Mechanisms of inflammation in proliferative vitreoretinopathy: from bench to bedside

Early use of intravitreal triamcinolone to inhibit traumatic proliferative vitreoretinopathy: a randomised clinical trial

AIMS

To evaluate the efficacy and safety of intravitreal triamcinolone acetonide (TA) injection at the end of emergency surgery for open globe injury (OGI) to suppress traumatic proliferative vitreoretinopathy (TPVR).

METHODS

A single-centre, participant-masked, prospective, randomised controlled clinical trial. A total of 68 globe rupture patients with zone III were randomised to the control group (n=34) or the TA group (n=34) in 1:1 allocation ratio. Patients were treated with 0.1 mL TA in the TA group and 0.1 mL balanced salt solution in the control group at the end of emergency surgery. The primary outcome was the assessment of TPVR during vitrectomy 10±3 days later. Secondary outcomes included visual acuity (VA), retinal attachment rate, macular attachment rate, proliferative vitreoretinopathy (PVR) recurrent rate, side effects 6 months after vitrectomy.

RESULTS

During vitrectomy, the TPVR grade of the control group was significantly more severe than the TA group (p=0.028). The TPVR score was significantly better in the TA group (9.30±0.82) than in the control group (6.44±1.06) (p=0.036). The final VA improved in 23 eyes (92%) in the TA group and in 14 eyes (63.64%) in the control group (p=0.008). The retinal attachment rates were 88% and 63.64% in the TA and control group, respectively (p=0.049). The two groups showed no significant difference in macular repositioning and PVR recurrent rate (p=0.215, 0.191). Temporary intraocular pressure elevation occurred in one eye in the TA group after emergency surgery.

CONCLUSIONS

Early intravitreal TA injection for OGI effectively reduces TPVR, increases surgical success and improves visual prognosis.

Initial Characterization of WDR5B Reveals a Role in the Proliferation of Retinal Pigment Epithelial Cells

The chromatin-associated protein WDR5 has been widely studied due to its role in histone modification and its potential as a pharmacological target for the treatment of cancer. In humans, the protein with highest sequence homology to WDR5 is encoded by the retrogene WDR5B, which remains unexplored. Here, we used CRISPR-Cas9 genome editing to generate WDR5B knockout and WDR5B-FLAG knock-in cell lines for further characterization. In contrast to WDR5, WDR5B exhibits low expression in pluripotent cells and is upregulated upon neural differentiation. Loss or shRNA depletion of WDR5B impairs cell growth and increases the fraction of non-viable cells in proliferating retinal pigment epithelial (RPE) cultures. CUT&RUN chromatin profiling in RPE and neural progenitors indicates minimal WDR5B enrichment at established WDR5 binding sites. These results suggest that WDR5 and WDR5B exhibit several divergent biological properties despite sharing a high degree of sequence homology.

The Effect of Steroid Intervention before Vitrectomy for Rhegmatogenous Retinal Detachment Associated with Choroidal Detachment: A Meta-Analysis and Systematic Review

PURPOSE

This meta-analysis discusses the effectiveness of steroid intervention before vitrectomy in patients with rhegmatogenous retinal detachment associated with choroidal detachment.

METHODS

We searched PubMed, MEDLINE, EMBASE, and the Cochrane Library for randomized controlled trials and observational studies published until August 2023. We included studies involving: patients with rhegmatogenous retinal detachment associated with choroidal detachment with proliferative vitreoretinopathy; an experimental group that was not administered steroids and a control group that was administered steroids; and assessment of visual acuity, retinal reattachment rate, and complications. The heterogeneity, publication bias, and sensitivity analysis were performed to ensure the statistical power and reliability of the analysis.

RESULTS

Two randomized controlled trials and four case-control studies involving 490 eyes were included in the meta-analysis. There were no significant differences in the primary and final retinal reattachment rates after surgery between the steroid and non-steroid groups (primary retinal reattachment rate: odds ratio = 1.01, 95% confidence interval = 0.63-1.63, p = .41; final retinal reattachment rate: odds ratio = 0.82, 95% confidence interval = 0.43-1.59, p = .33). There was no statistically significant difference in postoperative visual acuity improvement between the two groups (odds ratio = 1.19, confidence interval = 0.63-2.25, p = .69). In addition, subgroup analyses of different types of steroids showed that systemic and local administration of steroids had similar results for retinal reattachment rate and visual acuity improvement.

CONCLUSION

Patients with rhegmatogenous retinal detachment associated with choroidal detachment who did not receive preoperative steroids achieved the same effect as patients with rhegmatogenous retinal detachment associated with choroidal detachment who did receive preoperative steroids in terms of retinal reattachment rate and visual acuity. It is recommended that patients with rhegmatogenous retinal detachment associated with choroidal detachment undergo surgery as promptly as possible.

Proliferative vitreoretinopathy: an update on the current and emerging treatment options

Proliferative vitreoretinopathy (PVR) remains the main cause of failure in retinal detachment (RD) surgery and a demanding challenge for vitreoretinal surgeons. Despite the large improvements in surgical techniques and a better understanding of PVR pathogenesis in the last years, satisfactory anatomical and visual outcomes have not been provided yet. For this reason, several different adjunctive pharmacological agents have been investigated in combination with surgery. In this review, we analyze the current and emerging adjunctive treatment options for the management of PVR and we discuss their possible clinical application and beneficial role in this subgroup of patients.

Predictive values of systemic inflammation biomarkers in proliferative vitreoretinopathy associated with primary rhegmatogenous retinal detachment

CLINICAL RELEVANCE

Proliferative vitreoretinopathy (PVR) is still the leading cause of surgical failure after rhegmatogenous retinal detachment (RRD) repair. The factors that can predict the development of PVR remain to be elucidated.

BACKGROUND

This study evaluates the predictive values of the systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio in patients with primary RRD with and without PVR.

METHODS

A total of 150 patients with RRD and 51 age- and sex-matched healthy participants were included in the study. Patients who developed PVR within three months after surgery were enrolled as PVR cases (n = 75, Group 1), and those who did not develop PVR were enrolled in RRD without the PVR group (n = 75, Group 2). Ocular examination findings and medical records of all participants were analysed retrospectively. Peripheral blood samples were collected, and systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratios were calculated. The systemic immune-inflammation index calculation formula is: (Neutrophil/lymphocyte) × Platelet.

RESULTS

The median neutrophil-to-lymphocyte ratio and systemic immune-inflammation index levels were significantly higher in Group 1 patients compared to Group 2 and the control groups (p = 0.01, for both). However, the groups were similar regarding median platelet-to-lymphocyte ratio (p = 0.917). The optimal cut-off values of neutrophil-to-lymphocyte ratio and systemic immune-inflammation index were calculated as 1.72 (with 72% sensitivity and 48% specificity) and 407.9 (with 72% sensitivity and 49.3% specificity), respectively, for predicting PVR development in patients with RRD.

CONCLUSION

Neutrophil-to-lymphocyte ratio and systemic immune-inflammation index may be useful biomarkers for predicting the risk of PVR development in RRD patients.

Proliferative Vitreoretinopathy: A Reappraisal

Proliferative vitreoretinopathy (PVR) remains the main cause of failure after retinal detachment (RD) surgery. Despite the development of modern technologies and sophisticated techniques for the management of RD, the growth of fibrocellular membranes within the vitreous cavity and on both sides of the retinal surface, as well as intraretinal fibrosis, can compromise surgical outcomes. Since 1983, when the term PVR was coined by the Retina Society, a lot of knowledge has been obtained about the physiopathology and risk factors of PVR, but, despite the proposal of a lot of therapeutic challenges, surgical skills seem to be the only effective way to manage PVR complications.

Using Advanced Bioinformatics Tools to Identify Novel Therapeutic Candidates for Proliferative Vitreoretinopathy

Purpose

Proliferative vitreoretinopathy (PVR) is the dreaded cause of failure following retinal detachment repair; however, no cures or preventative therapies exist to date. The purpose of this study was to use bioinformatics tools to identify drugs or compounds that interact with biomarkers and pathways involved in PVR pathogenesis that could be eligible for further testing for the prevention and treatment of PVR.

Methods

We queried PubMed to compile a comprehensive list of genes described in PVR to date from human studies, animal models, and genomic studies found in the National Center for Biotechnology Information database. Gene enrichment analysis was performed using ToppGene on PVR-related genes against drug-gene interaction databases to construct a pharmacome and estimate the statistical significance of overrepresented compounds. Compounds with no clinical indications were filtered out from the resulting drug lists.

Results

Our query identified 34 unique genes associated with PVR. Out of 77,146 candidate drugs or compounds in the drug databases, our analysis revealed multiple drugs and compounds that have significant interactions with genes involved in PVR, including antiproliferatives, corticosteroids, cardiovascular agents, antioxidants, statins, and micronutrients. Top compounds, including curcumin, statins, and cardiovascular agents such as carvedilol and enalapril, have well-established safety profiles and potentially could be readily repurposed for PVR. Other significant compounds such as prednisone and methotrexate have shown promising results in ongoing clinical trials for PVR.

