Pathologic vs. protective roles of hypoxia-inducible factor 1 in RPE and photoreceptors in wet vs. dry age-related macular degeneration.

It has previously been reported that antioxidant vitamins can help reduce the risk of vision loss associated with progression to advanced age-related macular degeneration (AMD), a leading cause of visual impairment among the elderly. Nonetheless, how oxidative stress contributes to the development of choroidal neovascularization (CNV) in some AMD patients and geographic atrophy (GA) in others is poorly understood. Here, we provide evidence demonstrating that oxidative stress cooperates with hypoxia to synergistically stimulate the accumulation of hypoxia-inducible factor (HIF)-1α in the retinal pigment epithelium (RPE), resulting in increased expression of the HIF-1-dependent angiogenic mediators that promote CNV. HIF-1 inhibition blocked the expression of these angiogenic mediators and prevented CNV development in an animal model of ocular oxidative stress, demonstrating the pathological role of HIF-1 in response to oxidative stress stimulation in neovascular AMD. While human-induced pluripotent stem cell (hiPSC)-derived RPE monolayers exposed to chemical oxidants resulted in disorganization and disruption of their normal architecture, RPE cells proved remarkably resistant to oxidative stress. Conversely, equivalent doses of chemical oxidants resulted in apoptosis of hiPSC-derived retinal photoreceptors. Pharmacologic inhibition of HIF-1 in the mouse retina enhanced-while HIF-1 augmentation reduced-photoreceptor apoptosis in two mouse models for oxidative stress, consistent with a protective role for HIF-1 in photoreceptors in patients with advanced dry AMD. Collectively, these results suggest that in patients with AMD, increased expression of HIF-1α in RPE exposed to oxidative stress promotes the development of CNV, but inadequate HIF-1α expression in photoreceptors contributes to the development of GA.

Compartmentalized citrullination in Muller glial endfeet during retinal degeneration.

Muller glia (MG) play a central role in reactive gliosis, a stress response associated with rare and common retinal degenerative diseases, including age-related macular degeneration (AMD). The posttranslational modification citrullination​ targeting glial fibrillary acidic protein (GFAP) in MG was initially discovered in a panocular chemical injury model. Here, we report in the paradigms of retinal laser injury, a genetic model of spontaneous retinal degeneration (JR5558 mice) and human wet-AMD tissues that MG citrullination is broadly conserved. After laser injury, GFAP polymers that accumulate in reactive MG are citrullinated in MG endfeet and glial cell processes. The enzyme responsible for citrullination, peptidyl arginine deiminase-4 (PAD4), localizes to endfeet and associates with GFAP polymers. Glial cell-specific PAD4 deficiency attenuates retinal hypercitrullination in injured retinas, indicating PAD4 requirement for MG citrullination. In retinas of 1-mo-old JR5558 mice, hypercitrullinated GFAP and PAD4 accumulate in MG endfeet/cell processes in a lesion-specific manner. Finally, we show that human donor maculae from patients with wet-AMD also feature the canonical endfeet localization of hypercitrullinated GFAP. Thus, we propose that endfeet are a "citrullination bunker" that initiates and sustains citrullination in retinal degeneration.

Single-cell profiling transcriptomic reveals cellular heterogeneity and cellular crosstalk in choroidal neovascularization model.

Choroidal neovascularization (CNV) is a hallmark of neovascular age-related macular degeneration (nAMD) and a major contributor to vision loss in nAMD cases. However, the identification of specific cell types associated with nAMD remains challenging. Herein, we performed single-cell sequencing to comprehensively explore the cellular diversity and understand the foundational components of the retinal pigment epithelium (RPE)/choroid complex. We unveiled 10 distinct cell types within the RPE/choroid complex. Notably, we observed significant heterogeneity within endothelial cells (ECs), fibroblasts, and macrophages, underscoring the intricate nature of the cellular composition in the RPE/choroid complex. Within the EC category, four distinct clusters were identified and EC cluster 0 was tightly associated with choroidal neovascularization. We identified five clusters of fibroblasts actively involved in the pathogenesis of nAMD, influencing fibrotic responses, angiogenic effects, and photoreceptor function. Additionally, three clusters of macrophages were identified, suggesting their potential roles in regulating the progression of nAMD through immunomodulation and inflammation regulation. Through CellChat analysis, we constructed a complex cell-cell communication network, revealing the role of EC clusters in interacting with fibroblasts and macrophages in the context of nAMD. These interactions were found to govern angiogenic effects, fibrotic responses, and inflammatory processes. In summary, this study reveals noteworthy cellular heterogeneity in the RPE/choroid complex and provides valuable insights into the pathogenesis of CNV. These findings will open up potential avenues for deep understanding and targeted therapeutic interventions in nAMD.

