Age-related macular degeneration: etiology, pathogenesis, and therapeutic strategies

Effects of Lycium barbarum on the Visual System

Lycium barbarum (wolfberry, gogi berry, gouqizi, ) is one of the most widely used Chinese herbal medicines (CHMs) and is also one of the most scientifically studied. Indeed, the polysaccharide component of this berry (LBP) has been shown to have antioxidant, antiinflammatory, antiexcitotoxic, and antiapoptotic properties. These properties make it a particularly useful treatment option for the ocular environment. Although there are a handful of studies investigating the use of LBP to treat diseases affecting the lens, the vast majority of the published literature investigating LBP in the visual system focus on the retina. In this chapter, we have described what is currently understood concerning the effects of LBP treatment on various retinal diseases, including glaucoma, ischemia/reperfusion, age-related macular degeneration, retinitis pigmentosa, and diabetic retinopathy. We then describe the functions attributed to LBP using other cellular contexts to elucidate the full mechanisms this CHM utilizes in the retina. By making connections between what is known about the function of LBP in a variety of tissues and its function as a therapy for retinal degenerative diseases, we hope to further emphasize the continued use of this CHM in clinical medicine in addition to providing a platform for additional study.

Vision Loss after Intravitreal Injection of Autologous "Stem Cells" for AMD

Adipose tissue-derived "stem cells" have been increasingly used by "stem-cell clinics" in the United States and elsewhere to treat a variety of disorders. We evaluated three patients in whom severe bilateral visual loss developed after they received intravitreal injections of autologous adipose tissue-derived "stem cells" at one such clinic in the United States. In these three patients, the last documented visual acuity on the Snellen eye chart before the injection ranged from 20/30 to 20/200. The patients' severe visual loss after the injection was associated with ocular hypertension, hemorrhagic retinopathy, vitreous hemorrhage, combined traction and rhegmatogenous retinal detachment, or lens dislocation. After 1 year, the patients' visual acuity ranged from 20/200 to no light perception.

Functional impact of treatment with ranibizumab under a reactive strategy in patients with neovascular age-related macular degeneration

OBJECTIVE

To analyse the functional recovery using a pro re nata (PRN) dosing strategy with intravitreal injections of ranibizumab for patients with neovascular age-related macular degeneration (AMD).

MATERIAL AND METHODS

An observational, retrospective, single-centre study, was conducted on patients with neovascular AMD managed with a PRN strategy with ranibizumab, and were followed-up for a minimum of 18 months. Sociodemographic and clinical data were collected from medical records. The percentage of visual acuity (VA) recovered after losing 5 or more letters was calculated taking into account the previous visit, as well as considering the best VA recorded prior to the retreament.

RESULTS

The analysis included 128 patients. The mean (SD) follow-up period was 18.9 (2.3) months. The mean (SD) elapsed days between onset of symptoms and diagnosis, and between prescription and administration of treatment was 50.2 (57.4) and 10.9 (16.0), respectively. Only 108 patients were prescribed ranibizumab after losing 5 or more letters of VA. The mean (SD) VA recovery compared to the previous VA was 70.3% (114.4). On the other hand, the mean (SD) VA recovery when considering the best VA registered before the retreatment was 43.5% (112.9), with 59.4% of re-treatments having a VA recovery below 75%, and with 11.7% not presenting any VA recovery.

CONCLUSIONS

A PRN dosing strategy with intravitreal ranibizumab for neovascular AMD may not be efficient in preserving and/or recovering VA in the long-term, due to a cumulative irreversible VA loss.

Projection artifact removal improves visualization and quantitation of macular neovascularization imaged by optical coherence tomography angiography

PURPOSE

To visualize and quantify the size and vessel density of macular neovascularization (MNV) using optical coherence tomography angiography (OCTA) with a projection artifact removal algorithm.

DESIGN

Multicenter, observational study.

PARTICIPANTS

Subjects with MNV in at least one eye.

METHODS

Patients were imaged using either a swept-source OCT angiography (SS-OCTA) prototype system or a spectral-domain OCT angiography (SD-OCTA) prototype system. The optical microangiography (OMAG) algorithm was used to generate the OCTA images. Projection artifacts from the overlying retinal circulation were removed from the OMAG OCTA images using a novel algorithm. Following removal of the projection artifacts from the OCTA images, we assessed the size and vascularity of the MNV. Concurrent fluorescein angiography (FA) and indocyanine green angiography (ICGA) images were used to validate the artifact-free OMAG images whenever available.

MAIN OUTCOME MEASURES

Size and vascularity of MNV imaged with OCTA before and after the use of a projection-artifact removal algorithm.

RESULTS

A total of 30 subjects (40 eyes) diagnosed with MNV were imaged. Five patients were imaged before and after intravitreal injections of vascular endothelial growth factor (VEGF) inhibitors. Following the use of the projection artifact removal algorithm, we found improved visualization of the MNV. Lesion sizes and vascular densities were more easily measured on all the artifact-free OMAG images. In eyes treated with vascular endothelial growth factor inhibitors, vascular density was reduced in all five eyes after treatment, and in four eyes, the size of the MNV decreased. One of five patients showed a slight increase in lesion size, but a decrease in vascular density.

CONCLUSIONS

OCTA imaging of MNV using the OMAG algorithm combined with removal of projection artifacts resulted in improved visualization and measurements of the neovascular lesions. OMAG with projection artifact removal should be useful for assessing the response of MNV to treatment using OCTA imaging.

Can innate and autoimmune reactivity forecast early and advance stages of age-related macular degeneration?

Age-related macular degeneration (AMD) is a major cause of central vision loss in persons over 55years of age in developed countries. AMD is a complex disease in which genetic, environmental and inflammatory factors influence its onset and progression. Elevation in serum anti-retinal autoantibodies, plasma and local activation of complement proteins of the alternative pathway, and increase in secretion of proinflammatory cytokines have been seen over the course of disease. Genetic studies of AMD patients confirmed that genetic variants affecting the alternative complement pathway have a major influence on AMD risk. Because the heterogeneity of this disease, there is no sufficient strategy to identify the disease onset and progression sole based eye examination, thus identification of reliable serological biomarkers for diagnosis, prognosis and response to treatment by sampling patient's blood is necessary. This review provides an outline of the current knowledge on possible serological (autoantibodies, complement factors, cytokines, chemokines) and related genetic biomarkers relevant to the pathology of AMD, and discusses their application for prediction of disease activity and prognosis in AMD.

Nutritional Supplementation Inhibits the Increase in Serum Malondialdehyde in Patients with Wet Age-Related Macular Degeneration

Purpose. To compare serum levels of malondialdehyde (MDA) in patients with wet age-related macular degeneration (wAMD), patients with dry AMD (dAMD), and patients without AMD and to evaluate the efficacy of nutritional supplementation for treating elevated serum MDA in patients with wAMD. Methods. MDA levels were measured in sera from 20 patients with wAMD, 20 with dAMD, and 24 without AMD. Patients with wAMD were randomized to receive or not receive nutritional supplementation (10 patients in each group), and MDA levels were measured after 3 months of treatment. Results. MDA levels in patients with wAMD were significantly greater compared with patients without AMD. In eyes with wAMD, there was a significant correlation between MDA levels and choroidal neovascularization lesion area. Serum MDA levels decreased in most patients that received supplementation and significantly increased in those who did not. Conclusion. Baseline serum MDA levels were elevated in patients with wAMD, and MDA levels were directly correlated with choroidal neovascularization lesion area. In addition, nutritional supplementation appeared to exert a protective effect against oxidative stress in patients with wAMD.