Conclusions

This bioinformatics approach of studying drug-gene interactions can identify drugs that may affect genes and pathways implicated in PVR. Predicted bioinformatics studies require further validation by preclinical or clinical studies; however, this unbiased approach could identify potential candidates among existing drugs and compounds that could be repurposed for PVR and guide future investigations.

Translational Relevance

Novel repurposable drug therapies for PVR can be found using advanced bioinformatics models.

Inflammation and Oxidative Stress Gene Variability in Retinal Detachment Patients with and without Proliferative Vitreoretinopathy

This study investigated the association between certain genetic variations and the risk of developing proliferative vitreoretinopathy (PVR) after surgery. The study was conducted on 192 patients with primary rhegmatogenous retinal detachment (RRD) who underwent 3-port pars plana vitrectomy (PPV). The distribution of single nucleotide polymorphisms (SNPs) located in genes involved in inflammation and oxidative stress associated with PVR pathways were analyzed among patients with and without postoperative PVR grade C1 or higher. A total of 7 defined SNPs of 5 genes were selected for genotyping: rs4880 (SOD2); rs1001179 (CAT); rs1050450 (GPX1); rs1143623, rs16944, rs1071676 (IL1B); rs2910164 (MIR146A) using competitive allele-specific polymerase chain reaction. The association of SNPs with PVR risk was evaluated using logistic regression. Furthermore, the possible association of SNPs with postoperative clinical parameters was evaluated using non-parametric tests. The difference between two genotype frequencies between patients with or without PVR grade C1 or higher was found to be statistically significant: SOD2 rs4880 and IL1B rs1071676. Carriers of at least one polymorphic IL1B rs1071676 GG allele appeared to have better postoperative best-corrected visual acuity only in patients without PVR (p = 0.070). Our study suggests that certain genetic variations may play a role in the development of PVR after surgery. These findings may have important implications for identifying patients at higher risk for PVR and developing new treatments.

Steroid Drugs as an Adjunct for Reducing the Incidence of Proliferative Vitreoretinopathy after Rhegmatogenous Retinal Detachment Surgery: A Meta-Analysis of Randomized Controlled Studies

INTRODUCTION

The efficacy and influence of steroids for reducing the incidence of proliferative vitreoretinopathy (PVR) after rhegmatogenous retinal detachment (RRD) surgery remain controversial. Systematic review and meta-analysis were conducted to explore the effect of steroids versus placebo on risk of PVR.

METHODS

We searched PubMed, Embase, Web of science, EBSCO, and Cochrane library databases through September 2020 for randomized controlled trials (RCTs), assessing the effect of steroid drugs as an adjunct for reducing the incidence of PVR after RRD surgery. This meta-analysis was performed using the random-effect model. Data were extracted by two reviewers independently; the quality of RCTs was assessed by the Cochrane risk-of-bias tool. We calculated risk ratio (RR) and the 95% confidence intervals (CIs) of all outcomes and plotted on forest plots. I2 accessed using the χ2 test was applied to quantify the degree of heterogeneity.

RESULTS

Four RCTs involving 478 patients (478 eyes) are included in the meta-analysis. There was no significant difference in the incidence of PVR recurrence between steroid groups and control groups (RR: 0.87, 95% CI: 0.70-1.08, p = 0.19). However, the incidence of recurrent PVR was lower in the steroid group (RR: 0.67, 95% CI: 0.46-0.99, p = 0.04) than in the control group when only PVR grades A and B were taken into consideration. Besides, steroids could significantly reduce the incidence of macular edema after surgery (RR: 0.64, 95% CI: 0.47-0.88, p = 0.007). The steroid group and control group had comparable outcomes of retinal reattachment rate and reoperation rate after primary surgery. Additionally, there was no significant difference of the incidence of epiretinal membrane, and the incidence of surgery required by epiretinal membrane.

CONCLUSION

This meta-analysis reveals that RRD surgery combined with steroid drugs administration could significantly reduce the recurrence in PVR grade A and B subgroup, as well as the incidence of macular edema after surgery.

MicroRNA Expression in Subretinal Fluid in Eyes Affected by Rhegmatogenous Retinal Detachment

Proliferative vitreoretinopathy (PVR) is an abnormal intraocular scarring process that can complicate cases of rhegmatogenous retinal detachment (RRD). Although previous studies have examined the relevance of microRNAs (miRNAs) in ophthalmic diseases, only a few studies have evaluated the expression profiles of microRNAs in subretinal fluid. We hypothesized that the expression profiles of specific miRNAs may change in response to RRD, in the subretinal fluid that is directly in contact with photoreceptors and the retinal pigment epithelium (RPE). We looked for a potential correlation between the expression of specific miRNAs in eyes with RRD and known clinical risk factors of PVR. A total of 24 patients (59 ± 11 years) who underwent scleral buckling procedure were enrolled in this prospective study. Twenty-four undiluted subretinal fluid samples were collected, RNA was isolated and qRT-PCR was performed to analyze the expression of 12 miRNAs. We found the existence of a positive association between the expression of miR-21 (p = 0.017, r = 0.515) and miR-34 (p = 0.030, r = 0.624) and the duration of symptoms related to retinal detachment. Moreover, the expression of miR-146a tended to decrease in patients who developed PVR. Subretinal fluid constitutes an intriguing biological matrix to evaluate the role of miRNAs leading to the development of PVR.

NFκB-Mediated Expression of Phosphoinositide 3-Kinase δ Is Critical for Mesenchymal Transition in Retinal Pigment Epithelial Cells

Epithelial mesenchymal transition (EMT) plays a vital role in a variety of human diseases including proliferative vitreoretinopathy (PVR), in which retinal pigment epithelial (RPE) cells play a key part. Transcriptomic analysis showed that the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway was up-regulated in human RPE cells upon treatment with transforming growth factor (TGF)-β2, a multifunctional cytokine associated with clinical PVR. Stimulation of human RPE cells with TGF-β2 induced expression of p110δ (the catalytic subunit of PI3Kδ) and activation of NFκB/p65. CRISPR-Cas9-mediated depletion of p110δ or NFκB/p65 suppressed TGF-β2-induced fibronectin expression and activation of Akt as well as migration of these cells. Intriguingly, abrogating expression of NFκB/p65 also blocked TGF-β2-induced expression of p110δ, and luciferase reporter assay indicated that TGF-β2 induced NFκB/p65 binding to the promoter of the PIK3CD that encodes p110δ. These data reveal that NFκB/p65-mediated expression of PI3Kδ is essential in human RPE cells for TGF-β2-induced EMT, uncovering hindrance of TGF-β2-induced expression of p110δ as a novel approach to inhibit PVR.

Understanding Inflammation-associated Ophthalmic Pathologies: A Novel 3D Co-culture Model of Monocyte-myofibroblast Immunomodulation

PURPOSE

Inflammation is associated with, and may be causal of, a variety of ophthalmic pathologies. These pathologies are currently difficult to model in vitro because they involve complex interactions between the innate immune system, stromal cells, and other cells that normally maintain ocular tissue homeostasis. Using transscleral drainage channel fibrosis after glaucoma surgery as an example of inflammation-associated ocular fibrosis, we have assessed a simple but novel 3D cell culture system designed to reveal the immunomodulatory impacts of ocular connective tissue cells on monocytes, a major cellular component of the circulating immune system.

METHODS

Primary human Tenon's capsule fibroblasts derived from five unrelated patients were activated into myofibroblasts in 3D collagen matrices under isometric tension, with and without exposure to an inflammatory cytokine-enhanced milieu, and co-cultured with an immortalized human monocyte cell line (THP-1 cells). Quantitative PCR analyses were performed on 8 candidate genes to assess the impacts of inflammatory cytokines on the myofibroblasts and the monocytes in mono-cultures and compared to cells in co-culture to clearly distinguish any co-culture-induced impacts on gene expression.

RESULTS

Our data indicate that both Tenon's capsule myofibroblasts in 3D mono-culture and THP-1 monocytes in suspension mono-culture were responsive to inflammatory cytokine stimuli. Co-culture with Tenon's capsule myofibroblasts significantly modulated the gene expression responses of THP-1 monocytes to inflammatory cytokine stimulation, indicative of an immunomodulatory "feedback" system between these cell types.

CONCLUSION

Our findings provide proof of principle for the use of simple 3D co-culture systems as a means to enhance our understanding of ocular stromal cell interactions with cells of the innate immune system and to provide more informative in vitro models of inflammation-associated ophthalmic pathologies.