Examining the correlation of lymphangiogenesis biomarkers with clinical condition in Age-Related Macular Degeneration (AMD).

The aim of this study is to investigate the relationship between age-related macular degeneration (AMD) and lymphangiogenesis biomarkers, namely LYVE-1, Podoplanin, VEGF-C, VEGFR-2 and VEGFR-3. This prospective and interventional study includes 30 patients with AMD which may be dry or wet type and 30 controls for whom vitrectomy and phacoemulsification was indicated due to additional pathologies (epiretinal membrane, macular hole, retinal detachment, and cataract). 0.1-0,2 ml of aqueous humor and 0.5-1 ml of vitreous sample was taken during the operations. Before the operations 1 tube serum was also taken. All the lymphangiogenesis biomarkers in the study are examined by ELISA method. LYVE-1 (p = 0.001) and Podoplanin (p = 0.004) levels in the vitreous for the patient group are found to be significantly lower than the control group. Serum (p = 0.019), vitreous (p = 0.001), aqueous (p < 0.001) levels of VEGF-C for the patient group are significantly higher than the control group. VEGF-C/VEGFR-2 (p < 0.001), VEGF-C/VEGFR-3 (p < 0.001) ratios in the vitreous for the patient group are found to be significantly higher than the control group. Especially in wet AMD patients, LYVE-1 level is significantly lower in the vitreous (p = 0.002) and aqueous (p = 0.002) than the control group. In addition, Podoplanin level is observed as significantly lower in the vitreous (p = 0.014) and serum (p = 0.002) in comparison to control group. In the wet AMD group, VEGF-C level in the vitreous (p < 0.001), aqueous (p < 0.001) and serum (p = 0.001) is higher than the control group. The result of this study indicates a valid relationship between the weakening of lymphangiogenesis and the pathophysiology of AMD, especially for the wet type. It is observed that the levels of receptors that bind VEGF-C (VEGFR-2 and VEGFR-3) do not increase at the same rate as VEGF-C to compensate for the increase in VEGF-C. The absence of an increase in VEGFR-3, which is especially necessary for lymphangiogenesis, also suggests that lymphangiogenesis is weakened or decreased in AMD. In the future interventional studies with larger series, examination of lymphangiogenic biomarkers in inflammatory retinal diseases and glaucoma may reveal unexplored details.

Metabolic Regulation of Endothelial Cells: A New Era for Treating Wet Age-Related Macular Degeneration.

Wet age-related macular degeneration (wet AMD) is a primary contributor to visual impairment and severe vision loss globally, but the prevailing treatments are often unsatisfactory. The development of conventional treatment strategies has largely been based on the understanding that the angiogenic switch of endothelial cells (ECs) is mainly dictated by angiogenic growth factors. Even though treatments targeting vascular endothelial growth factor (VEGF), like ranibizumab, are widely administered, more than half of patients still exhibit inadequate or null responses, suggesting the involvement of other pathogenic mechanisms. With advances in research in recent years, it has become well recognized that EC metabolic regulation plays an active rather than merely passive responsive role in angiogenesis. Disturbances of these metabolic pathways may lead to excessive neovascularization in angiogenic diseases such as wet AMD, therefore targeted modulation of EC metabolism represents a promising therapeutic strategy for wet AMD. In this review, we comprehensively discuss the potential applications of EC metabolic regulation in wet AMD treatment from multiple perspectives, including the involvement of ECs in wet AMD pathogenesis, the major endothelial metabolic pathways, and novel therapeutic approaches targeting metabolism for wet AMD.

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium.

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-ß (TGF-ß)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

Factors That Can Prolong Ocular Treatment Duration in Age-Related Macular Degeneration.

