Complication Of Age-related Macular Degeneration Research Articles

Ophthalmologists' awareness of geographic atrophy: An Italian survey including 365 participants.

Geographic atrophy (GA) is a severe complication of age-related macular degeneration (AMD) and leads to irreversible visual decline. To date, no effective treatment is available for GA patients. However, a number of new therapies have recently been approved and several others are in the pipeline. This rapid evolution of prospects for GA patients requires constant updating of ophthalmologists' understanding of GA and its management so as to provide the appropriate treatment. For this reason, Società Italiana di Scienze Oftalmologiche (S.I.S.O.) has designed a specific survey to gauge the position of Italian ophthalmologists in this regard. The three hundred and sixty-five Italian ophthalmologists who agreed to take part received a seventeen-part questionnaire guaranteeing privacy and anonymity. The survey was compiled through an online portal and the results were sent directly to S.I.S.O. ETS. Two graders analyzed the data and recorded the results. The results showed a high level of self-assessed awareness and understanding of GA, as well as considerable willingness to further improve knowledge of the disease. Most of the participants claimed to have effective rules of conduct in place for managing GA patients, including prompt response, involving a high prevalence of nutraceutical prescriptions and lifestyle recommendations. This survey provided an overview of how GA patients are managed in Italy. The Italian ophthalmology community appears to be ready to adopt the upcoming treatments for GA.

Gene Expression Within a Human Choroidal Neovascular Membrane Using Spatial Transcriptomics.

Macular neovascularization is a relatively common and potentially visually devastating complication of age-related macular degeneration. In macular neovascularization, pathologic angiogenesis can originate from either the choroid or the retina, but we have limited understanding of how different cell types become dysregulated in this dynamic process. To study how gene expression is altered in focal areas of pathology, we performed spatial RNA sequencing on a human donor eye with macular neovascularization as well as a healthy control donor. We performed differential expression to identify genes enriched within the area of macular neovascularization and used deconvolution algorithms to predict the originating cell type of these dysregulated genes. Within the area of neovascularization, endothelial cells demonstrated increased expression of genes related to Rho family GTPase signaling and integrin signaling. Likewise, VEGF and TGFB1 were identified as potential upstream regulators that could drive the observed gene expression changes produced by endothelial and retinal pigment epithelium cells in the macular neovascularization donor. These spatial gene expression profiles were compared to previous single-cell gene expression experiments in human age-related macular degeneration as well as a model of laser-induced neovascularization in mice. As a secondary aim, we investigated regional gene expression patterns within the macular neural retina and between the macular and peripheral choroid. Overall, this study spatially analyzes gene expression across the retina, retinal pigment epithelium, and choroid in health and describes a set of candidate molecules that become dysregulated in macular neovascularization.

Bilateral Macular Choroidal Abnormalities with Drusenoid Deposits in Patients with Unilateral Peripheral Exudative Hemorrhagic Chorioretinopathy.

To investigate bilateral macular features on optical coherence tomography (OCT) in patients with unilateral peripheral exudative hemorrhagic chorioretinopathy (PEHCR). In this cross-sectional study, OCT features of affected eyes (PEHCR group, n = 30) and unaffected contralateral eyes (contralateral group, n = 30) were investigated. Age- and sex-matched patients with polypoidal choroidal vasculopathy (PCV group, n = 51) and healthy controls (normal group, n = 50) were included to compare choroidal thickness, measured at six points apart from the fovea, with the PEHCR group. Subretinal drusenoid deposits were the most common feature in PEHCR (20%) and contralateral (23%) groups, followed by soft drusen. Although the macular choroid was comparably thin in both PEHCR and contralateral groups, pachyvessels were also observed. The choroids of the PEHCR group were significantly thinner than those of the normal group at the subfovea and 1 mm temporal to the fovea and considerably thinner than those of the PCV group from 3 mm nasal to 3 mm temporal to the fovea. In patients with unilateral PEHCR, bilateral choroidal thinning and drusenoid deposit accumulation were noted in the macula. The pathophysiology of PEHCR may be a rare peripheral complication of age-related macular degeneration with pathologic choroid.

Choroidal Modifications Preceding the Onset of Macular Neovascularization in Age-Related Macular Degeneration.