Vitreous humor proteome: unraveling the molecular mechanisms underlying proliferative and neovascular vitreoretinal diseases

Proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and neovascular age-related macular degeneration (nAMD) are among the leading causes of blindness. Due to the multifactorial nature of these vitreoretinal diseases, omics approaches are essential for a deeper understanding of the pathophysiologic processes underlying the evolution to a proliferative or neovascular etiology, in which patients suffer from an abrupt loss of vision. For many years, it was thought that the function of the vitreous was merely structural, supporting and protecting the surrounding ocular tissues. Proteomics studies proved that vitreous is more complex and biologically active than initially thought, and its changes reflect the physiological and pathological state of the eye. The vitreous is the scenario of a complex interplay between inflammation, fibrosis, oxidative stress, neurodegeneration, and extracellular matrix remodeling. Vitreous proteome not only reflects the pathological events that occur in the retina, but the changes in the vitreous itself play a central role in the onset and progression of vitreoretinal diseases. Therefore, this review offers an overview of the studies on the vitreous proteome that could help to elucidate some of the pathological mechanisms underlying proliferative and/or neovascular vitreoretinal diseases and to find new potential pharmaceutical targets.

TSPAN4-positive migrasome derived from retinal pigmented epithelium cells contributes to the development of proliferative vitreoretinopathy

BACKGROUND

Proliferative vitreoretinopathy (PVR) is a blind-causing disease initiated by the activation of retinal pigmented epithelium (RPE) primarily induced by TGF-β families. Migrasome is a recently discovered type of extracellular vesicle related to cell migration.

RESULTS

Here, we used ex vivo, in vitro, and in vivo models, to investigate the characteristics and functions of migrasomes in RPE activation and PVR development. Results indicated that the migrasome marker tetraspanin-4 (TSPAN4) was abundantly expressed in human PVR-associated clinical samples. The ex vivo model PVR microenvironment is simulated by incubating brown Norway rat RPE eyecups with TGF-β1. Electron microscope images showed the formation of migrasome-like vesicles during the activation of RPE. Further studies indicated TGF-β1 increased the expression of TSPAN4 which results in migrasome production. Migrasomes can be internalized by RPE and increase the migration and proliferation ability of RPE. Moreover, TSPAN4-inhibited RPE cells are with reduced ability of initiating experimental PVR. Mechanically, TSPAN4 expression and migrasome production are induced through TGF-β1/Smad2/3 signaling pathway.

CONCLUSION

In conclusion, migrasomes can be produced by RPE under PVR microenvironment. Migrasomes play a pivotal role in RPE activation and PVR progression. Thus, targeting TSPAN4 or blocking migrasome formation might be a new therapeutic method against PVR.

Microfluidic outer blood-retinal barrier model for inducing wet age-related macular degeneration by hypoxic stress

Wet age-related macular degeneration (AMD) is a severe ophthalmic disease that develops in the outer blood-retinal barrier (oBRB), involving two types of cells, the retinal pigment epithelium (RPE) and the choriocapillaris endothelium (CCE). Unfortunately, the pathogenesis of AMD is unclear, and the risk of the only effective therapy (Anti-VEGF injection) has been consistently argued. Also, since oBRB is hard to observe in vivo, an in vitro model for the pathological study is necessary. Here, we propose an advanced oBRB model, enhanced in two major ways: fully vascularized CCE and the in vivo analogous distance between RPE and CCE. Our model consists of an RPE (ARPE-19) monolayer with adjacent CCE (HUVEC) embedded fibrin gel in the microfluidic chip and required four days to construct an oBRB. Notably, the intercellular distance was tuned to the in vivo scale (<100 μm) without any extraneous scaffold in between. Thus, the two cell layers can interact freely through the extracellular matrix (ECM) in vivo. This is significant as wet AMD is mainly developed through broken intercellular interaction. Thanks to this in vivo similarity, the model incubated under hypoxic conditions, similar to an oxygen-induced retinopathy animal model, showed upregulated vascularization comparable to the AMD condition. We envisage that our model can be used to assist the investigation of AMD.

MicroRNA-4516 suppresses proliferative vitreoretinopathy development via negatively regulating OTX1

Proliferative vitreoretinopathy (PVR) progression is associated with TGF-β2-induced epithelial–mesenchymal transition (EMT) in retinal pigment epithelial (RPE) cells. In cancer cells, miR-4516 downregulates orthodenticle homeobox 1 (OTX1)-mediated cell invasion. Moreover, OTX1 is shown to be involved in invasion and EMT. The purpose of this study was to assess whether microRNA (miR-4516) suppresses EMT in RPE cells. EMT features were assessed using Western blotting, immunocytochemical staining, scratch-wound healing, modified Boyden chamber assay, and collagen gel contraction assay. For in vivo testing, a rabbit model was used, which involved induction of PVR by injection of transfected spontaneously arising RPE (ARPE) cells into the vitreous chamber. The putative target of miR-4516 was identified by luciferase reporter assay. Results showed that TGF-β2-induced transdifferentiation and migration of RPE cells was inhibited by miR-4516 delivery. Overexpression of miR-4516 led to upregulation of zonula occludens-1, downregulation of α-smooth muscle actin and vimentin, and cell contractility—all EMT features—in the TGF-β2-treated ARPE-19 cells. MiR-4516 regulated OTX1 expression negatively by binding to its 3’-UTR. TGF-β2-induced phosphorylated ERK was inhibited in miR-4516-overexpressing ARPE-19 cells. MiR-4516 suppressed experimental PVR in vitro and in vivo. In conclusion, the overexpression of miR-4516 suppresses TGF-β2-induced EMT in a PVR model, and its role in PVR depends on OTX1/ERK. Further research is needed to develop a feasible treatment method to prevent and treat PVR.

A Novel Role of IL13Rα2 in the Pathogenesis of Proliferative Vitreoretinopathy

Proliferative vitreoretinopathy (PVR), an inflammatory and fibrotic blinding disease, is still a therapeutic challenge. Retinal pigment epithelial (RPE) cells dislodged in the vitreous play a central role in the PVR pathogenesis. To identify potential novel contributors to the pathogenesis of PVR, we investigated a profile of vitreous-induced changes in ARPE-19 cells by RNA sequencing. Bioinformatics analysis of the sequencing data showed that there were 258 genes up-regulated and 835 genes down-regulated in the ARPE-19 cells treated with human vitreous. Among these genes, there were three genes related to eye disease with more than threefold changes. In particular, quantitative PCR and western blot results showed that interleukin 13 receptor (IL13R)α2 that is over-expressed in a variety of cancers was up-regulated more than three times in the vitreous-treated ARPE-19 cells. Immunofluorescence analysis indicated that interleukin-13 receptor subunit α2 (IL13Rα2) was highly expressed in ARPE-19 cells within epiretinal membranes from patients with PVR. Importantly, blocking IL13Rα2 with its neutralizing antibody significantly inhibited vitreous-induced contraction of ARPE-19 cells, suggesting a novel role of IL13Rα2 in the PVR pathogenesis. These findings will improve our understanding of the molecular mechanisms by which PVR develops and provides potential targets for PVR therapeutics.

Comparison between Vascular Endothelial Growth Factor and Platelet-Derived Growth Factor Levels in Rhegmatogenous Retinal Detachment

Introduction

This study aimed to assess vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) levels within vitreous and blood serum samples of patients with rhegmatogenous retinal detachment (RRD) and their relationship to the development of proliferative vitreoretinopathy (PVR).

Methods

Seventeen eyes of patients with RRD were included in the RRD group and divided into three subgroups: RRD without PVR, RRD with PVR grades A and B, and RRD with PVR grade C. Five control eyes (nucleus and intraocular lens drop) were included in this study. Blood serum and vitreous samples were collected during vitrectomy. VEGF-A and PDGF-AA levels were determined by enzyme-linked immunosorbent assay.

Results

The mean vitreous VEGF-A level in the RRD group was 131.71 ± 58.25 pg/mL, and the mean vitreous PDGF-AA level was 174.62 ± 65.17 pg/mL. Both levels were significantly higher in the RRD group compared with the control group (p < 0.05). Vitreous VEGF-A and PDGF-AA levels were the highest in RRD with PVR grade C subgroup, with mean levels of 179.87 ± 21.02 pg/mL and 229.44 ± 14.09 pg/mL, respectively (p < 0.05). The vitreous VEGF-A/PDGF-AA ratios in the RRD subgroups were completely different.

Conclusion

Based on the tendency of VEGF-A and PDGF-AA levels, RRD surgery has to be performed as soon as possible prior to retinal cell death and membrane proliferative formation.

Inhibition of TGF-β2-induced migration and epithelial-mesenchymal transition in ARPE-19 by sulforaphane

AIM

To investigate the effects of sulforaphane (SFN) on transforming growth factor (TGF)-β2 stimulated migration and epithelial-mesenchymal transition (EMT) in ARPE-19 cells.