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) agents are used to treat wet age-related macular degeneration (wAMD); however, they are associated with a considerable treatment burden and poor real-world outcomes. The molecular size and charge of anti-VEGF agents influence drug pharmacokinetics in the vitreous and peak drug efficacy. This article reviews the established and novel strategies to prolong drug action, in the vitreal cavity, and thus reduce dosing frequency. Increased ocular residency can be attained by increasing drug size as with large molecules, such as KSI-301; adding polyethylene glycol to pegcetacoplan (APL-2) or avacincaptad pegol to increase molecular size; or binding to other targets that increase molecular size, such as vitreal albumin in the case of BI-X. Faricimab is a bispecific antibody in which the fragment crystallizable portion is engineered to prolong ocular residency and reduce systemic exposure. Conversely, small VEGF-binding molecules, such as brolucizumab, can be administered at higher clinical doses, with the potential for prolonged clinical activity versus larger molecules. Other important considerations include sustained drug delivery routes, such as the ranibizumab port delivery system or subconjunctival or suprachoroidal injection. More effective and longer-lasting treatments are needed for wAMD to prolong drug action and reduce dosing frequency. Several strategies are under investigation and the prevention of vision loss in patients with AMD or other retinal diseases may be attainable in the near future.

Efficacy and Safety of Biosimilar FYB201 Compared with Ranibizumab in Neovascular Age-Related Macular Degeneration.

PURPOSE: This trial was conducted to investigate the clinical equivalence of the proposed biosimilar FYB201 and reference ranibizumab in patients with treatment-naive, subfoveal choroidal neovascularization caused by neovascular age-related macular degeneration (nAMD). DESIGN: This was a prospective, multicenter, evaluation-masked, parallel-group, 48-week, phase III randomized study. PARTICIPANTS: A total of 477 patients were randomly assigned to receive FYB201 (n = 238) or reference ranibizumab (n = 239). METHODS: Patients received FYB201 or reference ranibizumab 0.5 mg by intravitreal (IVT) injection in the study eye every 4 weeks. MAIN OUTCOME MEASURES: The primary end point was change from baseline in best-corrected visual acuity (BCVA) by Early Treatment Diabetic Retinopathy Study (ETDRS) letters at 8 weeks before the third monthly IVT injection. Biosimilarity of FYB201 to its originator was assessed via a 2-sided equivalence test, with an equivalence margin in BCVA of 3 ETDRS letters. RESULTS: The BCVA improved in both groups, with a mean improvement of +5.1 (FYB201) and +5.6 (reference ranibizumab) ETDRS letters at week 8. The analysis of covariance (ANCOVA) least squares mean difference for the change from baseline between FYB201 and reference ranibizumab was -0.4 ETDRS letters with a 90% confidence interval (CI) of -1.6 to 0.9. Primary end point was met as the 90% CI was within the predefined equivalence margin. Adverse events were comparable between treatment groups. CONCLUSIONS: FYB201 is biosimilar to reference ranibizumab in terms of clinical efficacy and ocular and systemic safety in the treatment of patients with nAMD.

TNF-α signaling regulates RUNX1 function in endothelial cells.

Runt-related transcription factor 1 (RUNX1) acts as a mediator of aberrant retinal angiogenesis and has been implicated in the progression of proliferative diabetic retinopathy (PDR). Patients with PDR, retinopathy of prematurity (ROP), and wet age-related macular degeneration (wet AMD) have been found to have elevated levels of Tumor Necrosis Factor-alpha (TNF-α) in the eye. In fibrovascular membranes (FVMs) taken from patients with PDR RUNX1 expression was increased in the vasculature, while in human retinal microvascular endothelial cells (HRMECs), TNF-α stimulation causes increased RUNX1 expression, which can be modulated by RUNX1 inhibitors. Using TNF-α pathway inhibitors, we determined that in HRMECs, TNF-α-induced RUNX1 expression occurs via JNK activation, while NF-κB and p38/MAPK inhibition did not affect RUNX1 expression. JNK inhibitors were also effective at stopping high D-glucose-stimulated RUNX1 expression. We further linked JNK to RUNX1 through Activator Protein 1 (AP-1) and investigated the JNK-AP-1-RUNX1 regulatory feedback loop, which can be modulated by VEGF. Additionally, stimulation with TNF-α and D-glucose had an additive effect on RUNX1 expression, which was downregulated by VEGF modulation. These data suggest that the downregulation of RUNX1 in conjunction with anti-VEGF agents may be important in future treatments for the management of diseases of pathologic ocular angiogenesis.

