Three-year visual outcomes of intravitreal ranibizumab with or without photodynamic therapy for polypoidal choroidal vasculopathy.

PURPOSE: To compare 3-year visual outcomes after intravitreal ranibizumab (IVR) monotherapy and combination therapy of photodynamic therapy (PDT) with IVR for polypoidal choroidal vasculopathy (PCV). METHODS: Medical records for 45 eyes in 45 patients (34 men, 11 women; mean age, 73.8 years old; range, 62-86 years old) with treatment-naïve PCV were reviewed retrospectively. Of the 45 eyes, 20 were treated with IVR monotherapy and 25 with combination therapy. Mean change in best-corrected visual acuity, numbers of injections of IVR and length of treatment-free period from baseline at month 36 were observed. Adverse events were monitored. RESULTS: The change in visual acuity after combination therapy was significantly better than that after IVR monotherapy (p = 0.0399). At 36 months, improvement in visual acuity was seen in five eyes (25.0%) in the IVR monotherapy group and 13 eyes (52.0%) in the combination therapy group. The treatment-free period was significantly longer in the combination therapy group (p = 0.0008). Additional IVR therapy was required significantly more frequently in the IVR monotherapy group (p = 0.0026). Post-treatment subretinal haemorrhage or retinal pigment epithelium tear occurred only in the IVR monotherapy group, in one eye (5.0%) and one eye (5.0%), respectively. CONCLUSION: Initial therapy consisting of a single session of PDT combined with IVR improves vision in treatment-naïve PCV. Compared with IVR monotherapy, this combination therapy may be more effective for PCV.

Expression pattern of Ccr2 and Cx3cr1 in inherited retinal degeneration.

BACKGROUND: Though accumulating evidence suggests that microglia, resident macrophages in the retina, and bone marrow-derived macrophages can cause retinal inflammation which accelerates photoreceptor cell death, the details of how these cells are activated during retinal degeneration (RD) remain uncertain. Therefore, it is important to clarify which cells play a dominant role in fueling retinal inflammation. However, distinguishing between microglia and macrophages is difficult using conventional techniques such as cell markers (e.g., Iba-1). Recently, two mouse models for visualizing chemokine receptors were established, Cx3cr1 (GFP/GFP) and Ccr2 (RFP/RFP) mice. As Cx3cr1 is expressed in microglia and Ccr2 is reportedly expressed in activated macrophages, these mice have the potential to distinguish microglia and macrophages, yielding novel information about the activation of these inflammatory cells and their individual roles in retinal inflammation. METHODS: In this study, c-mer proto-oncogene tyrosine kinase (Mertk) (-/-) mice, which show photoreceptor cell death due to defective retinal pigment epithelium phagocytosis, were employed as an animal model of RD. Mertk (-/-) Cx3cr1 (GFP/+) Ccr2 (RFP/+) mice were established by breeding Mertk (-/-) , Cx3cr1 (GFP/GFP) , and Ccr2 (RFP/RFP) mice. The retinal morphology and pattern of inflammatory cell activation and invasion of Mertk (-/-) Cx3cr1 (GFP/+) Ccr2 (RFP/+) mice were evaluated using retina and retinal pigment epithelium (RPE) flat mounts, retinal sections, and flow cytometry. RESULTS: Four-week-old Mertk (-/-) Cx3cr1 (GFP/+) Ccr2 (RFP/+) mice showed Cx3cr1-GFP-positive microglia in the inner retina. Cx3cr1-GFP and Ccr2-RFP dual positive activated microglia were observed in the outer retina and subretinal space of 6- and 8-week-old animals. Ccr2-RFP single positive bone marrow-derived macrophages were observed to migrate into the retina of Mertk (-/-) Cx3cr1 (GFP/+) Ccr2 (RFP/+) mice. These invading cells were still observed in the subretinal space in 18-week-old animals. CONCLUSIONS: Cx3cr1-GFP-positive microglia and Ccr2-RFP-positive macrophages were distinguishable in the retinas of Mertk (-/-) Cx3cr1 (GFP/+) Ccr2 (RFP/+) mice. In addition, Ccr2 expression in Cx3cr1 positive microglia is a feature of microglial activation in RD. Mertk (-/-) Cx3cr1 (GFP/+) Ccr2 (RFP/+) mice enabled observation of microglial activation over time during RD and may be useful for developing inflammation-targeted treatment strategies for RD in the future.