METHODS

ARPE-19 cells were cultured in the presence or absence of SFN or TGF-β2. SFN toxicity was assessed by performing a lactate dehydrogenase assay (LDH) and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays, and cell migration was evaluated by Transwell migration assay. Actin stress fiber formation in ARPE-19 cells was determined using immunofluorescence analysis. Immunoblotting analysis was used to determine fibronectin and α-smooth muscle actin expressions along with the degree of Smad and Akt phosphorylation.

RESULTS

SFN inhibited ARPE-19 migration. Additionally, SFN attenuated TGF-β2-induced appearance of actin stress fibers as well as fibronectin and α-smooth muscle actin expressions in these cells. SFN also hindered the TGF-β2-stimulated phosphorylation of Smad2, Smad3, and Akt. SFN showed no cytotoxicity towards ARPE-19 cells.

CONCLUSION

SFN inhibits TGF-β2-stimulated migration and EMT in ARPE-19 cells, probably by preventing the establishment of actin stress fibers and Akt and Smad2/3 signaling.

Intravitreal connective tissue growth factor neutralizing antibody or bevacizumab alone or in combination for prevention of proliferative vitreoretinopathy in an experimental model

Connective tissue growth factor (CTGF) is released by retinal pigment epithelial (RPE) cells and detectable in proliferative membranes (PrMs). This experimental study was performed to investigate the mRNA and protein levels of both CTGF and vascular endothelial growth factor A (VEGF-A) in a rabbit model of proliferative vitreoretinopathy (PVR). In addition, the effects of a single intravitreal injection of the safe dose of anti-CTGF or bevacizumab as monotherapy and in combination were evaluated. PVR was induced in the right eye of albino rabbits by intravitreal injection of cultured adult human RPE cells. Quantitative real-time reverse transcription PCR (qRT-PCR) and Western blot analysis of CTGF and VEGF-A were performed on whole eye tissue in the PVR model versus controls at different time points. In the next step, the PVR models were assigned to five groups. The monotherapy groups received a single intravitreal injection of 0.1 ml of anti-CTGF 100 μg/ml (final concentration of 6.6 μg/ml in the vitreous) or 0.03 ml of 25 mg/ml bevacizumab. In the combined group, the abovementioned amounts of anti-CTGF and bevacizumab were injected intravitreally from separate sites in one session. No antibody injection was performed in the control group. Intravitreal injection of 0.1 ml of control IgG (1 mg/ml of isotype matched) antibody was performed in the placebo group. After 2 weeks, histologic evaluation including, trichrome staining for collagen, immunostaining by anti-alpha-smooth muscle actin for myofibroblasts, and anti-collagen type-1 antibody on paraffin embedded anterior-posterior sections was done. In addition, fundus photography was performed for clinically equivalent PVR staging. Twenty-four hours following PVR induction, CTGF mRNA and protein levels increased five- and- three-fold compared to controls, respectively (P < 0.001). VEGF-A mRNA and protein levels decreased significantly after 72 h of PVR induction compared to controls (P < 0.05). Means of PrM thickness and myofibroblast cell counts significantly decreased in the anti-CTGF group (P < 0.001 and P < 0.05, respectively). The mean area of collagen type-1 fibers of PrM in the mono- and combination therapy groups that received intravitreal anti-CTGF was significantly reduced (P < 0.001); in addition, mild PVR (stage-1 and 2) formation occurred in comparison with moderate to severe PVR (stage-4 and higher) in other groups. In conclusion, we found that intravitreal injection of CTGF neutralizing antibody resulted in a reduction in PrM thickness, collagen fibers and myofibroblast density in the PVR model. CTGF inhibition may represent a potential therapeutic target for PVR.

[Proliferative vitreoretinopathy process-To heal or not to heal]

BACKGROUND

Proliferative vitreoretinopathy (PVR) is still an unsolved problem after half a century of research.

METHODS

This article provides a review of mechanisms leading to PVR in the context of wound healing research.

RESULTS

Wound healing is a physiological repair process that occurs in a similar way in all organs and may end in scar formation. The development of PVR is based on this wound healing mechanism. The localization and structures involved lead to specific characteristics and consequences. Up to now the pharmacotherapeutic strategies were not sufficiently effective. The growing understanding of the mechanisms of scar-free fetal wound healing, could however lead to a solution of the PVR problem.

CONCLUSION

The PVR is a physiological process with a pathological result. The complex steps involved in vitreoretinal wound healing are well understood. There is currently no therapeutic approach neither in ophthalmology nor in other medical disciplines that is able to restore the original function and structure of the involved tissue or organ but there is hope that this can succeed in the future.

Hyaluronan-Conjugated Carbon Quantum Dots for Bioimaging Use

This work demonstrates the application of hyaluronan-conjugated nitrogen-doped carbon quantum dots (HA-nCQDs) for bioimaging of tumor cells and illustrates their potential use as carriers in targeted drug delivery. Quantum dots are challenging to deliver with specificity, which hinders their application. To facilitate targeted internalization by cancer cells, hyaluronic acid, a natural ligand of CD44 receptors, was covalently grafted on nCQDs. The HA-nCQD conjugate was synthesized by carbodiimide coupling of the amine moieties on nCQDs and the carboxylic acids on HA chains. Conjugated HA-nCQD retained sufficient fluorescence, although with 30% lower quantum efficiency than the original nCQDs. Confocal microscopy showed enhanced internalization of HA-nCQDs, facilitated by CD44 receptors. To demonstrate the specificity of HA-nCQDs toward human tumor cells, patient-derived breast cancer tissue with high-CD44 expression was implanted in adult mice. The tumors were allowed to grow up to 200-250 mm³ prior to the injection of HA-nCQDs. With either local or systemic injection, we achieved a high level of tumor specificity judged by a strong signal-to-noise ratio between the tumor and the surrounding tissue in vivo. Overall, the results show that HA-nCQDs can be used for imaging of CD44-specific tumors in preclinical models of human cancer and potentially used as carriers for targeted drug delivery into CD44-rich cells.

Topical delivery of a small molecule RUNX1 transcription factor inhibitor for the treatment of proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is the leading cause of retinal detachment surgery failure. Despite significant advances in vitreoretinal surgery, it still remains without an effective prophylactic or therapeutic medical treatment. After ocular injury or retinal detachment, misplaced retinal cells undergo epithelial to mesenchymal transition (EMT) to form contractile membranes within the eye. We identified Runt-related transcription factor 1 (RUNX1) as a gene highly expressed in surgically-removed human PVR specimens. RUNX1 upregulation was a hallmark of EMT in primary cultures derived from human PVR membranes (C-PVR). The inhibition of RUNX1 reduced proliferation of human C-PVR cells in vitro, and curbed growth of freshly isolated human PVR membranes in an explant assay. We formulated Ro5-3335, a lipophilic small molecule RUNX1 inhibitor, into a nanoemulsion that when administered topically curbed the progression of disease in a novel rabbit model of mild PVR developed using C-PVR cells. Mass spectrometry analysis detected 2.67 ng/mL of Ro5-3335 within the vitreous cavity after treatment. This work shows a critical role for RUNX1 in PVR and supports the feasibility of targeting RUNX1 within the eye for the treatment of an EMT-mediated condition using a topical ophthalmic agent.

Outcomes of simultaneous vs. sequential pars plana vitrectomy and cataract surgery

The coexistence of cataract and vitreoretinal diseases is common in clinical practice. The technological achievements of the last decade in both types of surgeries, allow simultaneous interventions on lens and retina. This retrospective study assessed the morphofunctional results obtained after performing simultaneous surgeries in a series of 87 patients presenting with both pathologies. The cases were retrospectively reviewed from their clinical records from 2017 to 2019. The patients were divided into two groups: group 1 comprising 41 cases underwent the combined procedure and group 2 comprising 46 patients underwent vitrectomy, followed by cataract surgery after 3-10 months. The functional and anatomical outcomes and the complications were assessed pre- and post-operatively. The statistical analysis was carried out by MaxStat software. The final best corrected visual acuity (BCVA), in group 1 was <0.1 in 4.88% of the cases, 0.1 to 0.3 in 17.07%, 0.3 to 0.5 in 51.22% and >0.5 in 26.83% eyes. In group 2, the final BCVA, after both surgeries were completed was <0.1 in 8.7% cases, 0.1 to 0.3 in 30.43%, 41.3% were 0.3 to 0.5 and 19.57% were >0.5. During the cataract surgery, the most common intraoperative complication was miosis, followed by posterior capsule rupture. Postoperative, 12.2% cases from group 1 developed an immediate inflammatory reaction in the anterior chamber, and 17.07% presented with posterior capsular opacification (PCO). Simultaneous surgery is safe and effective in obtaining a good morphological and functional result and offers the advantage of a clear eye media that allows a safer vitrectomy and thus a quicker rehabilitation of the patient. The analysis of the risks and benefits of each procedure should be taken into account and the cases selected individually for either simultaneous or sequential surgery in order to obtain the best outcomes.

