Reversible retinal vessel closure from VEGF-induced leukocyte plugging

Pharmacological depletion of pericytes induces diabetic retinopathy-like abnormal blood vessels in neonatal rat retina

Diabetic retinopathy is a major ocular complication associated with diabetes mellitus. Pericyte loss is a hallmark of diabetic retinopathy. The platelet-derived growth factor (PDGF)-B-PDGF receptor-β (PDGFRβ) signaling pathway plays an important role in the proliferation and migration of pericytes. Imatinib, an antineoplastic drug primarily used to treat chronic myelogenous leukemia, inhibits the PDGFRβ tyrosine kinase. In this study, we aimed to determine the time-course of pathological changes in the retinal vasculature following pharmacological depletion of pericytes with imatinib. Rats were injected with imatinib once daily for 1, 2, or 4 days starting on postnatal day (P) 4. The distribution of endothelial cells and pericytes in the retina was assessed at P4, P5, P6, P8, and P11. Single and multiple injections of imatinib (100 mg/kg) significantly decreased the pericyte coverage within the retinal capillaries on the day after the completion of each injection protocol. After pericyte coverage decreased, endothelial cell degeneration and microaneurysm formation were initiated. Following the elimination of the inhibitory effect of imatinib on the PDGFRβ signaling pathway, the pericyte coverage returned to control levels but structural abnormalities of the retinal vasculature with microaneurysms and dense capillaries were observed. Vascular pathological features are similar to those of the early clinical manifestations of diabetic retinopathy. Therefore, these rats could serve as animal models to study the mechanisms underlying the pathological changes that occur after pericyte loss in diabetic retinopathy.

The Effects of Anti-Vascular Endothelial Growth Factor Loading Injections on Retinal Microvasculature in Diabetic Macular Edema

Purpose

To evaluate changes in the retinal microvasculature using widefield swept-source optical coherence tomography angiography (SS-OCTA) following three anti-vascular endothelial growth factor (anti-VEGF) loading injections for diabetic macular edema (DME).

Methods

Thirty-four treatment-naïve patients with DME received an initial three loading injections, followed by injections on an as-needed basis. Macular ischemia was evaluated based on the foveal avascular zone (FAZ) area, perfusion density, and vessel density on a 3 × 3-mm SS-OCTA image. Midperipheral ischemia was analyzed by dividing a 12 × 12-mm image into 16 boxes to compare changes in the nonperfusion area (NPA). Participants were categorized as aggravated, stable, or improved based on changes in the NPA after three injections.

Results

Of the 34 included patients, eight (23.5%) demonstrated aggravation of the NPA, 23 (67.6%) remained stable, and three (8.8%) exhibited improvement. Although FAZ area, perfusion, and vessel density increased, the differences were not significant compared to baseline. The number of injections and glycated hemoglobin (HbA1c) levels in the NPA aggravation group were significantly higher than in the stable and improvement groups. Logistic regression analysis revealed that NPA aggravation was independently associated with the number of anti-VEGF injections.

Conclusions

Changes in NPA following anti-VEGF loading injections varied among patients with DME and were significantly associated with HbA1c levels and injection frequency. Worsening mid-peripheral NPA after the anti-VEGF injections independently risked DME recurrence.

Translational Relevance

We revealed that worsening mid-peripheral retinal ischemia after anti-VEGF loading injections contributes to the recurrence of DME.

Intravitreal anti-vascular endothelial growth factor therapy in the treatment of vision loss associated with hematologic malignancy

Purpose

To determine the effectiveness of anti-vascular endothelial growth factor (VEGF) therapy in the setting of optic disc edema secondary to hematologic malignancies.

Observations

The report features two patients (one male, one female) in their 70's with biopsy proven hematologic malignancies who subsequently developed optic disc edema. The patients were commenced on a trial of successive intravitreal Aflibercept 2mg/0.05mL therapy. The best corrected visual acuity for patient 1 improved from 20/50 oculus dexter (OD) and 20/80 oculus sinister (OS), to 20/20 OD (4 lines Early Treatment of Diabetic Retinopathy Study (ETDRS)) and 20/32 OS (4 lines ETDRS). Similarly, patient 2's best corrected visual acuity improved from 20/100 OU to 20/50 OD (3 lines ETDRS) and 20/40 OS (4 lines ETDRS) following initiation of treatment. In addition, optical coherence tomography imaging obtained before and after therapy demonstrated an improvement in both patient's optic disc edema and cystoid macular edema.

Conclusions and importance

The findings of this report suggest that in patients with a known hematologic malignancy, optic disc edema and cystoid macular edema may be amenable to anti-VEGF treatment, especially if there are clinical and angiographic features of vascular endothelial growth factor overexpression.

Perspectives of diabetic retinopathy-challenges and opportunities

Diabetic retinopathy (DR) may lead to vision-threatening complications in people living with diabetes mellitus. Decades of research have contributed to our understanding of the pathogenesis of diabetic retinopathy from non-proliferative to proliferative (PDR) stages, the occurrence of diabetic macular oedema (DMO) and response to various treatment options. Multimodal imaging has paved the way to predict the impact of peripheral lesions and optical coherence tomography-angiography is starting to provide new knowledge on diabetic macular ischaemia. Moreover, the availability of intravitreal anti-vascular endothelial growth factors has changed the treatment paradigm of DMO and PDR. Areas of research have explored mechanisms of breakdown of the blood-retinal barrier, damage to pericytes, the extent of capillary non-perfusion, leakage and progression to neovascularisation. However, knowledge gaps remain. From this perspective, we highlight the challenges and future directions of research in this field.

Regulation of Monocyte Activation by PPARα Through Interaction With the cGAS-STING Pathway

Monocyte activation plays an important role in diabetic complications such as diabetic retinopathy (DR). However, the regulation of monocyte activation in diabetes remains elusive. Fenofibrate, an agonist of peroxisome proliferator-activated receptor-α (PPARα), has shown robust therapeutic effects on DR in patients with type 2 diabetes. Here we found that PPARα levels were significantly downregulated in monocytes from patients with diabetes and animal models, correlating with monocyte activation. Fenofibrate attenuated monocyte activation in diabetes, while PPARα knockout alone induced monocyte activation. Furthermore, monocyte-specific PPARα overexpression ameliorated, while monocyte-specific PPARα knockout aggravated monocyte activation in diabetes. PPARα knockout impaired mitochondrial function while also increasing glycolysis in monocytes. PPARα knockout increased cytosolic mitochondrial DNA release and activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway in monocytes under diabetic conditions. STING knockout or STING inhibitor attenuated monocyte activation induced by diabetes or by PPARα knockout. These observations suggest that PPARα negatively regulates monocyte activation through metabolic reprogramming and interaction with the cGAS-STING pathway.

Vascular cell-adhesion molecule 1 (VCAM-1) regulates JunB-mediated IL-8/CXCL1 expression and pathological neovascularization

Vascular adhesion molecules play an important role in various immunological disorders, particularly in cancers. However, little is known regarding the role of these adhesion molecules in proliferative retinopathies. We observed that IL-33 regulates VCAM-1 expression in human retinal endothelial cells and that genetic deletion of IL-33 reduces hypoxia-induced VCAM-1 expression and retinal neovascularization in C57BL/6 mice. We found that VCAM-1 via JunB regulates IL-8 promoter activity and expression in human retinal endothelial cells. In addition, our study outlines the regulatory role of VCAM-1-JunB-IL-8 signaling on retinal endothelial cell sprouting and angiogenesis. Our RNA sequencing results show an induced expression of CXCL1 (a murine functional homolog of IL-8) in the hypoxic retina, and intravitreal injection of VCAM-1 siRNA not only decreases hypoxia-induced VCAM-1-JunB-CXCL1 signaling but also reduces OIR-induced sprouting and retinal neovascularization. These findings suggest that VCAM-1-JunB-IL-8 signaling plays a crucial role in retinal neovascularization, and its antagonism might provide an advanced treatment option for proliferative retinopathies.