Association between the major histocompatibility complex and clinical response to infliximab therapy in patients with Behçet uveitis.

PURPOSE: Our aim was to investigate whether major histocompatibility complex (MHC) polymorphisms are associated with response to infliximab therapy in Japanese patients with Behçet uveitis (BU). METHODS: We retrospectively reviewed 24 patients (17 men and seven women) treated with infliximab for BU. Of them, ten patients were genotyped as HLA A*2601, and nine as HLA B*5101. Therapeutic response levels in the two groups were compared based on ocular attacks and the Behçet disease ocular attack score 24 (BOS24) over 24 months of treatment. RESULTS: Mean frequencies of ocular attacks at 13-18 and 19-24 months after the start of treatment were significantly higher in the HLA A*2601 group (P = 0.0392 and 0.0177, respectively). Mean BOS24-6 M values for months 1-6, 7-12, 13-18, and 19-24 were also significantly higher in the HLA A*2601 group (P = 0.0459, 0.0150, 0.0394, and 0.0178, respectively). Shortening of the infusion interval was required in eight patients in the HLA A*2601 group but in one only in the HLA B*5101 group. Behçet-disease-related adverse events occurred in eight patients in the HLA A*2601 group and two in the HLA B*5101 group. Nonocular adverse events occurred in four patients in the HLA A*2601 group and none in the HLA B*5101 group. CONCLUSIONS: Although mean change from baseline in the number of ocular attack scores in the HLA A26 and HLA B51 groups seemed to be similar, the HLA-A26 group had a more severe disease course under infliximab therapy for ocular/extraocular involvement. These data suggest that response to infliximab therapy in Japanese patients with BU is partly due to genetic determinants in the HLA complex.

Presumed toxoplasmic central retinal artery occlusion and multifocal retinitis with perivascular sheathing.

Central retinal artery occlusion (CRAO) and multifocal retinitis with perivascular sheathing are rare in ocular toxoplasmosis. We report a case of toxoplasmic CRAO and multifocal retinitis with perivascular sheathing. A healthy 83-year-old male developed left panuveitis. Funduscopic examination of the left eye showed a swollen optic disc and sheathing of the retinal artery with a dense vitreous haze and a white retinal lesion. Serum anti-toxoplasma antibodies were positive in a latex agglutination assay. Vitrectomy was performed to improve visualization of the retinal lesions and for examination of causative microorganisms. A postoperative fundus examination revealed CRAO with optic disc involvement and multifocal retinitis with perivascular sheathing. Qualitative multiplex polymerase chain reaction detected the Toxoplasma gondii B1 gene in ocular fluid from both the aqueous and vitreous humor. The presumed diagnosis of ocular toxoplasmosis was made and treatment was started with prednisone and acetylspiramycin with subsequent improvement. Two months later, the patient developed active retinochoroiditis in the left eye. After 6 weeks of anti-toxoplasma therapy, the disease involuted. Retinal vascular occlusions and multifocal retinitis with perivascular sheathing are rare in toxoplasmosis. This is the first case report of toxoplasmic CRAO and multifocal retinitis with perivascular sheathing. The diagnosis of ocular toxoplasmosis should be considered in patients with retinal artery occlusions and multifocal retinitis with perivascular sheathing associated with inflammation.

Health- and vision-related quality of life in patients receiving infliximab therapy for Behcet uveitis.

