDGF, as the PI3-K inhibitors wortmannin or LY294002 had similar effects. Because PDGF is a known stimulus for PI3-K activation, it can be postulated that the observed decrease in VEGF, ang1/2, and PDGF mRNA levels on administration of the PDGF inhibitor is caused by the decreased activation of the PI3-K signaling cascade.

Androstadienes↗
PubMed2006

Pathological but not physiological retinal neovascularization is altered in TNF-Rp55-receptor-deficient mice.

PURPOSE: Tumor necrosis factor (TNF)-alpha is one of the major cytokines in inflammation and apoptosis. It has been demonstrated that inhibition of TNFalpha can reduce leukocyte adhesion, vascular leakage, and apoptotic endothelial cell death in diabetes. This study was conducted to investigate the effect of TNF-Rp55 and TNF-Rp75 on retinal development in oxygen-induced retinopathy. METHODS: TNF-Rp55- and TNF-Rp75-deficient mice, as well as their respective wild-type controls, were exposed to 75% oxygen from postnatal day P7 to P12. Retinal vascularization was investigated in flatmount preparations after concanavalin A labeling of endothelial cells on days P6, P14, P17, and P20. Retinal mRNA expression of VEGF, angiopoietin-1 and -2, and PDGF was examined at days P14 and P20. RESULTS: TNF-Rp55- and TNF-Rp75-deficient mice demonstrated similar retinal development and vascularization under normoxic conditions. In comparison to wild-type mice, the vascularized area remained stable during the observation time, although the gene expression of VEGF, angiopoietin (ang)-1 and -2, and PDGFb changed. Compared with that in the wild type mice, the relative expression of VEGF, ang-1, ang-2, and PDGFb changed 5.14-, 1.7-, 0.39-, and 0.36-fold in Rp55(-/-) mice and 4.1-, 9.5 x 10(-5)-, 0.12-, and 2975-fold in Rp75(-/-) mice, respectively. Treatment with oxygen resulted in a significantly reduced vascularization in Rp55(-/-) but not Rp75(-/-) mice on postnatal day (P)20. CONCLUSIONS: Inhibition of TNFalpha via TNF-Rp55 can alter retinal development and angiogenesis in a model of oxygen-induced retinopathy. The data underscore the potential effectiveness of TNF-inhibitory treatments as modulators in oxygen-induced retinopathy.

Angiopoietin-1↗
PubMed2005

Increased leukocyte-endothelial interactions in syndecan-1-deficient mice involve heparan sulfate-dependent and -independent steps.

PURPOSE: Increased leukocyte-endothelial interactions and angiogenesis are observed in the ocular vasculature of mice lacking the cell surface heparan sulfate proteoglycan syndecan-1. Here we investigate the interaction of defined leukocyte populations of syndecan-1 knockout (KO) and wild-type mice with endothelial cells in vitro. Heparin is used to substitute for the lack of syndecan-1 heparan sulfate. METHODS: The adhesion of polymorphonuclear cells and monocytes purified from syndecan-1 KO and wild-type mice to unstimulated and TNF-alpha-treated human umbilical vein endothelial cells (HUVECs) was measured in a static adhesion assay. RESULTS: Adhesion of syndecan-1 KO leukocytes to HUVECs is increased relative to wild-type leukocytes, being more pronounced in TNF-alpha-stimulated HUVECs. Heparin reverted this adhesion to wild-type levels in unstimulated endothelium. CONCLUSIONS: Syndecan-1 acts as a negative regulator of polymorphonuclear leukocytes (PMNs) and monocyte adhesion to endothelial cells. Its heparan sulfate chains play different roles in this process in unstimulated endothelia compared to TNF-alpha-stimulated endothelia.

Animals↗
PubMed2004

Influence on membrane-mediated cell activation by vesicles of silicone oil or perfluorohexyloctane.