Hematopoietic Cells Influence Vascular Development in the Retina

Hematopoietic cells play a crucial role in the adult retina in health and disease. Monocytes, macrophages, microglia and myeloid angiogenic cells (MACs) have all been implicated in retinal pathology. However, the role that hematopoietic cells play in retinal development is understudied. The temporal changes in recruitment of hematopoietic cells into the developing retina and the phenotype of the recruited cells are not well understood. In this study, we used the hematopoietic cell-specific protein Vav1 to track and investigate hematopoietic cells in the developing retina. By flow cytometry and immunohistochemistry, we show that hematopoietic cells are present in the retina as early as P0, and include microglia, monocytes and MACs. Even before the formation of retinal blood vessels, hematopoietic cells localize to the inner retina where they eventually form networks that intimately associate with the developing vasculature. Loss of Vav1 lead to a reduction in the density of medium-sized vessels and an increased inflammatory response in retinal astrocytes. When pups were subjected to oxygen-induced retinopathy, hematopoietic cells maintained a close association with the vasculature and occasionally formed 'frameworks' for the generation of new vessels. Our study provides further evidence for the underappreciated role of hematopoietic cells in retinal vasculogenesis and the formation of a healthy retina.

Analysis of the Cytokine Expression in the Aqueous Humor of Individuals with BRVO-Associated Macular Edema

Purpose

This study aimed to determine the expression levels of vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in the aqueous humor of patients with macular edema (ME) caused by branch retinal vein occlusion (BRVO), as well as to investigate the relationship between the cytokines as mentioned earlier and best-corrected visual acuity (BCVA), ME, and the degree of ME from the molecular level.

Methods

In a prospective observational study, fluorescein fundus angiography (FFA) and optical coherence tomography (OCT) were used to classify 58 patients with non-ischemic BRVO-ME into three groups according to the degree of ME: 14-mild, 17-moderate, and 27-severe. The specific concentration of IL-6, VEGF, ICAM-1, and VCAM-1 in the aqueous humor was detected using the BD CSCanto™ II Flow Cytometer (US). Spearman or Pearson correlation analysis was used to test the correlation between the levels of BCVA and severity of ME and the expression levels of IL-6, VEGF, ICAM-1, and VCAM-1 in the aqueous humor.

Results

According to the obtained data, BCVA did not correlate with the severity of ME, and these four cytokines expression levels in patients' aqueous humor (P > 0.05). Moreover, BCVA did not correlate with mild, moderate, or severe ME as well (P > 0.05). However, the levels of these four cytokines were correlated with the severity of the ME. These underlined cytokines were linked to the mild, moderate, and severe degrees of ME. VEGF was also significantly correlated (r > 0.8, P < 0.0001) with the severity of ME.

Conclusions

This study suggests that the severity of ME in BRVO-ME patients is significantly correlated with the expression levels of IL-6, VEGF, ICAM-1, and VCAM-1 in the aqueous humor. Lowering the level of disease-associated cytokines may potentially reduce the degree of ME. Therefore, an in-depth study of the levels and the relationship may provide some evidence for the pathogenesis, treatment, and prevention of BRVO-ME.

Disentangling the association between retinal non-perfusion and anti-VEGF agents in diabetic retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM) and the leading cause of blindness in patients with DM. In the pathogenesis of DR, chronic hyperglycemia leads to biochemical and structural alterations in retinal blood vessels' wall, resulting in hyperpermeability and non-perfusion. Since vascular endothelial growth factor (VEGF) has been found to play a significant role in the pathogenesis of DR, this review sheds light on the effect of intravitreal anti-VEGF agents on retinal non-perfusion in patients with DR. Based on the existing literature, anti-VEGF agents have been shown to improve DR severity, although they cannot reverse retinal ischemia. The results of the published studies are controversial and differ based on the location of retinal non-perfusion, as well as the imaging modality used to assess retinal non-perfusion. In cases of macular non-perfusion, most of studies showed no change in both fundus fluorescein angiography (FFA) and optical coherence tomography (OCTA) in patients with DR treated with intravitreal anti-VEGF agents, while few studies reported worsening of non-perfusion with enlargement of foveal avascular zone (FAZ). Regarding peripheral ischemia, studies using wide-field-FFA demonstrated an improvement or stability in non-perfusion areas after anti-VEGF treatment. However, the use of wide-field-OCTA revealed no signs of re-perfusion of retinal vessels post anti-VEGF treatment. Further prospective studies with long follow-up and large sample size are still needed to draw solid conclusions.

Study of Nonperfusion Area Changes after Ranibizumab Intravitreal Injection for Diabetic Macular Edema by Means of Widefield OCT Angiography

INTRODUCTION

The aim of this study was to evaluate changes in retinal capillary nonperfusion areas (RCNPA) and the retinal capillary vessel density (RCVD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) using widefield optical coherence tomography angiography (WFOCTA) in patients with diabetic retinopathy (DR) and diabetic macular edema (DME) treated with intravitreal ranibizumab injection (IRI).

MATERIALS AND METHODS

Twenty-four eyes of 24 patients with DR and DME candidates to a loading dose of IRI were enrolled. All patients underwent WFOCTA with the PLEX Elite 9000 device with 15 × 9 mm scans centered on the foveal center at baseline (T0) and 1 month after each intravitreal injection at 30 days (T1), 60 days (T2), and 90 days (T3). In all patients, the variation of RCNPA and the RCVD of the SCP and DCP were calculated using automatic software written in MATLAB (MathWorks, Natick, MA, USA).

RESULTS

The SCP showed a significant longitudinal variation of RCNPA (p = 0.04). Post hoc analysis revealed a statistically significant reduction of RCNPA at T1 (p = 0.04) and a nonsignificant reduction at T2 (p = 0.18) and T3 (p = 0.96). The DCP showed longitudinal changes in the RCNPA that tended to statistical significance (p = 0.09). Post hoc analysis revealed a trend toward a statistically significant reduction of RCNPA at T3 (p = 0.09) not statistically significant at T1 (p = 0.17) and T2 (p = 0.75). The RCVD of SCP and DCP showed no significant changes at any of the time points.

CONCLUSIONS

WFOCTA showed a decrease in RCNPA after IRI, probably related to the reperfusion of retinal capillaries.

The Changes of Irisin and Inflammatory Cytokines in the Age-Related Macular Degeneration and Retinal Vein Occlusion

Purpose

Age-related macular degeneration (AMD) and retinal vein occlusion (RVO) are irreversible chorioretinal diseases, which might induce severe damage in visual function. The metabolic factor and inflammatory factors might play important roles in the pathogenesis of AMD and RVO. The levels of irisin and 14 cytokines were analyzed in aqueous humor of AMD and RVO eyes to evaluate the roles of irisin and inflammatory factors.

Methods

We collected aqueous humor samples from patients with AMD (n = 27), RVO (n = 30), and cataract (as control, n = 23) eyes. Samples were assayed using ELISA kit for irisin and a multiplex immunoassay kit for 14 cytokines. The macular thickness (MT) was measured with OCT in all included eyes.