OBJECTIVE: To evaluate the changes in health-related and vision-related quality of life (HR-QoL and VR-QoL) in patients with Behçet uveitis (BU) receiving infliximab therapy. METHODS: Twenty patients with recurrent BU attacks were enrolled. All patients were treated with infliximab. We evaluated the mean number of uveitis attacks and the mean score of extraocular manifestations by Behçet disease current activity form (BDCAF) during the 6 months before and the 6 and 12 months after initiation of infliximab. The EuroQol-5D questionnaire (EQ-5D) and the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) were self-administered in all patients before treatment and, 6 and 12 months after treatment. Patients' pre- and post-treatment EQ-5D and NEI VFQ-25 scores were compared. RESULTS: By the 6- and 12-month follow-up, the frequency of uveitis attacks and the BDCAF scores was significantly decreased compared with the 6 months before starting infliximab (p<0.0001). Fully completed questionnaires were received from all patients. Infliximab therapy was associated with a significant improvement of the EQ-5D (p<0.0001), NEI VFQ-25 composite score (p=0.0001), general health score (p=0.0001) and mental health score (p=0.0001). This result shows a significant decrease in inflammatory activity of the disease and consequently improvement in HR-QoL and VR-QoL scores with a rising response pattern in all dimensions. CONCLUSIONS: Relief of uveitis attacks and extraocular manifestations by infliximab therapy significantly improved the HR-QoL and VR-QoL in patients with BU.

A microparticle/hydrogel combination drug-delivery system for sustained release of retinoids.

PURPOSE: To design and develop a drug-delivery system containing a combination of poly(D,L-lactide-co-glycolide) (PLGA) microparticles and alginate hydrogel for sustained release of retinoids to treat retinal blinding diseases that result from an inadequate supply of retinol and generation of 11-cis-retinal. METHODS: To study drug release in vivo, either the drug-loaded microparticle-hydrogel combination was injected subcutaneously or drug-loaded microparticles were injected intravitreally into Lrat(-/-) mice. Orally administered 9-cis-retinoids were used for comparison and drug concentrations in plasma were determined by HPLC. Electroretinography (ERG) and both chemical and histologic analyses were used to evaluate drug effects on visual function and morphology. RESULTS: Lrat(-/-) mice demonstrated sustained drug release from the microparticle/hydrogel combination that lasted 4 weeks after subcutaneous injection. Drug concentrations in plasma of the control group treated with the same oral dose rose to higher levels for 6-7 hours but then dropped markedly by 24 hours. Significantly increased ERG responses and a markedly improved retinal pigmented epithelium (RPE)-rod outer segment (ROS) interface were observed after subcutaneous injection of the drug-loaded delivery combination. Intravitreal injection of just 2% of the systemic dose of drug-loaded microparticles provided comparable therapeutic efficacy. CONCLUSIONS: Sustained release of therapeutic levels of 9-cis-retinoids was achieved in Lrat(-/-) mice by subcutaneous injection in a microparticle/hydrogel drug-delivery system. Both subcutaneous and intravitreal injections of drug-loaded microparticles into Lrat(-/-) mice improved visual function and retinal structure.

Retinal cone and rod photoreceptor cells exhibit differential susceptibility to light-induced damage.

All-trans-retinal and its condensation-products can cause retinal degeneration in a light-dependent manner and contribute to the pathogenesis of human macular diseases such as Stargardt's disease and age-related macular degeneration. Although these toxic retinoid by-products originate from rod and cone photoreceptor cells, the contribution of each cell type to light-induced retinal degeneration is unknown. In this study, the primary objective was to learn whether rods or cones are more susceptible to light-induced, all-trans-retinal-mediated damage. Previously, we reported that mice lacking enzymes that clear all-trans-retinal from the retina, ATP-binding cassette transporter 4 and retinol dehydrogenase 8, manifested light-induced retinal dystrophy. We first examined early-stage age-related macular degeneration patients and found retinal degenerative changes in rod-rich rather than cone-rich regions of the macula. We then evaluated transgenic mice with rod-only and cone-like-only retinas in addition to progenies of such mice inbred with Rdh8(-/-) Abca4(-/-) mice. Of all these strains, Rdh8(-/-) Abca4(-/-) mice with a mixed rod-cone population showed the most severe retinal degeneration under regular cyclic light conditions. Intense light exposure induced acute retinal damage in Rdh8(-/-) Abca4(-/-) and rod-only mice but not cone-like-only mice. These findings suggest that progression of retinal degeneration in Rdh8(-/-) Abca4(-/-) mice is affected by differential vulnerability of rods and cones to light.

