Placental growth factor and its potential role in diabetic retinopathy and other ocular neovascular diseases

Placental growth factor mediates pathological uterine angiogenesis by activating the NFAT5-SGK1 signaling axis in the endometrium: implications for preeclampsia development

After menstruation the uterine spiral arteries are repaired through angiogenesis. This process is tightly regulated by the paracrine communication between endometrial stromal cells (EnSCs) and endothelial cells. Any molecular aberration in these processes can lead to complications in pregnancy including miscarriage or preeclampsia (PE). Placental growth factor (PlGF) is a known contributing factor for pathological angiogenesis but the mechanisms remain poorly understood. In this study, we investigated whether PlGF contributes to pathological uterine angiogenesis by disrupting EnSCs and endothelial paracrine communication. We observed that PlGF mediates a tonicity-independent activation of nuclear factor of activated T cells 5 (NFAT5) in EnSCs. NFAT5 activated downstream targets including SGK1, HIF-1α and VEGF-A. In depth characterization of PlGF - conditioned medium (CM) from EnSCs using mass spectrometry and ELISA methods revealed low VEGF-A and an abundance of extracellular matrix organization associated proteins. Secreted factors in PlGF-CM impeded normal angiogenic cues in endothelial cells (HUVECs) by downregulating Notch-VEGF signaling. Interestingly, PlGF-CM failed to support human placental (BeWo) cell invasion through HUVEC monolayer. Inhibition of SGK1 in EnSCs improved angiogenic effects in HUVECs and promoted BeWo invasion, revealing SGK1 as a key intermediate player modulating PlGF mediated anti-angiogenic signaling. Taken together, perturbed PlGF-NFAT5-SGK1 signaling in the endometrium can contribute to pathological uterine angiogenesis by negatively regulating EnSCs-endothelial crosstalk resulting in poor quality vessels in the uterine microenvironment. Taken together the signaling may impact on normal trophoblast invasion and thus placentation and, may be associated with an increased risk of complications such as PE.

An examination of the mechanisms driving the therapeutic effects of an AAV expressing a soluble variant of VEGF receptor-1

In previous animal model studies, we demonstrated the potential of rAAV2-sVEGFRv-1, which encodes a truncated variant of the alternatively spliced soluble version of VEGF receptor-1 (VEGFR1), as a human gene therapy for age-related macular degeneration (AMD) and diabetic retinopathy (DR). Here, we elucidate in vitro some of the mechanisms by which rAAV2-sVEGFRv-1 exerts its therapeutic effects. Human umbilical vein endothelial cells (HUVECs) were infected with rAAV2-sVEGFRv-1 or a control virus vector in the presence of members of the VEGF family to identify potential binding partners via ELISA, which showed that VEGF-A, VEGF-B, and placental growth factor (PlGF) are all ligands of its transgene product. In order to determine the effects of rAAV2-sVEGFRv-1 on cell proliferation and permeability, processes that are important to the progression AMD and DR, HUVECs were infected with the therapeutic virus vector under the stimulation of VEGF-A, the major driver of the neovascularization that characterizes the forms of these conditions most associated with vision loss. rAAV2-sVEGFRv-1 treatment, as a result, markedly reduced the extent to which these processes occurred, with the latter determined by measuring zonula occludens 1 expression. Finally, the human microglial HMC3 cell line was used to show the effects of the therapeutic virus vector upon inflammatory processes, another major contributor to angiogenic eye disease pathophysiology, with rAAV2-sVEGFRv-1 reducing therein the secretion of pro-inflammatory cytokines interleukin (IL)-1β and IL-6. Combined with our previously published in vivo data, the in vitro activity of the expressed transgene here further demonstrates the great promise of rAAV2-sVEGFRv-1 as a potential human gene therapeutic for addressing angiogenic ocular conditions.

Switch to faricimab after initial treatment with aflibercept in eyes with diabetic macular edema

PURPOSE

To assess the effectiveness of a switch to faricimab in individuals affected by DME and previously treated with aflibercept.

METHODS

In this retrospective, single-center study, DME patients previously treated with at least 3 injections of aflibercept then switched to faricimab were enrolled. Best corrected visual acuity (BCVA) and central subfield thickness (CST) were recorded at baseline, at the time of the switch and at 6 months follow-up. At transition to faricimab, patients were categorized as "good visual responders" (≥ 5 letters from baseline) or "poor visual responders" (< 5 letters), and as "good anatomical responders" (any reduction in edema compared to baseline) or "poor anatomical responders" (no reduction or worsening of edema). Changes in BCVA and CST were recorded at 6 months after the switch to faricimab.

RESULTS

100 eyes of 100 patients (61 female, 61%) were switched to faricimab after a mean of 6.8 ± 3.3 aflibercept injections. At the 6 months follow-up, only "poor visual responders" (N = 62) demonstrated a meaningful increase in BCVA (Δswitch-6M =  + 5 letters; P = 0.007), coupled with a reduction in CST (Δswitch-6M = - 67.9 µm; P = 0.004); participants with "poor anatomical response" upon transitioning exhibited a significant functional gain (Δswitch-6M =  + 4.5 letters; p = 0.05) but limited CST enhancements (Δswitch-6M = - 95.1 µm; p = 0.05).

CONCLUSIONS

Faricimab shows a positive impact on anatomical and functional metrics in DME cases refractory to aflibercept.

Anti-angiogenic biomolecules in neovascular age-related macular degeneration; therapeutics and drug delivery systems

Blindness in the elderly is often caused by age-related macular degeneration (AMD). The advanced type of AMD known as neovascular AMD (nAMD) has been linked to being the predominant cause of visual impairment in these people. Multiple neovascular structures including choroidal neovascular (CNV) membranes, fluid exudation, hemorrhages, and subretinal fibrosis, are diagnostic of nAMD. These pathological alterations ultimately lead to anatomical and visual loss. It is known that vascular endothelial growth factor (VEGF), a type of proangiogenic factor, mediates the pathological process underlying nAMD. Therefore, various therapies have evolved to directly target the disease. In this review article, an attempt has been made to discuss general explanations about this disease, all common treatment methods based on anti-VEGF drugs, and the use of drug delivery systems in the treatment of AMD. Initially, the pathophysiology, angiogenesis, and different types of AMD were described. Then we described current treatments and future treatment prospects for AMD and outlined the advantages and disadvantages of each. In this context, we first examined the types of therapeutic biomolecules and anti-VEGF drugs that are used in the treatment of AMD. These biomolecules include aptamers, monoclonal antibodies, small interfering RNAs, microRNAs, peptides, fusion proteins, nanobodies, and other therapeutic biomolecules. Finally, we described drug delivery systems based on liposomes, nanomicelles, nanoemulsions, nanoparticles, cyclodextrin, dendrimers, and composite vehicles that are used in AMD therapy.

Intravitreal conbercept injection with panretinal photocoagulation for high-risk proliferative diabetic retinopathy with vitreous hemorrhage

AIM

To assess the clinical efficacy and safety of combining panretinal photocoagulation (PRP) with intravitreal conbercept (IVC) injections for patients with high-risk proliferative diabetic retinopathy (HR-PDR) complicated by mild or moderate vitreous hemorrhage (VH), with or without diabetic macular edema (DME).

METHODS

Patients diagnosed with VH with/without DME secondary to HR-PDR and received PRP combined with IVC injections were recruited in this retrospective study. Upon establishing the patient's diagnosis, an initial IVC was performed, followed by prompt administration of PRP. In cases who significant bleeding persisted and impeded the laser operation, IVC was sustained before supplementing with PRP. Following the completion of PRP, patients were meticulously monitored for a minimum of six months. Laser therapy and IVC injections were judiciously adjusted based on fundus fluorescein angiography (FFA) results. Therapeutic effect and the incidence of adverse events were observed.

RESULTS

Out of 42 patients (74 eyes), 29 were male and 13 were female, with a mean age of 59.17±12.74y (33-84y). The diabetic history was between 1wk and 26y, and the interval between the onset of visual symptoms and diagnosis of HR-PDR was 1wk-1y. The affected eye received 2.59±1.87 (1-10) IVC injections and underwent 5.5±1.02 (4-8) sessions of PRP. Of these, 68 eyes received PRP following 1 IVC injection, 5 eyes after 2 IVC injections, and 1 eye after 3 IVC injections. Complete absorption of VH was observed in all 74 eyes 5-50wk after initial treatment, with resolution of DME in 51 eyes 3-48wk after initial treatment. A newly developed epiretinal membrane was noted in one eye. Visual acuity significantly improved in 25 eyes. No complications such as glaucoma, retinal detachment, or endophthalmitis were reported.

CONCLUSION

The study suggests that the combination of PRP with IVC injections is an effective and safe modality for treating diabetic VH in patients with HR-PDR.