The Age-Related Eye Disease 2 Study: Micronutrients in the Treatment of Macular Degeneration

Age-related macular degeneration (AMD) is one of the leading causes of vision loss in the elderly. With an increasingly aged population worldwide, the need for the prevention of AMD is rising. Multiple studies investigating AMD with the use of animal models and cell culture have identified oxidative stress-related retinal damage as an important contributing factor. In general, diet is an excellent source of the antioxidants, vitamins, and minerals necessary for healthy living; moreover, the general public is often receptive to recommendations made by physicians and health care workers regarding diet and supplements as a means of empowering themselves to avoid common and worrisome ailments such as AMD, which has made epidemiologists and clinicians enthusiastic about dietary intervention studies. A wide variety of nutrients, such as minerals, vitamins, ω-3 (n-3) fatty acids, and various carotenoids, have been associated with reducing the risk of AMD. Initial results from the Age-Related Eye Disease Study (AREDS) indicated that supplementation with antioxidants (β-carotene and vitamins C and E) and zinc was associated with a reduced risk of AMD progression. The AREDS2 follow-up study, designed to improve upon the earlier formulation, tested the addition of lutein, zeaxanthin, and ω-3 fatty acids. In this review, we examine the science behind the nutritional factors included in these interventional studies and the reasons for considering their inclusion to lower the rate of AMD progression.

Minireview: Fibronectin in retinal disease

Retinal fibrosis, characterized by dysregulation of extracellular matrix (ECM) protein deposition by retinal endothelial cells, pigment epithelial cells, and other resident cell-types, is a unifying feature of several common retinal diseases. Fibronectin is an early constituent of newly deposited ECM and serves as a template for assembly of other ECM proteins, including collagens. Under physiologic conditions, fibronectin is found in all layers of Bruch's membrane. Proliferative vitreoretinopathy (PVR), a complication of retinal surgery, is characterized by ECM accumulation. Among the earliest histologic manifestations of diabetic retinopathy (DR) is capillary basement membrane thickening, which occurs due to perturbations in ECM homeostasis. Neovascularization, the hallmark of late stage DR as well as exudative age-related macular degeneration (AMD), involves ECM assembly as a scaffold for the aberrant new vessel architecture. Rodent models of retinal injury demonstrate a key role for fibronectin in complications characteristic of PVR, including retinal detachment. In mouse models of DR, reducing fibronectin gene expression has been shown to arrest the accumulation of ECM in the capillary basement membrane. Alterations in matrix metalloproteinase activity thought to be important in the pathogenesis of AMD impact the turnover of fibronectin matrix as well as collagens. Growth factors involved in PVR, AMD, and DR, such as PDGF and TGFβ, are known to stimulate fibronectin matrix assembly. A deeper understanding of how pathologic ECM deposition contributes to disease progression may help to identify novel targets for therapeutic intervention.

Gut microbiota influences pathological angiogenesis in obesity-driven choroidal neovascularization

Age-related macular degeneration in its neovascular form (NV AMD) is the leading cause of vision loss among adults above the age of 60. Epidemiological data suggest that in men, overall abdominal obesity is the second most important environmental risk factor after smoking for progression to late-stage NV AMD To date, the mechanisms that underscore this observation remain ill-defined. Given the impact of high-fat diets on gut microbiota, we investigated whether commensal microbes influence the evolution of AMD Using mouse models of NV AMD, microbiotal transplants, and other paradigms that modify the gut microbiome, we uncoupled weight gain from confounding factors and demonstrate that high-fat diets exacerbate choroidal neovascularization (CNV) by altering gut microbiota. Gut dysbiosis leads to heightened intestinal permeability and chronic low-grade inflammation characteristic of inflammaging with elevated production of IL-6, IL-1β, TNF-α, and VEGF-A that ultimately aggravate pathological angiogenesis.

Humanin Protects RPE Cells from Endoplasmic Reticulum Stress-Induced Apoptosis by Upregulation of Mitochondrial Glutathione

Humanin (HN) is a small mitochondrial-encoded peptide with neuroprotective properties. We have recently shown protection of retinal pigmented epithelium (RPE) cells by HN in oxidative stress; however, the effect of HN on endoplasmic reticulum (ER) stress has not been evaluated in any cell type. Our aim here was to study the effect of HN on ER stress-induced apoptosis in RPE cells with a specific focus on ER-mitochondrial cross-talk. Dose dependent effects of ER stressors (tunicamycin (TM), brefeldin A, and thapsigargin) were studied after 12 hr of treatment in confluent primary human RPE cells with or without 12 hr of HN pretreatment (1-20 μg/mL). All three ER stressors induced RPE cell apoptosis in a dose dependent manner. HN pretreatment significantly decreased the number of apoptotic cells with all three ER stressors in a dose dependent manner. HN pretreatment similarly protected U-251 glioma cells from TM-induced apoptosis in a dose dependent manner. HN pretreatment significantly attenuated activation of caspase 3 and ER stress-specific caspase 4 induced by TM. TM treatment increased mitochondrial superoxide production, and HN co-treatment resulted in a decrease in mitochondrial superoxide compared to TM treatment alone. We further showed that depleted mitochondrial glutathione (GSH) levels induced by TM were restored with HN co-treatment. No significant changes were found for the expression of several antioxidant enzymes between TM and TM plus HN groups except for the expression of glutamylcysteine ligase catalytic subunit (GCLC), the rate limiting enzyme required for GSH biosynthesis, which is upregulated with TM and TM+HN treatment. These results demonstrate that ER stress promotes mitochondrial alterations in RPE that lead to apoptosis. We further show that HN has a protective effect against ER stress-induced apoptosis by restoring mitochondrial GSH. Thus, HN should be further evaluated for its therapeutic potential in disorders linked to ER stress.

Oxalomalate reduces expression and secretion of vascular endothelial growth factor in the retinal pigment epithelium and inhibits angiogenesis: Implications for age-related macular degeneration

Clinical and experimental observations indicate a critical role for vascular endothelial growth factor (VEGF), secreted by the retinal pigment epithelium (RPE), in pathological angiogenesis and the development of choroidal neovascularization (CNV) in age-related macular degeneration (AMD). RPE-mediated VEGF expression, leading to angiogenesis, is a major signaling mechanism underlying ocular neovascular disease. Inhibiting this signaling pathway with a therapeutic molecule is a promising anti-angiogenic strategy to treat this disease with potentially fewer side effects. Oxalomalate (OMA) is a competitive inhibitor of NADP⁺-dependent isocitrate dehydrogenase (IDH), which plays an important role in cellular signaling pathways regulated by reactive oxygen species (ROS). Here, we have investigated the inhibitory effect of OMA on the expression of VEGF, and the associated underlying mechanism of action, using in vitro and in vivo RPE cell models of AMD. We found that OMA reduced the expression and secretion of VEGF in RPE cells, and consequently inhibited CNV formation. This function of OMA was linked to its capacity to activate the pVHL-mediated HIF-1α degradation in these cells, partly via a ROS-dependent ATM signaling axis, through inhibition of IDH enzymes. These findings reveal a novel role for OMA in inhibiting RPE-derived VEGF expression and angiogenesis, and suggest unique therapeutic strategies for treating pathological angiogenesis and AMD development.