Photoreceptor rescue of pigment epithelium-derived factor-impregnated nanoparticles in Royal College of Surgeons rats.

PURPOSE: To investigate the protective effect of intravitreal injection of pigment epithelium-derived factor-impregnated nanoparticles (PEDF-NPs) against photoreceptor degeneration in Royal College of Surgeons (RCS) rats. METHODS: Three-week-old RCS rats received an intravitreal injection of PBS, blank NPs, PEDF (2.5 µg), or PEDF-NPs (2.5 µg). Eyes were assessed with morphological, immunohistochemical, and physiologic analysis over the following 8 weeks. Cell death was examined using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) assay. RESULTS: In RCS rats, the a- and b-wave amplitudes on electroretinograms in eyes treated with PEDF-NPs were greater than those in retinas receiving other treatment. Immunocytochemistry showed consistently greater opsin preservation in eyes treated with PEDF-NPs. A significantly higher number of photoreceptors and significantly fewer TUNEL-positive cells were present after treatment with PEDF-NPs, compared to PEDF-treated eyes. CONCLUSIONS: The results suggest that intravitreally injected PEDF-NPs delayed photoreceptor degeneration by inhibiting apoptosis in the RCS rat retina due to targeting and sustained release of PEDF.

Mechanism of all-trans-retinal toxicity with implications for stargardt disease and age-related macular degeneration.

Compromised clearance of all-trans-retinal (atRAL), a component of the retinoid cycle, increases the susceptibility of mouse retina to acute light-induced photoreceptor degeneration. Abca4(-/-)Rdh8(-/-) mice featuring defective atRAL clearance were used to examine the one or more underlying molecular mechanisms, because exposure to intense light causes severe photoreceptor degeneration in these animals. Here we report that bright light exposure of Abca4(-/-)Rdh8(-/-) mice increased atRAL levels in the retina that induced rapid NADPH oxidase-mediated overproduction of intracellular reactive oxygen species (ROS). Moreover, such ROS generation was inhibited by blocking phospholipase C and inositol 1,4,5-trisphosphate-induced Ca(2+) release, indicating that activation occurs upstream of NADPH oxidase-mediated ROS generation. Because multiple upstream G protein-coupled receptors can activate phospholipase C, we then tested the effects of antagonists of serotonin 2A (5-HT(2A)R) and M(3)-muscarinic (M(3)R) receptors and found they both protected Abca4(-/-)Rdh8(-/-) mouse retinas from light-induced degeneration. Thus, a cascade of signaling events appears to mediate the toxicity of atRAL in light-induced photoreceptor degeneration of Abca4(-/-)Rdh8(-/-) mice. A similar mechanism may be operative in human Stargardt disease and age-related macular degeneration.

Primary amines protect against retinal degeneration in mouse models of retinopathies.

Vertebrate vision is initiated by photoisomerization of the visual pigment chromophore 11-cis-retinal and is maintained by continuous regeneration of this retinoid through a series of reactions termed the retinoid cycle. However, toxic side reaction products, especially those involving reactive aldehyde groups of the photoisomerized product, all-trans-retinal, can cause severe retinal pathology. Here we lowered peak concentrations of free all-trans-retinal with primary amine-containing Food and Drug Administration (FDA)-approved drugs that did not inhibit chromophore regeneration in mouse models of retinal degeneration. Schiff base adducts between all-trans-retinal and these amines were identified by MS. Adducts were observed in mouse eyes only when an experimental drug protected the retina from degeneration in both short-term and long-term treatment experiments. This study demonstrates a molecular basis of all-trans-retinal-induced retinal pathology and identifies an assemblage of FDA-approved compounds with protective effects against this pathology in a mouse model that shows features of Stargardt's disease and age-related retinal degeneration.

Sponge transgenic mouse model reveals important roles for the microRNA-183 (miR-183)/96/182 cluster in postmitotic photoreceptors of the retina.