IntroductionMacular neovascularization (MNV) is a common complication of age-related macular degeneration (AMD). Although several biomarkers may help to estimate the risk of MNV onset, neovascular complication is difficult to predict. Previous studies showed that the quantitative assessment of choroidal and choriocapillaris changes is useful for the assessment of atrophy expansion. On the other hand, scant data are available regarding the role of this kind of assessment in the setting of MNV. The aim of the study is to analyze choroidal and choriocapillaris changes occurring before the onset of MNV in patients affected by AMD using quantitative optical coherence tomography (OCT) and OCT angiography (OCTA).MethodsThe study was designed as a retrospective case series. Patients affected by AMD, categorized in eyes complicated by MNV and eyes not developing MNV, were retrospectively analyzed for 1 year of follow-up. Choroidal thickness (CT), Sattler layer thickness (SLT) and Haller layer thickness (HLT) were measured on OCT scans. Vessel density (VD) and choriocapillaris (CC) porosity were quantified on OCTA reconstructions. The main outcome measure was the relationship between choroidal and CC parameters, and MNV onset.ResultsWe included 50 eyes of 50 AMD patients (28 male; mean age 74 ± 5 years). Over the 1-year follow-up, 15/50 eyes developed MNV (9 type 1; 3 type 2; 3 mixed type 1–2). Mean best-corrected visual acuity (BCVA) was 0.15 ± 0.15 logMAR at baseline, remaining stable in eyes not developing MNV (0.15 ± 0.12 logMAR; p > 0.05), and worsening to 0.38 ± 0.20 logMAR in eyes developing MNV (p < 0.01). VD values were similar between eyes developing MNV and eyes not complicated by MNV at baseline, with significant worsening detected only in MNV eyes. CC porosity was significantly higher in MNV eyes already before the onset of MNV. Furthermore, SLT was significantly lower in eyes developing MNV. The onset of MNV was preceded by a significant increase in intraretinal hyperreflective foci, whereas choroidal hyperreflective foci showed no evident changes.ConclusionsThe degeneration of CC and the SLT thinning represent early an biomarker of MNV onset in AMD.

Surgical Transplantation of Human RPE Stem Cell-Derived RPE Monolayers into Non-Human Primates with Immunosuppression.

SummaryRecent trials of retinal pigment epithelium (RPE) transplantation for the treatment of disorders such as age-related macular degeneration have been promising. However, limitations of existing strategies include the uncertain survival of RPE cells delivered by cell suspension and the inherent risk of uncontrolled cell proliferation in the vitreous cavity. Human RPE stem cell-derived RPE (hRPESC-RPE) transplantation can rescue vision in a rat model of retinal dystrophy and survive in the rabbit retina for at least 1 month. The present study placed hRPESC-RPE monolayers under the macula of a non-human primate model for 3 months. The transplant was able to recover in vivo and maintained healthy photoreceptors. Importantly, there was no evidence that subretinally transplanted monolayers underwent an epithelial-mesenchymal transition. Neither gliosis in adjacent retina nor epiretinal membranes were observed. These findings suggest that hRPESC-RPE monolayers are safe and may be a useful source for RPE cell replacement therapy.

The Histone Deacetylase Inhibitor AN7, Attenuates Choroidal Neovascularization in a Mouse Model.

Choroidal neovascularization (CNV) is a complication of age-related macular degeneration and a major contributing factor to vision loss. In this paper, we show that in a mouse model of laser-induced CNV, systemic administration of Butyroyloxymethyl-diethyl phosphate (AN7), a histone deacetylase inhibitor (HDACi), significantly reduced CNV area and vascular leakage, as measured by choroidal flatmounts and fluorescein angiography. CNV area reduction by systemic AN7 treatment was similar to that achieved by intravitreal bevacizumab treatment. The expression of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF-2), and the endothelial cells marker CD31, was lower in the AN7 treated group in comparison to the control group at the laser lesion site. In vitro, AN7 facilitated retinal pigmented epithelium (RPE) cells tight junctions’ integrity during hypoxia, by protecting the hexagonal pattern of ZO-1 protein in the cell borders, hence reducing RPE permeability. In conclusion, systemic AN7 should be further investigated as a possible effective treatment for CNV.