•

Oxalomalate reduces VEGF expression in RPE cells by promoting HIF-1α degradation.

•

Oxalomalate activates pVHL-mediated HIF-1α degradation by regulation of ATM-Chk2-E2F1 axis.

•

Inhibition of IDH enzymes by oxalomalate activates ROS-mediated ATM signaling axis.

•

Oxalomalate inhibits CNV-related angiogenesis in in vivo mouse model of AMD.

C-reactive protein and complement factor H polymorphism interaction in advanced exudative age-related macular degeneration

PURPOSE

To determine the association of C-reactive protein (CRP) and complement factor H (CFH) gene with exudative age-related macular degeneration (AMD) and any possible interaction among these factors.

METHODS

In this case-control study, 139 unrelated patients with exudative AMD and 123 non-AMD controls were recruited. Blood sample was taken for analysis of the CRP levels and DNA testing. DNA fragments of CFH gene variants containing 4 single nucleotide polymorphisms including rs800292, rs1061170, rs2274700, and rs3753395 were assessed. A CRP level of ≥3 mg/L was considered as elevated. The association of elevated CRP and CFH gene variants polymorphism with exudative AMD was compared between the groups.

RESULTS

Mean age was 72.6 ± 6.4 for controls and 74.9 ± 7.4 for case group (P = 0.006). The difference between CRP levels in cases and controls was not statistically significant (P = 0.055). However, Y402H variant of CFH in both homozygous and heterozygous carriers C allele was significantly more frequent among exudative AMD patients than controls, 32.1 versus 6.5 % (P < 0.001). Evaluating various CRP levels in patients with CC and non-CC genotypes disclosed that in CC genotype group, higher CRP level (>3 mg/L) was associated with higher risk of developing exudative AMD (OR = 12.0, CI: 1.5-98.8) compared with the control group.

CONCLUSION

This study disclosed no difference in CRP levels per se between exudative AMD patients with control group. However, higher levels of CRP in the presence of C allele of Y402H might confer more risk for the development of exudative AMD.

Artemisinin protects human retinal pigment epithelial cells from hydrogen peroxide-induced oxidative damage through activation of ERK/CREB signaling

The pathological increase in the levels of reactive oxygen species (ROS) in the retinal pigment epithelium (RPE), is implicated in the development of age-related macular degeneration (AMD). The discovery of drug candidates to effectively protect RPE cells from oxidative damage is required to resolve the pathological aspects and modify the process of AMD. In this study, a FDA-approved anti-malaria drug, Artemisinin was found to suppress hydrogen peroxide (H2O2)-induced cell death in human RPE cell-D407 cells. Further study showed that Artemisinin significantly suppressed H2O2- induced D407 cell death by restoring abnormal changes in nuclear morphology, intracellular ROS, mitochondrial membrane potential and apoptotic biomarkers. Western blotting analysis showed that Artemisinin was able to activate extracellular regulated ERK/CREB survival signaling. Furthermore, Artemisinin failed to suppress H2O2-induced cytotoxicity and the increase of caspase 3/7 activity in the presence of the ERK inhibitor PD98059. Taken together, these results suggest that Artemisinin is a potential protectant with the pro-survival effects against H2O2 insult through activation of the ERK/CREB pathway.

Oral Bisphosphonates and Risk of Wet Age-Related Macular Degeneration

PURPOSE

To examine the risk of age-related macular degeneration (AMD) with oral bisphosphonates.

DESIGN

Three study designs were used: (1) disproportionality analysis; (2) case-control study; (3) self-controlled case series (SCCS).

METHODS

setting: (1) Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) Database; (2) 2 patient cohorts from British Columbia, Canada.

STUDY POPULATION

(1) All reports of AMD to the FDA with oral bisphosphoantes; (2) patients with wet AMD in British Columbia (2009-2013) and 1 million controls (2000-2007).

INTERVENTION

Oral bisphosphonates.

MAIN OUTCOME MEASURES

(1) Reports of AMD to the FDA; (2) first diagnosis of wet AMD verified by a retina specialist in British Columbia.

RESULTS

In the disproportionality analysis there were 133 cases of AMD reported with alendronate, 20 with ibandronate, and 14 with risedronate. The reported odds ratios (RORs) for alendronate, ibandronate, and risedronate were 3.82 (95% CI: 2.94-4.96), 2.40 (95% CI: 1.49-3.86), and 2.87 (95% CI: 1.58-5.19), respectively. In the case-control analysis there were 6367 cases and 6370 corresponding controls. The adjusted OR for wet AMD among regular users of bisphosphonates in the 1, 2, and 3 years prior to the index date were 1.24 (1.12-1.38), 1.38 (1.22-1.56), and 1.59 (1.38-1.82), respectively. In the SCCS analysis there were 198 cases of wet AMD on continuous bisphosphonate therapy. The rate ratio for wet AMD for continuous bisphosphonate use was 1.99 (95% CI: 1.41-2.79). We did not have information on intravenous bisphosphonates.

CONCLUSIONS

Continuous users of oral bisphosphonates are at a higher risk of developing wet AMD. Given the observational nature of this study and limitation of the data, future studies are needed to confirm these findings.

HTRA1 promoter variant differentiates polypoidal choroidal vasculopathy from exudative age-related macular degeneration

Exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) share similar abnormal choroidal vasculature, but responses to treatments are different. In this study, we sequenced the whole HTRA1 gene and its promoter by direct sequencing in a Hong Kong Chinese PCV cohort. We identified rs11200638, c.34delCinsTCCT, c.59C>T, rs1049331 and rs2293870 significantly associated with PCV. Notably, rs2672598 was significantly associated with exudative AMD (p = 1.31 × 10(-4)) than PCV (p = 0.11). Logistic regression indicated that rs2672598 (p = 2.27 × 10(-3)) remained significant after adjusting for rs11200638 in exudative AMD. Moreover, the rs11200638-rs2672598 joint genotype AA-CC conferred higher risk to exudative AMD (43.11 folds) than PCV (3.68 folds). Promoter analysis showed that rs2672598 C-allele showed higher luciferase expression than wildtype T-allele (p = 0.026), independent of rs11200638 genotype (p = 0.621). Coherently, vitreous humor HTRA1 expression with rs2672598 CC genotype was significantly higher than that with TT genotype by 2.56 folds (p = 0.02). Furthermore, rs2672598 C-allele was predicted to alter the transcription factor binding sites, but not rs11200638 A-allele. Our results revealed that HTRA1 rs2672598 is more significantly associated with exudative AMD than PCV in ARMS2/HTRA1 region, and it is responsible for elevated HTRA1 transcriptional activity and HTRA1 protein expression.

