Altered vascular microenvironment by bevacizumab in diabetic fibrovascular membrane

Single-cell transcriptome profiling highlights the role of APP in blood vessels in assessing the risk of patients with proliferative diabetic retinopathy developing Alzheimer's disease

Introduction: The incidence of diabetic retinopathy (DR) has been found to be associated with the risk of developing Alzheimer's disease (AD). In addition to the common properties of neurodegeneration, their progressions are involved with abnormal vascular functions. However, the interactions between them have not been fully understood. This study aimed to investigate the key factor for the underlying interactions and shared signaling pathways in the vasculature of DR and AD. Methods: We retrieved single-cell RNA sequencing (scRNA-seq) data regarding human fibrovascular membrane (FVM) of proliferative diabetic retinopathy (PDR) and human hippocampus vessels of AD from the NCBI-GEO database. GSEA analysis was performed to analyze AD-related genes in endothelial cells and pericytes of PDR. CellChat was used for predicting cell-cell communication and the signaling pathway. Results: The data suggested that amyloid-beta precursor protein (APP) signaling was found crucial in the vasculature of PDR and AD. Endothelial cells and pericytes could pose influences on other cells mainly via APP signaling in PDR. The endothelial cells were mainly coordinated with macrophages in the hippocampus vasculature of AD via APP signaling. The bulk RNA-seq in mice with PDR validated that the expression of APP gene had a significant correlation with that of the AD genome-wide association studies (GWAS) gene. Discussion: Our study demonstrates that the vasculopathy of PDR and AD is likely to share a common signaling pathway, of which the APP-related pathway is a potential target.

Angiogenic footprints in diabetic retinopathy: opportunities for drug development

Diabetic retinopathy is one of the withering disorders that has been making the lives of patients miserable. Arising as a result of chronic high blood sugar levels in diabetes patients, retinopathy has become a major reason causing permanent blindness, retinal detachment, vitreous humor, rage, or glaucoma among patients. Angiogenesis being the major culprit behind the development of this condition is the growth of new blood vessels from the earlier ones existing. The abnormal growth and poor development of blood vessels also lead to aggravation of the conditions, with vascular endothelial growth factor (VEGF) playing a major role in the process. Various anti-angiogenic therapies or anti-VEGF therapies are being explored for the treatment of this condition. 4 widely explored drugs being-Bevacizumab, pegaptanib sodium, ranibizumab, and aflibercept. The review article tries to summarize studies illustrating the efficacy of these drugs in the treatment of diabetic retinopathy along with some of the herbal therapeutic paradigms displaying anti-angiogenic action that is being used to treat this condition.

Cell-Matrix Interactions in the Eye: From Cornea to Choroid

The extracellular matrix (ECM) plays a crucial role in all parts of the eye, from maintaining clarity and hydration of the cornea and vitreous to regulating angiogenesis, intraocular pressure maintenance, and vascular signaling. This review focuses on the interactions of the ECM for homeostasis of normal physiologic functions of the cornea, vitreous, retina, retinal pigment epithelium, Bruch's membrane, and choroid as well as trabecular meshwork, optic nerve, conjunctiva and tenon's layer as it relates to glaucoma. A variety of pathways and key factors related to ECM in the eye are discussed, including but not limited to those related to transforming growth factor-β, vascular endothelial growth factor, basic-fibroblastic growth factor, connective tissue growth factor, matrix metalloproteinases (including MMP-2 and MMP-9, and MMP-14), collagen IV, fibronectin, elastin, canonical signaling, integrins, and endothelial morphogenesis consistent of cellular activation-tubulogenesis and cellular differentiation-stabilization. Alterations contributing to disease states such as wound healing, diabetes-related complications, Fuchs endothelial corneal dystrophy, angiogenesis, fibrosis, age-related macular degeneration, retinal detachment, and posteriorly inserted vitreous base are also reviewed.

Anti-VEGF crunch syndrome in proliferative diabetic retinopathy: A review

Anti-vascular endothelial growth factor (anti-VEGF) crunch syndrome describes the progression to tractional retinal detachment following intravitreal anti-VEGF therapy in an eye with proliferative diabetic retinopathy . We reviewed the literature on the anti-VEGF crunch using the PubMed and Cochrane databases. Anti-VEGF crunch typically manifests as sudden vision loss in the affected eye between 1 and 6 weeks following intravitreal anti-VEGF injection, with a mean onset of 13 days. Risk factors for crunch development include the use of a higher anti-VEGF dose and increased severity of diabetic retinopathy with fibrosis. Our review found that intravitreal anti-VEGF, in particular bevacizumab, should be used with caution when treating patients with severe proliferative diabetic retinopathy and pre-existing intraocular fibrosis. In patients where anti-VEGF is used before a planned vitrectomy, we recommend close monitoring for crunch symptoms and proceeding promptly with surgery if there is new or progression of tractional retinal detachment. For eyes with minimal preexisting traction that develop crunch after anti-VEGF treatment, surgeons should proceed to vitrectomy within 7 days. The existing literature on the anti-VEGF crunch is limited by heterogeneity in the way crunch is documented and characterized and the presence of panretinal photocoagulation as a confounding factor. Because of these methodological flaws, the relative frequency of the anti-VEGF crunch cannot be accurately estimated.