Effects of Brimonidine on Retinal Pigment Epithelial Cells and Müller Cells Exposed to Amyloid-Beta 1–42 Peptide In Vitro

To evaluate whether brimonidine can prevent cytotoxicity in human retinal pigment epithelial (RPE) and Müller (MIO) cells after exposure to amyloid-beta 1-42 (Aβ42). An in vitro model of geographic atrophy (GA), which is an end-stage complication of age-related macular degeneration (AMD), simulated with the application of Aβ42 in cell culture. RPE and MIO cells were pretreated with brimonidine for 6 hours, then exposed to 10μM Aβ42 for 24 hours. Several concentrations (one time [1×], two times [2×], and five times [5×]) of brimonidine were used to assess for a dose-related effect. Assays were immediately run following the treatment period. 2',7'-Dichlorofluorescein diacetate was used to assess reactive oxygen species production, the MTT assay was used to assess cell viability, and the JC-1 dye assay was used to assess mitochondrial membrane potential. The main outcome measures were reactive oxygen species (ROS) production, cell viability, and mitochondrial membrane potential (ΔΨm) of RPE and MIO cells following the treatment phase. High-dose (5×) brimonidine was capable of reducing ROS production in RPE and MIO cells with exposure to Aβ42. The application of Aβ42 alone did not trigger a rise in ROS production. Brimonidine was unable to rescue cell viability and ΔΨm after exposure to Aβ42 in both cell cultures. Instead, high-dose (5×) brimonidine appeared to increase the toxicity to cell viability and ΔΨm in cultures exposed to Aβ42. However, this was not due to medication toxicity alone, because high-dose (5×) brimonidine without exposure to Aβ42 did not affect the cell viability in both cell types. Brimonidine may have a role in preventing oxidative cellular injury in AMD. However, this role does not appear to translate into protection against some of the cytotoxic effects observed from this in vitro model of GA. In this cellular model of GA, brimonidine is able to reduce oxidative stress but is unable to rescue cell viability or prevent mitochondrial dysfunction. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:S23-S28.].

Different distributions of M1 and M2 macrophages in a mouse model of laser-induced choroidal neovascularization.

Choroidal neovascularization (CNV) is a serious complication of age-related macular degeneration. The aim of the present study was to investigate the expression and distribution of M1 and M2 macrophages in a laser-induced CNV adult mouse model. The mRNA expression levels of M1, M2 and pan macrophage markers, and macrophage-associated angiogenic cytokines, were determined by reverse transcription-quantitative polymerase chain reaction. Immunofluorescence studies were performed to determine the location of the macrophages. The expression levels of M1 macrophage markers increased to a greater extent compared with M2 markers in the retinal pigment epithelium (RPE)-choroid complexes following laser photocoagulation. By contrast, the expression levels of M2 macrophage markers increased primarily in the retinas. Immunofluorescence studies revealed that the increased number of cluster of differentiation (CD)206-positive cells were located primarily in the retina, whereas the CD80-positive cells were located around the site of CNVs in the RPE-choroid. In addition, the M1-associated cytokines increased to a greater extent in the RPE-choroid complexes, whereas the M2-associated cytokines were highly expressed in the retinas. These findings indicate that M1 and M2 macrophage numbers increased following CNV; however, the locations were different in this mouse model of laser-induced CNV. The results of the present study suggest that M1 macrophages have a more direct role in inhibiting the development of CNV.

Fluorocoxib A enables targeted detection of cyclooxygenase-2 in laser-induced choroidal neovascularization.

Ocular angiogenesis is a blinding complication of age-related macular degeneration and other retinal vascular diseases. Clinical imaging approaches to detect inflammation prior to the onset of neovascularization in these diseases may enable early detection and timely therapeutic intervention. We demonstrate the feasibility of a previously developed cyclooxygenase-2 (COX-2) targeted molecular imaging probe, fluorocoxib A, for imaging retinal inflammation in a mouse model of laser-induced choroidal neovascularization. This imaging probe exhibited focal accumulation within laser-induced neovascular lesions, with minimal detection in proximal healthy tissue. The selectivity of the probe for COX-2 was validated <italic<in vitro</italic< and by <italic<in vivo</italic< retinal imaging with nontargeted 5-carboxy-X-rhodamine dye, and by blockade of the COX-2 active site with nonfluorescent celecoxib prior to injection of fluorocoxib A. Fluorocoxib A can be utilized for imaging COX-2 expression <italic<in vivo</italic< for further validation as an imaging biomarker in retinal diseases.