Anti-angiogenic and antioxidant effects of axitinib in human retinal endothelial cells: implications in diabetic retinopathy

Diabetic retinopathy is a secondary microvascular complication of diabetes mellitus. This disease progresses from two stages, non-proliferative and proliferative diabetic retinopathy, the latter characterized by retinal abnormal angiogenesis. Pharmacological management of retinal angiogenesis employs expensive and invasive intravitreal injections of biologic drugs (anti-vascular endothelial growth factor agents). To search small molecules able to act as anti-angiogenic agents, we focused our study on axitinib, which is a tyrosine kinase inhibitor and represents the second line treatment for renal cell carcinoma. Axitinib is an inhibitor of vascular endothelial growth factor receptors, and among the others tyrosine kinase inhibitors (sunitinib and sorafenib) is the most selective towards vascular endothelial growth factor receptors 1 and 2. Besides the well-known anti-angiogenic and immune-modulatory functions, we hereby explored the polypharmacological profile of axitinib, through a bioinformatic/molecular modeling approach and in vitro models of diabetic retinopathy. We showed the anti-angiogenic activity of axitinib in two different in vitro models of diabetic retinopathy, by challenging retinal endothelial cells with high glucose concentration (fluctuating and non-fluctuating). We found that axitinib, along with inhibition of vascular endothelial growth factor receptors 1 (1.82 ± 0.10; 0.54 ± 0.13, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) and vascular endothelial growth factor receptors 2 (2.38 ± 0.21; 0.98 ± 0.20, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively), was able to significantly reduce (p < 0.05) the expression of Nrf2 (1.43 ± 0.04; 0.85 ± 0.01, protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) in retinal endothelial cells exposed to high glucose, through predicted Keap1 interaction and activation of melanocortin receptor 1. Furthermore, axitinib treatment significantly (p < 0.05) decreased reactive oxygen species production (0.90 ± 0.10; 0.44 ± 0.06, fluorescence units in high glucose vs . axitinib 1 µM, respectively) and inhibited ERK pathway (1.64 ± 0.09; 0.73 ± 0.06, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) in HRECs exposed to high glucose. The obtained results about the emerging polypharmacological profile support the hypothesis that axitinib could be a valid candidate to handle diabetic retinopathy, with ancillary mechanisms of action.

Treatment Outcomes of Intravitreal Aflibercept for Uveitic Macular Edema

BACKGROUND/AIMS

To evaluate the efficacy of intravitreal aflibercept for UME (uveitic macular).

METHODS

A retrospective review of records of patients that received aflibercept for UME from January 2017 to August 2022 was conducted. The primary outcomes were mean change in visual acuity (VA) and central subfield thickness (CST) 6 and 12 months from the start of aflibercept treatment.

RESULTS

A total of 16 eyes of 12 patients were included. Indications for treatment included eyes that had previously demonstrated a history of elevated intraocular pressure secondary to a steroid response (n = 10) or a history of non-response or partial response to local corticosteroids (n = 6). Fifteen eyes (94%) demonstrated a reduction in CST after their initial injection. At 6-months, mean VA gain was 2.6 ± 7.7 letters (p = 0.24) from a mean VA of 67.8 ± 10.7 letters at baseline and mean CST improved by 97.6 ± 113.5 μm (p = 0.004) from 458.6 ± 123.1 μm at baseline. Fourteen eyes had 12-months of follow up and received a median of 4 injections over 12 visits. The mean VA at 12-months remained stable compared to baseline (mean change of -1.4 ± 12.5 letters (p = 0.87)) while the CST improved by a mean of 90.9 ± 114.6 μm (p = 0.053) compared to baseline.

CONCLUSION

Intravitreal aflibercept injections resulted in reduced central subfield thickness at all time-points. It appears to be an effective treatment alternative for UME, particularly for patients who are not responsive to local corticosteroids or who have contraindications to corticosteroid treatment.

Crosstalk Between Microglia and Müller Glia in the Age-Related Macular Degeneration: Role and Therapeutic Value of Neuroinflammation

Age-related macular degeneration (AMD) is a progressive neurodegeneration disease that causes photoreceptor demise and vision impairments. In AMD pathogenesis, the primary death of retinal neurons always leads to the activation of resident microglia. The migration of activated microglia to the ongoing retinal lesion and their morphological transformation from branching to ameboid-like are recognized as hallmarks of AMD pathogenesis. Activated microglia send signals to Müller cells and promote them to react correspondingly to damaging stimulus. Müller cells are a type of neuroglia cells that maintain the normal function of retinal neurons, modulating innate inflammatory responses, and stabilize retinal structure. Activated Müller cells can accelerate the progression of AMD by damaging neurons and blood vessels. Therefore, the crosstalk between microglia and Müller cells plays a homeostatic role in maintaining the retinal environment, and this interaction is complicatedly modulated. In particular, the mechanism of mutual regulation between the two glia populations is complex under pathological conditions. This paper reviews recent findings on the crosstalk between microglia and Müller glia during AMD pathology process, with special emphasis on its therapeutic potentials.

Excessive endometrial PlGF- Rac1 signalling underlies endometrial cell stiffness linked to pre-eclampsia

Cell stiffness is regulated by dynamic interaction between ras-related C3 botulinum toxin substrate 1 (Rac1) and p21 protein-activated kinase 1 (PAK1) proteins, besides other biochemical and molecular regulators. In this study, we investigated how the Placental Growth Factor (PlGF) changes endometrial mechanics by modifying the actin cytoskeleton at the maternal interface. We explored the global effects of PlGF in endometrial stromal cells (EnSCs) using the concerted approach of proteomics, atomic force microscopy (AFM), and electrical impedance spectroscopy (EIS). Proteomic analysis shows PlGF upregulated RhoGTPases activating proteins and extracellular matrix organization-associated proteins in EnSCs. Rac1 and PAK1 transcript levels, activity, and actin polymerization were significantly increased with PlGF treatment. AFM further revealed an increase in cell stiffness with PlGF treatment. The additive effect of PlGF on actin polymerization was suppressed with siRNA-mediated inhibition of Rac1, PAK1, and WAVE2. Interestingly, the increase in cell stiffness by PlGF treatment was pharmacologically reversed with pravastatin, resulting in improved trophoblast cell invasion. Taken together, aberrant PlGF levels in the endometrium can contribute to an altered pre-pregnancy maternal microenvironment and offer a unifying explanation for the pathological changes observed in conditions such as pre-eclampsia (PE).

Diabetic Disease of the Eye in Canada: Consensus Statements from a Retina Specialist Working Group

Despite advances in systemic care, diabetic disease of the eye (DDE) remains the leading cause of blindness worldwide. There is a critical gap of up-to-date, evidence-based guidance for ophthalmologists in Canada that includes evidence from recent randomized controlled trials. Previous guidance has not always given special consideration to applying treatments and managing DDE in the context of the healthcare system. This consensus statement aims to assist practitioners in the field by providing a spectrum of acceptable opinions on DDE treatment and management from recognized experts in the field. In compiling evidence and generating consensus, a working group of retinal specialists in Canada addressed clinical questions surrounding the four themes of disease, patient, management, and collaboration. The working group reviewed literature representing the highest level of evidence on DDE and shared their opinions on topics surrounding the epidemiology and pathophysiology of diabetic retinopathy and diabetic macular edema; diagnosis and monitoring; considerations around diabetes medication use; strategic considerations for management given systemic comorbidities, ocular comorbidities, and pregnancy; treatment goals and modalities for diabetic macular edema, non-proliferative and proliferative diabetic retinopathy, and retinal detachment; and interdisciplinary collaboration. Ultimately, this work highlighted that the retinal examination in DDE not only informs the treating ophthalmologist but can serve as a global index for disease progression across many tissues of the body. It highlighted further that DDE can be treated regardless of diabetic control, that a systemic approach to patient care will result in the best health outcomes, and prevention of visual complications requires a multidisciplinary management approach. Ophthalmologists must tailor their clinical approach to the needs and circumstances of individual patients and work within the realities of their healthcare setting.

Analytical and Functional Similarity of Aflibercept Biosimilar ABP 938 with Aflibercept Reference Product

INTRODUCTION

ABP 938 is being developed as a biosimilar candidate to aflibercept reference product (RP), a biologic used for certain angiogenic eye disorders. This study was designed to provide a comparative analytical assessment of the structural and functional attributes of ABP 938 and aflibercept RP sourced from the United States (US) and the European Union (EU).

METHODS

Structural and functional characterization studies were performed using state-of-the-art analytical techniques that were appropriate to assess relevant quality attributes and capable of detecting qualitative and quantitative differences in primary structure, higher-order structure and biophysical properties, product-related substances and impurities, general properties, and biological activities.

RESULTS

ABP 938 had the same amino acid sequence and exhibited similar secondary and tertiary structures, and biological activity as aflibercept RP. There were minor differences in a small number of biochemical attributes which are not expected to impact clinical performance. In addition, aflibercept RP sourced from the US and EU were analytically similar.

CONCLUSIONS

ABP 938 was structurally and functionally similar to aflibercept RP. Since aflibercept RP sourced from the US and EU were analytically similar, this allows for the development of a scientific bridge such that a single-source RP can be used in nonclinical and clinical studies.

Aflibercept Off-Target Effects in Diabetic Macular Edema: An In Silico Modeling Approach

Intravitreal aflibercept injection (IAI) is a treatment for diabetic macular edema (DME), but its mechanism of action (MoA) has not been completely elucidated. Here, we aimed to explore IAI's MoA and its multi-target nature in DME pathophysiology with an in silico (computer simulation) disease model. We used the Therapeutic Performance Mapping System (Anaxomics Biotech property) to generate mathematical models based on the available scientific knowledge at the time of the study, describing the relationship between the modulation of vascular endothelial growth factor receptors (VEGFRs) by IAI and DME pathophysiological processes. We also undertook an enrichment analysis to explore the processes modulated by IAI, visualized the effectors' predicted protein activity, and specifically evaluated the role of VEGFR1 pathway inhibition on DME treatment. The models simulated the potential pathophysiology of DME and the likely IAI's MoA by inhibiting VEGFR1 and VEGFR2 signaling. The action of IAI through both signaling pathways modulated the identified pathophysiological processes associated with DME, with the strongest effects in angiogenesis, blood-retinal barrier alteration and permeability, and inflammation. VEGFR1 inhibition was essential to modulate inflammatory protein effectors. Given the role of VEGFR1 signaling on the modulation of inflammatory-related pathways, IAI may offer therapeutic advantages for DME through sustained VEGFR1 pathway inhibition.