Inhibition of ocular neovascularization by novel anti-angiogenic compound.

Aberrant angiogenesis lies at the heart of a wide range of ocular pathologies such as proliferative diabetic retinopathy, wet age-related macular degeneration and retinopathy of prematurity. This study explores the anti-angiogenic activity of a novel small molecule investigative compound capable of inhibiting profilin1-actin interaction recently identified by our group. We demonstrate that our compound is capable of inhibiting migration, proliferation and angiogenic activity of microvascular endothelial cells in vitro as well as choroidal neovascularization (CNV) ex vivo. In mouse model of laser-injury induced CNV, intravitreal administration of this compound diminishes sub-retinal neovascularization. Finally, our preliminary structure-activity relationship study (SAR) demonstrates that this small molecule compound is amenable to improvement in biological activity through structural modifications.

Peripheral blood CD163(+) monocytes and soluble CD163 in dry and neovascular age-related macular degeneration.

Macrophages are the main infiltrating immune cells in choroidal neovascularization (CNV), a hallmark of the human wet, or neovascular age-related macular degeneration (AMD). Due to their plasticity and ability to adapt to the local microenvironment in a tissue-dependent manner, macrophages display polar functional phenotypes characterized by their cell surface markers and their cytokine profiles. We found accumulation of hemoglobin-scavenging cluster of differentiation 163 (CD163)(+) macrophages in laser-induced CNV lesions and higher expression of CD163(+) monocytes in the peripheral blood on day 7 post injury in mice. In comparison, CD80(+) macrophages did not differ with laser-injury in young or aged mice and did not significantly change in the peripheral blood of CNV mice. We examined the percentages of CD163(+), CD206(+), and CD80(+) monocytes in the peripheral blood of patients with wet AMD, patients with dry AMD, and in age-matched individuals without AMD as controls. Percentages of peripheral blood CD163(+) monocytes in both dry AMD (P < .001) and wet AMD (P < .05) were higher than in age-matched non-AMD controls, while there was no difference between the groups in the percentages of peripheral CD206(+) and CD80(+) monocytes. Further, serum level of soluble CD163 (sCD163) was elevated only in patients with wet AMD (P < .05). An examination of 40 cytokine levels across the study groups revealed that anti-VEGF treated patients with wet AMD, who showed no exudative signs on the day of blood drawing had a cytokine profile that was similar to that of non-AMD individuals. These results indicate that CD163 could be further evaluated for its potential as a useful marker of disease activity in patients with neovascular AMD. Future studies will address the origin and potential mechanistic role of CD163(+) macrophages in wet AMD pathologies of angiogenesis and leakage of blood components.

Ocular Therapeutics and Molecular Delivery Strategies for Neovascular Age-Related Macular Degeneration (nAMD).

Age-related macular degeneration (AMD) is the leading cause of vision loss in geriatric population. Intravitreal (IVT) injections are popular clinical option. Biologics and small molecules offer efficacy but relatively shorter half-life after intravitreal injections. To address these challenges, numerous technologies and therapies are under development. Most of these strategies aim to reduce the frequency of injections, thereby increasing patient compliance and reducing patient-associated burden. Unlike IVT frequent injections, molecular therapies such as cell therapy and gene therapy offer restoration ability hence gained a lot of traction. The recent approval of ocular gene therapy for inherited disease offers new hope in this direction. However, until such breakthrough therapies are available to the majority of patients, antibody therapeutics will be on the shelf, continuing to provide therapeutic benefits. The present review aims to highlight the status of pre-clinical and clinical studies of neovascular AMD treatment modalities including Anti-VEGF therapy, upcoming bispecific antibodies, small molecules, port delivery systems, photodynamic therapy, radiation therapy, gene therapy, cell therapy, and combination therapies.