Results

MT in the RVO group is significantly higher than that in the AMD or control group. Irisin levels in the aqueous samples of AMD and RVO eyes were both significantly lower than that in the control. Furthermore, a positive correlation was found between irisin and MT in the RVO. Compared with the controls, AMD eyes had significantly higher levels of BDNF, VEGF-A, VEGF-R1, VEGF-R2, IL-10, TNF-α, VCAM-1, IP-10, and MCP-1. Similarly, RVO eyes had significantly higher levels of BDNF, VEGF-A, VEGF-R1, VEGF-R2, IL-6, IL-8, IL-10, TNF-α, ICAM-1, VCAM-1, IP-10, and MCP-1. However, there was no significant difference between the levels of PDGF-BB or TNF-β in these three groups. A negative correlation was found between VEGF-A and MT in AMD, as well as in control. Furthermore, a positive correlation was found between IL-6 and MT in the 80 included eyes, as well as in RVO. A positive correlation was found between ICAM-1 and MT in the 80 included eyes, as well as in RVO.

Conclusions

The metabolic factor, irisin levels in the aqueous humor are decreased in AMD and RVO eyes and show a positive correlation between irisin and MT in RVO eyes, prompting researchers to explore the relationship between irisin and macular edema. We also identified the higher expression of vascular growth factors (VEGF-A, VEGF-R1, and PDGF-BB), inflammatory cytokines (IL-6, IL-8, IL-10, and TNF-α), and chemokines (ICAM-1, VCAM-1, IP-10, and MCP-1) in AMD and RVO eyes.

Retinal non-perfusion in diabetic retinopathy

Diabetic retinopathy is a major cause of vision loss worldwide and areas of retinal non-perfusion (RNP) are a key pathologic feature of the vascular component of diabetic retinopathy. While there is a need for a more complete understanding of the natural history of RNP development and progression, overall, increasing RNP has been closely linked with worsening DR severity. Both traditional and novel approaches to quantitative image assessment are being explored to advance our understanding of the vascular, physiologic and functional changes associated with progressive RNP. Retinal ischemia secondary to RNP leads to tissue hypoxia and changes in the expression of a host of signalling molecules. Current anti-vascular endothelial growth factor and steroid pharmaceutical agents appear to be unable to reperuse areas of RNP, but may be able to slow the progressive longitudinal accumulation of RNP with regular retreatments. There remains a tremendous unmet need for pharmacotherapies that can slow RNP progression and ultimately reperfuse areas of the non-perfused retina. Towards this end, novel targets including the semaphorin family are being investigated.

[Long-term outcomes of anti-VEGF therapy for macular edema in retinal vein occlusion]

Antiangiogenic therapy (anti-VEGF) is the standard in the treatment of many retinal vascular diseases, including macular edema associated with retinal vein occlusion (RVO). A large evidentiary basis has been collected, consisting of randomized clinical trials in which anti-VEGF therapy demonstrated a significant advantage over laser photocoagulation and placebo in patients with RVO. However, in everyday clinical practice the results are not always comparable to randomized clinical trials. This review presents an analysis of the current studies based on actual clinical practice. Their results helped identify the main aspects of antiangiogenic therapy that could improve the treatment outcomes for patients with RVO. Additionally, the article discusses the predictive factors for therapy outcomes and the effect of anti-VEGF therapy on the development of neovascular complications in patients with ischemic RVO.

Microvascular Structure Changes After Intravitreal Ranibizumab Injection in Retinal Vein Occlusion Patients With and Without Macular Ischemia

Purpose: To investigate the changes in the macular microvascular structure after anti-vascular endothelial growth factor (anti-VEGF) treatment in retinal vein occlusion (RVO) patients with and without macular ischemia.

Methods: A total of 39 patients were divided into the macular ischemia group (n = 22) and the nonischemia group (n = 17) at baseline. All the patients received an intravitreal injection of ranibizumab with a 3+ pro re nata (PRN) regimen. The foveal avascular zone (FAZ) areas, macular vessel density (VD), and macular ischemic index (ISI) were evaluated at baseline and 3 and 6 months after treatment.

Results: After treatment, some patients in the macular ischemia group achieved obvious reperfusion in macular nonperfusion areas. The VD and macular ISI improved in RVO patients, but the changes in VD and macular ISI were different in the two groups. The improvement of best corrected visual acuity (BCVA) was positively correlated with the improvement of macular perfusion status. Macular perfusion remained stable in most patients in RVO and only one patient had macular ischemia aggravation.

Conclusion: The macular microvascular structures were stable in most RVO patients after anti-VEGF treatment. At the same time, some patients with macular ischemia presented reperfusion in macular nonperfusion areas, and still a few patients presented aggravated macular ischemia. Macular ISI is a good way to evaluate macular perfusion status in RVO compared to VD.

AS1411 Nucleolin-Specific Binding Aptamers Reduce Pathological Angiogenesis through Inhibition of Nucleolin Phosphorylation

Proliferative retinopathies produces an irreversible type of blindness affecting working age and pediatric population of industrialized countries. Despite the good results of anti-VEGF therapy, intraocular and systemic complications are often associated after its intravitreal use, hence novel therapeutic approaches are needed. The aim of the present study is to test the effect of the AS1411, an antiangiogenic nucleolin-binding aptamer, using in vivo, ex vivo and in vitro models of angiogenesis and propose a mechanistic insight. Our results showed that AS1411 significantly inhibited retinal neovascularization in the oxygen induced retinopathy (OIR) in vivo model, as well as inhibited branch formation in the rat aortic ex vivo assay, and, significantly reduced proliferation, cell migration and tube formation in the HUVEC in vitro model. Importantly, phosphorylated NCL protein was significantly abolished in HUVEC in the presence of AS1411 without affecting NFκB phosphorylation and -21 and 221-angiomiRs, suggesting that the antiangiogenic properties of this molecule are partially mediated by a down regulation in NCL phosphorylation. In sum, this new research further supports the NCL role in the molecular etiology of pathological angiogenesis and identifies AS1411 as a novel anti-angiogenic treatment.

Gene expression profile of the murine ischemic retina and its response to Aflibercept (VEGF-Trap)

Ischemic retinal dystrophies are leading causes of acquired vision loss. Although the dysregulated expression of the hypoxia-responsive VEGF-A is a major driver of ischemic retinopathies, implication of additional VEGF-family members in their pathogenesis has led to the development of multivalent anti-angiogenic tools. Designed as a decoy receptor for all ligands of VEGFR1 and VEGFR2, Aflibercept is a potent anti-angiogenic agent. Notwithstanding, the molecular mechanisms mediating Aflibercept's efficacy remain only partially understood. Here, we used the oxygen-induced retinopathy (OIR) mouse as a model system of pathological retinal vascularization to investigate the transcriptional response of the murine retina to hypoxia and of the OIR retina to Aflibercept. While OIR severely impaired transcriptional changes normally ensuing during retinal development, analysis of gene expression patterns hinted at alterations in leukocyte recruitment during the recovery phase of the OIR protocol. Moreover, the levels of Angiopoietin-2, a major player in the progression of diabetic retinopathy, were elevated in OIR tissues and consistently downregulated by Aflibercept. Notably, GO term, KEGG pathway enrichment, and expression dynamics analyses revealed that, beyond regulating angiogenic processes, Aflibercept also modulated inflammation and supported synaptic transmission. Altogether, our findings delineate novel mechanisms potentially underlying Aflibercept's efficacy against ischemic retinopathies.

Anatomic-Functional Correlates in Lesions of Retinal Vein Occlusion

Purpose

To evaluate anatomic–functional associations at sites of retinal lesions in retinal vein occlusion (RVO).