MicroRNA-183 (miR-183), miR-96, and miR-182 comprising the miR-183/96/182 cluster are highly expressed in photoreceptor cells. Although in vitro data have indicated an important role for this cluster in the retina, details of its in vivo biological activity are still unknown. To observe the impact of the miR-183/96/182 cluster on retinal maintenance and light adaptation, we generated a sponge transgenic mouse model that disrupted the activities of the three-component microRNAs simultaneously and selectively in the retina. Although our morphological and functional studies showed no differences between transgenic and wild type mice under normal laboratory lighting conditions, sponge transgenic mice displayed severe retinal degeneration after 30 min of exposure to 10,000 lux light. Histological studies showed that the outer nuclear layer thickness was dramatically reduced in the superior retina of transgenic mice. Real time PCR experiments in both the sponge transgenic mouse model and different microRNA stable cell lines identified Arrdc3, Neurod4, and caspase-2 (Casp2) as probable downstream targets of this cluster, a result also supported by luciferase assay and immunoblotting analyses. Further studies indicated that expression of both the cluster and Casp2 increased in response to light exposure. Importantly, Casp2 expression was enhanced in transgenic mice, and inhibition of Casp2 partially rescued their light-induced retinal degeneration. By connecting the microRNA and apoptotic pathways, these findings imply an important role for the miR-183/96/182 cluster in acute light-induced retinal degeneration of mice. This study demonstrates a clear involvement of miRs in the physiology of postmitotic cells in vivo.

Defective photoreceptor phagocytosis in a mouse model of enhanced S-cone syndrome causes progressive retinal degeneration.

Enhanced S-cone syndrome (ESCS), featuring an excess number of S cones, manifests as a progressive retinal degeneration that leads to blindness. Here, through optical imaging, we identified an abnormal interface between photoreceptors and the retinal pigment epithelium (RPE) in 9 patients with ESCS. The neural retina leucine zipper transcription factor-knockout (Nrl(-/-)) mouse model demonstrates many phenotypic features of human ESCS, including unstable S-cone-positive photoreceptors. Using massively parallel RNA sequencing, we identified 6203 differentially expressed transcripts between wild-type (Wt) and Nrl(-/-) mouse retinas, with 6 highly significant differentially expressed genes of the Pax, Notch, and Wnt canonical pathways. Changes were also obvious in expression of 30 genes involved in the visual cycle and 3 key genes in photoreceptor phagocytosis. Novel high-resolution (100 nm) imaging and reconstruction of Nrl(-/-) retinas revealed an abnormal packing of photoreceptors that contributed to buildup of photoreceptor deposits. Furthermore, lack of phagosomes in the RPE layer of Nrl(-/-) retina revealed impairment in phagocytosis. Cultured RPE cells from Wt and Nrl(-/-) mice illustrated that the phagocytotic defect was attributable to the aberrant interface between ESCS photoreceptors and the RPE. Overcoming the retinal phagocytosis defect could arrest the progressive degenerative component of this disease.

Toll-like receptor 3 is required for development of retinopathy caused by impaired all-trans-retinal clearance in mice.

Chronic inflammation is an important component that contributes to many age-related neurodegenerative diseases, including macular degeneration. Here, we report a role for toll-like receptor 3 (TLR3) in cone-rod dystrophy (CORD) of mice lacking ATP-binding cassette transporter 4 (ABCA4) and retinol dehydrogenase 8 (RDH8), proteins critical for all-trans-retinal clearance in the retina. Increased expression of toll-like receptor-signaling elements and inflammatory changes were observed in Rdh8(-/-)Abca4(-/-) eyes by RNA expression analysis. Unlike 3-month-old Rdh8(-/-)Abca4(-/-) mice that developed CORD, 6-month-old Tlr3(-/-)Rdh8(-/-)Abca4(-/-) mice did not evidence an abnormal retinal phenotype. Light-induced retinal degeneration in Tlr3(-/-)Rdh8(-/-)Abca4(-/-) mice was milder than that in Rdh8(-/-)Abca4(-/-) mice, and a 2-fold increased TLR3 expression was detected in light-illuminated retinas of Rdh8(-/-)Abca4(-/-) mice compared with nonilluminated retinas. Poly(I-C), a TLR3 ligand, caused caspase-8-independent cellular apoptosis. Whereas poly(I-C) induced retinal cell death in Rdh8(-/-)Abca4(-/-) and WT mice both in vivo and ex vivo, this was not seen in mice lacking Tlr3. Far fewer invasive macrophage/microglial cells in the subretinal space and weaker activation of Muller glial cells were exhibited by Tlr3(-/-)Rdh8(-/-) Abca4(-/-) mice compared with Rdh8(-/-)Abca4(-/-) mice at 3 and 6 months of age, indicating that loss of TLR3 inhibits local inflammation in the retina. Both poly(I-C) and endogenous products emanating from dying/dead retinal cells induced NF-κB and IRF3 activation. These findings demonstrate that endogenous products from degenerating retina stimulate TLR3 that causes cellular apoptosis and retinal inflammation and that loss of TLR3 protects mice from CORD.