Management of Cystoid Macular Edema After Vitrectomy for Proliferative Vitreoretinopathy

BACKGROUND AND OBJECTIVE

To assess therapies for cystoid macular edema (CME) following pars plana vitrectomy for proliferative vitreoretinopathy (PVR).

PATIENTS AND METHODS

Retrospective analysis of 42 eyes developing CME after PVR surgery. Treatments included topical therapy, sub-Tenon's triamcinolone acetonide (STTA), intravitreal bevacizumab and combinations thereof. Best-corrected visual acuity (BCVA) as well as central subfield thickness (CST) were tracked.

RESULTS

Mean Snellen BCVA improved from 20/598 to 20/297 (logMAR change -0.21; confidence interval [CI], -0.39 to -0.03; P = .03). Mean CST improved from 448 µm to 260 µm (CI, -248.70 to -126.06; P < 0.01). There was no difference in efficacy between treatment subgroups (analysis of variance, P = 0.16, 0.43), but STTA yielded statistically significant improvement in both categories (CI, -0.79 to -0.11; P = 0.01; and CI, -333.74 to 166.51; P < .01).

CONCLUSIONS

Treatment of CME following PVR surgery is possible with a variety of different options. STTA appears to yield anatomical and visual improvement. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:436-443.].

Employing Nanostructured Scaffolds to Investigate the Mechanical Properties of Adult Mammalian Retinae Under Tension

Numerous eye diseases are linked to biomechanical dysfunction of the retina. However, the underlying forces are almost impossible to quantify experimentally. Here, we show how biomechanical properties of adult neuronal tissues such as porcine retinae can be investigated under tension in a home-built tissue stretcher composed of nanostructured TiO₂ scaffolds coupled to a self-designed force sensor. The employed TiO₂ nanotube scaffolds allow for organotypic long-term preservation of adult tissues ex vivo and support strong tissue adhesion without the application of glues, a prerequisite for tissue investigations under tension. In combination with finite element calculations we found that the deformation behavior is highly dependent on the displacement rate which results in Young’s moduli of (760–1270) Pa. Image analysis revealed that the elastic regime is characterized by a reversible shear deformation of retinal layers. For larger deformations, tissue destruction and sliding of retinal layers occurred with an equilibration between slip and stick at the interface of ruptured layers, resulting in a constant force during stretching. Since our study demonstrates how porcine eyes collected from slaughterhouses can be employed for ex vivo experiments, our study also offers new perspectives to investigate tissue biomechanics without excessive animal experiments.

Preoperative, Intraoperative and Postoperative Corticosteroid Use as an Adjunctive Treatment for Rhegmatogenous Retinal Detachment

The treatment for rhegmatogenous retinal detachment (RRD) is surgery, including pars plana vitrectomy (PPV) and scleral buckling (SB). Despite surgical advances, degeneration of the photoreceptors and post-operative complications, such as proliferative vitreoretinopathy (PVR), often occurs as the result of inflammation, preventing complete visual recovery or causing RRD recurrence. There is increasing evidence that in the presence of RRD, the activation of inflammatory processes occurs and the surgery itself induces an inflammatory response. This comprehensive review focuses on the use of different formulations of corticosteroids (CCS), as an adjunctive treatment to surgery, either PPV or SB, for RRD repair. The purpose was to review the efficacy and safety of CCS in improving functional and anatomical outcomes and in preventing postoperative complications. This review is organized according to the timing of CCS administration: preoperative, intraoperative, and postoperative. The evidence reviewed supported the role of the pre-operative use of CCS in the treatment of combined RRD and choroidal detachment (CD), reducing CD height. No solid consensus exists on intraoperative and postoperative use of CCS to treat and prevent postoperative complications. However, a large randomized clinical trial including more than 200 eyes suggested that oral prednisone after surgery decreases the rate of postoperative grade B PVR.

Preoperative Steroid Use in Rhegmatogenous Retinal Detachment Associated with Choroidal Detachment after 23-Gauge Vitrectomy

Background

Rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD) is rare and the prognosis is poor. This retrospective study evaluated the effect of preoperative steroid on the clinical outcome of patients with RRDCD receiving 23-gauge pars plana vitrectomy (PPV).

Methods

Sixty-six patients (67 eyes) with diagnosed RRDCD underwent 23-gauge PPV. The patients assigned to receive systemic or subtenon injection of preoperative steroids were considered Group A (35 eyes) and did not receive are considered Control Group B (32 eyes). Most patients in Group A received subtenon injection of glucocorticoids. The cyclodialysis angle was measured with ultrasound biomicroscopy. Preoperative, intraoperative, and postoperative data were compared.

Results

The rates of retinal reattachment in Group A after the first and second operations were 68.8% (24/35 eyes) and 91.43% (32/35 eyes), respectively, which were not significantly different from that of Group B (78.1%, 25/32 eyes; 96.6%, 31/32 eyes). The logMAR (logarithm of the minimum angle of resolution) visual acuity in Group A (1.63 ± 0.75) was similar to that of Group B (1.34 ± 0.74). Postoperative intraocular pressure and ocular hypertension in Group A (17.94 ± 9.82 mmHg and 37.1%, respectively; 13/35 eyes) were comparable to that of Group B (20.93 ± 10.21 mmHg and 56.3%; 18/32 eyes). Logistic regression analysis showed that postoperative reattachment was negatively associated with preoperative cyclodialysis angle as measured with ultrasound biomicroscopy (P=0.048) but was not significantly associated with preoperative steroid use (P=0.907).

Conclusions

Preoperative steroid use does not improve retinal reattachment and visual acuity in patients with RRDCD after 23-gauge PPV. Preoperative measurement of the cyclodialysis angle with ultrasound biomicroscopy may be useful for predicting clinical outcomes.

MicroRNAs in the Vitreous Humor of Patients with Retinal Detachment and a Different Grading of Proliferative Vitreoretinopathy: A Pilot Study

Purpose

Although the expression of microRNAs (miRNAs) in retinal pigment epithelial (RPE) cells undergoing epithelial-mesenchymal transition (EMT) is involved in the pathogenesis of proliferative vitreoretinopathy (PVR), its expression in the vitreous of patients with primary retinal detachment (RD) and different PVR grading has not yet been investigated. We assessed the expression of miRNAs in the vitreous humor (VH) of patients diagnosed with RD and different grading of PVR.

Methods

The VH was extracted from the core of the vitreous chamber in patients who had undergone standard vitrectomy for primary RD. RNA was extracted and TaqMan Low-Density Arrays (TLDAs) were used for miRNA profiling that was performed by single TaqMan assays. A gene ontology (GO) analysis was performed on the differentially expressed miRNAs.

Results

A total of 15 eyes with RD, 3 eyes for each grade of PVR (A, B, C, and D) and 3 from unaffected individuals, were enrolled in this prospective comparative study. Twenty miRNAs were altered in the comparison among pathological groups. Interestingly, the expression of miR-143-3p, miR-224-5p, miR-361-5p, miR-452-5p, miR-486-3p, and miR-891a-5p increased with the worsening of PVR grading. We also identified 34 miRNAs showing differential expression in PVR compared to control vitreous samples. GO analysis showed that the deregulated miRNAs participate in processes previously associated with PVR pathogenesis.

Conclusions

The present pilot study suggested that dysregulated vitreal miRNAs may be considered as a biomarker of PVR and associated with the PVR-related complications in patients with RD.

Translational Relevance

The correlation between vitreal miRNAs and the pathological phenotypes are essential to identify the novel miRNA-based mechanisms underlying the PVR disease that would improve the diagnosis and treatment of the condition.

Inflammatory mediators of proliferative vitreoretinopathy: hypothesis and review

Purpose

To review the role of inflammatory mediators in proliferative vitreoretinopathy (PVR) development and the current treatment for PVR prevention.

Methods

A PubMed search was carried out using these keywords “PVR,” “inflammatory mediators,” “growth factors,” “cytokines” and “treatment.” Studies regarding inflammatory mediators and PVR therapy were included and published up to December 2019.

Results

Inflammatory mediators, namely growth factors and cytokines, have been implicated in the occurrence and development of PVR. Among various inflammatory mediators, transforming growth factor-β, platelet-derived growth factor, interleukin-6, interleukin-8 and tumor necrosis factor-α are considered to be particularly important. In this review, we focus on the hypothesis that growth factors and cytokines are involved in the development of PVR, and current treatment for the prevention of PVR.

Conclusion

We support the hypothesis that growth factors and cytokines may participate in the complex process of PVR development. More importantly, the identification of inflammatory mediators provides novel and efficacious therapeutic targets for the treatment of PVR.

PPV, Retinectomy, and Silicone Oil Without Scleral Buckle for Recurrent RRD From Proliferative Vitreoretinopathy

BACKGROUND AND OBJECTIVE

To analyze the anatomic success rate of pars plana vitrectomy (PPV), retinectomy, and silicone oil (SO) tamponade without scleral buckle (SB) for repair of recurrent rhegmatogenous retinal detachment (RRD) associated with proliferative vitreoretinopathy (PVR).