Methods

This pilot, prospective, observational study was conducted at the Northern Ireland Clinical Research Facility (NICRF) of Queen's University and the Belfast Health and Social Care Trust, Northern Ireland, between August 1, 2018, and September 30, 2019. The study included 10 treatment-naïve patients with RVO (10 RVO eyes and 10 fellow eyes). There were 81 points/sites assessed for each eye at baseline; six patients were re-assessed 6 months after anti-vascular endothelial growth factor therapy at the same locations. We investigated associations between retinal sensitivity and presence of structural RVO lesions, including retinal ischemia, hemorrhages, intraretinal fluid (IRF) and subretinal fluid outside the foveal/parafoveal regions. Comparisons were made between RVO eyes and fellow eyes at baseline, and between RVO eyes at baseline and at 6 months after treatment. Regression models were used to investigate anatomic–functional associations.

Results

At baseline, strong associations were found between reduced retinal sensitivity and presence of ischemia (estimate = −2.08 dB; P < 0.001), intraretinal fluid (estimate = −7.82 dB; P < 0.001), and subretinal fluid (estimate = −8.66 dB; P < 0.001). Resolution of subretinal fluid but not intraretinal fluid was associated with improved function (estimate = 2.40 dB [P = 0.022]; estimate = 1.16 dB [P = 0.228], respectively). However, reperfusion of ischemic retina, observed in 31 of 486 points (6%) 6 months after anti-vascular endothelial growth factor therapy, was associated with a further decrease in retinal sensitivity (estimate = −2.34 dB; P = 0.035).

Conclusions

Retinal sensitivity was decreased at sites of RVO lesions. Decreased function at sites of retinal ischemia did not recover after treatment, even when reperfusion occurred.

Investigation of the mechanisms of VEGF-mediated compensatory lung growth: the role of the VEGF heparin-binding domain

Morbidity and mortality for neonates with congenital diaphragmatic hernia-associated pulmonary hypoplasia remains high. These patients may be deficient in vascular endothelial growth factor (VEGF). Our lab previously established that exogenous VEGF164 accelerates compensatory lung growth (CLG) after left pneumonectomy in a murine model. We aimed to further investigate VEGF-mediated CLG by examining the role of the heparin-binding domain (HBD). Eight-week-old, male, C57BL/6J mice underwent left pneumonectomy, followed by post-operative and daily intraperitoneal injections of equimolar VEGF164 or VEGF120, which lacks the HBD. Isovolumetric saline was used as a control. VEGF164 significantly increased lung volume, total lung capacity, and alveolarization, while VEGF120 did not. Treadmill exercise tolerance testing (TETT) demonstrated improved functional outcomes post-pneumonectomy with VEGF164 treatment. In lung protein analysis, VEGF treatment modulated downstream angiogenic signaling. Activation of epithelial growth factor receptor and pulmonary cell proliferation was also upregulated. Human microvascular lung endothelial cells (HMVEC-L) treated with VEGF demonstrated decreased potency of VEGFR2 activation with VEGF121 treatment compared to VEGF165 treatment. Taken together, these data indicate that the VEGF HBD contributes to angiogenic and proliferative signaling, is required for accelerated compensatory lung growth, and improves functional outcomes in a murine CLG model.

SCORE2 Report 13: Intraretinal Hemorrhage Changes in Eyes With Central or Hemiretinal Vein Occlusion Managed With Aflibercept, Bevacizumab or Observation. Secondary Analysis of the SCORE and SCORE2 Clinical Trials

PURPOSE

To investigate the relationship between intraretinal macular hemorrhage and visual acuity outcomes in eyes with central retinal vein occlusion or hemiretinal vein occlusion managed with aflibercept, bevacizumab, or observation.

DESIGN

Retrospective analysis of data from 2 randomized clinical trials.

METHODS

A total of 362 participants were randomized in the Study of Comparative Treatments for Retinal Vein Occlusion 2, and 88 participants randomized to observation in the Standard Care vs Corticosteroid in Retinal Vein Occlusion Study. Participants received monthly intravitreal aflibercept or bevacizumab through month 6 or observation through month 8. The main outcome was visual acuity letter score (VALS).

RESULTS

Reduced area of hemorrhage by month 6 was observed in 70.7% (116 of 164) of aflibercept-treated eyes, 63.8% (104 of 163) of bevacizumab-treated eyes, and 42.2% (27 of 64) of observation eyes by month 8 (P < .01). Relative to eyes with hemorrhage during follow-up, aflibercept-treated eyes without hemorrhage at month 6 had a mean VALS improvement of 8.0 (99% confidence interval [CI]: 1.9, 14.2); bevacizumab-treated eyes without hemorrhage at month 6 had a mean VALS improvement of 3.2 (99% CI: -4.6, 11.0); and observation eyes without hemorrhage at month 8 had a mean VALS improvement of 13.5 (99% CI: 0.4, 26.5). At month 6, the presence of hemorrhage and the change in central subfield thickness (CST) were significantly associated with the change in VALS; however, CST was a more important predictor.

CONCLUSION

Improvement in hemorrhage during follow-up was associated with visual acuity improvements and predicted visual acuity changes beyond what was explained by CST. These findings suggest that intraretinal macular hemorrhage is an important indicator of disease severity in retinal vein occlusion.

Retinal vascular occlusions

Acute retinal vascular occlusions are common causes of visual impairment. Although both retinal artery occlusions and retinal vein occlusions are associated with increased age and cardiovascular risk factors, their pathophysiology, systemic implications, and management differ substantially. Acute management of retinal artery occlusions involves a multidisciplinary approach including neurologists with stroke expertise, whereas treatment of retinal vein occlusions is provided by ophthalmologists. Optimisation of systemic risk factors by patients' primary care providers is an important component of the management of these two disorders.

Sustained suppression of VEGF for treatment of retinal/choroidal vascular diseases

Neovascular age-related macular degeneration (NVAMD) is the most prevalent choroidal vascular disease, and diabetic retinopathy (DR) and retinal vein occlusion (RVO) are the most prevalent retinal vascular diseases. In each of these, hypoxia plays a central role by stabilizing hypoxia-inducible factor-1 which increases production of vascular endothelial growth factor (VEGF) and other hypoxia-regulated gene products. High VEGF causes excessive vascular permeability, neovascularization, and in DR and RVO, promotes closure of retinal vessels exacerbating hypoxia and creating a positive feedback loop. Hence once VEGF expression is elevated it tends to remain elevated and drives disease progression. While other hypoxia-regulated gene products also contribute to pathology in these disease processes, it is remarkable how much pathology is reversed by selective inhibition of VEGF. Clinical trials have demonstrated outstanding visual outcomes in patients with NVAMD, DR, or RVO from frequent intraocular injections of VEGF-neutralizing proteins, but for a variety of reasons injection frequency has been substantially less in clinical practice and visual outcomes are disappointing. Herein we discuss the rationale, preclinical, and early clinical results of new approaches that provide sustained suppression of VEGF. These approaches will revolutionize the management of these prevalent retinal/choroidal vascular diseases.