Levosulpiride for the treatment of diabetic macular oedema: a phase 2 randomized clinical trial

BACKGROUND/OBJECTIVE

The prokinetic levosulpiride elevates vasoinhibin levels in the vitreous of patients with proliferative diabetic retinopathy (PDR) suggesting clinical benefits due to the anti-vasopermeability and anti-angiogenic properties of vasoinhibin. We investigated the biological activity of levosulpiride in centre-involving diabetic macular oedema (DME).

PATIENTS/METHODS

Prospective, randomized, double-blinded, dual-centre, phase 2 trial in patients with centre-involving DME orally treated with placebo (n = 17) or levosulpiride (n = 17) for 8 weeks or in patients with PDR undergoing elective pars plana vitrectomy and receiving placebo (n = 18) or levosulpiride (n = 18) orally for the 1 week before vitrectomy.

RESULTS

Levosulpiride improved changes from baseline in best-corrected visual acuity (p ≤ 0.037), central foveal thickness (CFT, p ≤ 0.013), and mean macular volume (MMV, p ≤ 0.002) at weeks 4, 6, and 8 compared to placebo. At 8 weeks, the proportion of eyes gaining ≥5 ETDRS letters at 4 m (41% vs. 28%), losing ≥21 μm in CFT (55% vs. 28%), and dropping ≥0.06 mm3 in MMV (65% vs. 29%) was higher after levosulpiride than placebo. The overall grading of visual and structural parameters improved with levosulpiride (p = 0.029). Levosulpiride reduced VEGF (p = 0.025) and PlGF (p = 0.008) levels in the vitreous of PDR patients. No significant adverse side-effects were detected.

CONCLUSIONS

Oral levosulpiride for 8 weeks improved visual and structural outcomes in patients with centre-involving DME by mechanisms that may include intraocular upregulation of vasoinhibin and downregulation of VEGF and PlGF. Larger clinical trials evaluating long-term efficacy and safety are warranted.

A study of the relationship between cytokine levels and the response to anti-VEGF therapy in polypoid choroidal vasculopathy with different choroidal thicknesses

Purpose

Polypoidal choroidal vasculopathy (PCV) is an irreversible retinal choroidal disease. Individuals with PCV exhibit diverse baseline characteristics, including systemic characteristics, ocular traits, metabolic factor levels, and different responses to intravitreal anti-VEGF therapy. This study aims to investigate the pathogenesis of PCV by analyzing the systemic characteristics, ocular traits, and cytokine levels at baseline within a cohort of patients who exhibit different responses to anti-VEGF treatment.

Methods

We conducted a retrospective analysis involving 80 eyes diagnosed with PCV. Patients were categorized into two groups based on responses to suboptimal intravitreal ranibizumab injection therapy: those with suboptimal responses and optimal responses. Aqueous humor samples were collected from the experimental eyes, and cytokine expression levels were assessed using cytometric bead array analysis. All subjects were further stratified into two groups according to the median choroidal thickness. Subsequently, logistic regression analysis and the ROC curve were employed to examine the relationship between cytokine expression levels, choroidal thickness, and anti-VEGF response.

Results

The results revealed that compared to the group of optimal anti-VEGF response, the choroid in the suboptimal response group exhibited a significantly greater thickness. Additionally, compared to the suboptimal anti-VEGF response group, the expression levels of VEGF and VCAM-1 were markedly lower observed in the optimal anti-VEGF response group, while TNF-α showed the opposite trend. Logistic regression analysis indicated that VEGF, VCAM-1, and TNF-α in the aqueous humor were independent risk factors for a suboptimal anti-VEGF response. After adjusting other risk factors, the risk of suboptimal anti-VEGF response decreased to 0.998-fold, 0.997-fold, and 1.294-fold. The AUC values for VEGF, VCAM-1, and TNF-α were determined to be 0.805, 0.846, and 0.897, respectively. Furthermore, the risk of VEGF, VCAM-1, and TNF-α were significantly associated with an increased risk of suboptimal anti-VEGF response after correction for risk factors in the thick choroid group.

Conclusions

Our study demonstrated that PCV exhibits systemic and ocular characteristics variations based on different anti-VEGF responses. The levels of cytokines in aqueous humor were found to have a significant correlation with the anti-VEGF response in PCV. VEGF, VCAM-1, and TNF-α are potential targets for assessing treatment response in thick choroidal PCV.

Serum Placental Growth Factor as a Marker of Cerebrovascular Disease Burden in Alzheimer's Disease

BACKGROUND

Concomitant cerebrovascular diseases (CeVD) have been identified as an important determinant of Alzheimer's disease (AD) progression. Development of robust blood-based biomarkers will provide critical tools to evaluate prognosis and potential interventional strategies for AD with CeVD.

OBJECTIVE

This study investigated circulating placental growth factor (PlGF), a potent pro-angiogenic factor related to endothelial dysfunction and vascular inflammation, in an Asian memory clinic cohort of non-demented individuals as well as AD, including its associations with neuroimaging markers of CeVD.

METHODS

109 patients with AD, 76 cognitively impaired with no dementia (CIND), and 56 non-cognitively impaired (NCI) were included in this cross-sectional study. All subjects underwent 3T brain magnetic resonance imaging to assess white matter hyperintensities (WMH), lacunes, cortical infarcts, and cerebral microbleeds (CMBs). Serum PlGF concentrations were measured by electrochemiluminescence immunoassays.

RESULTS

Serum PlGF was elevated in AD, but not CIND, compared to the NCI controls. Adjusted concentrations of PlGF were associated with AD only in the presence of significant CeVD. Elevated PlGF was significantly associated with higher burden of WMH and with CMBs in AD patients.

CONCLUSIONS

Serum PlGF has potential utility as a biomarker for the presence of CeVD, specifically WMH and CMBs, in AD. Further studies are needed to elucidate the underlying pathophysiological mechanisms linking PlGF to CeVD, as well as to further assess PlGF's clinical utility.

Mitochondrial-targeted antioxidant attenuates preeclampsia-like phenotypes induced by syncytiotrophoblast-specific Gαq signaling

Syncytiotrophoblast stress is theorized to drive development of preeclampsia, but its molecular causes and consequences remain largely undefined. Multiple hormones implicated in preeclampsia signal via the Gαq cascade, leading to the hypothesis that excess Gαq signaling within the syncytiotrophoblast may contribute. First, we present data supporting increased Gαq signaling and antioxidant responses within villous and syncytiotrophoblast samples of human preeclamptic placenta. Second, Gαq was activated in mouse placenta using Cre-lox and DREADD methodologies. Syncytiotrophoblast-restricted Gαq activation caused hypertension, kidney damage, proteinuria, elevated circulating proinflammatory factors, decreased placental vascularization, diminished spiral artery diameter, and augmented responses to mitochondrial-derived superoxide. Administration of the mitochondrial-targeted antioxidant Mitoquinone attenuated maternal proteinuria, lowered circulating inflammatory and anti-angiogenic mediators, and maintained placental vascularization. These data demonstrate a causal relationship between syncytiotrophoblast stress and the development of preeclampsia and identify elevated Gαq signaling and mitochondrial reactive oxygen species as a cause of this stress.

The Slow Progression of Diabetic Retinopathy Is Associated with Transient Protection of Retinal Vessels from Death

The purpose of this study was to investigate the reason that diabetic retinopathy (DR) is delayed from the onset of diabetes (DM) in diabetic mice. To this end, we tested the hypothesis that the deleterious effects of DM are initially tolerated because endogenous antioxidative defense is elevated and thereby confers resistance to oxidative stress-induced death. We found that this was indeed the case in both type 1 DM (T1D) and type 2 DM (T2D) mouse models. The retinal expression of antioxidant defense genes was increased soon after the onset of DM. In addition, ischemia/oxidative stress caused less death in the retinal vasculature of DM versus non-DM mice. Further investigation with T1D mice revealed that protection was transient; it waned as the duration of DM was prolonged. Finally, a loss of protection was associated with the manifestation of both neural and vascular abnormalities that are diagnostic of DR in mice. These observations demonstrate that DM can transiently activate protection from oxidative stress, which is a plausible explanation for the delay in the development of DR from the onset of DM.

Association of Placental Growth Factor and Angiopoietin in Human Retinal Endothelial Cell-Pericyte co-Cultures and iPSC-Derived Vascular Organoids

PURPOSE

Placental growth factor (PlGF) and Angiopoietin (Ang)-1 are two proteins that are involved in the regulation of endothelial cell (EC) growth and vasculature formation. In the retina and endothelial cells, pericytes are the major source of both molecules. The purpose of this study is to examine the association of PlGF and Ang-1 with human EC/pericyte co-cultures and iPSC-derived vascular organoids.

METHODS

In this study, we used co-cultures of human primary retinal endothelial cells (HREC) and primary human retinal pericytes (HRP), western blotting, immunofluorescent analysis, TUNEL staining, LDH-assays, and RNA seq analysis, as well as human-induced pluripotent stem cells (iPSC), derived organoids (VO) to study the association between PlGF and Ang-1.