Geographic atrophy in patients with advanced dry age-related macular degeneration: current challenges and future prospects.

Geographic atrophy (GA) of the retinal pigment epithelium (RPE) is a devastating complication of age-related macular degeneration (AMD). GA may be classified as drusen-related (drusen-associated GA) or neovascularization-related (neovascular-associated GA). Drusen-related GA remains a large public health concern due to the burden of blindness it produces, but pathophysiology of the condition is obscure and there are no proven treatment options. Genotyping, cell biology, and clinical imaging point to upregulation of parainflammatory pathways, oxidative stress, and choroidal sclerosis as contributors, among other factors. Onset and monitoring of progression is accomplished through clinical imaging instrumentation such as optical coherence tomography, photography, and autofluorescence, which are the tools most helpful in determining end points for clinical trials at present. A number of treatment approaches with diverse targets are in development at this time, some of which are in human clinical trials. Neovascular-associated GA is a consequence of RPE loss after development of neovascular AMD. The neovascular process leads to a plethora of cellular stresses such as ischemia, inflammation, and dramatic changes in cell environment that further taxes RPE cells already dysfunctional from drusen-associated changes. GA may therefore develop secondary to the neovascular process de novo or preexisting drusen-associated GA may continue to worsen with the development of neovascular AMD. Neovascular-associated GA is a prominent cause of continued vision loss in patients with otherwise successfully treated neovascular AMD. Clearly, treatment with vascular endothelial growth factor (VEGF) inhibitors early in the course of the neovascular disease is of great clinical benefit. However, there is a rationale and some suggestive evidence that anti-VEGF agents themselves could be toxic to RPE and enhance neovascular-associated GA. The increasing prevalence of legal blindness from this condition due to the aging of the general population lends urgency to the search for a therapy to ameliorate GA.

Age Related Macular Degeneration and Total Hip Replacement Due to Osteoarthritis or Fracture: Melbourne Collaborative Cohort Study.

Osteoarthritis is the leading cause of total hip replacement, accounting for more than 80% of all total hip replacements. Emerging evidence suggests that osteoarthritis has a chronic inflammatory component to its pathogenesis similar to age-related macular degeneration. We evaluated the association between age-related macular degeneration and total hip replacement as proxy for severe osteoarthritis or fractured neck of femur in the Melbourne Collaborative Cohort Study. 20,744 participants had complete data on both age-related macular degeneration assessed from colour fundus photographs taken during 2003–2007 and total hip replacement. Total hip replacements due to hip osteoarthritis and fractured neck of femur during 2001–2011 were identified by linking the cohort records to the Australian Orthopedic Association National Joint Replacement Registry. Logistic regression was used to examine the association between age-related macular degeneration and risk of total hip replacement due to osteoarthritis and fracture separately, adjusted for confounders. There were 791 cases of total hip replacement for osteoarthritis and 102 cases of total hip replacement due to fractured neck of femur. After adjustment for age, sex, body mass index, smoking, and grouped country of birth, intermediate age-related macular degeneration was directly associated with total hip replacement for osteoarthritis (odds ratio 1.22, 95% CI 1.00–1.49). Late age-related macular degeneration was directly associated with total hip replacement due to fractured neck of femur (odds ratio 5.21, 95% CI2.25–12.02). The association between intermediate age-related macular degeneration and an increased 10-year incidence of total hip replacement due to osteoarthritis suggests the possibility of similar inflammatory processes underlying both chronic diseases. The association of late age-related macular degeneration with an increased 10-year incidence of total hip replacement due to fractured neck of femur may be due to an increased prevalence of fractures in those with poor central vision associated with the late complications of age-related macular degeneration.