The Role of Inflammation in Diabetic Retinopathy

Inflammation is central to pathogenic processes in diabetes mellitus and the metabolic syndrome and particularly implicates innate immunity in the development of complications. Inflammation is a primary event in Type 1 diabetes where infectious (viral) and/or autoimmune processes initiate disease; in contrast, chronic inflammation is typical in Type 2 diabetes and is considered a sequel to increasing insulin resistance and disturbed glucose metabolism. Diabetic retinopathy (DR) is perceived as a vascular and neurodegenerative disease which occurs after some years of poorly controlled diabetes. However, many of the clinical features of DR are late events and reflect the nature of the retinal architecture and its cellular composition. Retinal microvascular disease is, in fact, an early event pathogenetically, induced by low grade, persistent leukocyte activation which causes repeated episodes of capillary occlusion and, progressive, attritional retinal ischemia. The later, overt clinical signs of DR are a consequence of the retinal ischemia. Metabolic dysregulation involving both lipid and glucose metabolism may lead to leukocyte activation. On a molecular level, we have shown that macrophage-restricted protein tyrosine phosphatase 1B (PTP1B) is a key regulator of inflammation in the metabolic syndrome involving insulin resistance and it is possible that PTP1B dysregulation may underlie retinal microvascular disease. We have also shown that adherent CCR5⁺CD11b⁺ monocyte macrophages appear to be selectively involved in retinal microvascular occlusion. In this review, we discuss the relationship between early leukocyte activation and the later features of DR, common pathogenetic processes between diabetic microvascular disease and other vascular retinopathies, the mechanisms whereby leukocyte activation is induced in hyperglycemia and dyslipidemia, the signaling mechanisms involved in diabetic microvascular disease, and possible interventions which may prevent these retinopathies. We also address a possible role for adaptive immunity in DR. Although significant improvements in treatment of DR have been made with intravitreal anti-VEGF therapy, a sizeable proportion of patients, particularly with sight-threatening macular edema, fail to respond. Alternative therapies targeting inflammatory processes may offer an advantage.

Efficacy of intravitreal AFlibercept injection For Improvement of retinal Nonperfusion In diabeTic retinopathY (AFFINITY study)

INTRODUCTION

To evaluate the effects of intravitreal aflibercept injection on retinal nonperfusion in patients with diabetic retinopathy (DR) using ultrawide field (UWF) fluorescein angiography (FA).

RESEARCH DESIGN AND METHODS

Thirty-eight eyes of 38 consecutive patients with DR and substantial retinal nonperfusion (nonperfusion index (NPI): nonperfused/total gradable area >0.2) without macular edema were included in this prospective case series. Monthly injections of 2 mg aflibercept were given for 6 months. UWF-fundus photography and UWF-FA images were acquired at baseline, 6 months, and 12 months and evaluated by 2 masked, independent graders for the extent of retinal nonperfusion and vascular leakage. Twenty untreated fellow eyes were analyzed as controls.

RESULTS

Inter-grader agreement was strong (r=0.875) for NPI measurements. NPI was 0.46±0.10 at baseline; NPI was decreased to 0.43±0.08 (p=0.015) after 6 monthly injections of aflibercept and then slightly increased to 0.44±0.09 (p=0.123) after 6 months of observation. Vascular leakage also significantly decreased by 21.0% at 6 months (p=0.010). Untreated fellow eyes did not show significant changes in NPI and vascular leakage during follow-up. Reduction in retinal nonperfusion was associated with severe nonproliferative diabetic retinopathy (NPDR) (vs PDR, OR 19.119, p=0.025) and higher leakage index (per 0.1, OR 15.152, p=0.020).

CONCLUSIONS

Intensive aflibercept treatment was effective in reducing retinal capillary nonperfusion in patients with DR without macular edema. Severe NPDR and profound vascular leakage were significantly associated with retinal reperfusion after aflibercept treatment.

TRIAL REGISTRATION NUMBER

NCT03006081.

Aflibercept ameliorates retinal pericyte loss and restores perfusion in streptozotocin-induced diabetic mice

INTRODUCTION

Anti-vascular endothelial growth factor (VEGF) agents are used worldwide for advanced-stage diabetic retinopathy (DR). In contrast, apart from blood glucose control, there are no specific treatments that can limit the progression of early-stage DR that starts with pericyte loss and the destruction of the blood-retinal barrier. Here, we examined the efficacy of aflibercept, a potent anti-VEGF agent, against early-DR pathologies in a murine model of streptozotocin (STZ)-induced DR.

RESEARCH DESIGN AND METHODS

STZ was intraperitoneally administered in 8-week-old C57BL/6N male mice. After 4 weeks, the mice were divided into aflibercept-treated and saline-treated groups. Eight weeks after the STZ injection, vascular permeability/leakage was measured with fluorescein angiography in live mice. At 4, 6, and 8 weeks after the STZ injection, the eyes were enucleated, flat-mounted, and stained for platelet-derived growth factor receptor-β to assess pericyte abundance, CD45 to assess leukocyte recruitment, and fluorescein isothiocyanate dextran to assess perfusion. VEGF levels were quantified in each group. The effects of aflibercept on pericyte number, perfusion status, and leukocyte recruitment/accumulation on mice with diabetes retina were evaluated.

RESULTS

Our murine model successfully replicated the salient pathologies of DR such as pericytes loss, hyperpermeability, and perfusion blockage. Interestingly, numerous leukocytes and leukocyte clumps were found in diabetic retinal capillaries, especially in the non-perfused border area of the retina, suggesting a possible mechanism for non-perfusion and related pericyte damage. Treatment with aflibercept in mice with diabetes inhibited the upregulation of VEGF and the associated adhesion molecules while reducing the defects in perfusion. Aflibercept also attenuated pericyte loss in the diabetic retina.

CONCLUSION

VEGF inhibition through aflibercept treatment decreased leukocyte recruitment and aggregation, perfusion blockage, retinal hypoperfusion, and hyperpermeability in mice with diabetes and ultimately attenuated pericyte loss. Our findings suggest that anti-VEGF strategies may prove useful as possible therapies for limiting the progression of early-stage DR.

Clinical effect of conbercept on improving diabetic macular ischemia by OCT angiography

BACKGROUND

Varying degrees of macular ischemia generally occur in diabetic retinopathy (DR). This study aims to evaluate the effect of conbercept with 3+ pro re nata (PRN) on macular perfusion status in patients with diabetic macular edema (DME) and quantitatively assess changes in foveal avascular zone (FAZ) areas and capillary density in macular regions by applying optical coherence tomography angiography (OCTA).

METHODS

Fifty patients were divided into ischemic (n = 31) and non-ischemic (n = 19) groups according to the presence of ischemia on OCTA at baseline. All patients received intravitreal injections of 0.5 mg of conbercept with 3+ PRN principle. The FAZ areas and macular vessel density measured using OCTA were evaluated at baseline, 3 months, and 6 months after treatment in both groups.

RESULTS

At months 3 and 6, the FAZ area in the ischemic group changed from 0.510 ± 0.171 mm2 to 0.441 ± 0.158 mm2 then to 0.427 ± 0.153 mm2 (p = 0.003, p = 0.296); in the non-ischemic group, it remained stable (p = 0.269, p = 0.926). The superficial vessel density changed from 41.1 ± 4.1 to 42.5% ± 4.7% then to 42.6% ± 4.6% (p = 0.043, p = 0.812), and the deep vessel density changed from 40.7 ± 4.4 to 42.3% ± 3.6% then to 42.3% ± 4.7% (p = 0.072, p = 0.961) in the ischemic group. In the non-ischemic group, the superficial vessel density changed from 44.8 ± 3.2 to 46.0% ± 3.5% then to 45.7% ± 3.3% (p = 0.108, p = 0.666), whereas the deep vessel density changed from 43.6 ± 3.6 to 43.8% ± 3.2% then to 43.5% ± 4.5% (p = 0.882, p = 0.736). Reperfusion in macular nonperfusion areas was observed.