RESULTS

Inhibition of PlGF by PlGF neutralizing antibody in HREC-HRP co-cultures resulted in the increased expression of Ang-1 and Tie-2 in a dose-dependent manner. This upregulation was not observed in HREC and HRP monocultures but only in co-cultures suggesting the association of pericytes and endothelial cells. Furthermore, Vascular endothelial growth factor receptor 1 (VEGFR1) inhibition abolished the Ang-1 and Tie-2 upregulation by PlGF inhibition. The pericyte viability in high-glucose conditions was also reduced by VEGFR1 neutralization. Immunofluorescent analysis showed that Ang-1 and Ang-2 were expressed mainly by perivascular cells in the VO. RNA seq analysis of the RNA isolated from VO in high glucose conditions indicated increased PlGF and Ang-2 expressions in the VO. PlGF inhibition increased the expression of Ang-1 and Tie-2 in VO, increasing the pericyte coverage of the VO microvascular network.

CONCLUSION

Combined, these results suggest PlGF's role in the regulation of Ang-1 and Tie-2 expression through VEGFR1. These findings provide new insights into the neovascularization process in diabetic retinopathy and new targets for potential therapeutic intervention.

Retinopathy of prematurity: A review of pathophysiology and signaling pathways

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the retina and a leading cause of visual impairment and childhood blindness worldwide. The disease is characterized by an early stage of retinal microvascular degeneration, followed by neovascularization that can lead to subsequent retinal detachment and permanent visual loss. Several factors play a key role during the different pathological stages of the disease. Oxidative and nitrosative stress and inflammatory processes are important contributors to the early stage of ROP. Nitric oxide synthase and arginase play important roles in ischemia/reperfusion-induced neurovascular degeneration. Destructive neovascularization is driven by mediators of the hypoxia-inducible factor pathway, such as vascular endothelial growth factor and metabolic factors (succinate). The extracellular matrix is involved in hypoxia-induced retinal neovascularization. Vasorepulsive molecules (semaphorin 3A) intervene preventing the revascularization of the avascular zone. This review focuses on current concepts about signaling pathways and their mediators, involved in the pathogenesis of ROP, highlighting new potentially preventive and therapeutic modalities. A better understanding of the intricate molecular mechanisms underlying the pathogenesis of ROP should allow the development of more effective and targeted therapeutic agents to reduce aberrant vasoproliferation and facilitate physiological retinal vascular development.

Comprehensive assessment of growth factors, inflammatory mediators, and cytokines in vitreous from patients with proliferative diabetic retinopathy

AIM

To assess alterations in growth factors, inflammatory mediators, and cytokines associated with vitreous-retinal diseases in vitreous humor from patients with proliferative diabetic retinopathy (PDR), and to identify potential new treatment targets and strategies.

METHODS

Control vitreous samples were collected from patients with macular hole, epiretinal membranes, or rhegmatogenous retinal detachments, and PDR samples from patients with complications of PDR, who required pars plana vitrectomy. Specimens were stored at -80°C and then investigated by Luminex multi-factor assay. Parametric and nonparametric analyses of demographic characteristics and cytokine expression levels were conducted using SPSS.

RESULTS

There were no significant differences in demographic characteristics between patients with and without PDR. Expression levels of growth factors [platelet-derived growth factor (PDGF)-AA, glial cell line-derived neurotrophic factor (GDNF), and vascular endothelial growth factor A (VEGFA)], inflammatory mediators [interleukin (IL)-8, IL-11, and tumor necrosis factor-α (TNF-α)] and cytokines [chemokine C-X-C ligand (CXCL)10, interferon-γ (IFN-γ), and granulocyte macrophage-colony stimulating factor (GM-CSF)] were significantly elevated in vitreous humor from patients with PDR compared with those in the control group (all P<0.05). Further, VEGFA levels were lower in patients with PDR treated with anti-VEGF injection than those who were not (P<0.05), and there was no difference between the PDR group treated with anti-VEGF and controls (P>0.05).

CONCLUSION

This proof-of-concept study demonstrates the potential for combinational therapeutic strategies to ameliorate diabetic retinopathy progression by targeting growth factors, inflammatory factors, and cytokines, in addition to VEGFA.

TGFβ1 Induces Senescence and Attenuated VEGF Production in Retinal Pericytes

Diabetic retinopathy (DR) is a microvascular disease of the retina and a serious complication of type I and type II diabetes mellitus. DR affects working-age populations and can cause permanent vision loss if left untreated. The standard of care for proliferative DR is inhibiting VEGF. However, the mechanisms that induce excessive VEGF production in the retina remain elusive, although some evidence links elevated VEGF in the diabetic retina with local and systemic TGFβ1 upexpression. Here, we present evidence from animal models of disease suggesting that excessive TGFβ1 production in the early DR is correlated with VEGF mRNA and protein production by senescent pericytes and other retinal cells. Collectively, these results confirm that TGFβ1 is strongly implicated in the vascular complications of DR.

Functional and structural characteristics in patients with diabetic macular oedema after switching from ranibizumab to aflibercept treatment. Three year results in real world settings

Background

Our aim was to examine the long term anatomical and functional outcomes in patients with refractory diabetic macular oedema (DMO) undergoing treatment switch from ranibizumab to aflibercept.

Methods

Retrospective review of patients with DMO undergoing treatment switch from ranibizumab to aflibercept at a single centre between 2015 and 2017. Primary outcomes were best corrected visual acuity (BCVA) and central macular thickness (CMT).

Results

57 eyes from 44 patients were included. Following switch to aflibercept, median (IQR) BCVA improved to 73 (64–77) letters at 3 months (p = 0.0006), to 73 (61–78) letters at 6 months (p = 0.0042), to 73 (65–77) at 9 months (p = 0.0006), and to 73 (63–75) letters at 18 months (p = 0.0444). At 36 months following switch, 12 eyes had gained > 10 letters, 5 eyes had gained 5–9 letters, 25 remained stable (± 5 letters), 7 eyes lost 5–9 letters and 8 eyes lost > 10 letters. A significant reduction in CMT at all trimesters following treatment switch was found except at month 24.

Conclusions

We provide real world data suggesting a sustained anatomical and functional benefit of switching from ranibizumab to aflibercept in the treatment of refractory DMO.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40942-022-00373-5.

Retinopathy of prematurity: contribution of inflammatory and genetic factors

Retinopathy of prematurity (ROP) is a retinal vasoproliferative disorder that represents an important cause of childhood visual impairment and blindness. Although oxidative stress has long been implicated in ROP etiology, other prenatal and perinatal factors are also involved. This review focuses on current research involving inflammation and genetic factors in the pathogenesis of ROP. Increasing evidence suggests that perinatal inflammation or infection contributes to ROP pathogenesis. Cytokines and chemokines with a fundamental role in inflammatory responses and that significantly contributing to angiogenesis are analyzed. Microglia cells, the retinal-resident macrophages, are crucial for retinal homeostasis, however, under sustained pathological stimuli release exaggerated amounts of inflammatory mediators and can promote pathological neovascularization. Current modulation of angiogenic cytokines, such as treatment with antibodies to vascular endothelial growth factor (anti-VEGF), has shown efficacy in the treatment of ocular neovascularization; however, some patients are refractory to anti-VEGF agents, suggesting that other angiogenic or anti-angiogenic cytokines need to be identified. Much evidence suggests that genetic factors contribute to the phenotypic variability of ROP. Several studies have implicated the involvement of candidate genes from different signaling pathways in the development of ROP. However, a genetic component with a major impact on ROP has not yet been discovered. Most studies have limitations and did not replicate results. Future research involving bioinformatics, genomics, and proteomics may contribute to finding more genes associated with ROP and may allow discovering better solutions in the management and treatment of ROP.

The role of inflammation and neurodegeneration in diabetic macular edema

The pathogenesis of diabetic macular edema (DME) is complex. Persistently high blood glucose activates multiple cellular pathways and induces inflammation, oxidation stress, and vascular dysfunction. Retinal ganglion cells, macroglial and microglial cells, endothelial cells, pericytes, and retinal pigment epithelium cells are involved. Neurodegeneration, characterized by dysfunction or apoptotic loss of retinal neurons, occurs early and independently from the vascular alterations. Despite the increasing knowledge on the pathways involved in DME, only limited therapeutic strategies are available. Besides antiangiogenic drugs and intravitreal corticosteroids, alternative therapeutic options tackling inflammation, oxidative stress, and neurodegeneration have been considered, but none of them has been currently approved.