SIRT1 mediated inhibition of VEGF/VEGFR2 signaling by Resveratrol and its relevance to choroidal neovascularization

SIRT1, a NAD+ -dependent histone deacetylase, has been shown to act as a key regulator of angiogenesis. The purpose of this study was to determine the effects of resveratrol (RSV, a SIRT1 activator) on the vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathway and to establish its relevance to choroidal neovascularization (CNV), a blinding complication of age-related macular degeneration. Western blot and ELISA assay showed that RSV inhibited hypoxia-inducible factor (HIF)-1α accumulation and VEGF secretion induced by cobalt chloride (CoCl2) through SIRT1 in human retinal pigment epithelial (hRPE) cells. Furthermore, RSV down-regulated VEGFR2 phosphorylation and activation induced by VEGF in endothelial cells via SIRT1. Thus, the inhibitory effect of RSV on the HIF-1α/VEGF/VEGFR2 signaling axis is mediated, at least in part, through SIRT1. The results suggest that targeting SIRT1 could have therapeutic potential for the treatment of CNV.

Attenuation of choroidal neovascularization by histone deacetylase inhibitor.

Choroidal neovascularization (CNV) is a blinding complication of age-related macular degeneration that manifests as the growth of immature choroidal blood vessels through Bruch’s membrane, where they can leak fluid or hemorrhage under the retina. Here, we demonstrate that the histone deacetylase inhibitor (HDACi) trichostatin A (TSA) can down-regulate the pro-angiogenic hypoxia-inducible factor-1α and vascular endothelial growth factor (VEGF), and up-regulate the anti-angiogenic and neuro-protective pigment epithelium derived factor in human retinal pigment epithelial (RPE) cells. Most strikingly, TSA markedly down-regulates the expression of VEGF receptor-2 in human vascular endothelial cells and, thus, can knock down pro-angiogenic cell signaling. Additionally, TSA suppresses CNV-associated wound healing response and RPE epithelial-mesenchymal transdifferentiation. In the laser-induced model of CNV using C57Bl/6 mice, systemic administration of TSA significantly reduces fluorescein leakage and the size of CNV lesions at post—laser days 7 and 14 as well as the immunohistochemical expression of VEGF, VEGFR2, and smooth muscle actin in CNV lesions at post-laser day 7. This report suggests that TSA, and possibly HDACi’s in general, should be further evaluated for their therapeutic potential for the treatment of CNV.

Metabolic syndrome triggered by high-fructose diet favors choroidal neovascularization and impairs retinal light sensitivity in the rat.

Diabetic retinopathy and age-related macular degeneration are the leading causes of blindness in Western populations. Although it is a matter of controversy, large-scale population-based studies have reported increased prevalence of age-related macular degeneration in patients with diabetes or diabetic retinopathy. We hypothesized that metabolic syndrome, one of the major risk factors for type 2 diabetes, would represent a favorable environment for the development of choroidal neovascularization, the main complication of age-related macular degeneration. The fructose-fed rat was used as a model for metabolic syndrome in which choroidal neovascularization was induced by laser photocoagulation. Male Brown Norway rats were fed for 1, 3, and 6 months with a standard equilibrated chow diet or a 60%-rich fructose diet (n = 24 per time point). The animals expectedly developed significant body adiposity (+17%), liver steatosis at 3 and 6 months, hyperleptinemia at 1 and 3 months (two-fold increase) and hyperinsulinemia at 3 and 6 months (up to two-fold increase), but remained normoglycemic and normolipemic. The fructose-fed animals exhibited partial loss of rod sensitivity to light stimulus and reduced amplitude of oscillatory potentials at 6 months. Fructose-fed rats developed significantly more choroidal neovascularization at 14 and 21 days post-laser photocoagulation after 1 and 3 months of diet compared to animals fed the control diet. These results were consistent with infiltration/activation of phagocytic cells and up-regulation of pro-angiogenic gene expression such as Vegf and Leptin in the retina. Our data therefore suggested that metabolic syndrome would exacerbate the development of choroidal neovascularization in our experimental model.

Sodium iodate induced retinal degeneration: new insights from an old model.

Studies on the selective retinal degeneration induced by sodium iodate (NaIO3) date back to 1941; Sorsby (1941) described the effect of intravenously injected NaIO3 solution on the rabbit retina. Since then, NaIO3-induced retinal degeneration has been described in different mammalian species including sheep, rabbit, rat and mouse with varying doses and routes of administration. At the present time, the murine NaIO3 model is the most widely used because it results in reproducible, patchy retinal degeneration (Figure 1) and can be studied in a wide variety of wild type and genetic knockout strains. Many studies reporting the pathologic changes in retinal structure at specific time points and electrophysiological changes in retinal function over time have followed (Franco et al., 2009; Redfern et al., 2011). More recently, the model has gained a resurgence of interest because of the ability to utilize high resolution in vivo imaging to study structural changes in the retina in live animals. Techniques such as spectral domain optical coherence tomography (OCT) and confocal scanning laser ophthalmoscopy (cSLO) allow longitudinal evaluation of retinal structure (Machalinska et al., 2014; Yang et al., 2014); thus making this model amenable to evaluation of novel therapeutic approaches to retinal degeneration such as cellular therapies.