CONCLUSION

Anti-vascular endothelial growth factor treatment may have a positive effect on macular perfusion status. Furthermore, OCTA had advantages in quantifying and calculating blood flow index in the study of macular perfusion status.

A Custom-Made Semiautomatic Analysis of Retinal Nonperfusion Areas After Dexamethasone for Diabetic Macular Edema

Purpose

To evaluate the changes of retinal capillary nonperfusion areas and retinal capillary vessel density of the superficial capillary plexus (SCP) and deep capillary plexus in patients with diabetes with diabetic macular edema treated with an intravitreal dexamethasone implant (IDI).

Methods

We enrolled 28 patients with diabetic retinopathy and diabetic macular edema candidates to IDI. All patients underwent widefield optical coherence tomography angiography with PLEX Elite 9000 device with 15 × 9 mm scans centered on the foveal center at baseline, 1 month, 2 months, and 4 months after IDI. In all the patients, the variation of the retinal capillary nonperfusion areas and of the retinal vessel density of the SCP and deep capillary plexus were calculated using an automatic software written in Matlab (MathWorks, Natick, MA).

Results

During follow-up, SCP showed a statistically significant reduction of ischemic areas at 1 month after IDI (P = 0.04) and slightly increased not significantly thereafter (P = 0.15). The percentage of nonperfusion areas changed from 11.4% at baseline, to 6.3% at 1 month, 8.1%, at 2 months, and 10.2% at 4 months. The whole vessel density of SCP slightly increased (not significantly) from 35.30% at baseline to 38.00% at 1 month, and then decreased to 37.85% at 2 months and 36.04% at 4 months (P = 0.29). Retinal capillary nonperfusion areas and retinal vessel density at the deep capillary plexus did not change significantly (P = 0.31 and P = 0.73, respectively).

Conclusions

Widefield optical coherence tomography angiography showed a decrease in retinal capillary nonperfusion areas after dexamethasone implant suggesting a possible drug-related reperfusion of retinal capillaries particularly evident in the early period.

Translational Relevance

A custom-made automatic analysis of retinal nonperfusion areas may allow a better and precise evaluation of ischemic changes after intravitreal therapy.

Suppression of Ocular Vascular Inflammation through Peptide-Mediated Activation of Angiopoietin-Tie2 Signaling

Persistent inflammation is a complication associated with many ocular diseases. Changes in ocular vessels can amplify disease responses and contribute to vision loss by influencing the delivery of leukocytes to the eye, vascular leakage, and perfusion. Here, we report the anti-inflammatory activity for AXT107, a non-RGD, 20-mer αvβ3 and α5β1 integrin-binding peptide that blocks vascular endothelial growth factor (VEGF)-signaling and activates tyrosine kinase with immunoglobulin and EGF-like domains 2 (Tie2) using the normally inhibitory ligand angiopoietin 2 (Ang2). Tumor necrosis factor α (TNFα), a central inflammation mediator, induces Ang2 release from endothelial cells to enhance its stimulation of inflammation and vascular leakage. AXT107 resolves TNFα-induced vascular inflammation in endothelial cells by converting the endogenously released Ang2 into an agonist of Tie2 signaling, thereby disrupting both the synergism between TNFα and Ang2 while also preventing inhibitor of nuclear factor-κB α (IκBα) degradation directly through Tie2 signaling. This recovery of IκBα prevents nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) nuclear localization, thereby blocking NF-κB-induced inflammatory responses, including the production of VCAM-1 and ICAM-1, leukostasis, and vascular leakage in cell and mouse models. AXT107 also decreased the levels of pro-inflammatory TNF receptor 1 (TNFR1) without affecting levels of the more protective TNFR2. These data suggest that AXT107 may provide multiple benefits in the treatment of retinal/choroidal and other vascular diseases by suppressing inflammation and promoting vascular stabilization.

One-year follow-up of ischemic index changes after intravitreal dexamethasone implant for diabetic macular edema: an ultra-widefield fluorescein angiography study

AIM

To investigate late changes in peripheral ischemia in patients affected by diabetic macular edema (DME) and treated with repeated dexamethasone (DEX) intravitreal implants over a 1-year period.

METHODS

In this retrospective cohort study, patients older than 18 years of age and with type 2 non-proliferative treatment-naïve diabetic retinopathy (DR) and DME at baseline were included. All patients were treated with two intravitreal DEX implants within 1 year of follow-up. A minimum of two annual ultra-widefield fluorescein angiography (UWF FA) were required to ensure that all cases had a baseline UWF FA (< 2 weeks before first treatment with dexamethasone) and a UWF FA performed at 12 months of follow-up. On baseline and 1-year UWFA images, peripheral retinal ischemia was quantified using the ischemic index (ISI).

RESULTS

Six eyes of five patients (two males, three females) met the inclusion criteria and were enrolled in this study. Best-corrected visual acuity was 0.34 ± 0.22 LogMAR at baseline and improved to 0.21 ± 0.14 logMAR at the 1-year follow-up visit (P = 0.050). Mean ± SD central macular thickness was 467.6 ± 63.0 μm at baseline and 272.0 ± 14.7 μm at the 1-year follow-up visit (P = 0.043). Mean ± SD ISI was 26.7 ± 14.1% at baseline and reduced to 12.2 ± 5.0% at the 1-year follow-up visit (P = 0.012).

CONCLUSIONS

Improvement in retinal perfusion is still maintained 1 year after starting treatment with DEX implants. This improvement in retinal perfusion might be related to DEX implant-related positive effects on leukostasis.

Hepatocyte growth factor is upregulated in ischemic retina and contributes to retinal vascular leakage and neovascularization

In patients with macular edema due to ischemic retinopathy, aqueous levels of hepatocyte growth factor (HGF) correlate with edema severity. We tested whether HGF expression and activity in mice with oxygen-induced ischemic retinopathy supports a role in macular edema. In ischemic retina, HGF was increased in endogenous cells and macrophages associated with retinal neovascularization (NV). HGF activator was increased in and around retinal vessels potentially providing vascular targeting. One day after intravitreous injection of HGF, VE-cadherin was reduced and albumin levels in retina and vitreous were significantly increased indicating vascular leakage. Injection of VEGF caused higher levels of vitreous albumin than HGF, and co-injection of both growth factors caused significantly higher levels than either alone. HGF increased the number of macrophages on the retinal surface, which was blocked by anti-c-Met and abrogated in chemokine (C-C motif) ligand 2 (CCL2)-/- mice. Injection of anti-c-Met significantly decreased leakage within 24 hours and after 5 days it reduced retinal NV in mice with ischemic retinopathy, but had no effect on choroidal NV. These data indicate that HGF is a pro-permeability, pro-inflammatory, and pro-angiogenic factor and along with its activator is increased in ischemic retina providing support for a potential role of HGF in macular edema in ischemic retinopathies.

Foveal avascular zone area analysis in juvenile-onset type 1 diabetes using optical coherence tomography angiography

PURPOSE

Optical coherence tomography angiography (OCTA) was performed on patients with juvenile-onset type 1 diabetes (T1DM) but with no diabetic retinopathy to measure the foveal avascular zone (FAZ) area.

STUDY DESIGN

Retrospective single-facility study METHODS: Twenty-nine patients (58 eyes) with juvenile-onset T1DM were studied. Images (3 mm x 3 mm cube centered on the fovea) were acquired using an OCTA device. Age at examination was 16.1 ± 8.7 years; onset age was 6.4 ± 3.5 years; duration of diabetes was 9.7 ± 8.3 years. Twenty-four age-matched healthy individuals were studied as controls.