Probing mechanisms of photoreceptor degeneration in a new mouse model of the common form of autosomal dominant retinitis pigmentosa due to P23H opsin mutations.

Rhodopsin, the visual pigment mediating vision under dim light, is composed of the apoprotein opsin and the chromophore ligand 11-cis-retinal. A P23H mutation in the opsin gene is one of the most prevalent causes of the human blinding disease, autosomal dominant retinitis pigmentosa. Although P23H cultured cell and transgenic animal models have been developed, there remains controversy over whether they fully mimic the human phenotype; and the exact mechanism by which this mutation leads to photoreceptor cell degeneration remains unknown. By generating P23H opsin knock-in mice, we found that the P23H protein was inadequately glycosylated with levels 1-10% that of wild type opsin. Moreover, the P23H protein failed to accumulate in rod photoreceptor cell endoplasmic reticulum but instead disrupted rod photoreceptor disks. Genetically engineered P23H mice lacking the chromophore showed accelerated photoreceptor cell degeneration. These results indicate that most synthesized P23H protein is degraded, and its retinal cytotoxicity is enhanced by lack of the 11-cis-retinal chromophore during rod outer segment development.

[Stickler syndrome with rhegmatogenous retinal detachment].

BACKGROUND: Stickler syndrome is an autosomal dominant disease characterized by various disorders of the eyes and the connective tissues throughout the body. It can arise from a mutation in the collagen associated gene. We present a case of Stickler syndrome with rhegmatogenous retinal detachment. CASE: A 10-years-old boy was referred to us with rhegmatogenous retinal detachment of the right eye. His family history included eye disease and a cleft palate. He had high myopia, vitreous liquefaction and lattice degeneration in the both eye. He also had a cleft palate and a broad nasal bridge. His condition was diagnosed as Stickler syndrome. We performed vitrectomy, scleral buckling and encircling, and silicone oil injection in the right eye. We also did a reattachment of the retina in the right eye. CONCLUSIONS: Pediatric retinal detachment may indicate the presence of Stickler syndrome and a complete examination of the eye as well as a full family history must be obtained in such cases.

Palmitoylation stabilizes unliganded rod opsin.

S-palmitoylation is a conserved feature in many G protein-coupled receptors (GPCRs) involved in a broad array of signaling processes. The prototypical GPCR, rhodopsin, is S-palmitoylated on two adjacent C-terminal Cys residues at its cytoplasmic surface. Surprisingly, absence of palmitoylation has only a modest effect on in vitro or in vivo signaling. Here, we report that palmitoylation-deficient (Palm(-/-)) mice carrying two Cys to Thr and Ser mutations in the opsin gene displayed profound light-induced retinal degeneration that first involved rod and then cone cells. After brief bright light exposure, their retinas exhibited two types of deposits containing nucleic acid and invasive phagocytic macrophages. When Palm(-/-) mice were crossed with Lrat(-/-) mice lacking lecithin:retinol acyl transferase to eliminate retinoid binding to opsin and thereby rendering the eye insensitive to light, rapid retinal degeneration occurred even in 3- to 4-week-old animals. This rapid degeneration suggests that nonpalmitoylated rod opsin is unstable. Treatment of 2-week-old Palm(-/-)Lrat(-/-) mice with an artificial chromophore precursor prevented this retinopathy. In contrast, elimination of signaling to G protein in Palm(-/-)Gnat1(-/-) mice had no effect, indicating that instability of unpalmitoylated opsin lacking chromophore rather than aberrant signal transduction resulted in retinal pathology. Together, these observations provide evidence for a structural role of rhodopsin S-palmitoylation that may apply to other GPCRs as well.