Brivanib, a multitargeted small-molecule tyrosine kinase inhibitor, suppresses laser-induced CNV in a mouse model of neovascular AMD.

In age-related macular degeneration (AMD), choroidal neovascularization (CNV), a major pathologic feature of neovascular AMD (nAMD), affects 10% of patients, potentially causing serious complications, including vision loss. Vascular endothelial growth factor receptor 2 (VEGFR2) and fibroblast growth factor receptor 1 (FGFR1) contribute to the pathogenesis of CNV. Brivanib is an oral selective dual receptor tyrosine kinase (RTK) inhibitor of FGFRs and VEGFRs, especially VEGFR2 and FGFR1. In this study, brivanib inhibited zebrafish embryonic angiogenesis without impairing neurodevelopment. In a mouse CNV model, brivanib intravitreal injection blocked phosphorylation of FGFR1 and VEGFR2 and reduced CNV leakage, area, and formation without causing intraocular toxicity. Moreover, brivanib oral gavage reduced CNV leakage and area. Accordingly, brivanib remained at high concentrations (above 14,000 ng/ml) in retinal/choroidal/scleral tissues following intravitreal injection. Similarly, brivanib remained at high concentrations (over 10,000 ng/ml) in retinal/choroidal/scleral tissues following oral gavage. Finally, in vitro cell experiments demonstrated that brivanib inhibited the proliferation, migration and tube formation of microvascular endothelial cells. In conclusion, our study suggested that brivanib treatment could be a novel therapeutic strategy for nAMD.

Fibulin-7 C-terminal fragment and its active synthetic peptide suppress choroidal and retinal neovascularization.

Wet age-related macular degeneration (AMD) and diabetic retinopathy are the leading causes of blindness through increased angiogenesis. Although VEGF-neutralizing proteins provide benefit, inconsistent responses indicate a need for new therapies. We previously identified the Fibulin-7 C-terminal fragment (Fbln7-C) as an angiogenesis inhibitor in vitro. Here we show that Fbln7-C inhibits neovascularization in vivo, in both a model of wet AMD involving choroidal neovascularization (CNV) and diabetic retinopathy involving oxygen-induced ischemic retinopathy. Furthermore, a short peptide sequence from Fbln7-C is responsible for the anti-angiogenic properties of Fbln7-C. Our work suggests Fbln7-C as a therapeutic candidate for wet AMD and ischemic retinopathy.

The microRNAs miR-302d and miR-93 inhibit TGFB-mediated EMT and VEGFA secretion from ARPE-19 cells.

The transforming growth factor-beta (TGFB) plays an essential role in the pathogenesis of some ophthalmologic diseases, including neovascular age-related macular degeneration (nAMD) and proliferative vitreoretinopathy (PVR). TGFB activates the transcription factors SMAD2 and SMAD3 via the TGFB receptor, which together activate several genes, including VEGFA. TGFB treated ARPE-19 cells show an increased proliferation rate and undergo epithelial to mesenchymal transition (EMT). Since microRNAs (miRNAs) are capable of inhibiting the translation of multiple genes, we screened for miRNAs that regulate the TGFB signalling pathways at multiple levels. In this study, we focused on two miRNAs, miR-302d and miR-93, which inhibit TGFB signalling pathway and therefore TGFB-induced EMT transition as well as VEGFA secretion from ARPE-19 cells. Furthermore, we could show that both miRNAs can retransform TGFB-stimulated mesenchymal ARPE-19 cells towards the morphological epithelial-like state. Taken together, transient overexpression of these miRNAs in RPE cells might be a promising approach for further translational strategies.

The flicker response of venous oxygen saturation is significantly reduced in the early and late stages of age-related macular degeneration.