Surgical Treatment of Age-Related Macular Degeneration

Choroidal neovascularization (CNV) and geographic atrophy (GA) are serious and potentially devastating complications of age-related macular degeneration (AMD), a leading cause of blindness in the developed world. While anti-vascular endothelial growth factor (VEGF) therapies have emerged as the current standard treatment of choice for choroidal neovascularization, the requirement for indefinite injections places a tremendous burden on physicians and patients, and may have disappointing outcomes in hemorrhagic neovascular AMD. No superior agents exist to treat large subretinal hemorrhage and geographic atrophy. Over the years, several vitreoretinal surgical approaches have been developed to treat macular degeneration, and these surgical options may still play a role in the management of specific complications of AMD. This review summarizes the principles, techniques, and results of surgical treatments for neovascular and non-neovascular age-related macular degeneration, with emphasis on submacular surgery for removal of CNV, full and limited macular translocation, retinal pigment epithelium, and choroid transplants as well as treatment of thick subretinal hemorrhage.

Development of a Risk Score for Geographic Atrophy in Complications of the Age-related Macular Degeneration Prevention Trial

To develop a risk score for developing geographic atrophy (GA) involving easily obtainable information among patients with bilateral large drusen. Cohort study within a multicenter randomized clinical trial. We included 1052 participants with ≥ 10 large (>125 μm) drusen and visual acuity ≥ 20/40 in each eye. In the Complications of Age-related Macular Degeneration (AMD) Prevention Trial (CAPT), 1 eye of each participant was randomly assigned to laser treatment and the contralateral eye was assigned to observation to evaluate whether laser treatment of drusen could prevent vision loss. Gradings by a reading center were used to identify: CAPT end point GA (total area of GA [>250 μm] > 1 disc area), GA (>175 μm) involving the foveal center (CGA), and GA of any size and location (any GA). Established risk factors (age, smoking status, hypertension, Age-related Eye Disease Study simple severity scale score), both with and without a novel risk factor (night vision score), were used in assigning risk points. The risk scores were evaluated for the ability to discriminate and calibrate GA risk. Development of end point GA, CGA, and any GA. Among 942 CAPT participants who completed 5 years of follow-up and did not have any GA at baseline, 6.8% participants developed CAPT end point GA, 9.6% developed CGA, and 34.4% developed any GA. The 5-year incidence of end point GA in 1 or both eyes of a participant increased with the 15-point GA risk score, from 0.6% for <7 points to 15% for ≥ 12 points. The 5-factor risk score predicted development of GA moderately well with the area under the receiver operating characteristic curve (AUC) 0.76 (95% confidence interval [CI], 0.71-0.81) for end point GA; 0.76 (95% CI, 0.71-0.80) for CGA, and 0.68 (95% CI, 0.65-0.72) for any GA. Prediction from the risk score without the night vision score had lower AUCs (range, 0.67-0.72). If validated in other patients, the GA risk score will be useful for identifying high-risk patients for clinical trials of prevention of GA and for clinical assessment of GA risk in early AMD patients.

Inhibition of VEGF secretion and experimental choroidal neovascularization by picropodophyllin (PPP), an inhibitor of the insulin‐like growth factor‐1 receptor