PURPOSE: This study was conducted to investigate whether macrophage activation through cell membrane attachment might be supported by emulsified tamponade droplets of a certain vesicle size. It has been hypothesized that emulsification of vitreous tamponades might stimulate retinal membrane formation. METHODS: In this laboratory investigation, similarly sized vesicles of silicone oil and the partially fluorinated alkane perfluorohexyloctane (F6H8) were produced by extrusion through polycarbonate membranes. Human neutrophils were obtained from blood donors. Human monocytes were negatively isolated from mononuclear cells by depletion of other cells. Cell activation status of phagocyting blood neutrophils was measured by a chemiluminescence assay. Fluorescent attached or internalized vesicles were monitored by fluorescent microscopy. The main outcome measures were the altered activation status of monocytes after vesicle incubation and the ability of human macrophages to attach and/or internalize vesicles in vitro. RESULTS: Extruding silicone oil through a polycarbonate membrane resulted in the production of vesicles that remained stable for at least 2 days. F6H8 vesicles had to be stabilized with an emulsifier, in this case Pluronic PE6800 or Lipoid EPC. The mean vesicle diameter was similar with both components (F6H8: 13.08+/-2.95 microm, silicone oil: 10.05+/-4.6 microm). Neutrophil activation was not influenced by either emulsifier alone or by silicone oil vesicles without emulsifier. Stabilized F6H8 vesicles had a dose-dependent influence on blood neutrophil activation. Only silicone oil vesicles together with Lipoid EPC, not Pluronic PE6800, had a comparable influence on neutrophil activation. Neutrophil activation was influenced neither by 0.125% human serum albumin (HSA) alone nor by vesicles of F6H8 or silicone oil prepared with 0.125% HSA. Monocyte cell membrane attachment of silicone fluid was two times higher than that of F6H8 fluid. F6H8/Pluronic PE6800 vesicles enhanced this process 20-fold, whereas silicone oil vesicles did not enhance cell membrane attachment significantly. CONCLUSIONS: These in vitro data do not support the hypothesis that emulsification of the tamponades silicone oil or F6H8 in the microenvironment of the eye might easily activate neutrophils or stimulate phagocytosis by monocytes. A prerequisite is the combination of a vesicle shape of the tamponades with specific stabilizing or modifying surfactants. Emulsified tamponades stabilized by artificial surfactants, but not by the naturally occurring protein HSA, favor cell activation by cell membrane attachment.

Cytoplasmic Vesicles↗
PubMed2004

A central role for inflammation in the pathogenesis of diabetic retinopathy.

Diabetic retinopathy is a leading cause of adult vision loss and blindness. Much of the retinal damage that characterizes the disease results from retinal vascular leakage and nonperfusion. Diabetic retinal vascular leakage, capillary nonperfusion, and endothelial cell damage are temporary and spatially associated with retinal leukocyte stasis in early experimental diabetes. Retinal leukostasis increases within days of developing diabetes and correlates with the increased expression of retinal intercellular adhesion molecule-1 (ICAM-1) and CD18. Mice deficient in the genes encoding for the leukocyte adhesion molecules CD18 and ICAM-1 were studied in two models of diabetic retinopathy with respect to the long-term development of retinal vascular lesions. CD18-/- and ICAM-1-/- mice demonstrate significantly fewer adherent leukocytes in the retinal vasculature at 11 and 15 months after induction of diabetes with STZ. This condition is associated with fewer damaged endothelial cells and lesser vascular leakage. Galactosemia of up to 24 months causes pericyte and endothelial cell loss and formation of acellular capillaries. These changes are significantly reduced in CD18- and ICAM-1-deficient mice. Basement membrane thickening of the retinal vessels is increased in long-term galactosemic animals independent of the genetic strain. Here we show that chronic, low-grade subclinical inflammation is responsible for many of the signature vascular lesions of diabetic retinopathy. These data highlight the central and causal role of adherent leukocytes in the pathogenesis of diabetic retinopathy. They also underscore the potential utility of anti-inflammatory treatment in diabetic retinopathy.

Animals↗
PubMed2004

Visual outcome of patients with macular edema after pars plana vitrectomy and indocyanine green-assisted peeling of the internal limiting membrane.

PURPOSE: To evaluate the efficacy of inner limiting membrane (ILM) peeling in persistent macular edema. METHODS: This retrospective review analyzed a series of 23 eyes from 23 patients with persistent macular edema treated by pars plana vitrectomy (PPV) with indocyanine green (ICG)-assisted peeling of the ILM. Thirteen female and 10 male patients with a mean age of 57.2+/-15.6 (24-77) years underwent operation between May 2000 and October 2001. The main diagnoses were uveitis (anterior, intermediate, posterior and panuveitis) ( n=9), central retinal vein occlusion (CRVO) (n=4), diabetic retinopathy (DR) ( n=5), vitreoretinal traction syndrome ( n=2), and Irvine-Gass syndrome ( n=3). Nine eyes had undergone phacoemulsification (PE) previously and two eyes had been subjected to combined PE and ILM peeling. The eyes were tamponaded with gas (3), silicone oil (5) or air (11). In four cases no endotamponade was used. Improvement in visual acuity of 2 lines or more was regarded as significant. RESULTS: Visual acuity improved after 3 months in 9 of the 23 patients. After 6 months and at the follow-up, a significant improvement was found in 6/21 and 7/21 patients. This improvement was predominantly seen in patients with uveitis (5/9), or diabetic maculopathy (3/5); One patient with Irvine-Gass syndrome showed a significant reduction, one with vitreoretinal traction an improvement in visual acuity. The group of patients with CRVO showed no significant change during the follow-up. The choice of endotamponade did not alter the visual acuity outcome. CONCLUSIONS: Different patient groups respond differently to ILM peeling. Although overall significant visual acuity improvement was observed in only one third of all cases 12 months after ILM peeling for persistent macular edema, patients with uveitis and nonproliferative diabetic maculopathy demonstrated a benefit. The lack of long-term improvement in the majority of cases is in accordance with the hypothesis that ILM peeling may reduce the intraretinal edema, but does not affect the underlying mechanism causing macular edema. So far, only diabetics have shown improvement (still unproven) from ILM peeling, and this study provides no justification for extending the treatment to macular edema of other causes. Large-scale investigations are needed to evaluate the efficacy in certain diagnosis groups.