RESULTS

FAZ area was significantly larger in T1DM patients than in controls (0.29 ± 0.09 vs. 0.25 ± 0.08 mm², P = 0.0234). Parafoveal vessel density was not significantly different between patients and controls (50.43 ± 4.24 vs. 50.07 ± 4.64, P = 0.8842). By generalized linear model analysis, annual HbA1c (P = 0.0190), number of serious hypoglycemic attacks (P = 0.0210), and onset age (P = 0.0447) were identified as variables significantly associated with FAZ area. Age, gender, duration of disease, total cholesterol, high or low-density lipoprotein, triglycerides, and body mass index were not significantly associated with FAZ area.

CONCLUSION

Patients with juvenile-onset T1DM and no diabetic retinopathy had increased FAZ, but no significant difference in parafoveal vessel density compared to healthy controls. Larger FAZ area was associated with higher annual HbA1c, more episodes of severe hypoglycemic attacks, and older onset age.

Sustained treatment of retinal vascular diseases with self-aggregating sunitinib microparticles

Neovascular age-related macular degeneration and diabetic retinopathy are prevalent causes of vision loss requiring frequent intravitreous injections of VEGF-neutralizing proteins, and under-treatment is common and problematic. Here we report incorporation of sunitinib, a tyrosine kinase inhibitor that blocks VEGF receptors, into a non-inflammatory biodegradable polymer to generate sunitinib microparticles specially formulated to self-aggregate into a depot. A single intravitreous injection of sunitinib microparticles potently suppresses choroidal neovascularization in mice for six months and in another model, blocks VEGF-induced leukostasis and retinal nonperfusion, which are associated with diabetic retinopathy progression. After intravitreous injection in rabbits, sunitinib microparticles self-aggregate into a depot that remains localized and maintains therapeutic levels of sunitinib in retinal pigmented epithelium/choroid and retina for more than six months. There is no intraocular inflammation or retinal toxicity. Intravitreous injection of sunitinib microparticles provides a promising approach to achieve sustained suppression of VEGF signaling and improve outcomes in patients with retinal vascular diseases.

Neovascular age-related macular degeneration and diabetic retinopathy are currently treated with repeated intravitreous injections of VEGF neutralizing proteins. Here the authors develop a microparticle-loaded tyrosine kinase inhibitor therapy, which is effective for six months after a single injection in preclinical models.

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.

Ursodeoxycholic Acid Attenuates the Retinal Vascular Abnormalities in Anti-PDGFR-β Antibody-Induced Pericyte Depletion Mouse Models

As a clinical manifestations of diabetic retinopathy (DR), pericytes (PCs) loss from the capillary walls is thought to be an initial pathological change responsible for the breakdown of the blood-retinal barrier (BRB). This study was performed to investigate the effects of ursodeoxycholic acid (UDCA) in PC depletion mice by injection of an antibody against platelet-derived growth factor reception-β (PDGFR-β clone APB5). To assess the integrity of the retinal vessels, their density, diameters, vessel branching points, and number of acellular capillaries were evaluated. While all types of retinal vessels became enlarged in APB5-induced mice, treatment with UDCA rescued the vasculature; the vessel density, diameter of the veins and capillaries, and vessel branching points were significantly lower in mice treated with UDCA. Although APB5-induced mice displayed progressive exacerbation of retinal edema, whole retinal thickness upon treatment with UDCA was significantly decreased. Additionally, UDCA reduced the expression of F4/80⁺ macrophages in the APB5-induced retina according to immunofluorescent labeling. UDCA also reduced the increased expression of angiogenic factors and inflammatory mediators (vascular endothelial growth factor, intercellular adhesion molecule-1, and monocyte chemotactic protein-1). These findings suggest that UDCA can be used to prevent the progression of and treat DR.

Intravitreal Aflibercept for Retinal Nonperfusion in Proliferative Diabetic Retinopathy: Outcomes from the Randomized RECOVERY Trial

PURPOSE

Evaluate the impact of intravitreal aflibercept (Eylea; Regeneron, Tarrytown, NY) on retinal nonperfusion (RNP) in eyes with proliferative diabetic retinopathy (PDR).

DESIGN

Prospective, randomized clinical trial.

PARTICIPANTS

Eyes with treatment-naïve PDR and extensive RNP without diabetic macular edema.

METHODS

Patients were randomized 1:1 to intravitreal 2 mg aflibercept every 4 weeks (monthly) or every 12 weeks (quarterly).

MAIN OUTCOME MEASURES

The primary outcome measure was change in total RNP area (in square millimeters) from baseline to year 1. Secondary outcomes included ischemic index (ISI), diabetic retinopathy severity scale (DRSS) scores, visual acuity, central retinal thickness, and adverse events. The mean and 95% confidence interval were calculated for each outcome.

RESULTS

Through 1 year, the monthly (n = 20) and quarterly (n = 20) cohorts received 11.0 and 3.95 mean aflibercept injections, and DRSS scores improved 2 steps or more in 74% and 67% of patients, respectively. Among all patients through 1 year, mean total area of RNP increased from 235 mm² to 266 mm² (P = 0.18) and ISI increased from 25.8% to 31.9% (P = 0.004). Retinal nonperfusion outcomes favored monthly dosing. Mean total RNP increased from 207 mm² at baseline to 268 mm² (P = 0.01) at 1 year in the quarterly cohort and remained stable at 264 mm² at baseline and 1 year (P = 0.70) in the monthly cohort (P = 0.05, monthly vs. quarterly cohorts). Although many eyes demonstrated increased areas of RNP longitudinally (n = 24 [66.7%]), this was more common with quarterly dosing (n = 14 [77.8%]), and a proportion of eyes (n = 12 [33.3%]) demonstrated localized areas of apparent reperfusion of nonperfused retina, more commonly in the monthly cohort (n = 8 [44.4%]).

CONCLUSIONS

Widespread evidence of retinal reperfusion with aflibercept dosing of PDR eyes with extensive RNP was not identified, and therefore the primary outcome of the current study was not met. Nevertheless, zones of apparent reperfusion were detected in some patients, and a dose response was identified with a reduction of RNP progression with monthly compared to quarterly dosing.

Gene expression patterns of COX-1, COX-2 and iNOS in H. Pylori infected histopathological conditions

BACKGROUND

Research indicates that Helicobacter pylori can inflict severe histological damage through the modulation of host-related genes. The current study investigated the effect of H. pylori genotypes in the outcome of disease, and the expression of anti-apoptotic related genes, COX-1, COX-2, and iNOS genes in benign, pre-malignant, and malignant lesions of gastric carcinogenesis.

MATERIALS AND METHODS

Tissue samples from H. pylori positive patients were graded based on the genotype of the infected H. pylori strain. Expression of COX-1, COX-2 and iNOS was assessed using a combination of real-time PCR and immunohistochemistry.

RESULTS

Gene expression studies confirmed that COX-2 and iNOS expression was highly and selectively induced in epithelium with premalignant changes such as atrophic conditions, metaplasia and dysplasia, suggesting an important role of these genes in the sequence to gastric carcinoma of the intestinal type. Furthermore, the expression of COX-2 and iNOS was also dependent on the genotype of H. pylori and subjects with genotype-1 exhibited significantly higher expressions of COX-2 and iNOS compared to other genotypes. Comparison of the expression levels among infected and uninfected individuals demonstrated significant difference in the expression pattern of COX-2 gene whereas iNOS expression was found only in subjects infected H. pylori (p < 0.001). Immunohistochemical staining showed 1.5619 folds higher propensity of COX-2 and 3.2941 folds higher intensity of iNOS expression in subjects infected with H. pylori genotype 1.

