Motohiro Kamei

Drusen proteome analysis: An approach to the etiology of age-related macular degeneration

Drusen are extracellular deposits that accumulate below the retinal pigment epithelium on Bruchs membrane and are risk factors for developing age-related macular degeneration (AMD). The progression of AMD might be slowed or halted if the formation of drusen could be modulated. To work toward a molecular understanding of drusen formation, we have developed a method for isolating microgram quantities of drusen and Bruchs membrane for proteome analysis. Liquid chromatography tandem MS analyses of drusen preparations from 18 normal donors and five AMD donors identified 129 proteins. Immunocytochemical studies have thus far localized ≈16% of these proteins in drusen. Tissue metalloproteinase inhibitor 3, clusterin, vitronectin, and serum albumin were the most common proteins observed in normal donor drusen whereas crystallin was detected more frequently in AMD donor drusen. Up to 65% of the proteins identified were found in drusen from both AMD and normal donors. However, oxidative protein modifications were also observed, including apparent crosslinked species of tissue metalloproteinase inhibitor 3 and vitronectin, and carboxyethyl pyrrole protein adducts. Carboxyethyl pyrrole adducts are uniquely generated from the oxidation of docosahexaenoate-containing lipids. By Western analysis they were found to be more abundant in AMD than in normal Bruchs membrane and were found associated with drusen proteins. Carboxymethyl lysine, another oxidative modification, was also detected in drusen. These data strongly support the hypothesis that oxidative injury contributes to the pathogenesis of AMD and suggest that oxidative protein modifications may have a critical role in drusen formation.

Efficacy of intravitreal bevacizumab for polypoidal choroidal vasculopathy

Aims: The aim of the study was to assess the short-term efficacy of intravitreal injections of bevacizumab for polypoidal choroidal vasculopathy (PCV). Methods: Intravitreal bevacizumab (1 mg) was injected into 11 eyes of 11 patients with PCV in this retrospective, interventional case series. The main outcome measure was the change in the polypoidal vessels on indocyanine green angiography (IA) 3 months after injection. The foveal height determined by optical coherence tomography and the best-corrected visual acuity (BCVA) also were evaluated before and after treatment. Results: At baseline, subretinal fluid was observed in five eyes and a pigment epithelial detachment in eight eyes. The foveal height 1 month after injection decreased significantly (p = 0.023), but at 3 months, no significant decrease was observed, although an additional injection was administrated in five of 11 eyes. The IA at 3 months showed resolution of polyps in one eye but residual or enlarged lesions in the other ten eyes. The BCVA did not improve significantly, although the subjects had relatively good BCVA at baseline (mean 0.45). Conclusion: Intravitreal injection of bevacizumab may reduce the fluid from PCV but seems to be ineffective for diminishing its choroidal vascular changes.

Complications in patients after intravitreal injection of bevacizumab

Purpose:  To report complications in patients after intravitreal injection of bevacizumab to treat ocular diseases associated with vascular endothelial growth factor.

Intravitreal Bevacizumab to Treat Iris Neovascularization and Neovascular Glaucoma Secondary to Ischemic Retinal Diseases in 41 Consecutive Cases

PURPOSE To evaluate the biologic efficacy of intravitreal bevacizumab (IVB) for iris neovascularization (INV) or neovascular glaucoma (NVG) in patients with ischemic retinal disorders. DESIGN Retrospective, consecutive, interventional case series. PARTICIPANTS Thirty patients (41 eyes) with INV or NVG secondary to ischemic retinal disorders. METHODS Patients received IVB (1 mg) as the initial treatment for INV or NVG and were followed up for at least 6 months. Ophthalmic evaluations included measurement of visual acuity and intraocular pressure (IOP), a complete ophthalmic examination, and fluorescein angiography. Patients were divided into 3 subgroups: INV without elevated IOP (INV group), NVG with an open angle (O-NVG group), and NVG with angle closure (C-NVG group) for outcomes analysis. MAIN OUTCOME MEASURES The controllability of IOP by IVB, incidence of recurrence, and requirement for surgery to treat NVG. RESULTS No significant ocular or systemic adverse events developed during follow-up (range, 6-22 months; mean, 13.3 months). The mean IOP levels were 14.7, 31.2, and 44.9 mmHg at baseline in the INV, O-NVG, and C-NVG groups, respectively. In the INV group (9 eyes), the INV regressed or resolved after 1 injection. Iris neovascularization recurred in 4 eyes by 6 months and stabilized after repeated injections without IOP elevation. In the O-NVG group (17 eyes), rapid neovascular regression with successful IOP normalization (<or=21 mmHg) occurred in 12 eyes (71%) within 1 week after 1 injection. Five (29%) of the 17 eyes required surgery by 6 months despite repeated IVB injections, and a total of 7 eyes (41%) underwent surgery during follow-up. In the C-NVG group (15 eyes), IVB caused INV resolution but failed to lower the IOP. Fourteen (93%) of 15 eyes required surgery by 2 months after initial IVB and achieved IOP stabilization. The mean interval between IVB and surgery was significantly shorter in the C-NVG group than in the O-NVG group (P<0.001). CONCLUSIONS Intravitreal bevacizumab is well tolerated, effectively stabilized INV activity, and controlled IOP in patients with INV alone and early-stage NVG without angle closure. In advanced NVG, IVB cannot control IOP but may be used adjunctively to improve subsequent surgical results. Further evaluation in controlled randomized studies is warranted.