Dysregulated Serum Lipid Metabolism Promotes the Occurrence and Development of Diabetic Retinopathy Associated With Upregulated Circulating Levels of VEGF-A, VEGF-D, and PlGF

Purpose: This study aims to explore the correlations of arteriosclerosis-associated plasma indices with various severity levels of diabetic retinopathy (DR) and to test the hypothesis that elevated circulating level of known angiogenic cytokines induced by hyperglycemia is associated with dyslipidemia on DR. Methods: This cross-sectional study consists of 131 patients with type 2 diabetes. The patients were categorized based on their DR status into those with no DR (diabetes mellitus, DM), non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR) groups. The biochemical profile including fasting glucose, glycated hemoglobin (HbA1c), lipid profile were estimated, plasma angiogenic cytokines (vascular endothelial growth factor, VEGF-A, -C, -D) and placental growth factor (PlGF) were analyzed by protein microarrays. The atherogenic plasma index (API) was defined as low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL-C/HDL-C); atherogenic index (AI) was calculated as (TC-(HDL-C))/HDL-C and atherogenic index of plasma (AIP) was defined as log (TG/HDL-C). Results: No significant differences were detected in the duration of hypertension, age, and gender between the three groups. Serum TC and LDL-C, AI, and API in the NPDR group and PDR group were significantly higher than those in the DM group. The circulating level of PlGF, VEGF-A, and VEGF-C were significantly correlated with the severity of DR. VEGF-D is a risk factor independent of API (Z = -2.61, P = 0.009) and AI (Z = -2.40, P = 0.016). Multivariate logistic regression showed that AI and API are strong risk factors for the occurrence and severity of DR. Associated with AI and API, VEGF-D and PlGF contribute to DR: VEGF-D [AI: P = 0.038, odd ratio (OR) = 1.38; VEGF-D: P = 0.002, OR = 1.00. API: P = 0.027, OR = 1.56, VEGF-D:P = 0.002, OR = 1.00] and PlGF [AI: P = 0.021, OR = 1.43; VEGF-D: P = 0.004, OR = 1.50. API: P = 0.011, OR = 1.66; VEGF-D: P = 0.005, OR = 1.49]. Conclusions: Total cholesterol (TC) and LDL-C are risk factors for presence of any DR. Atherogenic index and API are novel and better predictive indicators for the occurrence and severity of DR in comparion with the traditional lipid profiles. Abnormal lipid metabolism are associated with the upregulation of circulating cytokines that are linked to the severity of DR.

Cytokine profiles of macular neovascularization in the elderly based on a classification from a pachychoroid/drusen perspective

PURPOSE

To classify macular neovascularization (MNV) based on pachychoroid and drusen features and to examine the aqueous humor cytokine signatures of each group.

METHODS

In total, 106 consecutive eyes with treatment-naïve MNV and 104 control eyes were examined. The aqueous humor concentrations of 15 cytokines were compared among the MNV groups classified based on the presence of drusen and/or pachychoroid features. Multidimensional scaling analysis was used to visualize the similarity level of the MNV subtypes according to their cytokine profiles.

RESULTS

Thirty-one, 18, 43, and 10 eyes were classified into the pachychoroid-associated, drusen-associated, pachychoroid/drusen-associated, and non-drusen/non-pachychoroid MNV groups, respectively. Compared with the control group, cytokines were differently upregulated among the MNV groups. CRP and CXCL12 were significantly upregulated in all MNV groups, whereas CXCL13 and IL-8 were significantly upregulated in three MNV groups, excluding the non-pachychoroid/non-drusen-associated MNV group. Ang-2 was significantly upregulated in three MNV groups except the drusen-associated MNV group. PlGF was significantly upregulated in the pachychoroid-associated and drusen-associated MNV groups. CCL-2 was significantly upregulated in the pachychoroid-associated and pachychoroid/drusen-associated MNV groups. VEGF was downregulated in the pachychoroid-associated and drusen-associated MNV groups, respectively. Multidimensional scaling analysis showed a distinct cytokine profile for each MNV group.

CONCLUSION

All MNV groups showed distinct cytokine profiles. Eyes with "neovascular age-related macular degeneration with drusen and concomitant pachychoroid" may share a similar etiology to those with "pachychoroid neovasculopathy" and "choroidal neovascularization with drusen," but have a distinct etiology to those without these. These findings suggest the importance of evaluating drusen and the choroid during the diagnosis of neovascular age-related macular degeneration.

VEGFR1 signaling in retinal angiogenesis and microinflammation

Five vascular endothelial growth factor receptor (VEGFR) ligands (VEGF-A, -B, -C, -D, and placental growth factor [PlGF]) constitute the VEGF family. VEGF-A binds VEGF receptors 1 and 2 (VEGFR1/2), whereas VEGF-B and PlGF only bind VEGFR1. Although much research has been conducted on VEGFR2 to elucidate its key role in retinal diseases, recent efforts have shown the importance and involvement of VEGFR1 and its family of ligands in angiogenesis, vascular permeability, and microinflammatory cascades within the retina. Expression of VEGFR1 depends on the microenvironment, is differentially regulated under hypoxic and inflammatory conditions, and it has been detected in retinal and choroidal endothelial cells, pericytes, retinal and choroidal mononuclear phagocytes (including microglia), Müller cells, photoreceptor cells, and the retinal pigment epithelium. Whilst the VEGF-A decoy function of VEGFR1 is well established, consequences of its direct signaling are less clear. VEGFR1 activation can affect vascular permeability and induce macrophage and microglia production of proinflammatory and proangiogenic mediators. However the ability of the VEGFR1 ligands (VEGF-A, PlGF, and VEGF-B) to compete against each other for receptor binding and to heterodimerize complicates our understanding of the relative contribution of VEGFR1 signaling alone toward the pathologic processes seen in diabetic retinopathy, retinal vascular occlusions, retinopathy of prematurity, and age-related macular degeneration. Clinically, anti-VEGF drugs have proven transformational in these pathologies and their impact on modulation of VEGFR1 signaling is still an opportunity-rich field for further research.

Development of strategies to modulate gene expression of angiogenesis-related molecules in the retina

Intravitreal anti-vascular endothelial growth factor agents are the gold standard treatment of ocular neovascular diseases. However, their short-term efficacy implies frequent intravitreal injections. Gene therapy has the ability to provide longer duration of the therapeutic effect. We have previously described the effectiveness of the self-replicating episomal vector, pEPito, in long-term gene expression in mouse retina. In this study, we evaluated different constructs to overexpress pigment epithelium-derived factor (PEDF), an angiogenesis inhibitor, and simultaneously, to silence placental growth factor (PlGF), a key player in neovascularization. We employed the human cytomegalovirus promoter to drive the expression of PEDF and PlGF shRNA, in conjunction with cis-acting ribozymes, using pEPito as expressing vector. Our results demonstrated that the non-viral systems were able to efficiently promote a sustained increase of the PEDF: PlGF ratio in the mice retina, decreased in pathological conditions. This innovative approach could open avenues for the development of new therapeutic strategies.

Anti-VEGF therapy prevents Müller intracellular edema by decreasing VEGF-A in diabetic retinopathy

Background

Although vascular endothelial growth factor A (VEGF-A) is known to play a key role in causing retinal edema, whether and how VEGF-A induces intracellular edema in the retina still remains unclear.

Methods

Sprague-Dawley rats were rendered diabetic with intraperitoneal injection of streptozotocin. Intravitreal injection of ranibizumab was performed 8 weeks after diabetes onset. rMC-1 cells (rat Müller cell line) were treated with glyoxal for 24 h with or without ranibizumab. The expression levels of inwardly rectifying K⁺ channel 4.1 (Kir4.1), aquaporin 4 (AQP4), Dystrophin 71 (Dp71), VEGF-A, glutamine synthetase (GS) and sodium-potassium-ATPase (Na⁺-K⁺-ATPase) were examined using Western blot. VEGF-A in the supernatant of the cell culture was detected with ELISA. The intracellular potassium and sodium levels were detected with specific indicators.

Results

Compared with normal control, protein expressions of Kir4.1 and AQP4 were down-regulated significantly in diabetic rat retinas, which were prevented by ranibizumab. The above changes were recapitulated in vitro. Similarly, the intracellular potassium level in glyoxal-treated rMC-1 cells was increased, while the intracellular sodium level and Na⁺-K⁺-ATPase protein level remained unchanged, compared with control. However, ranibizumab treatment decreased intracellular sodium, but not potassium.

Conclusion

Ranibizumab protected Müller cells from diabetic intracellular edema through the up-regulation of Kir4.1 and AQP4 by directly binding VEGF-A. It also caused a reduction in intracellular osmotic pressure.

Amine oxidase copper-containing 3 (AOC3) inhibition: a potential novel target for the management of diabetic retinopathy

Background

Diabetic retinopathy (DR), a microvascular complication of diabetes, is the leading cause of visual impairment in people aged 20–65 years and can go undetected until vision is irreversibly lost. There is a need for treatments for non-proliferative diabetic retinopathy (NPDR) which, in comparison with current intravitreal (IVT) injections, offer an improved risk–benefit ratio and are suitable for the treatment of early stages of disease, during which there is no major visual impairment. Efficacious systemic therapy for NPDR, including oral treatment, would be an important and convenient therapeutic approach for patients and physicians and would reduce treatment burden. In this article, we review the rationale for the investigation of amine oxidase copper-containing 3 (AOC3), also known as semicarbazide-sensitive amine oxidase and vascular adhesion protein 1 (VAP1), as a novel target for the early treatment of moderate to severe NPDR. AOC3 is a membrane-bound adhesion protein that facilitates the binding of leukocytes to the retinal endothelium. Adherent leukocytes reduce blood flow and in turn rupture blood vessels, leading to ischemia and edema. AOC3 inhibition reduces leukocyte recruitment and is predicted to decrease the production of reactive oxygen species, thereby correcting the underlying hypoxia, ischemia, and edema seen in DR, as well as improving vascular function.