PATIENTS AND METHODS

Retrospective, consecutive, single-surgeon case series of 28 eyes of 28 patients with PVR-associated RRD repaired with PPV, retinectomy, and SO tamponade without SB.

RESULTS

The single-procedure anatomic success rate was 85.2% at 3 months and 82.1% at 12 months. Final reattachment rate was 100.0%. There were no preoperative factors that predicted single procedure anatomic success. Mean logarithm of the minimal angle of resolution visual acuity (VA) was improved at 3 months (1.61 to 1.51, P = .732) and at 12 months (1.61 to 1.41; P = .271). VA outcome was related to preoperative macula and lens status.

CONCLUSION

The single-procedure anatomic success rate of PPV, retinectomy, and SO tamponade without SB for PVR-related recurrent RRD is comparable to prior reports of similar surgery incorporating SB. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:e278-e287.].

Detection of Retinal Fibrosis in a Rabbit Model of Penetrating Eye Injury

INTRODUCTION

To establish a rabbit model of posterior penetrating eye injury as a platform to test potential therapeutics.

MATERIALS AND METHODS

Anesthetized rabbits received posterior penetrating eye injury in one eye, whereas contralateral eyes were maintained as uninjured controls. Rabbits were randomized into two experimental groups. Group A was euthanized on Day 14 postinjury to determine retinal fibrosis at an early phase of disease progression. Group B was euthanized on Day 28 postinjury to examine retinal fibrosis at a late phase of disease progression. We examined animals on postinjury Days 7, 14, 21, and 28 with indirect ophthalmoscope and fundus photography. After euthanasia, eyes were processed for histology and immunofluorescence labeling of fibrotic proteins α-smooth muscle actin and collagen I.

RESULTS

Early fibrosis was detected by Day 14, as indicated by indirect ophthalmoscopy and fundus imaging. Fibrotic membranes were visible at sites of injury. Immunofluorescence analysis detected α-smooth muscle actin and collagen I within the fibrotic membranes.

CONCLUSIONS

These data show that ocular fibrosis can be detected within 14 days after initial injury, with more severe fibrosis detected at 28 days postinjury. These results will be used to determine the optimal time points for later studies designed to test treatment strategies.

Vitreous levels of Lipocalin-2 on patients with primary rhegmatogenous retinal detachment

Purpose

To measure vitreous levels of Lipocalin2 (LCN2) in patients with rhegmatogenous retinal detachment (RRD) and investigate potential association with presence of proliferative vitreoretinopathy (PVR).

Materials and methods

Collection of undiluted vitreous samples from 24 patients suffering from RRD and 10 control patients undergoing vitrectomy for: vitreomacular traction (VMT) (n = 2), idiopathic epiretinal membrane (iERM) (n = 6) and full thickness macular hole (FTMH) (n = 2). Quantitative analysis of LCN2 has been made with flow cytometry. Lens status, duration of symptoms, quadrants of detachment, as well as level of PVR, were assessed. Statistical analysis included Mann-Whitney test, Kruskal-Wallis test, t-test, Spearman’s correlation coefficient and Fisher's exact test.

Results

Median LCN2 was significantly higher in the RRD group as compared to control (p<0.001). Within the RRD group there was a positive correlation between LCN2 and PVR grade (r_s = 0.94, p<0.001). Median LCN2 was 35,759 pg/ml (IR = 55,347) in grade C PVR, 9,387 pg/ml (IR = 3721) in grade B, 4,917 pg/ml (IR = non computable) in grade A and 3,921 pg/ml (2132) in the no PVR group. Median LCN2 was also significantly higher in pseudophakic patients as compared to phakic patients (p = 0.007). LCN2 also correlates with the extend of detachment (≤2 vs >2 quadrants, p<0.001) as well as with duration of symptoms (r_s = 0.87, p<0.001). After multivariate linear regression analysis, only PVR was independently related with LCN2 concentration. In particular, increased PVR grading was associated with increased LCN2 concentration (coefficient b = 2.97, 95% confidence interval = 1.89 to 4.67, p<0.001).

Conclusion

A positive correlation between vitreous levels of LCN2 and PVR grading reveals a potential role in the pathogenesis and progression of PVR. Further studies could elucidate if LCN2 could be a therapeutic target.

Neutrophil-to-lymphocyte ratio in ocular diseases: a systematic review

AIM

To summarize the results of studies investigating neutrophil-to-lymphocyte ratio (NLR) and to identify the role of NLR in ocular diseases.

METHODS

With the aim of identifying the studies related to NLR, a search was conducted on http://www.ncbi.nlm.nih.gov/pubmed by utilizing the key words "neutrophil lymphocyte ratio, ocular diseases, and eye diseases" up to February 2018. All of the original articles were assessed according to date of publications, countries, clinics and topics. Studies about ocular inflammatory diseases were evaluated according to their qualifications, review methods and results.

RESULTS

A total of 4473 publications, including original research articles and reviews were screened. The number of publications was shown a regular logarithmic increase over the years. The majority of studies were performed by clinics in Turkey and many of these publications were performed by oncology and cardiology clinics. A total of 75 publications were identified to be about ocular diseases.

CONCLUSION

Elevated NLR as a cheap, reproducible, and readily available marker could be used as a diagnostic and/or prognostic marker in ocular diseases.

The effect of infliximab and octreotide on cytokine levels experimental proliferative vitreoretinopathy

Purpose: To investigate the efficiency of intravitreal octreotide, which has previously been shown to have benefits in the treatment of proliferative vitreoretinopathy (PVR), and intravitreal infliximab as a novel option in an experimental dispase-induced PVR model.Methods: A total of 28 pigmented guinea pigs were divided into four groups, and each group consisted of seven subjects. Group 1 (control) was treated with a 0.2 mL saline solution intravitreally from 1.5 mm behind the limbus. Group 2 (sham) was treated with 0.07 IU/0.1 mL dispase 0.1 mL saline solution using the same method. Group 3(infliximab) received 0.07 IU/0.1 mL dispase and 1 mg/0.1 mL infliximab, and group 4(octreotide) was treated with 0.07 IU/0.1 mL dispase and 1 mg/0.1 mL octreotide. An intravitreal injection of infliximab and octreotide was administered to groups 3 and 4 two times during the experiment. The subjects were held for a 10-week period to await for the formation of PVR. At the end of ten weeks, the eyes were enucleated, and tumour necrosis factor-alpha (TNF-α), interleukin 1(IL-1), interleukin 6 (IL-6), transforming growth factor (TGF-β), and platelet-derived growth factor (PDGF) and levels in homogenised retina tissue were measured using the enzyme linked-immuno-sorbent assay (ELISA) method.Results: Retinal TNF-α, IL-1, IL-6, and PDGF levels had significantly decreased in treatment groups compared to the sham group (p < 0.05). The decrease in the level of TGF-β was not statistically significant between the treatment and the sham groups (p > 0.05).Conclusions: Intravitreal infliximab can inhibit the development of PVR and reduce levels of cytokine, which plays an essential role in the pathogenesis of PVR. The results of our study suggest that it may be possible to identify the ideal adjuvant pharmacological drugs that are effective in preventing PVR.

Idelalisib inhibits vitreous-induced Akt activation and proliferation of retinal pigment epithelial cells from epiretinal membranes

Proliferative vitreoretinopathy (PVR) is a blinding fibrotic eye disease that develops in 8-10% of patients who undergo primary retinal detachment-reparative surgery and in 40-60% of patients with open-globe injury. At present, there is no pharmacological treatment for this devastating disease. Vitreal growth factors activate their respective receptors of cells in the vitreous, trigger their downstream signaling transduction (e.g. phosphoinositide 3 kinases (PI3Ks)/Akt), and drive cellular responses intrinsic to the pathogenesis of PVR. PI3Ks play a central role in experimental PVR. However, which isoform(s) are involved in PVR pathogenesis remain unknown. Herein, we show that p110δ, a catalytic subunit of receptor-regulated PI3K isoform δ, is highly expressed in epiretinal membranes from patients with PVR, and that idelalisib, a specific inhibitor of PI3Kδ, effectively inhibits vitreous-induced Akt activation, proliferation, migration and contraction of retinal pigment epithelial cells derived from an epiretinal membrane of a PVR patient. Small molecules of kinase inhibitors have shown great promise as a class of therapeutics for a variety of human diseases. The data herein suggest that idelalisib is a promising PVR prophylactic.