Intravitreal injection of bevacizumab for choroidal neovascularisation associated with pathological myopia

Aim: To assess the efficacy and safety of an intravitreal injection of bevacizumab (Avastin®) for myopic choroidal neovascularisation (mCNV). Methods: Intravitreal bevacizumab (1 mg) was injected into eight eyes of eight patients with mCNV in this non-randomised, interventional case series. The best-corrected visual acuity (BCVA) was measured and the optical coherence tomography (OCT) and fluorescein angiography findings were examined before and after treatment. The minimum follow-up time was 3 months. Results: The mean BCVA was 0.26 before treatment and 0.51 at the last visit (p = 0.009). The BCVA improved to two or more lines in six eyes (75%) and remained the same in two eyes (25%). Leakage from the mCNV on fluorescein angiography decreased in seven eyes (87.5%). The choroidal neovascularisation area on fluorescein angiography (p = 0.049) and the foveal thickness on OCT images decreased significantly (p = 0.027) after the treatment. No major complications developed. Conclusion: Intravitreal injection of bevacizumab seems to be an effective and safe treatment for mCNV.

Testing of semichronically implanted retinal prosthesis by suprachoroidal-transretinal stimulation in patients with retinitis pigmentosa.

PURPOSE To examine the safety and effectiveness of a retinal prosthesis that is implanted semichronically in two patients with advanced retinitis pigmentosa (RP). METHODS Two eyes of two patients with advanced RP had a retinal prosthesis implanted in a sclera pocket of one eye. The visual acuity of both eyes before the implantation was bare light perception. Phosphenes were elicited by suprachoroidal-transretinal stimulation (STS). The internal devices of the STS were implanted under the skin on the temporal side of the head, and the 49 electrode-array was implanted in the scleral pocket of one eye. Biphasic electrical pulses (duration, 0.5 ms; frequency, 20 Hz) were delivered through nine active electrodes. The threshold current was determined by currents ≤1 mA. Behavioral tasks were used to determine the functioning of the prosthesis. RESULTS The surgery was completed without a retinal detachment and retinal/vitreous hemorrhage. The implanted STS system remained functional for the 4-week test period. Phosphenes were elicited by currents delivered through six electrodes in Patient 1 and through four electrodes in Patient 2. The success of discriminating two bars was better than the chance level in both patients. In Patient 2, the success of a grasping task was better than the chance level, and the success rate of identifying a white bar on a touch panel increased with repeated testing. CONCLUSIONS Semichronic implantation of a microelectrode-STS system showed that it was safe and remained functional for at least 4 weeks in two patients with advanced RP. (www.umin.ac.jp/ctr number, R000002690.).

Semaphorin‐4A, an activator for T‐cell‐mediated immunity, suppresses angiogenesis via Plexin‐D1

Originally identified as axon guidance molecules, semaphorins are now known to be widely expressed mediators that play significant roles in immune responses and organ morphogenesis. However, not much is known about the signaling pathways via which they exert their organ‐specific effects. Here we demonstrate that Sema4A, previously identified as an activator of T‐cell‐mediated immunity, is expressed in endothelial cells, where it suppresses vascular endothelial growth factor (VEGF)‐mediated endothelial cell migration and proliferation in vitro and angiogenesis in vivo. Mice lacking Sema4A exhibit enhanced angiogenesis in response to VEGF or inflammatory stimuli. In addition, binding and functional experiments revealed Plexin‐D1 to be a receptor for Sema4A on endothelial cells, indicating that Sema4A exerts organ‐specific activities via different receptor‐mediated signaling pathways: via Plexin‐D1 in the endothelial cells and via T‐cell immunoglobulin and mucin domain‐2 in T cells. The effects of Sema4A on endothelial cells are dependent on its ability to suppress VEGF‐mediated Rac activation and integrin‐dependent cell adhesion. It thus appears that Sema4A–Plexin‐D1 signaling negatively regulates angiogenesis.