Evaluation of potential therapies for a mouse model of human age-related macular degeneration caused by delayed all-trans-retinal clearance.

PURPOSE: Evaluate the efficacy of potential therapeutics in Rdh8(-/-)Abca4(-/-) mice, a rodent model of human age-related macular degeneration (AMD). METHODS: Therapeutic efficacy of several antioxidant agents (ascorbic acid, alpha-lipoic acid, alpha-tocopherol, Mn(III)-tetrakis(4-benzoic acid)-porphyrin, and butylated hydroxytoluene), an immunosuppressive agent with antivascular endothelial growth factor (VEGF) activity (sirolimus, also known as rapamycin), a retinoid cycle inhibitor (retinylamine), and an artificial chromophore (9-cis-retinyl acetate) were evaluated side by side in a recently described murine model of AMD, the Rdh8(-/-)Abca4(-/-) mouse. This animal exhibits a retinopathy caused by delayed all-trans-retinal clearance resulting from the absence of both ATP-binding cassette transporter 4 (Abca4) and retinol dehydrogenase 8 (Rdh8) activities. Drug efficacy was evaluated by retinal histologic analyses and electroretinograms (ERGs). RESULTS: All tested agents partially prevented atrophic changes in the Rdh8(-/-)Abca4(-/-) retina with retinylamine demonstrating the greatest efficacy. A significant reduction of complement deposition on Bruch's membrane was observed in sirolimus-treated mice, although the severity of retinal degeneration was similar to that observed in antioxidant- and 9-cis-retinyl acetate-treated mice. Sirolimus treatment of 6-month-old Rdh8(-/-)Abca4(-/-) mice for 4 months prevented choroidal neovascularization without changing retinal VEGF levels. CONCLUSIONS: Mechanism-based therapy with retinylamine markedly attenuated degenerative retinopathy in Rdh8(-/-)Abca4(-/-) mice. Further understanding of pathogenic mechanisms involved in AMD is needed to develop more effective therapeutics.

WITHDRAWN: Retinol dehydrogenase RDH11 protects the mouse retina from light-induced degeneration.

Withdrawn at the request of the author.

Prolonged protective effect of basic fibroblast growth factor-impregnated nanoparticles in royal college of surgeons rats.

PURPOSE: To investigate the protective effect of intravitreal injection of basic fibroblast growth factor-impregnated nanoparticles (bFGF-NPs) against photoreceptor degeneration in Royal College of Surgeons (RCS) rats. METHODS: Three-week-old RCS rats received intravitreal injection of PBS, blank NPs, bFGF (2.5 microg), or bFGF-NPs (2.5 microg). Eyes were assessed by morphologic, immunohistochemical, and physiological analyses for the following 8 weeks. Cell death was examined using the TUNEL assay, and bFGF protein levels in the retina were measured by Western blot analysis. Rhodamine (Rh)-labeled bFGF-NPs were injected intravitreally and visualized by confocal microscopy to determine the localization of the nanoparticles in the retina. RESULTS: Intravitreally injected Rh-labeled bFGF-NPs were found in the outer nuclear layer 6 and 8 weeks after injection. ERG a- and b-wave amplitudes in bFGF-NP-treated retinas were greater than amplitudes in retinas receiving other treatment. Immunocytochemical analysis showed consistently greater opsin preservation in bFGF-NP-treated retinas, and a significantly higher number of photoreceptors and significantly fewer TUNEL-positive cells were present after bFGF-NP treatment than after bFGF treatment. Western blot analysis showed a significant increase in the bFGF level in bFGF-NP-treated retinas. CONCLUSIONS: The results suggest that intravitreally injected bFGF-NPs prevent photoreceptor degeneration by inhibiting apoptosis in the RCS rat retina because of targeting and sustained release of bFGF. This novel drug delivery system for bFGF may serve as a potential short-term treatment for photoreceptor degeneration in humans.