CONCLUSION

The up-regulation of COX-2 and iNOS was associated with the genotype of the H. pylori strain and the presence of certain genotype may greatly affect early events during carcinogenesis.

Widefield OCT-Angiography and Fluorescein Angiography Assessments of Nonperfusion in Diabetic Retinopathy and Edema Treated with Anti-Vascular Endothelial Growth Factor

PURPOSE

To assess change in retinal nonperfusion (NP) after anti-vascular endothelial growth factor (VEGF) therapy for diabetic macular edema (DME) using 2 different imaging modalities: swept-source widefield (SS-WF) OCT angiography (OCTA) and ultra-widefield (UWF) fluorescein angiography (FA).

DESIGN

Observational case series.

PARTICIPANTS

Ten eyes of 9 patients with severe nonproliferative diabetic retinopathy (NPDR) or proliferative DR (PDR) initiating 3 monthly anti-VEGF intravitreal injections for DME.

METHODS

All eyes were imaged with UWF color fundus photographs (CFPs), UWF FA, and SS-WF OCTA at baseline (M0) and 1 month after the third anti-VEGF injection (M3). All images were aligned and divided into 16 boxes for analysis of NP areas by 2 blinded retina specialists.

MAIN OUTCOME MEASURES

The number of discrepancies between SS-WF OCTA and UWF FA regarding the detection of NP areas and small vessels passing through NP areas; assessment of DR severity on UWF CFP; and change in each NP area between M0 and M3: number of boxes/eye with presence of at least 1 NP area, number of arterioles or venules that disappeared or reappeared, and number of NP areas in which capillaries disappeared or reappeared.

RESULTS

The diabetic retinopathy (DR) severity score improved by at least 1 stage in 8 of 10 eyes, with a significant decrease in the mean number of microaneurysms and retinal hemorrhages on UWF CFP at M3 versus M0 (n = 40±28 vs. 121±57; P = 0.0020) and regression of fundus neovascularization when present. All NP areas detected on FA were seen on SS-WF OCTA, but additional NP areas were detected on SS-WF OCTA at M0 in 29% (46/160) of boxes. No reperfusion of arterioles or venules was observed at M3 on FA or SS-WF OCTA. Retinal capillaries were only visible on OCTA, and no reperfusion in NP areas was observed even when a reduction in dark areas was visible on FA.

CONCLUSIONS

No reperfusion of vessels or capillary network was detected in NP areas using 2 imaging techniques, UWF FA and SS-WF OCTA, in eyes with DR after 3 anti-VEGF injections. The detection rate of NP areas was higher with SS-WF OCTA than with UWF FA.

Branch Retinal Vein Occlusion: Treatment Outcomes According to the Retinal Nonperfusion Area, Clinical Subtype, and Crossing Pattern

This prospective study examined 58 eyes with branch retinal vein occlusion (BRVO) to investigate the effects of the nonperfusion area (NPA), clinical subtype, and crossing pattern on the 2-year outcomes of ranibizumab therapy for the macular edema (ME). All eyes received three initial monthly injections, followed by additional pro re nata (PRN) injections. The final best corrected visual acuity (BCVA) and ranibizumab injection number were not associated with the macular NPA or total NPA at baseline or month 12, and they showed no significant differences between the clinical subtypes. However, the incidence of neovascular changes was higher in the major BRVO group than in the macular BRVO group (P = 0.030). Twelve and 19 of the 34 eyes with major BRVO exhibited arterial overcrossing and venous overcrossing, respectively. At baseline, the total NPA did not differ according to the crossing pattern, however, the total NPA was significantly larger in the venous overcrossing group at month 12 (P = 0.047). At month 24, the incidence of neovascular changes was higher in the venous overcrossing group (P = 0.030). Following ranibizumab therapy for BRVO-associated ME, the clinical subtype and the arteriovenous crossing pattern may be associated with neovascular changes.

Growth factor signaling pathways in vascular development and disease

Angiogenic blood vessel growth is essential to ensure organs receive adequate blood supply to support normal organ function and homeostasis. Angiogenesis involves a complex series of cellular events through which new vessels grow out from existing vasculature. Growth factor signaling, layered over a range of other signaling inputs, orchestrates this process. The response of endothelial cells (ECs) to growth factor signals must be carefully controlled through feedback mechanisms to prevent excessive vessel growth, remodeling or destabilization. In this article, we summarize recent findings describing how ECs respond to growth factor signals during blood vessel development and homeostasis and how perturbation of these responses can lead to disease.

Longitudinal Quantification of Retinal Nonperfusion in the Macula of Eyes With Retinal Vein Occlusion Receiving Anti-VEGF Therapy: Secondary Analysis of the WAVE Randomized Trial

BACKGROUND AND OBJECTIVE

Longitudinal quantification of retinal nonperfusion (RNP) in eyes with retinal vein occlusion (RVO) undergoing anti-vascular endothelial growth factor therapy.

PATIENTS AND METHODS

Thirty eyes with ischemic RVO were randomized to ranibizumab (Lucentis; Genentech, South San Francisco, CA) (monotherapy) or ranibizumab plus peripheral laser (combination therapy) in a 12-month, prospective trial. RNP on fluorescein angiography was quantified within the macula through 12 months of follow-up.

RESULTS

Baseline mean macular RNP areas were 5.04 mm² and 8.30 mm² in the monotherapy (n = 5) and combination therapy (n = 15) cohorts, respectively. Through month 12, mean macular RNP area increased 0.36 mm² and 0.53 mm² in the monotherapy and combination therapy cohorts, respectively (P = .77). Marked, progressive RNP was observed in three eyes (12%). No areas of reperfusion were detected in any eye.

CONCLUSION

Among ischemic RVO eyes in WAVE, macular RNP was common at baseline and remained stable over time in most eyes, though marked RNP progression occurred in a minority of eyes. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:258-264.].

Molecular mechanisms of retinal ischemia

Each day, the retina converts an immense number of photons into chemical signals that are then transported to higher order neural centers for interpretation. This process of photo transduction requires large quantities of cellular energy and anabolic precursors, making the retina one of the most metabolically active tissues in the body. With such a large metabolic demand, the retina is understandably sensitive to perturbations in perfusion and hypoxia. Indeed, retinal ischemia underlies many prevalent retinal disorders including diabetic retinopathy (DR), retinal vein occlusion (RVO), and retinopathy of prematurity (ROP). Retinal ischemia leads to the expression of growth factors, cytokines, and other cellular mediators which promote inflammation, vascular dysfunction, and ultimately, vision loss. This review aims to highlight the most recent and compelling findings that have advanced our understanding of the molecular mechanisms underlying retinal ischemias.

Recent advances in understanding and managing retinal vein occlusions

Retinal vein occlusions are the second most common form of retinal vascular disease. Previously, laser treatment for branch retinal vein occlusion and intravitreal triamcinolone acetonide for central retinal vein occlusion were the standard of care. Recent studies have demonstrated that anti-vascular endothelial growth factor (anti-VEGF) agents have a superior safety and efficacy profile for the treatment of both branch and central retinal vein occlusions. The use of wide-field fluorescein angiography has also allowed better visualization of the retinal periphery. Despite the better documentation of retinal non-perfusion, laser photocoagulation to the areas of non-perfusion does not seem to result in a reduction of macular edema or reduction in treatment burden and has been relegated to patients who develop rubeosis or neovascularization of the retina. More recently, several studies have demonstrated the use of a long-acting dexamethasone implant administered intravitreally or triamcinolone administered in the suprachoroidal space as a viable approach to treat retinal vein occlusion.