Conclusion

There is substantial unmet need for convenient, non-invasive treatments targeting moderately severe and severe NPDR to reduce progression and preserve vision. The existing pharmacotherapies (IVT corticosteroids and IVT anti-vascular endothelial growth factor-A) target inflammation and angiogenesis, respectively. Unlike these treatments, AOC3 inhibition is predicted to address the underlying hypoxia and ischemia seen in DR. AOC3 inhibitors represent a promising therapeutic strategy for treating patients with DR and could offer greater choice and reduce treatment burden, with the potential to improve patient compliance.

Intravitreal Aflibercept versus Ranibizumab for Diabetic Macular Edema in a Taiwanese Health Service Setting

Purpose: To compare the visual and anatomical outcomes between intravitreal aflibercept and ranibizumab for diabetic macular edemaMethods: A total of 194 eyes from 194 patients (aflibercept n = 95, ranibizumab n = 99) were retrospectively enrolled in the study. All eyes fulfilled the key criteria including a baseline best-corrected visual acuity (BCVA) between 20 and 70 ETDRS letters, a central subfield thickness (CST) 300 µm or more. Primary outcomes were BCVA and CST at 1, 3, 6, and 12 months. Maintenance of vision was defined as visual loss of less than 5 letters over 6 to 12 months. Predictors for final visual acuity and visual maintenance were analyzed using multivariate regression models.Results: Both agents achieved comparable visual and anatomical outcomes at any time point over the course of follow-up (all p > .05). At 12 months, aflibercept group had higher proportions of visual gains 5, 10 and 15 letters or more (p = .014, p = .011, and p = .034, respectively). The mean number of injections was 5.0 ± 1.9 in ranibizumab group and 4.5 ± 1.9 in aflibercept group (p = .09). Ranibizumab predicted poor maintenance of vision (p = .009), but not the final visual acuity (univariate p = .1). Ranibizumab was more likely to have recurrence of subretinal fluid than aflibercept in 12 months after resolution of subretinal fluid at baseline (p = .016). Both aflibercept and ranibizumab had similar rates of loss to follow-up (p = .47) and occurrence of vitreous hemorrhage (p = .21).Conclusion: While both agents improved vision with resolution of edema, aflibercept maintained vision more effectively with less recurrence of subretinal fluid at 12 months in real-world settings.

Aflibercept in Diabetic Retinopathy

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Dual-Acting Antiangiogenic Gene Therapy Reduces Inflammation and Regresses Neovascularization in Diabetic Mouse Retina

Intravitreal injections of anti-vascular endothelial growth factor drugs have become the gold standard treatment for diabetic retinopathy (DR). However, several patients are classified as non-responders or poor responders to treatment. Therefore, it is essential to study alternative target molecules. We have previously shown that the progression of DR in the Ins2^Akita mouse reflects the imbalance between pro- and anti-angiogenic molecules found in the human retina. We report, for the first time, the therapeutic potential of a dual-acting antiangiogenic non-viral gene therapy. We have used an expressing vector encoding both the pigment epithelium-derived factor gene and a short hairpin RNA (shRNA) targeted to the placental growth factor to restore the balance between these factors in the retina. Twenty-one days after a single subretinal injection, we observed a marked decrease in the inflammatory response in the neural retina and in the retinal pigment epithelium, together with reduced vascular retinal permeability in the treated diabetic mouse. These results were accompanied by the restoration of the retinal capillary network and regression of neovascularization, with significant improvement of DR hallmarks. Concomitant with the favorable therapeutic effects, this approach did not affect retinal ganglion cells. Hence our results provide evidence toward the use of this approach in DR treatment.

Synergistic interactions of PlGF and VEGF contribute to blood-retinal barrier breakdown through canonical NFκB activation

To investigate the role of placental growth factor/vascular endothelial growth factor (PlGF-VEGF) heterodimers are involved in the blood-retinal barrier (BRB) breakdown and the associated mechanism, human retinal endothelial cells (HRECs) were treated with recombinant human (rh)PlGF-VEGF heterodimers and rhPlGF and studied in normal and high-glucose conditions. HREC barrier function was evaluated by the measurement of trans-endothelial electrical resistance (TEER). Adeno-Associated Virus Type 5 (AAV5) vectors overexpressed PlGF in the retina by intravitreal injection into the C57BL6 mouse eye. AAV5-GFP vector and naïve animals were used as controls. Immunofluorescence (IF) and western blots examined the protein expression of PlGF-VEGF heterodimers, VEGF, PlGF, NFκB, p-IκBα, ZO-1, and VE-cadherin in HREC and mouse retina. PlGF-VEGF heterodimers were detected predominantly in the HREC cell nuclei based on IF and cytoplasmic and nuclear fractionation experiments. High glucose treatment increased PlGF-VEGF nuclear abundance. Dot immunoblotting demonstrated a strong affinity of the 5D11D4 antibody to PlGF-VEGF heterodimers. rhPlGF-VEGF disrupted the barrier function of HREC, which was prevented by the neutralization of PlGF-VEGF by the 5D11D4 antibody. Stimulation of HRECs with rhPlGF also led to an increase in the nuclear signals for PlGF-VEGF, p-IκBα, and colocalization of NFκB p65 and PlGF-VEGF in the nuclei. The selective IKK2 inhibitor IMD0354 disrupted the nuclear colocalization. Treatment with IMD0354 restored the barrier function of HREC, as indicated by the ZO-1 and VE-cadherin expression. In the mouse retinas, PlGF overexpression by AAV5 vector reduced ZO-1 expression and increased abundance of pIκBα. PIGF/VEGF heterodimers mediate BRB breakdown potentially through the canonical NFκB activation.

Inflammatory and angiogenic biomarkers in diabetic retinopathy

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus (DM) and a leading cause of blindness in working-age adults in developed countries. Numerous investigations have recognised inflammation and angiogenesis as important factors in the development of this complication of diabetes. Current methods of DR treatment are predominantly used at advanced stages of the disease and could be associated with serious side effects. Therefore, new diagnostic methods are needed in order to identify the initial stages of DR as well as monitoring the effects of applied therapy. Biochemical biomarkers are molecules found in blood or other biological fluid and tissue that indicate the existence of an abnormal condition or disease. They could be a valuable tool in detecting early stages of DR, identifying patients most susceptible to retinopathy progression and monitoring treatment outcomes. Biomarkers related to DR can be measured in the blood, retina, vitreous, aqueous humour and recently in tears. As the retina represents a small part of total body mass, a circulating biomarker for DR needs to be highly specific. Local biomarkers are more reliable as indicators of the retinal pathology; however, obtaining a sample of aqueous humour, vitreous or retina is an invasive procedure with potential serious complications. As a non-invasive novel method, tear analysis offers a promising direction in further research for DR biomarker detection. The aim of this paper is to review systemic and local inflammatory and angiogenic biomarkers relevant to this sight threatening diabetic complication.

Traditional Chinese medicine formulas, extracts, and compounds promote angiogenesis

Ischemic diseases, such as ischemic heart diseases and ischemic stroke, are the leading cause of death worldwide. Angiogenic therapy is a wide-ranging approach to fighting ischemic diseases. However, compared with anti-angiogenesis therapy for tumors, less attention has been paid to therapeutic angiogenesis. Recently, Traditional Chinese medicine (TCM) has garnered increasing interest for its definite curative effect and low toxicity. A growing number of studies have reported that TCM formulas, extracts, and compounds from herbal medicines exert pro-angiogenic activity, which has been confirmed in a few clinical trials. For comprehensive analysis of relevant literature, global and local databases including PubMed, Web of Science, and China National Knowledge Infrastructure were searched using keywords such as "angiogenesis," "neovascularization," "traditional Chinese medicine," "formula," "extract," and "compound." Articles were chosen that are closely and directly related to pro-angiogenesis. This review summarizes the pro-angiogenic activity and the mechanism of TCM formulas, extracts, and compounds; it delivers an in-depth understanding of the relationship between TCM and pro-angiogenesis and will provide new ideas for clinical practice.

Pericyte-Endothelial Interactions in the Retinal Microvasculature

Retinal microvasculature is crucial for the visual function of the neural retina. Pericytes and endothelial cells (ECs) are the two main cellular constituents in the retinal microvessels. Formation, maturation, and stabilization of the micro-vasculatures require pericyte-endothelial interactions, which are perturbed in many retinal vascular disorders, such as retinopathy of prematurity, retinal vein occlusion, and diabetic retinopathy. Understanding the cellular and molecular mechanisms of pericyte-endothelial interaction and perturbation can facilitate the design of therapeutic intervention for the prevention and treatment of retinal vascular disorders. Pericyte-endothelial interactions are indispensable for the integrity and functionality of retinal neurovascular unit (NVU), including vascular cells, retinal neurons, and glial cells. The essential autocrine and paracrine signaling pathways, such as Vascular endothelial growth factor (VEGF), Platelet-derived growth factor subunit B (PDGFB), Notch, Angipointein, Norrin, and Transforming growth factor-beta (TGF-β), have been well characterized for the regulation of pericyte-endothelial interactions in the neo-vessel formation processes (vasculogenesis and angiogenesis) during embryonic development. They also play a vital role in stabilizing and remodeling mature vasculature under pathological conditions. Awry signals, aberrant metabolisms, and pathological conditions, such as oxidative stress and inflammation, can disrupt the communication between pericytes and endothelial cells, thereby resulting in the breakdown of the blood-retinal barrier (BRB) and other microangiopathies. The emerging evidence supports extracellular exosomes' roles in the (mis)communications between the two cell types. This review summarizes the essential knowledge and updates about new advancements in pericyte-EC interaction and communication, emphasizing the retinal microvasculature.