Transretinal Electrical Stimulation with a Suprachoroidal Multichannel Electrode in Rabbit Eyes

PurposeSeveral approaches for placing an electrode device for visual prosthesis have been previously proposed. In this study, we investigated if transretinal stimulation from the suprachoroidal space can elicit an electrical evoked potential (EEP) in albino rabbits.MethodsA flat electrode array (polyimide plate, platinum electrode) was developed and used for this study. After performing a scleral incision at 2–2.5 mm from the limbus and placing an anchoring suture, the array was inserted into the suprachoroidal space in the posterior portion of the eye by direct observation under a microscope. A platinum wire was implanted into the vitreous space as a reference electrode. For electrical stimulation, a biphasic pulse was used. When the electrode was stimulated, the EEP was recorded.ResultsWhen the electrical stimulation from the suprachoroidal space was applied, the EEP could be recorded with an epidural electrode, and the threshold was 66.0 ± 32.1μA (42.0μC/cm2). Histological examination indicated the absence of major damage to the retina and choroid from the insertion and placement of the array and the electrical stimulation.ConclusionsTransretinal electrical stimulation from the suprachoroidal space could elicit EEP, suggesting that this approach may be useful for a retinal prosthesis system.

Intravitreal Aflibercept for Macular Edema Secondary to Central Retinal Vein Occlusion: 18-Month Results of the Phase 3 GALILEO Study

PURPOSE To evaluate intravitreal aflibercept for treatment of macular edema secondary to central retinal vein occlusion (CRVO). DESIGN Randomized, double-masked, phase 3 study. METHODS A total of 177 patients with macular edema secondary to CRVO were randomized to receive 2 mg intravitreal aflibercept (n = 106) or sham (n = 71) every 4 weeks for 20 weeks. From weeks 24 to 48, patients were monitored every 4 weeks; the former group received intravitreal aflibercept as needed (PRN), and the sham group received sham. From weeks 52 to 76, patients were monitored every 8 weeks, and both groups received intravitreal aflibercept PRN. The primary endpoint (proportion of patients who gained ≥15 letters) was at week 24. This study reports exploratory outcomes at week 76. RESULTS The proportion of patients who gained ≥15 letters in the intravitreal aflibercept and sham groups was 60.2% vs 22.1% at week 24 (patients discontinued before week 24 were considered nonresponders; P < .0001), 60.2% vs 32.4% at week 52 (last observation carried forward, P < .001), and 57.3% vs 29.4% at week 76 (last observation carried forward; P < .001). Mean μm change from baseline central retinal thickness was -448.6 vs -169.3 at week 24 (P < .0001), -423.5 vs -219.3 at week 52 (P < .0001), and -389.4 vs -306.4 at week 76 (P = .1122). Over 76 weeks, the most common ocular serious adverse event in the intravitreal aflibercept group was macular edema (3.8%). CONCLUSIONS The visual and anatomic improvements seen after fixed, monthly dosing at week 24 were largely maintained when treatment intervals were extended. Patients with macular edema following CRVO benefited from early treatment with intravitreal aflibercept.

Chronic Photo-oxidative Stress And Subsequent Mcp-1 Activation As Causative Factors For Age-related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly in developed countries. Although pathogenic factors, such as oxidative stress, inflammation and genetics are thought to contribute to the development of AMD, little is known about the relationships and priorities between these factors. Here, we show that chronic photo-oxidative stress is an environmental factor involved in AMD pathogenesis. We first demonstrated that exposure to light induced phospholipid oxidation in the mouse retina, which was more prominent in aged animals. The induced oxidized phospholipids led to an increase in the expression of monocyte chemoattractant protein-1, which then resulted in macrophage accumulation, an inflammatory process. Antioxidant treatment prevented light-induced phospholipid oxidation and the subsequent increase of monocyte chemoattractant protein-1 (also known as C-C motif chemokine 2; CCL2), which are the beginnings of the light-induced changes. Subretinal application of oxidized phospholipids induced choroidal neovascularization, a characteristic feature of wet-type AMD, which was inhibited by blocking monocyte chemoattractant protein-1. These findings strongly suggest that a sequential cascade from photic stress to inflammatory processes through phospholipid oxidation has an important role in AMD pathogenesis. Finally, we succeeded in mimicking human AMD in mice with low-level, long-term photic stress, in which characteristic pathological changes, including choroidal neovascularization formation, were observed. Therefore, we propose a consecutive pathogenic pathway involving photic stress, oxidation of phospholipids and chronic inflammation, leading to angiogenesis. These findings add to the current understanding of AMD pathology and suggest protection from oxidative stress or suppression of the subsequent inflammation as new potential therapeutic targets for AMD.