Clinical presentation and prognostic factors affecting surgical outcomes of secondary macular holes after retinal vein occlusions

PURPOSE

To describe clinical presentation, morphological features and surgical outcomes of macular hole (MH) secondary to retinal vein occlusion (RVO).

METHOD

This prospective interventional study evaluated eight eyes with atypical MH (secondary to RVO) and data regarding medical management, pars plana vitrectomy, postoperative anatomical hole closure, visual acuity improvement, morphological features of hole were noted till the last follow-up.

RESULTS

Eight eyes with full-thickness MH in an RVO eye were followed-up for a minimum period of 3 months postoperatively. Five subjects had a RVO episode which occurred more than 6 months before the onset of the recent symptoms (Group 1; 4 branch RVO and 1 central RVO), and 3 subjects had a recent onset branch RVO within 6 months (Group 2). All FTMH cases except one showed closure at the last follow-up. Visual acuity of all eyes improved from 0.91 ± 0.57 logMAR to 0.5 ± 0.3 logMAR (p = 0.093). At baseline, visual acuities of the two groups had no significant difference. Postoperatively, group 1 holes had better visual prognosis, than Group 2 holes, further substantiated by persistence of subretinal fluid in Group 2 eyes till last follow-up. Minimum hole diameter was higher in the recent RVO group, although anatomical closure was obtained in all of these eyes. Most holes had favorable morphological hole features like raised configuration with rounded edges.

CONCLUSION

In the presence of favorable morphological features, secondary macular holes associated with retinal vein occlusion may show optimal outcomes after surgery. It is not clear whether acutely created holes in recent onset RVO should be operated early. Older holes may have better prognosis.

APOPTOSIS AND ANGIOFIBROSIS IN DIABETIC TRACTIONAL MEMBRANES AFTER VASCULAR ENDOTHELIAL GROWTH FACTOR INHIBITION: Results of a Prospective Trial. Report No. 2

PURPOSE

We sought to characterize the angiofibrotic and apoptotic effects of vascular endothelial growth factor (VEGF)-inhibition on fibrovascular epiretinal membranes in eyes with traction retinal detachment because of proliferative diabetic retinopathy.

METHODS

Membranes were excised from 20 eyes of 19 patients (10 randomized to intravitreal bevacizumab, 10 controls) at vitrectomy. Membranes were stained with antibodies targeting connective tissue growth factor (CTGF) or VEGF and colabeled with antibodies directed against endothelial cells (CD31), myofibroblasts, or retinal pigment epithelium markers. Quantitative and colocalization analyses of antibody labeling were obtained through immunofluorescence confocal microscopy. Masson trichrome staining, cell counting of hematoxylin and eosin sections, and terminal dUTP nick-end labeling staining were performed.

RESULTS

High levels of fibrosis were observed in both groups. Cell apoptosis was higher (P = 0.05) in bevacizumab-treated membranes compared with controls. The bevacizumab group had a nonsignificant reduction in colocalization in CD31-CTGF and cytokeratin-VEGF studies compared with controls. Vascular endothelial growth factor in extracted membranes was positively correlated with vitreous levels of VEGF; CTGF in extracted membranes was negatively correlated with vitreous levels of CTGF.

CONCLUSION

Bevacizumab suppresses vitreous VEGF levels, but does not significantly alter VEGF or CTGF in diabetic membranes that may be explained by high baseline levels of fibrosis. Bevacizumab may cause apoptosis within fibrovascular membranes.

Intravitreal bevacizumab improves the clearance of vitreous haemorrhage and visual outcomes in patients with proliferative diabetic retinopathy

Objective

To evaluate the occurrence of vitreous haemorrhage (VH) secondary to proliferative diabetic retinopathy (PDR) and the efficacy of intravitreal bevacizumab (IVB) for VH in 5-year real-life data.

Methods and analysis

850 adult patients with type 1 (T1D) or type 2 diabetes (T2D) with PDR were screened for VH. The effect of IVB was evaluated by the clearage of VH and the change in best corrected visual acuity (BCVA). The rates of VHs, reinjections, macular oedema, complications, additional treatments and outcomes of spontaneous resorption, panretinal photocoagulation or pars plana vitrectomy (PPV) for VH were also investigated.