Daily Optical Coherence Tomography Examinations after First Antivascular Endothelial Growth Factor Injections: An Interventional Case Series

Purpose. To evaluate daily spectral-domain optical coherence tomography (SD-OCT) changes in naive-treatment patients with diagnosis of exudative age-related macular degeneration (AMD) treated with intravitreous bevacizumab (1.25 mg), during a 30-day follow-up period. Methods. In prospective, interventional study, SD-OCT was performed daily for 30 days after the first intravitreal injection. The baseline, initial-decrease, minimal, and final central retinal thicknesses (CRTs) were assessed. Results. Nine eyes of nine patients with neovascular AMD were enrolled. The mean baseline CRT was 625.3 ± 182.5 μm, and the mean final CRT was 383.4 ± 163.0 μm (mean difference, 206.1 ± 167.6 μm), a difference that reached significance (P = 0.006). After the first injection, the initial decrease in the CRT was seen as an average of one day after injection (mean CRT, 503.6 ± 189.10 μm; P = 0.0431). The speed of the reduction in the CRT tended to decrease by day 17. The mean CRT was 336.5 ± 105.44 μm and the mean minimal CRT on day 30 was 320.75 ± 96.38 μm. Conclusion. The CRT decreased early after the first injection. We observed a tendency for reductions in the speed with which the CRT decreased by day 17 after the first injection, which may affect retreatment regime.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY VERSUS TRADITIONAL MULTIMODAL IMAGING IN ASSESSING THE ACTIVITY OF EXUDATIVE AGE-RELATED MACULAR DEGENERATION: A New Diagnostic Challenge

PURPOSE

To compare optical coherence tomography angiography (OCTA) with traditional multimodal imaging in patients with exudative age-related macular degeneration in terms of guiding the treatment decision.

METHODS

Prospective case series of 80 eyes of 73 consecutive patients with exudative age-related macular degeneration (39 women, mean age: 79.4 ± 5.3 years) diagnosed with different types of choroidal neovascularization (CNV) (58 Type I, 2 Type II, 6 mixed Type I and II, 3 retinal angiomatous proliferation, and 11 age-related macular degeneration-related polyps). The data obtained from traditional multimodal imaging, based on fluorescein angiography, indocyanine green angiography, and OCT were used to assess the need for treatment, those obtained from OCTA to identify two different patterns of CNV. Traditional multimodal imaging and OCTA findings were then compared with evaluate possible correspondence between treatment decision and CNV aspect on OCTA.

RESULTS

A CNV lesion was identified as Group A (requiring treatment) in 58 eyes (72.5%) in traditional multimodal imaging. On OCTA in 59 eyes (73.7%), the lesion was defined as Pattern I and the remaining 21 (26.3%) as Pattern II. There was 94.9% correspondence between the Pattern I CNV on OCTA and the cases Group A on conventional multimodal imaging. It was also computed 90.5% correspondence between Pattern II CNV on OCTA and the Group B (not requiring treatment) cases on conventional multimodal imaging. There was high (P < 0.05) interobserver agreement both for treatment decision in conventional multimodal and for Patterns (I or II) defining on OCTA imaging analysis.

CONCLUSION

This study demonstrates a high level of correspondence, in patients with exudative age-related macular degeneration, between different CNV patterns identified on OCTA and treatment decisions established on conventional multimodal imaging. Although fluorescein angiography remains the gold standard for determining the presence of leakage, and OCT shows fluid accumulation and its variations, OCTA may now offer noninvasive monitoring of the CNV, aiding for each treatment decision during the follow-up.

Association of Age Related Macular Degeneration and Age Related Hearing Impairment

Purpose:

To evaluate the association between age-related macular degeneration (ARMD) and sensory neural hearing impairment (SHI).

Methods:

In this case-control study, hearing status of 46 consecutive patients with ARMD were compared with 46 age-matched cases without clinical ARMD as a control group. In all patients, retinal involvements were confirmed by clinical examination, fluorescein angiography (FA) and optical coherence tomography (OCT). All participants were examined with an otoscope and underwent audiological tests including pure tone audiometry (PTA), speech reception threshold (SRT), speech discrimination score (SDS), tympanometry, reflex tests and auditory brainstem response (ABR).

Results:

A significant (P = 0.009) association was present between ARMD, especially with exudative and choroidal neovascularization (CNV) components, and age-related hearing impairment primarily involving high frequencies. Patients had higher SRT and lower SDS against anticipated presbycusis than control subjects. Similar results were detected in exudative, CNV and scar patterns supporting an association between late ARMD with SRT and SDS abnormalities. ABR showed significantly prolonged wave I and IV latency times in ARMD (P = 0.034 and 0.022, respectively). Average latency periods for wave I in geographic atrophy (GA) and CNV, and that for wave IV in drusen patterns of ARMD were significantly higher than controls (P = 0.030, 0.007 and 0.050, respectively).

Conclusion:

The association between ARMD and age-related SHI may be attributed to common anatomical components such as melanin in these two sensory organs.

Effect of substance P on recovery from laser-induced retinal degeneration

Retinal degeneration is caused by neovascularization and persistent inflammation in the retinal pigment epithelium (RPE) and choroid, and causes serious eye disease including age-related macular degeneration (AMD). Thus, inhibiting inflammation and neovascularization may be a primary approach to protect the retina from degeneration. The purpose of this study was to determine whether substance P (SP), which can suppress inflammation and mobilize stem cells, can protect the RPE from degeneration. The effect of SP was evaluated by analyzing systemic inflammation, cell survival, and neovascularization within the argon laser-injured retina of mice. At 1 week postinjury, the SP-treated group had lower tumor necrosis factor-alpha and higher interleukin-10 serum concentrations, and a more intact retinal structure compared to the vehicle-treated group. In mice administered SP repeatedly for 4 weeks, the retinal structure appeared normal and showed sparse neovascularization, whereas the vehicle-treated group showed severe retinal destruction and dense neovascularization. Moreover, the efficacy of SP was identical to that of mesenchymal stem cells that were transplanted into the vitreous after retinal injury. This study highlights the potential for the endogenous neuropeptide SP as a treatment for retinal damage to prevent conditions such as AMD.

Histamine H4 receptor as a new therapeutic target for choroidal neovascularization in age-related macular degeneration

BACKGROUND AND PURPOSE

The present treatment for choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD) is not sufficient. Hence, we examined the therapeutic efficacy of reducing histamine H4 receptor expression on CNV in mice.

EXPERIMENTAL APPROACH

H4 receptor expression was examined in CNVs from patients with AMD. In mice, laser photocoagulation was performed in the retina to induce experimental CNV (laser CNV). Protein and mRNA expression levels were determined and CNV volume measured in wild-type and Hrh4(-/-) mice with laser CNV. The effects of JNJ7777120, an H4 receptor antagonist, administered intravitreously, on CNV volume and pathological vessel leakage were determined in mice with laser CNV and controls. Fundus imaging, retinal histology and electroretinography were performed on eyes injected with JNJ7777120 to evaluate retinal toxicity.

KEY RESULTS

Human H4 receptors were only confirmed in CNV samples from AMD patients and not in the other subretinal tissues. Mouse H4 receptors were expressed in retinal pigment epithelium only after inducing laser CNV in wild-type mice, and were co-localized with the macrophage marker F4/80. Laser CNV volume was reduced in Hrh4(-/-) mice compared with that in wild-type mice, and JNJ7777120 suppressed laser-induced CNV volume and pathological CNV leakage in wild-type mice. Also eyes injected with JNJ7777120 did not show retinal degeneration.

CONCLUSIONS AND IMPLICATIONS

H4 receptors are expressed in macrophages that accumulate around CNVs. Suppressing H4 receptor expression prevented the pathological vessel leakage without showing retinal toxicity, indicating that the H4 receptor has potential as a novel therapeutic target in AMD.