Paxillin promotes the migration and angiogenesis of HUVECs and affects angiogenesis in the mouse cornea

Neonatal vascular ophthalmopathy is a refractory ophthalmologic disease, and is a major cause of blindness. Occurrence of neonatal vascular ophthalmopathy may be associated with Paxillin, a cellular adhesion molecule which promotes the migration of endothelial cells and angiogenesis. To explore the role of PXN in corneal angiogenesis, human umbilical vein endothelial cells were divided into five groups: i) Control group; ii) Empty vector-transfected control group; iii) PXN knockdown group (shPXN group); iv) PXN-negative control (NC) group; and v) PXN over-expressed group (overExp group). PXN protein levels, migration and tube formation were assessed in the different experimental groups. Mice were divided into four groups: i) Control; ii) Model; iii) shPXN; and iv) overExp groups. Tube formation was significantly increased in the overExp group compared with the empty vector-transfected control group (P<0.01). Tube formation was significantly decreased in the shPXN group compared with the PXN-NC group (P<0.01). In mice, blood corpuscles were significantly decreased in the shPXN group. PXN promoted the migration of endothelial cells and corneal angiogenesis. The results of the present study suggest a role for PXN in corneal angiogenesis and provide a theoretical basis and potential target for the treatment of corneal angiogenesis.

Targeting Netrin-1 and -4 as a Novel Diagnostic Parameter and Treatment Option for Diabetic Retinopathy

Diabetic retinopathy (DR) is a retinal vascular disorder associated with both type 1 and type 2 diabetes mellitus (DM). It is characterized by specific loss of pericytes, which leads to an augmented blood vessel permeability, and development of new blood vessels (retinal neovascularization). Moreover, stiffening of eye membrane, inflammation, and apoptosis of endothelial cells also lead to damage of the blood-retinal barrier and blindness in most cases unless it's detected and managed early. Hence, this review was intended to assess the potential roles of Netrin-1 and -4 as new/alternative biomarkers and therapeutic options for DR. Netrin-1 and -4 have been the most known ligands and are well known for their role in neural guidance. DR has both neural and vascular components; therefore, biomarkers used for both neural and vascular retinal tissues are potentially important. According to different experimental and clinical studies, as compared to the normal groups, there was a significant increment in both retinal Netrin-1 and -4 mRNA and protein levels in the retinopathy groups. In addition, exogenous supplementation of these proteins is also used as a therapeutic agent for DR.

Aqueous humour cytokine changes during a loading phase of intravitreal ranibizumab or dexamethasone implant in diabetic macular oedema

PURPOSE

To determine the effect of intravitreal ranibizumab and a dexamethasone implant on aqueous humour cytokine, protein and enzyme levels and to correlate findings to morphologic and functional changes.

METHODS

In a prospective, randomized, controlled, double-blind study, patients with clinically significant diabetic macular oedema (CSME) were randomly allocated to receive either monthly intravitreal injections of ranibizumab (Lucentis, Novartis Pharma) or a single dexamethasone implant (Ozurdex, Pharm-Allergan) at baseline (BL). Aqueous humour samples were collected at BL and weeks 2, 8 and 20.

RESULTS

The study included 18 eyes of 18 patients. In the dexamethasone implant group, soluble intercellular adhesion molecule 1 (sICAM-1) (weeks 2 and 8), CXCL9/monokine induced by gamma interferon (MIG) (weeks 2 and 8), soluble vascular cell adhesion protein 1 (sVCAM-1) (weeks 2 and 8) and monocyte chemo-attractant protein 1 (MCP-1) (week 2) levels were significantly decreased compared with baseline. In the ranibizumab group, placental growth factor (PIGF) (week 2) and vascular endothelial growth factor (VEGF) (week 2 and 8) levels were significantly decreased compared with baseline. No significant changes in central retinal thickness (CRT) or Early Treatment Diabetic Retinopathy Study (ETDRS) best corrected visual acuity (BCVA) were observed in the Ozurdex group at any time-points. ETDRS scores significantly increased at week 20 (84.88 ± 8.88 letters) compared with baseline (74.78 ± 14.85 letters), and the CRT decreased significantly at week 4 (381.00 ± 114.64 μm) compared with baseline (440 ± 144 μm) in the Lucentis group.

CONCLUSION

The dexamethasone implant affected the aqueous cytokines and proteins MCP-1, sICAM-1, sVCAM-1 and MIG, whereas ranibizumab treatments reduced VEGF and PIGF levels. Morphological changes may diverge from cytokine changes. Results may indicate a rationale for a combination therapy for CSME using both agents, the dexamethasone implant and repeatedly administered ranibizumab injections.

PlGF silencing combined with PEDF overexpression: Modeling RPE secretion as potential therapy for retinal neovascularization

Ocular neovascularization is a defining feature of several blinding diseases. We have previously described the effectiveness of long-term pigment epithelium-derived factor (PEDF) expression in the retina of diabetic mice in ameliorating some diabetic retinopathy hallmarks. In this study, we aimed to investigate if the antiangiogenic potential of PEDF overexpression was enhanced in combination with placental growth factor (PlGF) silencing. Human RPE cells were transfected with a self-replicating episomal vector (pEPito) for PEDF overexpression and/or a siRNA targeting PlGF gene. Conditioned media from PEDF overexpression, from PlGF inhibition and from their combination thereof were used to culture human umbilical vein endothelial cells, and their proliferation rate, migration capacity, apoptosis and ability to form tube-like structures were analyzed in vitro. We here demonstrate that pEPito-driven PEDF overexpression in combination with PlGF silencing in RPE cells does not affect their viability and results in an enhanced antiangiogenic activity in vitro. We observed a significant decrease in the migration and proliferation of endothelial cells, and an increase in apoptosis induction as well as a significant inhibitory effect on tube formation. Our findings demonstrate that simultaneous PEDF overexpression and PlGF silencing strongly impairs angiogenesis compared with the single approaches, providing a rationale for combining these therapies as a new treatment for retinal neovascularization.

Identification of potential molecular targets associated with proliferative diabetic retinopathy

BACKGROUND

This study aimed to identify and evaluate potential molecular targets associated with the development of proliferative diabetic retinopathy (DR).

METHODS

The microarray dataset "GSE60436" generated from fibrovascular membranes (FVMs) associated with proliferative DR was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) from the active FVMs and control or inactive FVMs and control were evaluated and co-DEGs were identified using VEEN analysis. Functional enrichment analysis, and protein-protein interactions (PPI) network and module analyses were performed on the upregulated and downregulated coDEGs. Finally, several predictions regarding microRNAs (miRNAs) and transcription factors (TFs) were made to construct a putative TF-miRNA-target network.

RESULTS

A total of 1475 co-DEGs were screened in active/inactive FVM samples, including 461 upregulated and 1014 downregulated genes, which were enriched for angiogenesis [Hypoxia Inducible Factor 1 Subunit Alpha (HIF1A) and Placental Growth Factor (PGF)] and visual perception, respectively. In the case of the upregulated co-DEGs, Kinesin Family Member 11 (KIF11), and BUB1 Mitotic Checkpoint Serine/Threonine Kinase (BUB1) exhibited the highest values in both the PPI network and module analyses, as well as the genes related to mitosis. In the case of downregulated co-DEGs, several G protein subunits, including G Protein Subunit Beta 3 (GNB3), exhibited the highest values in both the PPI network and module analyses. The genes identified in the module analysis were found to be from the signal transduction-related pathways. In addition, we were able to identify four miRNAs and five TFs, including miR-136 and miR-374.

CONCLUSIONS

In brief, HIF1A, PGF, KIF11, G protein subunits, and miR-136, miR-374 may all be involved in angiogenesis, retinal endothelial cell proliferation, and visual signal transduction in proliferative DR. This study provides a number of novel insights that may aid the development of future studies dedicated to discovering novel therapeutic targets in proliferative DR.

Coats-like Exudative Vitreoretinopathy in Retinitis Pigmentosa: Ocular Manifestations and Treatment Outcomes

PURPOSE

To provide a comprehensive review of the ocular manifestations, outcomes, and genetic findings in patients with Coats-like retinitis pigmentosa (RP).

DESIGN

Multicenter, retrospective, nonconsecutive case series.

PARTICIPANTS

Patients with a diagnosis of RP demonstrating Coats-like exudative vitreoretinopathy between January 1, 2008, and October 1, 2019.

METHODS

Evaluation of ocular findings at RP diagnosis and at time of presentation of Coats-like exudative vitreoretinopathy, pedigree analysis, genetic testing, retinal imaging, and anatomic outcomes after treatment.

MAIN OUTCOME MEASURES

Visual acuity, ophthalmoscopy results, OCT results, fluorescein angiography results, and identification of genetic mutations.

RESULTS

Nine patients diagnosed with RP and demonstrating Coats-like exudative vitreoretinopathy were included. Median age at time of RP diagnosis was 8 years (range, 1-22 years), and median age at presentation of Coats-like exudative vitreoretinopathy was 18 years (range, 1-41 years). Seven patients were female, and 2 were male. The genetic cause of disease was identified in 6 patients. Three patients demonstrated Coats-like fundus findings at the time of RP diagnosis. Exudative retinal detachment (ERD) localized to the infratemporal periphery was present in all patients, with bilateral disease observed in 7 patients. In all treated patients, focal laser photocoagulation was used to treat leaking telangiectasias and to limit further ERD expansion. Cystoid macular edema refractory to carbonic anhydrase inhibitor therapy and ultimately amenable to treatment with intravitreal anti-vascular endothelial growth factor injection was observed in 4 patients.