Results

VH occurred in 16% of patients with T1D and 9% of patients with T2D with PDR. 336 VHs in 140 eyes of 103 patients were documented. VH was cleared in 92% of cases in less than 3 months by the initial IVB. IVB was superior to other treatment methods in shortening the time for clearance of VH (Kaplan-Meier, p<0.0001). The average rate of IVB reinjections was 1.7±1.1 and the reinjection interval was 7.2±3.9 weeks. BCVA increased 0.73±0.04 logarithm of the minimum angle of resolution units after IVB (generalised estimating equations, p=0.0004). In 5 years, the patients had 2.2±2.7 recurrence of VHs. A simultaneous 72% decrease in the rate of PPVs was documented (p<0.0001).

Conclusion

VH occurs mostly in patients with T1D. The therapeutic effect of IVB for VH was significant and led to improved clearance of VH and visual outcome. Moreover, IVB prevented persistent and recurrent VHs and decreased the need for costly PPV.

Innate immune response in retinal homeostasis and inflammatory disorders

Innate immune cells such as neutrophils, monocyte-macrophages and microglial cells are pivotal for the health and disease of the retina. For the maintenance of retinal homeostasis, these cells and immunosuppressive molecules in the eye actively regulate the induction and the expression of inflammation in order to prevent excessive activation and subsequent tissue damage. In the disease context, these regulatory mechanisms are modulated genetically and/or by environmental stimuli such as damage-associated molecular patterns (DAMPs), and a chronic innate immune response regulates or contributes to the formation of diverse retinal disorders such as uveitis, retinitis pigmentosa, retinal vascular diseases and retinal fibrosis. Here we summarize the recent knowledge regarding the innate immune response in both ocular immune regulation and inflammatory retinal diseases, and we describe the potential of the innate immune response as a biomarker and therapeutic target.

Branch retinal artery occlusion in the untreated contralateral eye following aflibercept injections during heparin treatment: Possible contribution of a heparin-induced thrombocytopenia-like condition

PURPOSE

In this study, we report a case of branch retinal artery occlusion (BRAO) in the contralateral eye the day after aflibercept treatment during systemic heparin administration.

OBSERVATIONS

A 63-year-old woman with diabetic macular edema underwent repeated intravitreal injection of anti-VEGF drugs (0.5mg ranibizumab or 2mg aflibercept) for her left eye. The day after intravitreal injection of aflibercept, she presented with sudden painless blurred vision that was limited to the inferior visual field defect in the contralateral eye (right eye) during hemodialysis with the anti-coagulant heparin. Optical coherence tomography angiography (OCTA) showed decreased artery perfusion and the patient was diagnosed with contralateral BRAO.

CONCLUSIONS

Previous in vitro and in vivo studies have reported that the Fc portion of anti-VEGF drugs activates platelets with heparin. Therefore, careful anti-VEGF drug selection may be necessary in cases with concomitant heparin treatment.

Rho-Kinase/ROCK as a Potential Drug Target for Vitreoretinal Diseases

Rho-associated kinase (Rho-kinase/ROCK) was originally identified as an effector protein of the G protein Rho. Its involvement in various diseases, particularly cancer and cardiovascular disease, has been elucidated, and ROCK inhibitors have already been applied clinically for cerebral vasospasm and glaucoma. Vitreoretinal diseases including diabetic retinopathy, age-related macular degeneration, and proliferative vitreoretinoapthy are still a major cause of blindness. While anti-VEGF therapy has recently been widely used for vitreoretinal disorders due to its efficacy, attention has been drawn to new unmet needs. The importance of ROCK in pathological vitreoretinal conditions has also been elucidated and is attracting attention as a potential therapeutic target. ROCK is involved in angiogenesis and hyperpermeability and also in the pathogenesis of various pathologies such as inflammation and fibrosis. It has been expected that ROCK inhibitors will become new molecular target drugs for vitreoretinal diseases. This review summarizes the recent progress on the mechanisms of action of ROCK and their applications in disease treatment.

Intravitreal Bevacizumab for the Treatment of Vitreous Hemorrhage Due to Proliferative Diabetic Retinopathy

PURPOSE

To evaluate the outcomes of intravitreal bevacizumab (IVB) use in patients with a vitreous hemorrhage (VH) secondary to proliferative diabetic retinopathy (PDR).

DESIGN

Retrospective, interventional case series.

METHODS

Patients who presented to Scheie Eye Institute between January 2008 and January 2015 with a new VH secondary to PDR and treated with IVB were included. Exclusion criteria consisted of IVB treatment prior to the study, a history of pars plana vitrectomy (PPV), and less than 1 year of follow-up. Outcomes of interest were additional treatments including PPV, injections, and panretinal photocoagulation (PRP), as well as visual acuity at baseline and at 1 year.