Malondialdehyde induces autophagy dysfunction and VEGF secretion in the retinal pigment epithelium in age-related macular degeneration

Age-related macular degeneration (AMD) is a major cause of blindness in developed countries and is closely related to oxidative stress, which leads to lipid peroxidation. Malondialdehyde (MDA) is a major byproduct of polyunsaturated fatty acid (PUFA) peroxidation. Increased levels of MDA have been reported in eyes of AMD patients. However, little is known about the direct relationship between MDA and AMD. Here we show the biological importance of MDA in AMD pathogenesis. We first confirmed that MDA levels were significantly increased in eyes of AMD patients. In ARPE-19 cells, a human retinal pigment epithelial cell line, MDA treatment induced vascular endothelial growth factor (VEGF) expression alternation, cell junction disruption, and autophagy dysfunction that was also observed in eyes of AMD patients. The MDA-induced VEGF increase was inhibited by autophagy-lysosomal inhibitors. Intravitreal MDA injection in mice increased laser-induced choroidal neovascularization (laser-CNV) volumes. In a mouse model fed a high-linoleic acid diet for 3 months, we found a significant increase in MDA levels, autophagic activity, and laser-CNV volumes. Our study revealed an important role of MDA, which acts not only as a marker but also as a causative factor of AMD pathogenesis-related autophagy dysfunction. Furthermore, higher dietary intake of linoleic acid promoted CNV progression in mice with increased MDA levels.

Prolactin protects retinal pigment epithelium by inhibiting sirtuin 2-dependent cell death

The identification of pathways necessary for retinal pigment epithelium (RPE) function is fundamental to uncover therapies for blindness. Prolactin (PRL) receptors are expressed in the retina, but nothing is known about the role of PRL in RPE. Using the adult RPE 19 (ARPE-19) human cell line and mouse RPE, we identified the presence of PRL receptors and demonstrated that PRL is necessary for RPE cell survival via anti-apoptotic and antioxidant actions. PRL promotes the antioxidant capacity of ARPE-19 cells by reducing glutathione. It also blocks the hydrogen peroxide-induced increase in deacetylase sirtuin 2 (SIRT2) expression, which inhibits the TRPM2-mediated intracellular Ca(2+) rise associated with reduced survival under oxidant conditions. RPE from PRL receptor-null (prlr(-/-)) mice showed increased levels of oxidative stress, Sirt2 expression and apoptosis, effects that were exacerbated in animals with advancing age. These observations identify PRL as a regulator of RPE homeostasis.

Role of Chemokines in Shaping Macrophage Activity in AMD

Age-related macular degeneration (AMD) is a multifactorial disorder that affects millions of individuals worldwide. While the advent of anti-VEGF therapy has allowed for effective treatment of neovascular 'wet' AMD, no treatments are available to mitigate the more prevalent 'dry' forms of the disease. A role for inflammatory processes in the progression of AMD has emerged over a period of many years, particularly the characterisation of leukocyte infiltrates in AMD-affected eyes, as well as in animal models. This review focuses on the burgeoning understanding of chemokines in the retina, and their potential role in shaping the recruitment and activation of macrophages in AMD. Understanding the mechanisms which promote macrophage activity in the degenerating retina may be key to controlling the potentially devastating consequences of inflammation in diseases such as AMD.

[Serous vascularized pigment epithelial detachment in exudative AMD. Morphological typing and risk of tears in the RPE]

PURPOSE

Are there any morphological parameters in pigment epithelial detachment (PED) in eyes with age-related macular degeneration (AMD), which could identify the development of tears (RIP) in the retinal pigment epithelium (RPE) before initiation of anti-vascular endothelial growth factor (VEGF) therapy?

METHODS

Retrospectively, the spectral domain optical coherence tomography (SD-OCT), FLA and near infrared (NIR) images of 98 eyes with PED in exudative AMD before treatment (ranibizumab or bevacizumab) were analyzed. Eyes in which a tear in the RPE (RIP group) could be observed during treatment were compared to eyes without the development of RIP (PED group) in the following morphological parameters of PED: height, number of peaks, presence of hyporeflective fissures at the base of the PED, structure of the RPE, presence of floating structures in the PED with maximum hyperreflectivity, amount and localization of hyperreflectivity in the PED and hyperreflectivity in the NIR images.

RESULTS

In the 80 eyes of the PED group the mean PED height was 373.7± 197 µm and in the 18 eyes of the RIP group the mean PED height was higher (694.2± 284.3 µm, p < 0.0001). A difference was also seen in the number of peaks per PED (PED group 43%, RIP group 72%, p = 0.039) and in the hyperreflectivity in NIR images (PED group 68%, RIP group 94%, p = 0.033). There were no significant differences in the other morphological parameters. A classification into four types of PED was found by the parameters height and number of peaks. The PED type with a height > 350 µm and one peak (RIP 43%) developed tears more often (p = 0.001) than the PED type < 350 µm with one peak (RIP 0%, p = 0.001). A trend in the visual acuity over 156 weeks was seen: in PED types with heights > 350 µm there was a lower increase in the visual acuity than in PED types < 350 µm (rm ANOVA p = 0.18; ɛ HH = 0.88). Furthermore, in PED types > 350 µm with multiple peaks the total number of injections necessary was higher than in the other PED types (p = 0.032).

CONCLUSION

Morphological parameters, such as PED height, number of peaks per PED in OCT images and hyperreflectivity in NIR images are prognostic factors for RPE tears in exudative AMD. The PED height and number of peaks per PED are useful for classification of PED in the daily routine.

Drusen volume development over time and its relevance to the course of age-related macular degeneration

Aims

To quantify the change in drusen volume over time and identify its prognostic value for individual risk assessment.

Methods

A prospective observational study over a minimum of 3 years and maximum of 5 years and follow-up examination every 3 months was conducted at the ophthalmology department of the Medical University of Vienna. 109 patients presenting early and intermediate age-related macular degeneration (AMD) were included, of which 30 patients concluded a regular follow-up for at least 3 years. 50 eyes of 30 patients were imaged every 3 months using spectral-domain and polarisation-sensitive optical coherence tomography (OCT). Drusen volume was measured using an automated algorithm. Data of a 6-month follow-up were segmented manually by expert graders.

Results

Gradings from 24 000 individual B-scans showed solid correlation between manual and automated segmentation with an initial mean drusen volume of 0.17 mm³. The increase in drusen volume was shown to be comparable among all eyes, and a model for long-term drusen volume development could be fitted as a cubic polynomial function and an R²=0.955. Spontaneous drusen regression was observed in 22 of 50 eyes. In this group, four eyes developed choroidal neovascularisation and three geographic atrophy.

Conclusions

Drusen volume increase over time can be described by a cubic function. Spontaneous regression appears to precede conversion to advanced AMD. OCT might be a promising tool for predicting the individual risk of progression of AMD.

Pharmacology of the retinal pigment epithelium, the interface between retina and body system

The retinal pigment epithelium (RPE) is a close, interactive partner to the photoreceptors as well as an interface with the endothelium of the choroid and thus with the body's circulatory system. To fulfill these roles, the RPE communicates with neighboring tissue by secretion of a large variety of factors and is able to react to secreted factors via a plethora of transmembrane receptors. Clinically relevant local pharmacological effects are caused by anti-VEGF-A treatment in choroidal neovascularization or by carboanhydrase inhibitors reducing fluid accumulation in the macula. Being exposed to the bloodstream, the RPE reacts to systemic disease, such as diabetes or hypertension, but also to systemic pharmacological intervention, for example to hypotensive drugs acting on the renin-angiotensin-system. Sustained pharmacological treatments, in particular, cause side effects at the RPE with consequences for both RPE function and photoreceptor survival. Among these are systemic inhibition of angiotensin-converting enzyme, insulin treatment in diabetes and anti-VEGF-A therapy. Given the special anatomical and functional relationships of the RPE, pharmacological intervention targeting either the eye or the body systemically should take potential alteration of RPE and subsequently photoreceptor function into account.