CONCLUSIONS

Coats-like vitreoretinopathy is present in up to 5% of all RP patients. The term Coats-like RP is used colloquially to describe this disease state, which can present at the time of RP diagnosis or, more commonly, develops late during the clinical course of patients with longstanding RP. Coats-like RP is distinct from Coats disease in that exudative pathologic features occur exclusively in the setting of a coexisting RP diagnosis, is restricted to the infratemporal retina, can affect both eyes, and does not demonstrate a male gender bias. Given the risk of added vision loss posed by exudative vitreoretinopathy in patients with RP, a heightened awareness of this condition is critical in facilitating timely intervention.

Comparison of aqueous humor levels of PlGF and VEGF in proliferative diabetic retinopathy before and after intravitreal conbercept injection

AIMS

The aim of this paper is to observe the change of aqueous humor levels of placenta growth factor (PlGF) and vascular endothelial growth factor (VEGF) in proliferative diabetic retinopathy (PDR) patients before and one week after intravitreal conbercept injection.

METHODS

A prospective case series study was conducted in 24 active PDR patients (24 eyes). All the patients had received 0.5 mg of intravitreal conbercept followed by vitrectomy one week later. The aqueous humor was collected before conbercept injection and at the beginning of vitrectomy.

RESULTS

Before conbercept injection, the aqueous humor median levels of VEGF-A, VEGF-B and PlGF were457.0pg/mL(IQRfrom392.9to860.6pg/mL), 43.6pg/mL(IQRfrom33.6to81.6pg/mL), 37.5pg/mL(IQRfrom25.0to53.6pg/mL), respectively. One week after conbercept injection, the aqueous humor levels of VEGF-A, VEGF-B and PiGF decreased significantly. The aqueous humor VEGF-A levels in PDR patients with fibrovascular membranes were lower than those without them. There was positive correlation between aqueous humor VEGF-B and PiGF levels (P = 0.007). No significant correlation was found between VEGF-A and PiGF levels. No ocular and systemic adverse events were observed.

CONCLUSIONS

The aqueous humor levels of PlGF was correlated with VEGF-B, and levels of VEGF-A, VEGF-B, and PlGF decreased after intravitreal conbercept injection in active PDR patients.

AFLIBERCEPT FOR PERSISTENT DIABETIC MACULAR EDEMA: Forty-Eight-Week Outcomes

PURPOSE

To evaluate functional and anatomical outcomes after a switch from intravitreal bevacizumab to aflibercept in patients with persistent diabetic macular edema.

METHODS

Prospective, single-arm, open-label clinical trial of patients with persistent diabetic macular edema, despite previous treatment with bevacizumab. Five loading doses of intravitreal aflibercept were administered every 4 weeks with subsequent injections administered every 8 weeks. Patients were reviewed every 4 weeks, and best-corrected visual acuity and central macular thickness were recorded. Primary outcome measures included change in central macular thickness and best-corrected visual acuity at week 48 compared with baseline. Paired t-tests were used to assess change between baseline and follow-up visits.

RESULTS

At baseline, 43 eyes from 43 patients were recruited with a median (interquartile range) of 12 (7-24) previous intravitreal anti-vascular endothelial growth factor injections over a period of 18 (8-34) months. Mean ± SD central macular thickness reduced by 59 ± 114 μm (P = 0.002), and best-corrected visual acuity improved by 3.9 ± 7.0 letters (P = 0.001) after 48 weeks in the 41 patients who completed the trial. Best-corrected visual acuity improvements were more marked in patients who gained ≥5 letters after the first injection (8.9 ± 5.7 vs. 1.8 ± 6.5 letter gain at 48 weeks, P = 0.002), a difference which remained significant after regression analysis with baseline best-corrected visual acuity . Vision gains and central macular thickness reduction were similar in 9 fellow eyes eligible for inclusion being concurrently treated for diabetic macular edema with bevacizumab.

CONCLUSION

Intravitreal aflibercept was effective in improving anatomical and visual outcomes among patients with an incomplete response to intravitreal bevacizumab with 48 weeks of follow-up. Patients with a good early response subsequent to switching had a better improvement in vision at 48 weeks.

Identification of novel differentially expressed genes in retinas of STZ-induced long-term diabetic rats through RNA sequencing

BACKGROUND

The aim of this research was to investigate the retinal transcriptome changes in long-term streptozotocin (STZ)-induced rats' retinas using RNA sequencing (RNA-seq), to explore the molecular mechanisms of diabetic retinopathy (DR), and to identify novel targets for the treatment of DR by comparing the gene expression profile we obtained.

METHODS

In this study, 6 healthy male SD rats were randomly divided into wild-type (WT) group and streptozotocin (STZ)-induced group, 3 rats each group. After 6 months, 3 normal retina samples and 3 DM retina samples (2 retinas from the same rat were considered as 1 sample) were tested and differentially expressed genes (DEGs) were measured by RNA-seq technology. Then, we did Gene Ontology (GO) enrichment analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis and validated the results of RNA-seq through qRT-PCR.

RESULTS

A total of 118 DEGs were identified, of which 72 were up-regulated and 46 were down-regulated. The enriched GO terms showed that 3 most significant enrichment terms were binding (molecular function), cell part (cellular component), and biological regulation (biological process). The results of the KEGG pathway analysis revealed a significant enrichment in cell adhesion molecules, PI3K-Akt signaling pathway, and allograft rejection, etc. CONCLUSION: Our research has identified specific DEGs and also speculated their potential functions, which will provide novel targets to explore the molecular mechanisms of DR.

Relationship Between Aqueous Humor Levels of Cytokines and Axial Length in Patients With Diabetic Retinopathy

PURPOSE

A negative relationship between intraocular vascular endothelial growth factor-A (VEGFA) and axial length was found, which may help explain why myopia with long axial length was a protective factor for development of diabetic retinopathy (DR). The aim of this study is to further assess the relationship between the aqueous humor levels of interlukin (IL)-8, IL-10, VEGFA, vascular adhesion molecule-1 (VCAM-1), basic fibroblast growth factor, VEGFB, and placental growth factor (PLGF) and axial length in eyes with DR.

DESIGN

Retrospective, single-center, unmasked study.

METHODS

Patients with age-related cataract and with/without DR who visited the Department of Ophthalmology at the Affiliated Hospital of Inner Mongolia Medical University were enrolled. The level of IL-8, IL-10, VEGFA, VCAM-1, and basic fibroblast growth factor were measured by cytometric bead array, and VEGFB and PLGF were measured by enzyme-linked immunosorbent assay. Axial length was measured by biometry.

RESULTS

Totally 65 eyes of 65 patients were enrolled, including 14 patients with nonproliferative diabetic retinopathy, 16 patients with proliferative diabetic retinopathy (PDR), and 35 patients with age-related cataract as control. In the nonproliferative diabetic retinopathy group, the aqueous level of PLGF was negatively correlated with axial length (r = -0.576, P = 0.031), whereas the aqueous levels of IL-10 (r = 0.533, P = 0.049) and VCAM-1 (r = 0.566, P = 0.035) were positively correlated with axial length. In the proliferative diabetic retinopathy group, all cytokines did not significantly correlate with axial length.

CONCLUSIONS

Among patients with diabetic retinopathy, we further found that aqueous levels of PLGF were negatively correlated with axial length, whereas VCAM-1 and IL-10 were positively correlated with axial length. These findings may suggest that these cytokines play a role in the development of DR, and further explain the relationship between the axial length and DR.

Genetic biomarkers in the VEGF pathway predicting response to anti-VEGF therapy in age-related macular degeneration

Objective

Age-related macular degeneration (ARMD) is a leading cause of visual impairment. Intravitreal injections of anti-vascular endothelial growth factor (VEGF) are the standard treatment for wet ARMD. There is however, variability in patient responses, suggesting patient-specific factors influencing drug efficacy. We tested whether single nucleotide polymorphisms (SNPs) in genes encoding VEGF pathway members contribute to therapy response.

Methods and analysis

A retrospective cohort of 281 European wet ARMD patients treated with anti-VEGF was genotyped for 138 tagging SNPs in the VEGF pathway. Per patient, we collected best corrected visual acuity at baseline, after three loading injections and at 12 months. We also registered the injection number and changes in retinal morphology after three loading injections (central foveal thickness (CFT), intraretinal cysts and serous neuroepithelium detachment). Changes in CFT after 3 months were our primary outcome measure. Association of SNPs to response was assessed by binomial logistic regression. Replication was attempted by associating visual acuity changes to genotypes in an independent Japanese cohort.

Results

Association with treatment response was detected for seven SNPs, including in FLT4 (rs55667289: OR=0.746, 95% CI 0.63 to 0.88, p=0.0005) and KDR (rs7691507: OR=1.056, 95% CI 1.02 to 1.10, p=0.005; and rs2305945: OR=0.963, 95% CI 0.93 to 1.00, p=0.0472). Only association with rs55667289 in FLT4 survived multiple testing correction. This SNP was unavailable for testing in the replication cohort. Of six SNPs tested for replication, one was significant although not after multiple testing correction.

Conclusion

Identifying genetic variants that define treatment response can help to develop individualised therapeutic approaches for wet ARMD patients and may point towards new targets in non-responders.