RESULTS

Of the 111 eligible eyes, 55 (49.5%) had PRP, 35 (31.6%) were managed with injections alone, and 21 (18.9%) had PPV after 1 year. The overall average number of injections during this time was 2 (range, 1-9), and 13 (11.7%) eyes were managed with a single injection alone. Of the 69 eyes with 2 years of follow-up, 43 (62.3%) had PRP, 16 (23.2%) were treated with injections alone, and 10 (14.5%) had PPV.

CONCLUSIONS

This study underscores the potentially important role that IVB injections have in the management of patients with VH secondary to PDR. The results indicate that a proportion of patients may be treated with a minimal amount of intervention requiring 1 or 2 anti-vascular endothelial growth factor injections only. Also, the rate of PPV at 2 years (27.9%, n = 31) suggests that most patients may be managed nonsurgically.

Effects of anti-vascular endothelial growth factor monoclonal antibody (bevacizumab) on lens epithelial cells

The molecular and cellular effects of anti-vascular endothelial growth factor monoclonal antibody (bevacizumab) on lens epithelial cells (LECs) were examined using both an immortalized human lens epithelial cell line and a porcine capsular bag model. After treatment with various concentrations of bevacizumab, cell viability and proliferation patterns were evaluated using the water-soluble tetrazolium salt assay and 5-bromo-2′-deoxyuridine enzyme-linked immunosorbent assay, respectively. The scratch assay and Western blot analysis were employed to validate the cell migration pattern and altered expression levels of signaling molecules related to the epithelial–mesenchymal transition (EMT). Application of bevacizumab induced a range of altered cellular events in a concentration-dependent manner. A 0.1–2 mg/mL concentration demonstrated dose-dependent increase in proliferation and viability of LECs. However, 4 mg/mL decreased cell proliferation and viability. Cell migrations displayed dose-dependent retardation from 0.1 mg/mL bevacizumab treatment. Transforming growth factor-β2 expression was markedly increased in a dose-dependent manner, and α-smooth muscle actin, matrix metalloproteinase-9, and vimentin expression levels showed dose-dependent changes in a B3 cell line. Microscopic observation of porcine capsular bag revealed changes in cellular morphology and a decline in cell density compared to the control after 2 mg/mL treatment. The central aspect of posterior capsule showed delayed confluence, and the factors related to EMT revealed similar expression patterns to those identified in the cell line. Based on these results, bevacizumab modulates the proliferation and viability of LECs and induces morphological alterations through the modulation of expression patterns of specific factors related to the EMT.

Macular hole formation following intravitreal injection of ranibizumab for branch retinal vein occlusion: a case report

Background

Macular hole formation after anti-vascular endothelial growth factor therapy is a rare complication. We report macular hole formation after intravitreal ranibizumab injection for branch retinal vein occlusion.

Case presentation

A 63-year-old Asian male was treated with intravitreal ranibizumab injection for chronic macular edema with branch retinal vein occlusion in his right eye. Before treatment, best-corrected visual acuity in his right eye was 20/200. Nine days after injection, a full thickness macular hole developed with reduction of macular edema. After pars plana vitrectomy combined with cataract surgery, the macular hole was successfully closed, and the best-corrected visual acuity in his right eye improved to 20/40.

Conclusion

The possibility of an infrequent complication like macular hole should be considered for intravitreal ranibizumab for macular edema with branch retinal vein occlusion.

Surgical management of diabetic retinopathy

Surgery for late complications of proliferative diabetic retinopathy remains the cornerstone of management even in patients who have received optimal laser photocoagulation and medical therapy. With improvisation in the surgical techniques and development of micro-incision surgical techniques for vitrectomy, the indications for surgical intervention are expanding to include diabetic macular edema with a greater number of patients undergoing early intervention. This review describes the current indications, surgical techniques, adjunctive anti-vascular endothelial growth factor therapy, surgical outcomes, and postoperative complications of pars plana vitrectomy for proliferative diabetic retinopathy and macular edema.

[VEGF inhibitors in vitreoretinal interventions]

Vascular endothelial growth factor (VEGF) inhibitors are being used for an increasing number of indications. Beyond the classical use in exudative macular degeneration and macular edema, they are being used, for example off-label as additive treatment together with panretinal laser photocoagulation or in preparation for vitrectomy for ischemic retinopathy. In preparation for vitreoretinal surgery VEGF inhibitors are usually given prior to surgery. When given as an adjunct to laser treatment, VEGF inhibitors can be given either consecutively or parallel to laser photocoagulation. In most cases, however, anti-VEGF treatment does not render laser coagulation dispensable. The greatest danger with anti-VEGF treatment in the context of ischemic retinopathies lies in the fact that proliferative membranes are misjudged or overlooked. In these cases, anti-VEGF treatment can induce contraction of these membranes with induction of consecutive tractional retinal detachment. This review summarizes the current knowledge on VEGF inhibition as an adjunct to vitreoretinal surgery and also points out the gaps in the current knowledge and the need for further research.