The Diagnostic Accuracy of Optical Coherence Tomography Angiography for Neovascular Age-Related Macular Degeneration: A Comparison with Fundus Fluorescein Angiography

Purpose. To describe the morphological characteristics and efficacy of OCTA in detecting CNV in nAMD. We retrospectively reviewed 53 patients (86 eyes) with suspected CNV secondary to wet AMD. All the patients underwent a multimodal assessment for CNV. Two independent readers calculated the sensitivity and specificity of OCTA in detecting CNV compared with FA. A qualitative analysis of OCTA was also performed to describe the morphological appearance of CNV. Among 86 eyes of 53 patients, 52 eyes were diagnosed as having CNV based on the FA imaging analysis. According to FA, CNV was classified as classic in 28 eyes, predominantly classic in 6 eyes, minimally classic in 9 eyes, and occult in 9 eyes. In 56 eyes, CNV was visualized on OCTA and corresponding OCT B-scans. In total, 46.4% (26/56) had well-circumscribed vessels, and 53.6% (30/56) showed poorly circumscribed vessels. There were 11 false positives and 7 false negatives using OCTA. The specificity of OCTA for the detection of CNV was 67.6%, with sensitivity of 86.5%. OCTA may help in the noninvasive diagnosis of CNV and may provide a method for monitoring the evolution of CNV.

Mfsd2a Is a Transporter for the Essential ω-3 Fatty Acid Docosahexaenoic Acid (DHA) in Eye and Is Important for Photoreceptor Cell Development

Eye photoreceptor membrane discs in outer rod segments are highly enriched in the visual pigment rhodopsin and the ω-3 fatty acid docosahexaenoic acid (DHA). The eye acquires DHA from blood, but transporters for DHA uptake across the blood-retinal barrier or retinal pigment epithelium have not been identified. Mfsd2a is a newly described sodium-dependent lysophosphatidylcholine (LPC) symporter expressed at the blood-brain barrier that transports LPCs containing DHA and other long-chain fatty acids. LPC transport via Mfsd2a has been shown to be necessary for human brain growth. Here we demonstrate that Mfsd2a is highly expressed in retinal pigment epithelium in embryonic eye, before the development of photoreceptors, and is the primary site of Mfsd2a expression in the eye. Eyes from whole body Mfsd2a-deficient (KO) mice, but not endothelium-specific Mfsd2a-deficient mice, were DHA-deficient and had significantly reduced LPC/DHA transport in vivo Fluorescein angiography indicated normal blood-retinal barrier function. Histological and electron microscopic analysis indicated that Mfsd2a KO mice exhibited a specific reduction in outer rod segment length, disorganized outer rod segment discs, and mislocalization of and reduction in rhodopsin early in postnatal development without loss of photoreceptors. Minor photoreceptor cell loss occurred in adult Mfsd2a KO mice, but electroretinography indicated visual function was normal. The developing eyes of Mfsd2a KO mice had activated microglia and up-regulation of lipogenic and cholesterogenic genes, likely adaptations to loss of LPC transport. These findings identify LPC transport via Mfsd2a as an important pathway for DHA uptake in eye and for development of photoreceptor membrane discs.

Molecular Selection, Modification and Development of Therapeutic Oligonucleotide Aptamers

Monoclonal antibodies are the dominant agents used in inhibition of biological target molecules for disease therapeutics, but there are concerns of immunogenicity, production, cost and stability. Oligonucleotide aptamers have comparable affinity and specificity to targets with monoclonal antibodies whilst they have minimal immunogenicity, high production, low cost and high stability, thus are promising inhibitors to rival antibodies for disease therapy. In this review, we will compare the detailed advantages and disadvantages of antibodies and aptamers in therapeutic applications and summarize recent progress in aptamer selection and modification approaches. We will present therapeutic oligonucleotide aptamers in preclinical studies for skeletal diseases and further discuss oligonucleotide aptamers in different stages of clinical evaluation for various disease therapies including macular degeneration, cancer, inflammation and coagulation to highlight the bright commercial future and potential challenges of therapeutic oligonucleotide aptamers.

Nucleoside Reverse Transcriptase Inhibitors Suppress Laser-Induced Choroidal Neovascularization in Mice

PURPOSE

To evaluate the efficacy of nucleoside reverse transcriptase inhibitors (NRTIs) in the laser-induced mouse model of choroidal neovascularization (CNV).

METHODS

We evaluated the NRTIs lamivudine (3TC), zidovudine (AZT), and abacavir (ABC) and the P2X7 antagonist A438079. Choroidal neovascularization was induced by laser injury in C57BL/6J wild-type, Nlrp3-/-, and P2rx7-/- mice, and CNV volume was measured after 7 days by confocal microscopy. Drugs were administered by intravitreous injection immediately after the laser injury. Vascular endothelial growth factor-A in RPE-choroid lysates was measured 3 days after laser injury by ELISA. HEK293 cells expressing human and mouse P2X7 were exposed to the selective P2X7 receptor agonist 2', 3'-(benzoyl-4-benzoyl)-ATP (Bz-ATP) with or without 3TC, and VEGF-A levels in media were measured by ELISA.

RESULTS

Intravitreous injection of 3TC, AZT, and ABC significantly suppressed laser-induced CNV in C57BL/6J wild-type and Nlrp3-/- mice (P < 0.05) but not in P2rx7-/- mice. Intravitreous injection of A438079 also suppressed the laser-induced CNV (P < 0.05). The NRTIs 3TC, AZT, and ABC blocked VEGF-A levels in the RPE/choroid after laser injury in wild-type (P < 0.05) but not P2rx7-/- mice. Moreover, there was no additive effect of 3TC on CNV inhibition when coadministered with a neutralizing VEGF-A antibody. Stimulation of human and mouse P2X7-expressing HEK293 cells with Bz-ATP increased VEGF secretion (P < 0.001), which was abrogated by 3TC (P < 0.001). Stimulation of primary human RPE cells with Bz-ATP increased VEGFA and IL6 mRNA levels, which were abrogated by 3TC.

CONCLUSIONS

Multiple clinically relevant NRTIs suppressed laser-induced CNV and downregulated VEGF-A, via P2X7.

The Mitochondrial-Derived Peptide Humanin Protects RPE Cells From Oxidative Stress, Senescence, and Mitochondrial Dysfunction

PURPOSE

To investigate the expression of humanin (HN) in human retinal pigment epithelial (hRPE) cells and its effect on oxidative stress-induced cell death, mitochondrial bioenergetics, and senescence.

METHODS

Humanin localization in RPE cells and polarized RPE monolayers was assessed by confocal microscopy. Human RPE cells were treated with 150 μM tert-Butyl hydroperoxide (tBH) in the absence/presence of HN (0.5-10 μg/mL) for 24 hours. Mitochondrial respiration was measured by XF96 analyzer. Retinal pigment epithelial cell death and caspase-3 activation, mitochondrial biogenesis and senescence were analyzed by TUNEL, immunoblot analysis, mitochondrial DNA copy number, SA-β-Gal staining, and p16INK4a expression and HN levels by ELISA. Oxidative stress-induced changes in transepithelial resistance were studied in RPE monolayers with and without HN cotreatment.