Adult↗
PubMed2004

Pharmacokinetics and safety of intravitreally delivered etanercept.

BACKGROUND: The anti-inflammatory drug etanercept may be an effective therapeutic agent in diabetic retinopathy. In order to further evaluate its potential, the pharmacokinetics and safety of this drug after intravitreal delivery were investigated. METHODS: After intravitreal administration of etanercept in rabbits, clinical examination, electroretinography (ERG), visually evoked potentials (VEP) and histology were evaluated. The pharmacokinetics and distribution of etanercept were analyzed using fluorescence-coupled protein at 0, 2, 4, and 8 weeks after injection in vitreous, retina, and choroid. RESULTS: No adverse effects and signs of toxicity were found. Etanercept showed peak concentrations after 4 weeks in the retina and choroid. CONCLUSIONS: Intravitreally delivered etanercept is safe and results in high concentrations in the retina and choroid over a long period of time.

Animals↗
PubMed2004

Activin a in the regulation of corneal neovascularization and vascular endothelial growth factor expression.

Activin A, a dimeric glycoprotein that belongs to the transforming growth factor-beta superfamily, governs cellular differentiation in a wide variety of models and has been implicated in the regulation of angiogenesis. We examined the role of activin A and its downstream signaling pathway in a murine model of inflammatory corneal neovascularization induced by mechanical injury (debridement), and in vitro in corneal epithelial cells. Activin A expression increased steadily from day 2 until day 8 after mechanical debridement in vivo, paralleling vascular endothelial growth factor (VEGF) expression. Administration of recombinant activin A in mice increased the area of neovascularization, VEGF expression, and the kinase activities of p38 and p42/44 MAPKs after mechanical debridement. Systemic inhibition of activin A in vivo with a neutralizing antibody reduced the area of neovascularization, VEGF expression, and p38 and p42/44 MAPK activity, whereas administration of an isotype-matched control antibody had no effect. In vitro treatment with activin A increased VEGF secretion, as well as p38 and p42/44 MAPK activity in corneal epithelial cells, whereas concurrent administration of specific inhibitors of p38 or p42/44 MAPK abolished the stimulatory effect of activin A on VEGF production. We conclude that activin A stimulates inflammatory corneal angiogenesis by increasing VEGF levels through a p38 and p42/44 MAPK-dependent mechanism.

Activins↗
PubMed2004

Insulin-like growth factor-I plays a pathogenetic role in diabetic retinopathy.

Diabetic retinopathy is a leading cause of blindness in the Western world. Aberrant intercellular adhesion molecule-1 expression and leukocyte adhesion have been implicated in its pathogenesis, raising the possibility of an underlying chronic inflammatory mechanism. In the current study, the role of insulin-like growth factor (IGF)-I in these processes was investigated. We found that systemic inhibition of IGF-I signaling with a receptor-neutralizing antibody, or with inhibitors of PI-3 kinase (PI-3K), c-Jun kinase (JNK), or Akt, suppressed retinal Akt, JNK, HIF-1alpha, nuclear factor (NF)-kappaB, and AP-1 activity, vascular endothelial growth factor (VEGF) expression, as well as intercellular adhesion molecule-1 levels, leukostasis, and blood-retinal barrier breakdown, in a relevant animal model. Intravitreous administration of IGF-I increased retinal Akt, JNK, HIF-1alpha, NF-kappaB, and AP-1 activity, and VEGF levels. IGF-I stimulated VEGF promoter activity in vitro, mainly via HIF-1alpha, and secondarily via NF-kappaB and AP-1. In conclusion, IGF-I participates in the pathophysiology of diabetic retinopathy by inducing retinal VEGF expression via PI-3K/Akt, HIF-1alpha, NF-kappaB, and secondarily, JNK/AP-1 activation. Taken together, these in vitro and in vivo signaling studies thus identify potential targets for pharmacological intervention to preserve vision in patients with diabetes.

Animals↗