Macular Edema after Successful Pars Plana Vitrectomy for Rhegmatogenous Retinal Detachment: Factors Affecting Edema Development and Considerations for Treatment

Purpose: To investigate the incidence of macular edema after pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD) repair, the factors affecting its development and the efficacy of intravitreal dexamethasone implant for its treatment.Methods: Participants in this study 86 patients with RRD. All patients were examined postoperatively and those with macular edema were treated with intravitreal dexamethasone implant and were followed-up for 12 months.Results: 14 out of 86 patients presented macular edema post PPV for RRD repair. Patients with preoperative macula off RRD, duration of RRD >1 week and proliferative vitreoretinopathy were more prone to develop macular edema. There was a statistically significant improvement in best corrected visual acuity and central retinal thickness at month 12 post intravitreal dexamethasone implant compared to baseline.Conclusions: The incidence of macular edema post PPV for RRD repair was found to be 16.3%. Intravitreal dexamethasone implant seemed to be safe and effective in cases with post-PPV macular edema after RRD repair.

TRActional DIabetic reTInal detachment surgery with co-adjuvant intravitreal dexamethasONe implant: the TRADITION STUDY

AIM

Main failure of diabetic tractional retinal detachment (TRD) surgery is the development of proliferative vitreoretinopathy (PVR), causing higher re-detachment rates. We investigated whether the use of dexamethasone (DEX) implant at the end of pars plana vitrectomy (PPV) with silicone oil tamponade might have an impact on these outcomes.

DESIGN

Comparative, nonrandomized, retrospective study.

PARTICIPANTS

A total of 148 eyes from 148 patients that underwent PPV with silicone oil tamponade for diabetic TRD (with DEX implant, n = 52; without DEX implant, n = 96).

METHODS

Consecutive patients' records were reviewed for time between TRD diagnosis and surgery; lens status before surgery and after 6, 12, and 24 months; retina attachment rate after primary PPV; change in postoperative PVR severity; rate of re-detachment at 6, 12, and 24 months; use of IOP lowering treatment after 6, 12, and 24 months; surgery details; intra- and postoperative complications. Correlations between outcome measures, postoperative PVR severity, and re-detachment rates were analyzed.

MAIN OUTCOME MEASURES

Change in postoperative PVR severity and retinal re-detachment rates with and without the adjuvant use of DEX implant.

RESULTS

Retinal re-detachment rates were significantly higher in the group of patients that did not receive DEX implant [11/96 (11.5%) vs. 0/52 (0%), p = 0.049; 11/84 (12.9%) vs. 4/52 (7.7%), p = 0.007; 14/71 (19.7%) vs. 5/52 (10%) p < 0.001 at 6, 12, and 24 months, respectively]. PVR severity correlated with retinal status at 12 and 24 months (p = 0.018 and p = 0.027, respectively). The difference in PVR severity between the two groups was statistically significant at 6, 12, and 24 months (p < 0.001).

CONCLUSIONS

DEX implant at the end of PPV in patients with diabetic TRD improves PVR severity and decreases re-detachment rates. This should be considered as an option in the customized treatment of TRD.

Effect of etanercept on post-traumatic proliferative vitreoretinopathy

AIM

To evaluate the safety and efficacy of intravitreal etanercept in the inhibiting of proliferative vitreoretinopathy (PVR) in a model of penetrating ocular injury.

METHODS

Penetrating ocular injury on the retina of rabbit was induced, which was subsequently treated using 0.1 mL of sterile water or 0.1 mL of 12.5 mg/mL etanercept. The development of PVR was evaluated by fundus images, the B-scan, and the histopathology. The mRNA and protein expressions of tumor necrosis factor-α (TNF-α), transforming growth factor β (TGF-β) as well as connective tissue growth factor (CTGF) were examined at various time points after the etanercept injection with the reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The safety of etanercept was evaluated by injection of 12.5 mg/mL etanercept into a normal rabbit eye without penetrating trauma.

RESULTS

Clinical assessment and grading clearly demonstrated that the PVR formation was prevented in etanercept-treated animals, which was confirmed via fundus images, B-scan and histopathology. The RT-PCR and Western blotting showed increased mRNA and protein expression of TNF-α, TGF-β as well as CTGF in the retina of rabbits following penetrating ocular injury, and these factors were dramatically mitigated by ocular etanercept treatment. In addition, there was no adverse effect of etanercept intravitreal injection in normal eyes without penetrating trauma, it showed normal structure and histology.

CONCLUSION

The etanercept is a potential therapy for inhibiting PVR development. To assess the clinic application of the etanercept in preventing PVR, further clinical studies are required.

Thomas A. Swift's Electric Rifle Injuries to the Eye and Ocular Adnexa: The Management of Complex Trauma

PURPOSE

To report the ocular and adnexal injuries sustained by patients with Thomas A. Swift's electric rifles (TASER; TASER International, Scottsdale, AZ), review the literature, and discuss the management of this complex trauma.

DESIGN

Multicenter, retrospective case series and literature review.

PARTICIPANTS

Seventeen eyes of 16 patients (5 eyes of 5 patients treated at 3 institutions, and 12 eyes of 11 previously reported cases).

METHODS

The clinical data of 17 eyes were pooled. Spearman's correlation coefficient was used to assess the association between the extent of TASER injury and patient outcomes.

MAIN OUTCOME MEASURES

Extent of TASER injury (zone of injury, penetrating vs. perforating) and association with patient outcomes (visual acuity [VA] and retinal detachment [RD]).

RESULTS

In our cohort, 4 patients were transported by law enforcement and 1 was transferred from a community hospital. Four patients were taken to the operating room for TASER removal and globe repair; 1 patient underwent removal in the emergency room. Of 17 pooled cases, 12 (71%) involved open-globe injury. Of these, there was a high rate of zone 3 injuries (100%; n = 12) and a high incidence of RD (73%; 8 of 11, eviscerated eye excluded). Among patients with closed-globe injury (n = 5), 1 patient demonstrated exudative RD and 1 patient demonstrated retinal dialysis with RD. Of 10 patients with RD, 1 (10%) achieved resolution with monitoring (exudative RD); 1 (10%) underwent cryopexy and pneumatic retinopexy; 3 (30%) underwent vitrectomy, and 5 (50%) with poor prognosis did not undergo vitreoretinal surgery. In the 3 patients who underwent vitrectomy, all 3 (100%) demonstrated redetachment resulting from proliferative vitreoretinopathy and required additional surgery. Visual acuity on presentation was significantly correlated with final VA (ρ = 0.783; P = 0.02). Men (94%) were more likely than women (6%) to sustain TASER trauma. Median age was 26 years. There was a 50% rate of loss to follow-up.

CONCLUSIONS

Thomas A. Swift's electric rifle injuries to the eyes or ocular adnexa represent complex trauma. Zone 3 injuries are common. The visual prognosis is guarded, and eyes may require multiple surgeries to preserve vision. Patients are at high risk for loss to follow-up by way of incarceration.

Utility of Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium for an In Vitro Model of Proliferative Vitreoretinopathy

The advent of stem cell technology, including the technology to induce pluripotency in somatic cells, and direct differentiation of stem cells into specific somatic cell types, has created an exciting new field of scientific research. Much of the work with pluripotent stem (PS) cells has been focused on the exploration and exploitation of their potential as cells/tissue replacement therapies for personalized medicine. However, PS and stem cell-derived somatic cells are also proving to be valuable tools to study disease pathology and tissue-specific responses to injury. High-throughput drug screening assays using tissue-specific injury models have the potential to identify specific and effective treatments that will promote wound healing. Retinal pigment epithelium (RPE) derived from induced pluripotent stem cells (iPS-RPE) are well characterized cells that exhibit the phenotype and functions of in vivo RPE. In addition to their role as a source of cells to replace damaged or diseased RPE, iPS-RPE provide a robust platform for in vitro drug screening to identify novel therapeutics to promote healing and repair of ocular tissues after injury. Proliferative vitreoretinopathy (PVR) is an abnormal wound healing process that occurs after retinal tears or detachments. In this chapter, the role of iPS-RPE in the development of an in vitro model of PVR is described. Comprehensive analyses of the iPS-RPE response to injury suggests that these cells provide a physiologically relevant tool to investigate the cellular mechanisms of the three phases of PVR pathology: migration, proliferation, and contraction. This in vitro model will provide valuable information regarding cellular wound healing responses specific to RPE and enable the identification of effective therapeutics.

Proliferative Vitreoretinopathy: A Review

Proliferative vitreoretinopathy (PVR) is the most common cause for failure of rhegmatogenous retinal detachment repair and is characterized by the growth and contraction of cellular membranes within the vitreous cavity and on both sides of the retinal surface as well as intraretinal fibrosis. Currently, PVR is thought to be an abnormal wound healing response that is primarily driven by inflammatory, retinal, and RPE cells. At this time, surgery is the only management option for PVR as there is no proven pharmacologic agent for the treatment or prevention of PVR. Laboratory research to better understand PVR pathophysiology and clinical trials of various agents to prevent PVR formation are ongoing.