RESULTS

A prominent localization of HN was found in the cytoplasmic and mitochondrial compartments of hRPE. Humanin cotreatment inhibited tBH-induced reactive oxygen species formation and significantly restored mitochondrial bioenergetics in hRPE cells. Exogenous HN was taken up by RPE and colocalized with mitochondria. The oxidative stress-induced decrease in mitochondrial bioenergetics was prevented by HN cotreatment. Humanin treatment increased mitochondrial DNA copy number and upregulated mitochondrial transcription factor A, a key biogenesis regulator protein. Humanin protected RPE cells from oxidative stress-induced cell death by STAT3 phosphorylation and inhibiting caspase-3 activation. Humanin treatment inhibited oxidant-induced senescence. Polarized RPE demonstrated elevated cellular HN and increased resistance to cell death.

CONCLUSIONS

Humanin protected RPE cells against oxidative stress-induced cell death and restored mitochondrial function. Our data suggest a potential role for HN therapy in the prevention of retinal degeneration, including AMD.

Mining Retrospective Data for Virtual Prospective Drug Repurposing: L-DOPA and Age-related Macular Degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a leading cause of visual loss among the elderly. A key cell type involved in AMD, the retinal pigment epithelium, expresses a G protein-coupled receptor that, in response to its ligand, L-DOPA, up-regulates pigment epithelia-derived factor, while down-regulating vascular endothelial growth factor. In this study we investigated the potential relationship between L-DOPA and AMD.

METHODS

We used retrospective analysis to compare the incidence of AMD between patients taking vs not taking L-DOPA. We analyzed 2 separate cohorts of patients with extensive medical records from the Marshfield Clinic (approximately 17,000 and approximately 20,000) and the Truven MarketScan outpatient and databases (approximately 87 million) patients. We used International Classification of Diseases, 9th Revision codes to identify AMD diagnoses and L-DOPA prescriptions to determine the relative risk of developing AMD and age of onset with or without an L-DOPA prescription.

RESULTS

In the retrospective analysis of patients without an L-DOPA prescription, AMD age of onset was 71.2, 71.3, and 71.3 in 3 independent retrospective cohorts. Age-related macular degeneration occurred significantly later in patients with an L-DOPA prescription, 79.4 in all cohorts. The odds ratio of developing AMD was also significantly negatively correlated by L-DOPA (odds ratio 0.78; confidence interval, 0.76-0.80; P <.001). Similar results were observed for neovascular AMD (P <.001).

CONCLUSIONS

Exogenous L-DOPA was protective against AMD. L-DOPA is normally produced in pigmented tissues, such as the retinal pigment epithelium, as a byproduct of melanin synthesis by tyrosinase. GPR143 is the only known L-DOPA receptor; it is therefore plausible that GPR143 may be a fruitful target to combat this devastating disease.

The broad-spectrum chemokine inhibitor NR58-3.14.3 modulates macrophage-mediated inflammation in the diseased retina

Background

The activity of macrophages is implicated in the progression of retinal pathologies such as atrophic age-related macular degeneration (AMD), where they accumulate among the photoreceptor layer and subretinal space. This process is aided by the local expression of chemokines, which furnish these cells with directional cues that augment their migration to areas of retinal injury. While these qualities make chemokines a potential therapeutic target in curtailing damaging retinal inflammation, their wide variety and signalling redundancy pose challenges in broadly modulating their activity. Here, we examine the efficacy of the broad-spectrum chemokine inhibitor NR58-3.14.3—a suppressor of Ccl- and Cxcl- chemokine pathways—in suppressing macrophage activity and photoreceptor death, using a light-induced model of outer retinal atrophy and inflammation.

Methods

Photo-oxidative damage was induced in SD rats via exposure to 1000 lux of light for 24 h, after which animals were euthanized at 0- or 7-day post-exposure time points. Prior to damage, NR58-3.14.3 was injected intravitreally. Retinas were harvested and evaluated for the effect of NR58-3.14.3 on subretinal macrophage accumulation and cytokine expression profile, as well as photoreceptor degeneration.

Results

We report that intravitreal administration of NR58-3.14.3 reduces the accumulation of macrophages in the outer retina following exposure to light damage, at both 0- and 7-day post-exposure time points. Injection of NR58-3.14.3 also reduced the up-regulation of inflammatory markers including of Il6, Ccl3, and Ccl4 in infiltrating macrophages, which are promoters of their pathogenic activity in the retina. Finally, NR58-3.14.3-injected retinas displayed markedly reduced photoreceptor death following light damage, at both 0 and 7 days post-exposure.

Conclusions

Our findings indicate that NR58-3.14.3 is effective in inhibiting subretinal macrophage accumulation in light-induced retinal degeneration and illustrate the potential of broad-spectrum chemokine inhibitors as novel therapeutic agents in thwarting retinal inflammation. Although broad-spectrum chemokine inhibitors may not be appropriate for all retinal inflammatory conditions, our results suggest that they may be beneficial for retinal dystrophies in which chemokine expression and subretinal macrophage accumulation are implicated, such as advanced AMD.

Higher plasma levels of complement C3a, C4a and C5a increase the risk of subretinal fibrosis in neovascular age-related macular degeneration: Complement activation in AMD

Background

The aim of this study was to investigate the plasma levels of complement C3a, C4a, and C5a in different types of neovascular age-related macular degeneration (nAMD) and whether the levels were related to patients’ responsiveness to anti-VEGF therapy.

Results

Ninety-six nAMD patients (including 61 with choroidal neovascularisation (CNV), 17 with retinal angiomatous proliferation (RAP), 14 with polypoidal choroidal vasculopathy (PCV) and 4 unclassified patients) and 43 controls were recruited to this case–control study. Subretinal fibrosis was observed in 45 nAMD patients and was absent in 51 nAMD patients. In addition, the responsiveness to anti-VEGF (Lucentis) therapy was also evaluated in nAMD patients. Forty-four patients were complete responders, 48 were partially responders, and only 4 patients did not respond to the therapy. The plasma levels of C3a, C4a and C5a were significantly higher in nAMD patients compared to controls. Further analysis of nAMD subgroups showed that the levels of C3a, C4a and C5a were significantly increased in patients with CNV but not RAP and PCV. Significantly increased levels of C3a, C4a and C5a were also observed in nAMD patients with subretinal fibrosis but not in those without subretinal fibrosis. Higher levels of C3a were observed in nAMD patients who responded partially to anti-VEGF therapy.

Conclusions

Our results suggest increased systemic complement activation in nAMD patients with CNV but not RAP and PCV. Our results also suggest that higher levels of systemic complement activation may increase the risk of subretinal fibrosis in nAMD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-016-0060-5) contains supplementary material, which is available to authorized users.

[Optical coherence tomography angiography in the diagnosis of neovascular age-related macular degeneration]

AIM

to determine optical coherence tomography (OCT) angiography signs of classic and occult choroidal neovascularization (CNV) in patients with age-related macular degeneration (AMD) and evaluate their information value in monitoring the effect of anti-VEGF therapy.