BACKGROUND: Retinal oxygen saturation (SO2) during flicker light stimulation was measured non-invasively in humans with age-related macular degeneration (AMD). Furthermore, the differences between early and late stages of AMD were evaluated. METHODS: In 60 eyes of 45 AMD patients (74 ± 8.3 years) and 23 eyes of 23 healthy controls (73.4 ± 7.4 years), the SO2 of arterioles and venules was measured with the oximetry module of the Retinal Vessel Analyzer. Arterial SO2, venous SO2 and arteriovenous SO2 difference at baseline and with the flicker were assessed and compared with controls. From the difference between the arteriovenous SO2 under flicker stimulation and at baseline, the parameter delta av. Diff was calculated. Subgroup analyses of non-exudative (dry) AMD, exudative (wet) AMD and their end stages, geographic atrophy (GA) and disciform scar (DS) were performed. RESULTS: In comparison with healthy subjects (mean - 4.90, CI [- 6.32, - 3.43]), the parameter delta av. Diff was significantly reduced in all AMD patients (mean - 2.20, CI - 3.15, -1.23, p = 0.003), dry AMD (mean - 1.97, CI - 3.31, -0.63, p = 0.013) and wet AMD (mean - 2.35, CI - 3.50, - 1.19, p = 0.025). The comparison between wet and dry AMD revealed no significant results (p = 1). The comparison between AMD subgroups and healthy controls (median (IQR) - 4.29 (- 8.32; - 2.42) %) showed significant differences in non-neovascular (early dry AMD) (median (IQR) - 2.43 (- 4.59; - 0.74) %, p = 0.038), GA (median (IQR) 0.10 (- 4.02; 3.15) %, p = 0.019) and DS (median (IQR) - 1.67 (- 3.52; - 0.12) %, p = 0.03). A nearly significant reduction was observed in exudative (early wet) AMD (median (IQR) - 2.71 (- 5.84; - 0.2) %, p = 0.055). Minimal, not statistically significant differences of delta av. Diff were found between AMD subgroups. None of the baseline parameters was significantly different between patients and healthy controls, even after flicker light stimulation. CONCLUSIONS: Non-invasive retinal oximetry with flicker light stimulation seems to be a suitable method to study the pathogenetic mechanisms of AMD. The mathematically derived parameter delta av. Diff appears to be more sensitive than arteriovenous SO2 difference. Results suggest that the regulation of retinal oxygen supply, oxygen consumption or both is impaired in AMD.

PHARMACOKINETIC STUDY OF INTRAVITREAL AFLIBERCEPT IN HUMANS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To investigate the half-life of aflibercept in aqueous humor after a single intravitreal injection in patients with neovascular age-related macular degeneration. METHODS: Prospective, noncomparative, interventional case series of five eyes with neovascular age-related macular degeneration naive to anti-vascular endothelial growth factor therapy were enrolled and treated with intravitreal aflibercept. At baseline, best-corrected visual acuity, optical coherence tomography imaging, and aqueous humor (treatment eye) and blood/plasma samples were taken. Patients underwent best-corrected visual acuity, optical coherence tomography imaging, and sampling of aqueous humor from the eye and blood/plasma at six additional post-treatment time points of 4 hours and Days 1, 3, 7, 14, and 28. Concentrations of aflibercept were quantified using an enzyme-linked immunosorbent assay. RESULTS: Median peak concentration (Cmax) of free aflibercept in the aqueous was 122 mg/L. The median half-life of free aflibercept was 11 days in the eye. In plasma, the concentrations of free aflibercept were low and transient, reaching undetectable levels during the first week after injection, and undetectable in all patients at time points beyond 7 days. CONCLUSION: The pharmacokinetic profile in the aqueous humor described here together with the previously reported affinity of aflibercept for vascular endothelial growth factor is consistent with and adds to our understanding for the duration of its clinical efficacy.

THE RAP STUDY, REPORT TWO: The Regional Distribution of Macular Neovascularization Type 3, a Novel Insight Into Its Etiology.

PURPOSE: To explore the regional distribution of macular neovascularization type 3 (MNV3). METHODS: Seventy-eight eyes of 78 patients were reviewed. We defined the location of each lesion after applying a modified ETDRS grid and the incidence of simultaneous MNV1 or 2. Also, we investigated the distribution of MNV3 at the outline of the foveal avascular zone and when the diameter of foveal avascular zone was less than 325 µm. RESULTS: The distribution of MNV3 was 4 lesions (5%) from the center to 500 µm, 72 (92%) from 500 µm to 1500 µm, and 2 (3%) from 1,500 µm to 3000 µm. The distribution in respect of the ETDRS fields was 7 (9%) nasal, 16 (20%) superior, 32 (40%) temporal, and 23 (31%) inferior. No additional MNV1 or 2 were found elsewhere. Most lesions tended to distribute along straight bands radiating from the perifoveal area, mainly in the temporal half (72%). None of the cases had MNV3 at the boundary of the foveal avascular zone. Only five cases had foveal avascular zone diameter of less than 325 µm, the closest lesion was 425 µm away from the center. CONCLUSION: MNV3 lesions are most likely neither symmetrical nor uniformly distributed. They have a higher affinity to distribute radially in the temporal perifoveal area.