Microglia Regulate Neuroglia Remodeling in Various Ocular and Retinal Injuries

Reactive microglia and infiltrating peripheral monocytes have been implicated in many neurodegenerative diseases of the retina and CNS. However, their specific contribution in retinal degeneration remains unclear. We recently showed that peripheral monocytes that infiltrate the retina after ocular injury in mice become permanently engrafted into the tissue, establishing a proinflammatory phenotype that promotes neurodegeneration. In this study, we show that microglia regulate the process of neuroglia remodeling during ocular injury, and their depletion results in marked upregulation of inflammatory markers, such as Il17f, Tnfsf11, Ccl4, Il1a, Ccr2, Il4, Il5, and Csf2 in the retina, and abnormal engraftment of peripheral CCR2⁺ CX3CR1⁺ monocytes into the retina, which is associated with increased retinal ganglion cell loss, retinal nerve fiber layer thinning, and pigmentation onto the retinal surface. Furthermore, we show that other types of ocular injuries, such as penetrating corneal trauma and ocular hypertension also cause similar changes. However, optic nerve crush injury-mediated retinal ganglion cell loss evokes neither peripheral monocyte response in the retina nor pigmentation, although peripheral CX3CR1⁺ and CCR2⁺ monocytes infiltrate the optic nerve injury site and remain present for months. Our study suggests that microglia are key regulators of peripheral monocyte infiltration and retinal pigment epithelium migration, and their depletion results in abnormal neuroglia remodeling that exacerbates neuroretinal tissue damage. This mechanism of retinal damage through neuroglia remodeling may be clinically important for the treatment of patients with ocular injuries, including surgical traumas.

Quercetin inhibits transforming growth factor β1-induced epithelial-mesenchymal transition in human retinal pigment epithelial cells via the Smad pathway

Purpose

The purpose of this study was to evaluate the effect and mechanism of quercetin on TGF-β1-induced retinal pigment epithelial (RPE) cell proliferation, migration, and extracellular matrix secretion.

Materials and methods

Cell counting kit-8, transwell, wound-healing assays, and ELISA were used to assess viability, migration, and collagen I secretion, respectively. Western blot analysis and qPCR were employed to detect mRNA and protein expression levels, respectively.

Results

Quercetin suppressed TGF-β1-induced cell proliferation, migration, and collagen I secretion. The results also showed that mRNA and protein expression of epithelial–mesenchymal transition (EMT)-related markers such as alpha-smooth muscle actin and N-cadherin was downregulated by quercetin in TGF-β1-treated RPE cells; conversely, quercetin upregulated the expression of E-cadherin and tight junction protein 1 (ZO-1). In addition, quercetin could inhibit mRNA and protein expression of matrix metalloproteinases. Quercetin may reverse the progression of EMT via the Smad2/3 pathway.

Conclusion

Our results demonstrate the protective effects of quercetin on RPE cell EMT, revealing a potential therapeutic agent for proliferative vitreoretinopathy treatment.

Determining the effect of low-dose isotretinoin on proliferative vitreoretinopathy: the DELIVER trial

PURPOSE

To examine the effect of low-dose, oral isotretinoin in lowering the risk of proliferative vitreoretinopathy (PVR) following rhegmatogenous retinal detachment (RRD) repair.

METHODS

Prospective, open label, dual-cohort study with pathology-matched historical controls. The prospective experimental arms included two cohorts, composed of 51 eyes with recurrent PVR-related RRD and 58 eyes with primary RRD associated with high-risk features for developing PVR. Eyes in the experimental arms received 20 mg of isotretinoin by mouth once daily for 12 weeks starting the day after surgical repair. The primary outcome measure was single surgery anatomical success rate at 3 months following the study surgery.

RESULTS

The single surgery anatomic success rate was 78.4% versus 70.0% (p=0.358) in eyes with recurrent PVR-related retinal detachment exposed to isotretinoin versus historical controls, respectively. In eyes with RRD at high risk for developing PVR, the single surgery success rate was 84.5% versus 61.1% (p=0.005) for eyes exposed to isotretinoin versus historical controls, respectively. For eyes enrolled in the experimental arms, the most common isotretinoin-related side effects were dry skin/mucus membranes in 106 patients (97.2%), abnormal sleep/dreams in 4 patients (3.7%) and fatigue in 3 patients (2.8%).

CONCLUSION

The management and prevention of PVR is challenging and complex. At the dose and duration given in this study, oral istotretinoin may reduce the risk of PVR-associated recurrent retinal detachment in eyes with primary RRD at high risk of developing PVR.

5-Fluorouracyl added infusion fluid in patients with recurrent rhegmatogeneous retinal detachment

Purpose

To compare the efficacy of 5-fluorouracil (5-FU) added the infusion fluid with a control group in the event of grade C PVR in recurrent retinal detachment (RD).

Methods

The records of the patients with recurrent retinal detachment with grade C PVR who underwent vitrectomy for retinal detachment surgery between April 2003 and October 2004 were reviewed retrospectively for this comparative study. The recurrent retinal detachment patients with grade C PVR who underwent vitrectomy and had a minimum post-operative follow-up period of 12 months were included. The patients were divided into two groups as study and control groups. 5-FU (200 microgram/ml) and low-molecular-weight-heparin (LMWH) (5 IU/ml) was added into the infusion solution of the study group. Primary outcome measure of this study was the single operation anatomical success at month 12.

Results

A total of 43 eyes of 43 patients were included. The control group was consisted of 26 eyes (60.5%) and the 5-FU group was consisted of 17 eyes (39.5%). At month 12, single operation anatomical success was obtained in 14 of the 26 patients (53.8%) in the control group and in 16 of the 17 patients (94.1%) in the 5-FU group (p = 0.005).

Conclusion

Favorable outcomes were obtained in the patients with recurrent RD and grade C PVR in whom 5-FU and LMWH added infusion fluid which was used during vitrectomy.

Repair of primary RRD - comparing pars plana vitrectomy procedure with combined phacovitrectomy with standard foldable intraocular lens implantation

Background

Pars plana vitrectomy (PPV) combined with phacoemulsification and primary intraocular lens implantation can be performed for the repair of primary rhegmatogenous retinal detachment (RRD; PHACOVIT group). The safety and efficacy of this combined ophthalmic procedure on RRD surgery outcomes remain unclear compared with more conventional PPV technique alone (VITRET group). We explored the need for reoperation after primary surgical procedure in these two groups.

Methods

Retrospective, longitudinal, register-based cohort of RRD patients was operated in University Eye Clinic, Helsinki, Finland, during 2008–2014. The main outcome measure was reoperation rate during a postoperative follow-up period of 1 year due to retinal re-detachment, vitreous rehemorrhage, postoperative endophthalmitis, secondary pucker, macular hole or other reasons.

Results

We analyzed 1,690 consecutive RRD cases, out of which 1,564 patients were treated in the PPV VITRET group and 126 patients in the PHACOVIT-operated group. Risk for reoperation was 2.67 times higher in the PHACOVIT group compared to the PPV VITRET group (95% CI 1.85–3.85).

Conclusion

The reoperation rate was higher in RRD eyes operated with combined cataract surgery plus PPV, suggesting that RRD eyes should not primarily undergo combined PHACOVIT surgery.

Statin use and vitreoretinal surgery: Findings from a Finnish population-based cohort study

PURPOSE

Vitreoretinal (VR) surgery is the third most common intraocular surgery after refractive and cataract surgery. The impact of statin therapy on VR surgery outcomes remains unclear, despite a potentially beneficial effect. We explored the association of preoperative statin therapy and the need for revitrectomy after primary vitrectomy.

METHODS

Our historical, population-based, register-based, VR surgery cohort consisted of 5709 patients operated in a tertiary, academic referral hospital in Finland, during 2008-2014, covering 6.5 years. Subgroup analysis was performed as follows: eyes operated due to (i) rhegmatogenous retinal detachment (RRD), (ii) VR interface diseases (macular pucker/hole), (iii) diabetic maculopathy or proliferative retinopathy, (iv) vitreous haemorrhage, (v) lens subluxation, (vi) vitreous opacities or (vii) other VR indication. The primary end-point event was revitrectomy during a postoperative follow-up period of 1 year due to retinal redetachment, vitreous rehaemorrhage, postoperative endophthalmitis, recurrent pucker or unclosed macular hole.

RESULTS

Rhegmatogenous retinal detachment (RRD) was the second most frequent indication of VR surgery, including 1916 patients, with 305 re-operations with rate 0.20 (95% CI 0.18-0.23) per person-year. Statin treatment in time of operation was associated with lower risk of re-operation according to relative scale (incidence rate ratio 0.72, 95% CI 0.53-0.97), but not in absolute scale (incidence rate difference -0.58, 95% CI -4.30 to 3.15 for 100 person-years). No association with statin therapy and vitrectomy outcome was observed in the other VR subgroups.

CONCLUSION

Use of statin treatment was associated with a 28% lower risk of revitrectomy in patients operated due to RRD. Further randomized clinical trials are highly warranted.