MATERIAL AND METHODS

The study enrolled 76 patients (87 eyes), including 68 patients (72 eyes) with wet AMD and 8 patients (15 eyes) with no signs of neovascularization. All patients underwent spectral-domain OCT, OCT angiography, and fluorescein angiography (FA). OCT angiography was used to evaluate neovascular networks in terms of their location, shape, size, and extent of visualization. Sensitivity and specificity of the method were assessed separately in a group of 37 CNV eyes and 15 unsuspicious eyes, specific findings at FA being the main diagnostic criteria. To determine the information value of OCT angiography in monitoring the effect of intravitreal ranibizumab therapy, 9 patients (9 eyes) were selected, in whom the exam was performed the day before the injection and then at days 3, 10, 17, 24, and 31.

RESULTS

The patients were divided into two groups. Group 1 consisted of 43 eyes with occult CNV, group 2--of 29 eyes with classic CNV. Neovascular loops underneath the retinal pigment epithelium were found in 76.74% of occult CNV cases. In patients with classic CNV, the neovasculature was clearly visible in 82.76% of eyes, loop-like and tree-like networks occurring with similar frequency (51.72% and 42.28% respectively). OCT angiography results obtained prior to and following ranibizumab injection revealed a change in not only the size of neovascularization, but also the density, thickness, and branching pattern of newly formed blood vessels. Sensitivity and specificity of OCT angiography has been shown to be 89.2% and 93.3% respectively.

CONCLUSION

OCT angiography enables diagnosis of both classic and occult choroidal neovascularization in patients with AMD as well as dynamic assessment of the size of the neovascular complex during anti-VEGF treatment. The method has high sensitivity and specificity.

Liposomal hypocrellin B as a potential photosensitizer for age-related macular degeneration: pharmacokinetics, photodynamic efficacy, and skin phototoxicity in vivo

Photodynamic therapy (PDT) has been successfully implemented as a treatment for wet age-related macular degeneration (AMD), but very few photosensitizers have been developed for clinical use. Herein, we describe a novel formulation of liposomal hypocrellin B (LHB) that was prepared by high-pressure homogenization. The encapsulation efficiency and PDT efficacy in vitro of this new preparation were found to remain nearly constant over 1 year. Moreover, LHB is rapidly cleared from the blood, with a half-life of 2.319 ± 0.462 h and a very low serum concentration at 24 h after injection. Testing in a rat model of choroidal neovascularization (CNV) showed that leakage of blood vessels in CNV lesions was significantly reduced when LHB PDT was given at a dose of 1 mg kg(-1) along with yellow laser irradiation; the damage to the collateral retina and the retinal pigment epithelium was minimal. Skin phototoxicity assays showed that only two of the 200 mice given a 4 mg per kg dose of LHB experienced an inflammatory reaction in the auricle irradiated at 24 h after dosing. These data collectively indicate that LHB may be a safe and effective photosensitizer for vascular-targeted PDT of AMD.

Melissa Officinalis L. Extracts Protect Human Retinal Pigment Epithelial Cells against Oxidative Stress-Induced Apoptosis

BACKGROUND

We evaluated the protective effect of ALS-L1023, an extract of Melissa officinalis L. (Labiatae; lemon balm) against oxidative stress-induced apoptosis in human retinal pigment epithelial cells (ARPE-19 cells).

METHODS

ARPE-19 cells were incubated with ALS-L1023 for 24 h and then treated with hydrogen peroxide (H2O2). Oxidative stress-induced apoptosis and intracellular generation of reactive oxygen species (ROS) were assessed by flow cytometry. Caspase-3/7 activation and cleaved poly ADP-ribose polymerase (PARP) were measured to investigate the protective role of ALS-L1023 against apoptosis. The protective effect of ALS-L1023 against oxidative stress through activation of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) was evaluated by Western blot analysis.

RESULTS

ALS-L1023 clearly reduced H2O2-induced cell apoptosis and intracellular production of ROS. H2O2-induced oxidative stress increased caspase-3/7 activity and apoptotic PARP cleavage, which were significantly inhibited by ALS-L1023. Activation of the PI3K/Akt pathway was associated with the protective effect of ALS-L1023 on ARPE-19 cells.

CONCLUSIONS

ALS-L1023 protected human RPE cells against oxidative damage. This suggests that ALS-L1023 has therapeutic potential for the prevention of dry age-related macular degeneration.

Analysing the Progression Rates of Macular Lesions with Autofluorescence Imaging Modes in Dry Age-Related Macular Degeneration

OBJECTIVES

In this study we aimed to compare the sensitivity of blue-light fundus autofluorescence (FAF) and near-infrared autofluorescence (NI-AF) imaging for determining the progression rates of macular lesions in dry age-related macular degeneration (AMD).

MATERIALS AND METHODS

The study was designed retrospectively and included patients diagnosed with intermediate and advanced stage dry AMD. Best corrected visual acuities and FAF and NI-AF images were recorded in 46 eyes of 33 patients. Lesion borders were drawn manually on the images using Heidelberg Eye Explorer software and lesion areas were calculated using Microsoft Excel software. BCVA and lesion areas were compared with each other.

RESULTS

Patients' mean follow-up time was 30.98±13.30 months. The lesion area progression rates were 0.85±0.93 mm2/y in FAF and 0.93±1.01 mm2/y in NI-AF, showing statistically significant correlation with each other (r=0.883; p<0.01). Both imaging methods are moderately correlated with visual acuity impairment (r=0.362; p<0.05 and r=0.311; p<0.05, respectively). In addition, larger lesions showed higher progression rates than smaller ones in both imaging methods.

CONCLUSION

NI-AF imaging is as important and effective as FAF imaging for follow-up of dry AMD patients.

LASER RESENSITIZATION OF MEDICALLY UNRESPONSIVE NEOVASCULAR AGE-RELATED MACULAR DEGENERATION: Efficacy and Implications

PURPOSE

Drug tolerance is the most common cause of treatment failure in neovascular age-related macular degeneration. "Low-intensity/high-density" subthreshold diode micropulse laser (SDM) has been reported effective for a number of retinal disorders without adverse effects. It has been proposed that SDM normalizes retinal pigment epithelial function. On this basis, it has been postulated that SDM treatment might restore responsiveness to anti-vascular endothelial growth factor drugs in drug-tolerant eyes.

METHODS

Subthreshold diode micropulse laser treatment was performed in consecutive eyes unresponsive to all anti-vascular endothelial growth factor drugs, including at least three consecutive ineffective aflibercept injections. Monthly aflibercept was resumed 1 month after SDM treatment.

RESULTS

Thirteen eyes of 12 patients, aged 73 to 97 years (average, 84 years), receiving 16 to 67 (average, 34) anti-vascular endothelial growth factor injections before SDM treatment were included and followed for 3 months to 7 months (average, 5 months) after SDM treatment. After SDM treatment and resumption of aflibercept, 92% (12 of 13) of eyes improved, with complete resolution of macular exudation in 69% (9 of 13). Visual acuity remained unchanged. Central and maximum macular thicknesses significantly improved.

CONCLUSION

Subthreshold diode micropulse laser treatment restored drug response in drug-tolerant eyes with neovascular age-related macular degeneration. Based on these findings, a theory of SDM action is proposed, suggesting a wider role for SDM as retinal reparative/protective therapy.

Complement pathway biomarkers and age-related macular degeneration

In the age-related macular degeneration (AMD) 'inflammation model', local inflammation plus complement activation contributes to the pathogenesis and progression of the disease. Multiple genetic associations have now been established correlating the risk of development or progression of AMD. Stratifying patients by their AMD genetic profile may facilitate future AMD therapeutic trials resulting in meaningful clinical trial end points with smaller sample sizes and study duration.