Choroidal neovascularization (CNV) is a debilitating complication of age-related macular degeneration (AMD) and a leading cause of vision loss. Along with other angiogenic factors like vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-1) and its receptor, IGF-1R, have been implicated in CNV. We have previously shown that the cyclolignan picropodophyllin (PPP) efficiently blocks the insulin-like growth factor-1 receptor (IGF-1R) activity and causes cell death in uveal melanoma cell lines and in an in-vivo model. In this study we investigated the effect of PPP on VEGF expression both in vitro and in vivo and whether this effect has anti-angiogenic consequences in a murine CNV model. C57BL/6J mice with laser-induced CNVs were treated with PPP. Effects on CNV area were assayed by image analysis. VEGF levels in choroids and retinal pigment epithelial cells (APRE-19) were measured by Western blot or ELISA. Transcriptional activation of the VEGF promoter was determined by luciferase reporter gene assay. Mice treated with PPP, administered intraperitoneally or orally, showed 22-32% (p = 0.002) decrease in CNV area. Furthermore, VEGF levels in the choroids were significantly reduced. In cultured APRE-19 cells, IGF-1 was shown to increase VEGF secretion. This increase was completely blocked by PPP. We could confirm that PPP reduced the level of transcriptional activity of VEGF promoter. PPP reduces IGF-1 dependent VEGF expression and CNV in vivo. Accordingly, IGF-1R inhibitors may be useful tools in the therapy of conditions associated with CNV including neovascular AMD.

Inhibition of VEGF Secretion and Experimental Choroidal Neovascularization by Picropodophyllin (PPP), an Inhibitor of the Insulin-like Growth Factor-1 Receptor

Choroidal neovascularization (CNV) is a debilitating complication of age-related macular degeneration (AMD) and a leading cause of vision loss. Along with other angiogenic factors such as vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF)-1 and its receptor, IGF-1R, have been implicated in CNV. A prior study has shown that the cyclolignan picropodophyllin (PPP) efficiently blocks the insulin-like growth factor-1 receptor (IGF-1R) activity and causes cell death in uveal melanoma cell lines and in an in vivo model. In this study we investigated the effect of PPP on VEGF expression, both in vitro and in vivo, and whether this effect has antiangiogenic consequences in a murine CNV model. C57BL/6J mice with laser-induced CNVs were treated with PPP. Effects on CNV area were assayed by image analysis. VEGF levels in the choroid and retinal pigment epithelial cells (ARPE-19) were measured by Western blot or ELISA. Transcriptional activation of the VEGF promoter was determined by luciferase reporter gene assay. Mice treated with PPP, administered intraperitoneally or orally, showed a 22% to 32% (P = 0.002) decrease in CNV area. Furthermore, VEGF levels in the choroid were significantly reduced. In cultured ARPE-19 cells, IGF-1 was shown to increase VEGF secretion. This increase was completely blocked by PPP. PPP reduced the level of transcriptional activity of the VEGF promoter. PPP reduces IGF-1-dependent VEGF expression and CNV in vivo. Accordingly, IGF-1R inhibitors may be useful tools in the treatment of conditions associated with CNV, including neovascular AMD.

Current Treatment of Age-Related Macular Degeneration

To review proved and experimental treatments for exudative and nonexudative complications of age-related macular degeneration (AMD), to consider the impact of current therapy on the structure of future clinical trials, and to consider the role of improved diagnostic imaging techniques on the effectiveness of current therapy as well as the structure of future clinical trials in AMD patients. Defining the cell biology of choroidal new vessel (CNV) formation and geographic atrophy will lead to identification of different biochemical pathways that are the target of AMD treatment. Many treatments and treatment combinations are under study for AMD, but all work through a finite number of pathways. Currently, the most effective proved therapy for AMD-associated CNVs is administered by repeated intravitreal injection of agents that inhibit vascular endothelial growth factor, e.g., ranibizumab. Improved drug delivery will enhance patient satisfaction and possibly will enhance the effectiveness and reduce the risk of current pharmacotherapy for AMD-associated CNVs. Combination therapy (e.g., verteporfin-photodynamic therapy + ranibizumab) appears to reduce the risk and enhance the effectiveness of CNV treatment compared with monotherapy with currently available agents. Improved noninvasive diagnostic imaging may lead to better visual outcomes with existing therapeutic modalities. Improved imaging also may alter favorably the design of future clinical trials for AMD-associated CNVs and thus reduce cost and increase the diversity of sight-saving treatments. Delineation of the biochemical basis for CNV formation has led to development of pathway-based pharmacotherapy for AMD patients. Areas of investigation that will advance the field further include combination therapy, improved drug delivery, and improved noninvasive, high-resolution diagnostic imaging. The logistics of future clinical trials will be complicated by the need for an active treatment control group, more stringent definition of successful treatment, and the increased numbers of patients required for combination therapy studies.