Comparison of cytokine levels in the aqueous humor of polypoidal choroidal vasculopathy and neovascular age-related macular degeneration patients.

BACKGROUND: The concentrations of cytokines in the aqueous humor from neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV) may vary. The study was conducted to compare various cytokine levels in the aqueous humor of eyes with PCV, nAMD and control. METHODS: The present case control study included 49 treatment-naïve eyes from 49 patients (PCV 24, nAMD 11, and cataract 14 eyes). Totally 34 angiogenic and inflammatory cytokines in the aqueous humor were measured by Luminex bead-based multiplex array. RESULTS: After adjusting for gender and age by multivariate logistic analysis, concentrations of IL-31, LIF, SDF1-α, VEGF-A, VEGF-D were significantly higher in eyes with nAMD or PCV compared with control eyes (all P < 0.05, times in nAMD: 59.5, 6.0, 7.0, 4.5, 5.6, respectively, times in PCV: 51.9, 5.21, 6.6, 4.0, 5.1, respectively), and concentrations of HGF, IP-10, MCP-1, IL-13 were significantly lower in eyes with nAMD or PCV than in control eyes (all P < 0.05, times in nAMD: 2.6, 2.0, 4.5, 4.7, respectively, times in PCV: 1.9, 3.0, 3.0, 2.8, respectively), but none of the 34 cytokines, including VEGF and IL-8, showed significantly different between eyes with nAMD and PCV. CONCLUSIONS: Various cytokines involved in inflammation and angiogenesis including elevated IL-31, LIF, SDF1-α, VEGF-A, VEGF-D might be involved in the pathogenesis of nAMD or PCV. None of the 34 cytokines may help to differentiate nAMD and PCV.

Evidence for Activation of Lectin and Classical Pathway Complement Components in Aqueous Humor of Neovascular Age-Related Macular Degeneration.

PURPOSE: The complement system is activated via 3 different pathways; the lectin pathway (LP), classical pathway (CP), and alternative pathway. To investigate the possible roles for the LP or CP in the development of neovascular age-related macular degeneration (nAMD), we compared aqueous humor levels of complement proteins of the LP and CP between eyes with nAMD and those with cataract as controls. METHODS: Seventeen eyes from 17 patients with treatment-naïve nAMD and 9 eyes from 9 patients with cataract were studied. Aqueous humor samples were collected before intravitreal aflibercept or ranibizumab injection for the nAMD patients and before cataract surgery for the cataract patients. Aqueous humor levels of complement C4 of the LP and CP, complement C3 of all 3 complement pathways, and mannose-binding lectin-associated serine protease (MASP)-2 of the LP were measured by enzyme-linked immunosorbent assay. Aqueous humor levels of C4a and C3a, the activation products of C4 and C3, respectively, were measured by a bead-based immunoassay. The ratios of C4a to C4 and C3a to C3, representing the degree of C4 and C3 activation, respectively, were calculated in individual patients. RESULTS: The aqueous humor levels of C4, C3, and MASP-2 were significantly lower in the nAMD eyes compared to the controls (p = 0.008, p = 0.011, and p = 0.018, respectively). In contrast, the aqueous humor levels of C4a and C3a, as well as the C4a/C4 and C3a/C3 ratios, were significantly higher in the nAMD eyes compared to the controls (p = 0.039, p = 0.003, p < 0.001, and p < 0.001, respectively). CONCLUSIONS: This study provides evidence for significant intraocular activation of either or both of the LP and CP in nAMD eyes that might be involved in the development of nAMD. The significantly lower levels of MASP-2 in the aqueous humor of the nAMD eyes were likely due to MASP-2 consumption by activation of the LP.